U.S. patent application number 15/480811 was filed with the patent office on 2017-11-30 for mitigating necrosis in transgenic glyphosate-tolerant cotton plants treated with herbicidal glyphosate formulations.
This patent application is currently assigned to Monsanto Technology LLC. The applicant listed for this patent is Monsanto Technology LLC. Invention is credited to David Z. Becher, Eduardo Casanova, David R. Eaton, Eric A. Haupfear, Stephen D. Prosch, Peter E. Rogers, Michael E. Seitz.
Application Number | 20170339950 15/480811 |
Document ID | / |
Family ID | 36928557 |
Filed Date | 2017-11-30 |
United States Patent
Application |
20170339950 |
Kind Code |
A1 |
Prosch; Stephen D. ; et
al. |
November 30, 2017 |
Mitigating Necrosis in Transgenic Glyphosate-Tolerant Cotton Plants
Treated with Herbicidal Glyphosate Formulations
Abstract
This invention relates generally to improved methods and
herbicidal glyphosate compositions for use in controlling the
growth of weeds and unwanted vegetation, and particularly for use
in controlling weeds in a crop of transgenic glyphosate-tolerant
cotton plants by over-the-top, foliar application of a herbicidal
glyphosate formulation.
Inventors: |
Prosch; Stephen D.;
(Ballwin, MO) ; Seitz; Michael E.; (Dublin,
CA) ; Eaton; David R.; (Kirkwood, MO) ;
Becher; David Z.; (St. Louis, MO) ; Haupfear; Eric
A.; (St. Charles, MO) ; Casanova; Eduardo;
(Chesterfield, MO) ; Rogers; Peter E.; (St. Louis,
MO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Monsanto Technology LLC |
St. Louis |
MO |
US |
|
|
Assignee: |
Monsanto Technology LLC
St. Louis
MO
|
Family ID: |
36928557 |
Appl. No.: |
15/480811 |
Filed: |
April 6, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15155290 |
May 16, 2016 |
9642359 |
|
|
15480811 |
|
|
|
|
13370625 |
Feb 10, 2012 |
9364003 |
|
|
15155290 |
|
|
|
|
11368344 |
Mar 3, 2006 |
8129564 |
|
|
13370625 |
|
|
|
|
60713948 |
Sep 1, 2005 |
|
|
|
60659001 |
Mar 4, 2005 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A01N 57/20 20130101;
A01N 25/32 20130101; A01N 2300/00 20130101; A01N 25/00 20130101;
A01N 25/32 20130101; A01N 57/20 20130101; A01N 57/20 20130101 |
International
Class: |
A01N 25/32 20060101
A01N025/32; A01N 57/20 20060101 A01N057/20 |
Claims
1-34. (canceled)
35. A herbicidal glyphosate composition useful for killing or
controlling the growth of weeds in a field containing a crop of
transgenic glyphosate-tolerant cotton plants, comprising:
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof; N-(phosphonomethyl)iminodiacetic acid or salt thereof; and
a safening agent in a concentration sufficient to inhibit
significant leaf necrosis in said crop induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
the herbicidal glyphosate composition, said safening agent selected
from the group consisting of an adjuvant, metal ions, antioxidants,
humectants, light absorbing compounds, and mixtures thereof.
36-54. (canceled)
55. The herbicidal glyphosate composition of claim 35 wherein the
safening agent comprises an antioxidant selected to inhibit
significant leaf necrosis in said crop of transgenic
glyphosate-tolerant cotton plants induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
said herbicidal glyphosate composition.
56. The composition of claim 55 wherein the antioxidant is selected
from the group consisting of hydroquinone, resorcinol, BHA, BHT and
mixtures thereof.
57. The composition of claim 55 wherein the molar ratio of
antioxidant to N-(phosphonomethyl)iminodiacetic acid equivalent is
from about 50:1 to about 1:1.
58. The herbicidal glyphosate composition of claim 35 wherein the
safening agent comprises a humectant selected to inhibit
significant leaf necrosis in said crop of transgenic
glyphosate-tolerant cotton plants induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
said herbicidal glyphosate composition.
59. The composition of claim 58 wherein the humectant is
hygroscopic and substantially non-ionizable in water.
60. The composition of claim 58 wherein the humectant comprises a
polyhydroxy alcohol.
61. The composition of claim 60 wherein the humectant is selected
from the group consisting of sorbitol, xylitol, inositol, mannitol,
pantothenol, glycerol and derivatives and mixtures thereof.
62. (canceled)
63. The herbicidal glyphosate composition of claim 35 wherein the
safening agent comprises a light absorbing compound selected to
inhibit significant leaf necrosis in said crop of transgenic
glyphosate-tolerant cotton plants induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
said herbicidal glyphosate composition.
64-80. (canceled)
81. An aqueous herbicidal concentrate composition comprising at
least about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof and less than 5 grams per liter (on an acid equivalent
basis) of N-(phosphonomethyl)iminodiacetic acid or salt thereof,
wherein: the composition further comprises aminomethylphosphonic
acid and the weight ratio of N-(phosphonomethyl)iminodiacetic acid
or a salt thereof to aminomethylphosphonic acid is not more than
0.25:1; or the composition further comprises at least one
surfactant other than an alkoxylated alkyl amine or an alkoxylated
phosphate ester; or the N-(phosphonomethyl)glycine is present
predominantly in the form of the potassium, dipotassium,
monoammonium, diammonium, sodium, monoethanolamine, n-propylamine,
ethylamine, ethylenediamine, hexamethylenediamine or
trimethylsulfonium salt thereof; or the composition further
comprises a surfactant component comprising an alkoxylated
alkylamine and an alkoxylated phosphate ester; or the
N-(phosphonomethyl)glycine is present predominantly in the form of
the isopropylamine salt thereof.
82-111. (canceled)
112. A technical grade glyphosate composition comprising: (i) at
least 95 wt. % N-(phosphonomethyl)glycine acid equivalent, less
than 0.15 wt. % N-(phosphonomethyl)iminodiacetic acid or a salt
thereof, and a byproduct selected from not more than 0.7 wt. %
N-formyl-N-(phosphonomethyl)glycine and not more than 0.03 wt. %
N-methyliminodiacetic acid, the weight percentages being on a dry
basis; or (ii) at least 90 wt. % N-(phosphonomethyl)glycine acid
equivalent, less than 0.6 wt. % N-(phosphonomethyl)iminodiacetic
acid or a salt thereof, and aminomethylphosphonic acid, wherein the
weight ratio of N-(phosphonomethyl)iminodiacetic acid or a salt
thereof to aminomethylphosphonic acid is not more than 0.18:1,
0.19:1, 0.20:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1 or 0.25:1, the
weight percentages being on a dry basis; or (iii) at least 90 wt. %
N-(phosphonomethyl)glycine acid or salt thereof, less than 0.45 wt.
% N-(phosphonomethyl)iminodiacetic acid or a salt thereof, and at
least 0.02 wt. % glycine or salt thereof, the weight percentages
being on a dry acid equivalent basis; or (iv) at least 90 wt. %
N-(phosphonomethyl)glycine acid equivalent, between about 0.02 wt.
% and about 0.25 wt. % N-(phosphonomethyl)iminodiacetic acid or a
salt thereof, and a byproduct selected from not more than 0.6 wt. %
N-formyl-N-(phosphonomethyl)glycine and not more than 0.03 wt. %
N-methyliminodiacetic acid, the weight percentages being on a dry
acid equivalent basis.
113-159. (canceled)
160. An aqueous herbicidal concentrate composition comprising: (i)
at least about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof; less than 5 grams per liter (on an acid equivalent basis)
of N-(phosphonomethyl)iminodiacetic acid or salt thereof; and
aminomethylphosphonic acid (acid equivalent), wherein the weight
ratio of N-(phosphonomethyl)iminodiacetic acid or a salt thereof to
aminomethylphosphonic acid is not more than 0.25:1; or (ii) at
least about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof, less than about 5 grams per liter (on an acid equivalent
basis) of N-(phosphonomethyl)iminodiacetic acid or salt thereof,
and at least one surfactant other than an alkoxylated alkyl amine
or an alkoxylated phosphate ester; or (iii) at least about 360
grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine predominantly in the form of the
potassium, dipotassium, monoammonium, diammonium, sodium,
monoethanolamine, n-propylamine, ethylamine, ethylenediamine,
hexamethylenediamine or trimethylsulfonium salt thereof, and less
than about 5 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)iminodiacetic acid or salt thereof; or (iv) at
least about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof, less than about 5 grams per liter (on an acid equivalent
basis) of N-(phosphonomethyl)iminodiacetic acid or salt thereof,
and at least one surfactant component comprising an alkoxylated
alkyl amine or an alkoxylated phosphate ester; or (v) at least
about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine predominantly in the form of the
isopropylamine salt thereof, and less than about 5 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)iminodiacetic
acid or salt thereof; or (vi) at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof; less than 0.45 wt. % of
N-(phosphonomethyl)iminodiacetic acid or salt thereof (acid
equivalent) on a glyphosate, a.e., basis; and aminomethylphosphonic
acid, wherein the weight ratio of N-(phosphonomethyl)iminodiacetic
acid or a salt thereof (acid equivalent) to aminomethylphosphonic
acid (acid equivalent) is not more than 0.25:1; or (vii) at least
about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof, less than about 0.45 wt. % of
N-(phosphonomethyl)iminodiacetic acid or salt thereof (acid
equivalent) on an N-(phosphonomethyl)glycine, a.e., basis, and at
least one surfactant other than an alkoxylated alkyl amine or an
alkoxylated phosphate ester; or (viii) at least about 360 grams per
liter (on an acid equivalent basis) of N-(phosphonomethyl)glycine
predominantly in the form of the potassium, dipotassium,
monoammonium, diammonium, sodium, monoethanolamine, n-propylamine,
ethylamine, ethylenediamine, hexamethylenediamine or
trimethylsulfonium salt thereof, and less than about 0.45 wt. %
(phosphonomethyl)iminodiacetic acid or salt thereof (acid
equivalent) on an N-(phosphonomethyl)glycine, a.e., basis; or (ix)
at least about 360 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof, less than about 0.45 wt. %
N-(phosphonomethyl)iminodiacetic acid or salt thereof on an
N-(phosphonomethyl)glycine basis, and at least one surfactant
component comprising an alkoxylated alkyl amine or an alkoxylated
phosphate ester; or (x) at least about 360 grams per liter (on an
acid equivalent basis) of N-(phosphonomethyl)glycine predominantly
in the form of the isopropylamine salt thereof, and less than about
0.45 wt. % N-(phosphonomethyl)iminodiacetic acid or salt thereof
(acid equivalent) on an N-(phosphonomethyl)glycine, a.e., basis; or
(xi) at least about 360 grams per liter (on an acid equivalent
basis) of N-(phosphonomethyl)glycine predominantly in the form of a
salt thereof, less than about 0.45 wt. %
N-(phosphonomethyl)iminodiacetic acid or salt (acid equivalent),
and at least about 0.02 wt. % glycine or a salt thereof (acid
equivalent), the weight percentages being on an acid equivalent
basis relative to N-(phosphonomethyl)glycine, a.e.
161-240. (canceled)
241. A process for the preparation of glyphosate by oxidation of
N-(phosphonomethyl)iminodiacetic acid wherein the glyphosate
product has a low N-(phosphonomethyl)iminodiacetic acid content,
the process comprising: contacting an aqueous reaction medium
containing N-(phosphonomethyl)iminodiacetic acid with a gas
comprising molecular oxygen in the presence of a catalyst for the
oxidation; recovering a glyphosate product from glyphosate obtained
in the resulting product reaction solution, wherein (i) the
recovery of said glyphosate product comprises separating such
product from an aqueous mixture wherein the ratio of total
N-(phosphonomethyl)iminodiacetic acid content to total glyphosate
content is at least 25% greater than the corresponding ratio in
said product reaction solution, oxygen having been caused to flow
through said aqueous reaction medium in the presence of said
catalyst to an extent sufficient to reduce the
N-(phosphonomethyl)iminodiacetic acid content of said product
reaction solution to a level such that said recovered glyphosate
product has an N-(phosphonomethyl)iminodiacetic acid content less
than about 600 ppm, basis glyphosate; or (ii) oxygen having been
caused to flow through said aqueous reaction medium in the presence
of said catalyst to an extent sufficient to reduce the
N-(phosphonomethyl)iminodiacetic acid content of said product
reaction solution to a level such that said recovered glyphosate
product has an N-(phosphonomethyl)iminodiacetic acid content less
than about 600 ppm, basis glyphosate; and removing said glyphosate
product from the process.
242-258. (canceled)
259. A process for the preparation of glyphosate by oxidation of
N-(phosphonomethyl)iminodiacetic acid wherein the glyphosate
product has a low N-(phosphonomethyl)iminodiacetic acid content,
the process comprising: oxidizing N-(phosphonomethyl)iminodiacetic
acid in an aqueous reaction medium to produce a product reaction
solution containing glyphosate and unreacted
N-(phosphonomethyl)iminodiacetic acid; and recovering glyphosate
from said product reaction solution in a product form having a
N-(phosphonomethyl)iminodiacetic acid content not greater than 600
ppm on a glyphosate basis, wherein the recovery of said product
form comprises (i) contacting an aqueous solution comprising said
product reaction solution, or a solution comprising
N-(phosphonomethyl)iminodiacetic acid derived from said product
reaction solution, with an anion exchange resin which has a
selective affinity for N-(phosphonomethyl)iminodiacetic acid in
preference to glyphosate; or (ii) crystallizing glyphosate from a
crystallizer feed solution comprising or derived from said product
reaction solution; subjecting the resulting slurry of glyphosate
crystals in mother liquor to solid/liquid separation; purging a
fraction of said mother liquor for removal of
N-(phosphonomethyl)iminodiacetic acid from the process; and
recycling another fraction of said mother liquor to a crystallizer
in which glyphosate is crystallized from said feed solution, the
volume of said purge fraction relative to the volume of said
recycle fraction being sufficient that the solid glyphosate
crystals separated in said solid/liquid separation step have an
N-(phosphonomethyl)iminodiacetic acid content lower than 600 ppm or
can be contacted with an aqueous wash medium to produce a solid
glyphosate product having such lower
N-(phosphonomethyl)iminodiacetic acid content.
260-271. (canceled)
272. A process a set forth in claim 259 wherein, prior to purging a
fraction of said mother liquor, the mother liquor is contacted with
an anion exchange resin having a selective affinity for
N-(phosphonomethyl)iminodiacetic acid greater than for
glyphosate.
273. A process as set forth in claim 259 wherein said mother liquor
is contacted in a chloride ion exchange zone with a anion exchange
resin that is selective for chloride in preference to
N-(phosphonomethyl)iminodiacetic acid, and in a PMIDA ion exchange
zone with an anion exchange resin that is selective
N-(phosphonomethyl)iminodiacetic acid in preference to
glyphosate.
274-275. (canceled)
276. A process for the preparation of glyphosate by oxidation of
N-(phosphonomethyl)iminodiacetic acid wherein the glyphosate
product has a low N-(phosphonomethyl)iminodiacetic acid content,
the process comprising: (i) contacting an aqueous medium containing
N-phosphonomethyl-iminodiacetic acid in a primary reaction system
with a gas comprising molecular oxygen in the presence of a
particulate catalyst for the oxidation to produce a product slurry
comprising a product reaction solution comprising glyphosate and
unreacted N-(phosphonomethyl)iminodiacetic acid, and having said
particulate catalyst suspended therein; separating said catalyst
from said reaction product solution to produce a filtered product
reaction solution; and contacting an aqueous solution comprising
said filtered product reaction solution, or derived therefrom, with
an oxidizing agent in a polishing reaction zone for further
conversion of N-phosphonomethyl-iminodiacetic acid to glyphosate;
or (ii) contacting an aqueous reaction medium containing
N-(phosphonomethyl)iminodiacetic acid with a gas comprising
molecular oxygen in the presence of a noble metal on carbon
catalyst, and in the absence of a concentration of a non-noble
metal promoter that would be effective to either retard the
oxidation of N-(phosphonomethyl)iminodiacetic acid or causes the
rate of consumption of oxygen in the oxidation of formaldehyde or
formic acid to be materially increased relative to the rate of
consumption of oxygen in the oxidation of
N-(phosphonomethyl)iminodiacetic acid; and maintaining contact of
said reaction medium with gas comprising molecular oxygen for a
time sufficient to reduce the N-(phosphonomethyl)iminodiacetic acid
content of the resulting product reaction solution to not greater
than 250 ppm; or (iii) oxidizing N-(phosphonomethyl)iminodiacetic
acid in an aqueous reaction medium to produce a product reaction
solution containing glyphosate and unreacted
N-(phosphonomethyl)iminodiacetic acid; transferring said product
reaction solution to a product recovery process by which a
plurality of glyphosate products are produced; and operating said
product recovery process to produce at least two separate
glyphosate salt products of differing
N-(phosphonomethyl)iminodiacetic acid content wherein the
glyphosate basis N-(phosphonomethyl)iminodiacetic acid content of
one of said products is less than about 1000 ppm and at least 25%
lower than the N-(phosphonomethyl)iminodiacetic acid content of
another of said plurality of glyphosate products; or (iv)
contacting N-(phosphonomethyl)iminodiacetic acid with an oxidizing
agent in an aqueous reaction medium within an oxidation reaction
zone in the presence of a catalyst for the oxidation, thereby
effecting oxidation of N-(phosphonomethyl)iminodiacetic acid and
producing a reaction solution comprising glyphosate or another
intermediate which can be converted to glyphosate; and further
processing said reaction solution to produce a glyphosate product
containing not more than about 600 ppm
N-(phosphonomethyl)iminodiacetic acid or salt thereof, wherein the
oxidation of N-(phosphonomethyl)iminodiacetic acid in said aqueous
reaction medium is continued until the concentration of
N-(phosphonomethyl)iminodiacetic acid in said reaction medium has
been reduced to a terminal concentration such that said further
processing yields a not greater than about 600 ppm, basis
glyphosate.
277-329. (canceled)
330. The herbicidal glyphosate composition of claim 35 wherein the
safening agent comprises an adjuvant and the
N-(phosphonomethyl)glycine is predominantly in the form of an
agronomically acceptable salt thereof selected from the group
consisting of alkali metal salts, alkylamine salts and alkanolamine
salts of N-(phosphonomethyl)glycine, wherein the concentration of
said adjuvant in the herbicidal glyphosate formulation is selected
such that the rate of transfer of N-(phosphonomethyl)iminodiacetic
acid or salt thereof into the foliar tissues of said crop of
transgenic glyphosate-tolerant cotton plants is sufficiently slow
to inhibit significant leaf necrosis in said crop induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
the herbicidal glyphosate formulation.
331. The herbicidal glyphosate composition of claim 330 wherein
said adjuvant is selected from the group consisting of an alkyl
polyglucoside, a diol, a triol, a polyol, a dialkanolamine, a
trialkanolamine, a polyalkylene glycol, a dialkylene glycol, a
trialkylene glycol, a polyhydric alcohol ester, an alkoxylated
amide, an alkoxylated alkylphenol, an alkoxylated arylphenol, a
fatty alcohol alkoxylate, an alcohol alkoxylate and mixtures
thereof.
332. The herbicidal glyphosate composition of claim 331 further
comprising a salt of N-(phosphonomethyl)glycine other than ammonium
or diammonium.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. nonprovisional
patent application Ser. No. 15/155,290, filed May 16, 2016, which
is a continuation of U.S. nonprovisional patent application Ser.
No. 13/370,625, filed Feb. 10, 2012 (now U.S. Pat. No. 9,364,003,
issued Jun. 14, 2016), which is a division of U.S. nonprovisional
patent application Ser. No. 11/368,344, filed Mar. 3, 2006 (now
U.S. Pat. No. 8,129,564, issued Mar. 6, 2012), and claims the
benefit of U.S. provisional application Ser. No. 60/659,001, filed
Mar. 4, 2005, and U.S. provisional application Ser. No. 60/713,948,
filed Sep. 1, 2005, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to improved methods for
controlling weeds in a crop of transgenic glyphosate-tolerant
cotton plants by over-the-top, foliar application of a herbicidal
glyphosate formulation. The present invention is further directed
to herbicidal glyphosate compositions useful in practicing the weed
control methods disclosed herein.
[0003] Cotton (i.e., Gossypium hirsutum) provides an ideal fiber
for textile manufacture as well as oil for human consumption, feed
for livestock and base chemicals for a variety of industrial
products. Cotton production is well-established in the United
States and many other areas of the world. As in other cultivated
crops, weeds can cause significant yield losses and require careful
management by the grower as they interfere through their
competition for available resources including water, nutrients and
light. In cotton, weeds can also impede harvest and have a negative
economic impact on the grower by not only reducing cotton lint
yields, but also lint quality. Weed control practices in cotton
have included cultural, mechanical, biological and chemical
methods. Among these, chemical weed control has been widely adopted
along with the use of tillage (e.g., seed bed preparation, tillage)
and cultural (e.g., crop rotation, field selection) methods.
[0004] N-(phosphonomethyl)glycine, known in the agricultural
chemical art as glyphosate, is a highly effective and commercially
important broad spectrum phytotoxicant useful in controlling the
growth of germinating seeds, emerging seedlings, maturing and
established woody and herbaceous vegetation, and aquatic plants.
Glyphosate is used as a post-emergent herbicide to control the
growth of a wide variety of annual and perennial grass and
broadleaf weed species in cultivated crop lands, including cotton
production, and is the active ingredient in the ROUNDUP family of
herbicides available from Monsanto Company (Saint Louis, Mo.).
[0005] Glyphosate and salts thereof are conveniently applied in
aqueous herbicidal formulations, usually containing one or more
surfactants, to the foliar tissues (i.e., the leaves or other
photosynthesizing organs) of the target plant. After application,
the glyphosate is absorbed by the foliar tissues and translocated
throughout the plant. Glyphosate noncompetitively blocks an
important biochemical pathway that is common to virtually all
plants. More specifically, glyphosate inhibits the shikimic acid
pathway that leads to the biosynthesis of aromatic amino acids.
Glyphosate inhibits the conversion of phosphoenolpyruvic acid and
3-phosphoshikimic acid to 5-enolpyruvyl-3-phosphoshikimic acid by
inhibiting the enzyme 5-enolpyruvyl-3-phosphoshikimic acid synthase
(EPSP synthase or EPSPS) found in plants.
[0006] Advances in genetic engineering have provided the requisite
tools to transform cotton and other cultivated plants to contain
foreign genes for improvement of certain agronomic traits and the
quality of the product. One such trait of particular agronomic and
environmental importance is herbicide tolerance, in particular,
tolerance to glyphosate herbicide. Glyphosate-resistant or tolerant
crop plants may reduce the need for tillage to control weeds,
thereby effectively reducing soil erosion. Further,
glyphosate-tolerant crop plants provide greater simplicity and
flexibility in attaining adequate weed control.
[0007] Glyphosate-tolerant cotton can be produced, for example, by
introducing into the genome of the plant, the capacity to express
various native and variant plant or bacterial EPSPS enzymes that
have a lower affinity for glyphosate and therefore retain their
catalytic activity in the presence of glyphosate (See, for example,
U.S. Pat. Nos. 5,633,435, 5,094,945, 4,535,060, 6,040,497 and
6,740,488). Glyphosate-tolerance has been introduced into cotton
plants and is a successful product now widely used in cotton
production. The current commercial ROUNDUP READY cotton event
designated 1445 available from Monsanto Company provides excellent
resistance to glyphosate. Glyphosate is typically applied
over-the-top (OTT) of ROUNDUP READY cotton from emergence through
the four leaf node stage of development (e.g., at rates of up to
about 0.75 pounds glyphosate acid equivalent per acre (lb a.e./A or
about 0.84 kg a.e./ha). ROUNDUP READY cotton varieties used in
combination with ROUNDUP glyphosate herbicidal formulations have
become the standard program for weed management in cotton
production in the United States. The primary advantage to growers
for using the ROUNDUP READY cotton system is that it allows simple
and convenient application of glyphosate, a broad spectrum,
post-emergence herbicide, to effectively control weeds and grasses
with excellent crop safety and less dependence on pre-plant
herbicide applications. Other benefits include a better fit into
no-till and reduced tillage systems. ROUNDUP READY cotton has
expanded the options for weed management and made the practice of
weed control much easier, less expensive and more flexible. Growers
have reported making fewer trips across fields to apply herbicides
as well as making fewer cultivation trips, which conserves fuel and
reduces soil erosion. Glyphosate-tolerant cotton, therefore,
decreases the environmental risks posed by herbicides while at the
same time increasing the efficacy of necessary chemical weed
control.
[0008] Although widely accepted as a standard in cotton production,
ROUNDUP READY cotton varieties do however impose some limitations
on the grower. ROUNDUP READY cotton varieties possess reproductive
bodies that are susceptible to glyphosate-mediated injury that may,
in some cases, result in delayed maturity or reproductive injury as
measured by flower pollen shed, flower drop, boll drop, and/or lint
yield loss. Accordingly, in order to avoid or minimize such
reproductive injury, over-the-top applications of glyphosate
herbicides to cotton plants grown from seed of ROUNDUP READY cotton
event 1445 and progeny thereof are generally discontinued from the
fifth leaf node stage and beyond (e.g., through layby) and instead
glyphosate is usually applied as a post-directed spray between the
crop rows during this period of growth in order to minimize contact
with the cotton plants. Directed herbicide application requires
specialized equipment that is often susceptible to misapplication,
must be operated at lower speeds and requires a greater number of
trips per acre compared to broadcast applicators.
[0009] It is believed that the lack of reproductive glyphosate
tolerance that limits later stage foliar application of glyphosate
to cotton plants corresponding to ROUNDUP READY cotton event
designated 1445 is the result of insufficient CP4 EPSPS expression
in critical tissues, higher sensitivity of these tissues to
glyphosate, and accumulation of high amounts of glyphosate in those
strong sink tissues. Recently, as disclosed in International
Publication No. WO 2004/072235, Monsanto Company has developed a
new glyphosate-tolerant cotton event (designated MON 88913, to be
commercially named ROUNDUP READY FLEX cotton and having seed
deposited with American Type Culture Collection with Accession No.
PTA-4854) to provide cotton growers with an improved product for
management of economically damaging weeds. ROUNDUP READY FLEX
cotton provides an increased margin of fruit retention and crop
safety, due to increased tolerance to glyphosate in reproductive
tissues. This allows for an expanded window for over-the-top ground
application of glyphosate agricultural herbicides (e.g., at rates
of up to about 1.125 pounds glyphosate acid equivalent per acre (lb
a.e./A or about 1.26 kg a.e./ha) extending from cotton emergence up
to layby, the critical timing for weed control in cotton. Through
these enhanced treatment opportunities, the grower can more
effectively manage weed control in cotton using over-the-top
herbicide applications as compared to post-directed or
hooded-sprayer applications.
[0010] Despite the widely-recognized advantages in weed control
provided by ROUNDUP READY and ROUNDUP READY FLEX cotton, it has
been observed that these transgenic cotton varieties, under certain
environmental conditions, exhibit a susceptibility to leaf tissue
necrosis following over-the-top application of glyphosate
herbicides. In the case of over-the-top application of glyphosate
herbicides to ROUNDUP READY FLEX cotton at later stages of plant
development, the appearance of necrotic lesions on the treated
cotton plants may appear to be more pronounced due to the more
fully developed canopy and greater available leaf area. This
phenomenon is rare and such leaf injury, if it is encountered at
all, is generally limited with little or no further expression of
injury and the cotton plants recover with essentially no yield loss
or deleterious effect on fertility under standard or recommended
ROUNDUP treatment protocols. In particular, the cotton apical
growing point and subsequent leaves appear unaffected.
[0011] Accordingly, there exists a need for methods and herbicidal
glyphosate formulations useful for over-the-top, foliar application
to transgenic glyphosate-tolerant cotton plants that are effective
in weed control and consistently avoid inducing significant leaf
necrosis in the treated plants in the variable environmental
conditions that may be encountered during the growing season.
SUMMARY OF THE INVENTION
[0012] As discussed in detail below, in accordance with the present
invention, it has been discovered that the leaf necrosis phenomenon
sometimes observed in transgenic glyphosate-tolerant cotton plants
following over-the-top application of glyphosate herbicides and
under certain growing conditions is induced, at least in part, by
N-(phosphonomethyl)iminodiacetic acid (PMIDA) and/or salts thereof
which are often present at relatively low concentrations in
glyphosate herbicidal formulations. The present invention
encompasses various aspects and embodiments directed to strategies
for mitigating PMIDA-induced necrosis in transgenic
glyphosate-tolerant cotton plants treated with herbicidal
glyphosate formulations, including methods of weed control,
glyphosate herbicidal compositions and formulations for use in the
practice of such weed control methods as well as methods of
manufacturing technical grade glyphosate product for use in
preparing such glyphosate herbicidal compositions and formulations.
Although the present invention has specific application in
mitigating PMIDA-induced necrosis in transgenic glyphosate-tolerant
cotton plants, many aspects and embodiments of the invention
disclosed herein have wider application.
[0013] Accordingly, in various embodiments, methods are provided
for selectively controlling weeds in a field containing a crop of
transgenic glyphosate-tolerant cotton plants. The methods comprise
applying a sufficient amount of a herbicidal glyphosate formulation
comprising N-(phosphonomethyl)glycine or an agronomically
acceptable salt thereof to the crop foliage and weeds to control
growth of the weeds. In some embodiments, the crop of transgenic
glyphosate-tolerant cotton plants have increased glyphosate
tolerance in vegetative and reproductive tissues such that
application of the herbicidal glyphosate formulation when at least
five leaf nodes are present on a cotton plant of the crop does not
incur significant glyphosate-mediated reproductive injury to the
plant. In one embodiment, the concentration of
N-(phosphonomethyl)iminodiacetic acid and salts thereof present in
the glyphosate formulation and the application rate of the
herbicidal glyphosate formulation are controlled so as to not
induce significant leaf necrosis in the cotton plants.
[0014] In another embodiment, the glyphosate formulation comprises
N-(phosphonomethyl)iminodiacetic acid or salt thereof and a
safening agent in a concentration sufficient to inhibit significant
leaf necrosis in the crop induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
the glyphosate formulation.
[0015] In another embodiment, the herbicidal glyphosate formulation
applied to the crop of transgenic glyphosate-tolerant cotton plants
comprises N-(phosphonomethyl)iminodiacetic acid or salt thereof and
an adjuvant other than an alkoxylated alkylamine. The adjuvant is
present in an amount effective to decrease cell membrane
permeability within the crop to decrease cellular uptake of the
N-(phosphonomethyl)iminodiacetic acid or salt thereof in the crop
treated with the formulation as compared to crops treated with an
application mixture having the same composition as the formulation
except that an alkoxylated alkylamine is substituted for the
adjuvant.
[0016] Alternatively, the herbicidal glyphosate formulation
comprises N-(phosphonomethyl)glycine, predominantly in the form of
an agronomically acceptable salt thereof selected from the group
consisting of alkali metal salts, alkylamine salts and alkanolamine
salts of N-(phosphonomethyl)glycine,
N-(phosphonomethyl)iminodiacetic acid or salt thereof and a
safening agent comprising an adjuvant. The concentration of the
adjuvant in the herbicidal glyphosate formulation is selected such
that the rate of transfer of N-(phosphonomethyl)iminodiacetic acid
or salt thereof into the foliar tissues of the crop of transgenic
glyphosate-tolerant cotton plants is sufficiently slow to inhibit
significant leaf necrosis in the crop induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
the glyphosate formulation.
[0017] The present invention further provides herbicidal glyphosate
compositions (e.g., spray solutions, tank mixes and concentrates)
useful for killing or controlling the growth of weeds in a field
containing a crop of transgenic glyphosate-tolerant cotton plants
as well as in other weed control applications. In one embodiment,
the composition comprises N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof,
N-(phosphonomethyl)iminodiacetic acid or salt thereof, and a
safening agent in a concentration sufficient to inhibit significant
leaf necrosis in the crop induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
the glyphosate composition. Suitable safening agents may be
selected from the group consisting of metal ions, antioxidants,
humectants, light absorbing compounds, and mixtures thereof.
[0018] In another embodiment, the aqueous herbicidal concentrate
composition comprises at least about 360 grams per liter (on an
acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof and less than 5 grams per
liter (on an acid equivalent basis) of
N-(phosphonomethyl)iminodiacetic acid or salt thereof. The
composition further comprises aminomethylphosphonic acid and the
weight ratio of N-(phosphonomethyl)iminodiacetic acid or a salt
thereof to aminomethylphosphonic acid is not more than 0.25:1; or
the composition further comprises at least one surfactant other
than an alkoxylated alkyl amine or an alkoxylated phosphate ester;
or the N-(phosphonomethyl)glycine is present predominantly in the
form of the potassium, dipotassium, monoammonium, diammonium,
sodium, monoethanolamine, n-propylamine, ethylamine,
ethylenediamine, hexamethylenediamine or trimethylsulfonium salt
thereof; or the composition further comprises a surfactant
component comprising an alkoxylated alkylamine and an alkoxylated
phosphate ester; or the N-(phosphonomethyl)glycine is present
predominantly in the form of the isopropylamine salt thereof.
[0019] In another embodiment, the herbicidal glyphosate composition
comprises N-(phosphonomethyl)glycine predominantly in the form of
an agronomically acceptable salt thereof selected from the group
consisting of alkali metal salts, alkylamine salts and alkanolamine
salts of N-(phosphonomethyl)glycine;
N-(phosphonomethyl)iminodiacetic acid or salt thereof, and a
safening agent comprising an adjuvant in a concentration selected
such that the rate of transfer of N-(phosphonomethyl)iminodiacetic
acid or salt thereof into the foliar tissues of the crop of
transgenic glyphosate-tolerant cotton plants is sufficiently slow
to inhibit significant leaf necrosis in the crop induced by
N-(phosphonomethyl)iminodiacetic acid or salt thereof present in
the glyphosate formulation.
[0020] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, the concentration of the
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof being at least about 360 or more grams per liter on an acid
equivalent basis; N-(phosphonomethyl)iminodiacetic acid or salt
thereof, a metal ion safening agent that is subject to formation of
a complex or salt with N-(phosphonomethyl)iminodiacetic acid or an
anion formed by deprotonation or partial deprotonation thereof,
wherein the molar ratio of metal ions to
N-(phosphonomethyl)iminodiacetic acid equivalent is at least about
0.4:1; and a surfactant component comprising at least one cationic
surfactant.
[0021] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, less than 5 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)iminodiacetic
acid or salt thereof; and aminomethylphosphonic acid (acid
equivalent), wherein the weight ratio of
N-(phosphonomethyl)iminodiacetic acid or a salt thereof to
aminomethylphosphonic acid is not more than 0.25:1.
[0022] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, less than about 5 grams per
liter (on an acid equivalent basis) of
N-(phosphonomethyl)iminodiacetic acid or salt thereof, and at least
one surfactant other than an alkoxylated alkyl amine or an
alkoxylated phosphate ester.
[0023] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine
predominantly in the form of the potassium, dipotassium,
monoammonium, diammonium, sodium, monoethanolamine, n-propylamine,
ethylamine, ethylenediamine, hexamethylenediamine or
trimethylsulfonium salt thereof, and less than about 5 grams per
liter (on an acid equivalent basis) of
N-(phosphonomethyl)iminodiacetic acid or salt thereof.
[0024] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, less than about 5 grams per
liter (on an acid equivalent basis) of
N-(phosphonomethyl)iminodiacetic acid or salt thereof, and at least
one surfactant component comprising an alkoxylated alkyl amine or
an alkoxylated phosphate ester.
[0025] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine
predominantly in the form of the isopropylamine salt thereof, and
less than about 5 grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)iminodiacetic acid or salt thereof.
[0026] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, less than 0.45 wt. % of
N-(phosphonomethyl)iminodiacetic acid or salt thereof (acid
equivalent) on a glyphosate, acid equivalent (a.e.), basis; and
aminomethylphosphonic acid, wherein the weight ratio of
N-(phosphonomethyl)iminodiacetic acid or a salt thereof (acid
equivalent) to aminomethylphosphonic acid (acid equivalent) is not
more than 0.25:1.
[0027] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, less than about 0.45 wt. %
of N-(phosphonomethyl)iminodiacetic acid or salt thereof (acid
equivalent) on an N-(phosphonomethyl)glycine, a.e., basis, and at
least one surfactant other than an alkoxylated alkyl amine or an
alkoxylated phosphate ester.
[0028] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine
predominantly in the form of the potassium, dipotassium,
monoammonium, diammonium, sodium, monoethanolamine, n-propylamine,
ethylamine, ethylenediamine, hexamethylenediamine or
trimethylsulfonium salt thereof, and less than about 0.45 wt. %
(phosphonomethyl)iminodiacetic acid or salt thereof (acid
equivalent) on an N-(phosphonomethyl)glycine, a.e., basis.
[0029] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine or an
agronomically acceptable salt thereof, less than about 0.45 wt. %
N-(phosphonomethyl)iminodiacetic acid or salt thereof on an
N-(phosphonomethyl)glycine basis, and at least one surfactant
component comprising an alkoxylated alkyl amine or an alkoxylated
phosphate ester.
[0030] In another embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine
predominantly in the form of the isopropylamine salt thereof, and
less than about 0.45 wt. % N-(phosphonomethyl)iminodiacetic acid or
salt thereof (acid equivalent) on an N-(phosphonomethyl)glycine,
a.e., basis.
[0031] In a further embodiment, the aqueous concentrate herbicidal
glyphosate composition comprises at least about 360 grams per liter
(on an acid equivalent basis) of N-(phosphonomethyl)glycine
predominantly in the form of a salt thereof, less than about 0.45
wt. % N-(phosphonomethyl)iminodiacetic acid or salt (acid
equivalent), and at least about 0.02 wt. % glycine or a salt
thereof (acid equivalent), the weight percentages being on an acid
equivalent basis relative to N-(phosphonomethyl)glycine, a.e.
[0032] In a still further embodiment, the aqueous concentrate
herbicidal glyphosate composition comprises at least about 360
grams per liter (on an acid equivalent basis) of
N-(phosphonomethyl)glycine predominantly in the form of a salt
thereof, the preparation of the composition comprising hydrolyzing
a dialkyl phosphonate intermediate, the intermediate comprising a
carboxylic acid salt of dialkyl N-(phosphonomethyl)glycine or
otherwise derived from reaction of a dialkylphosphite with
N-methylolglycine.
[0033] The present invention also provides various technical grade
glyphosate compositions useful in the preparation of herbicidal
glyphosate compositions and formulations. In one embodiment the
technical grade glyphosate composition comprises, on a dry basis,
at least 95 wt. % N-(phosphonomethyl)glycine acid equivalent, less
than 0.15 wt. % N-(phosphonomethyl)iminodiacetic acid or a salt
thereof, and a byproduct selected from not more than 0.7 wt. %
N-formyl-N-(phosphonomethyl)glycine or not more than 0.03 wt. %
N-methyliminodiacetic acid.
[0034] In accordance with another embodiment, the technical grade
glyphosate composition comprises at least 90 wt. %
N-(phosphonomethyl)glycine acid equivalent, less than 0.6 wt. %
N-(phosphonomethyl)iminodiacetic acid or a salt thereof, and
aminomethylphosphonic acid, wherein the weight ratio of
N-(phosphonomethyl)iminodiacetic acid or a salt thereof to
aminomethylphosphonic acid is not more than 0.25:1, the weight
percentages being on a dry basis.
[0035] In accordance with another embodiment, the technical grade
glyphosate composition comprises at least 90 wt. %
N-(phosphonomethyl)glycine acid or salt thereof, less than 0.45 wt.
% N-(phosphonomethyl)iminodiacetic acid or a salt thereof, and at
least 0.02 wt. % glycine or salt thereof, the weight percentages
being on a dry acid equivalent basis.
[0036] In accordance with a further embodiment, the technical
glyphosate composition comprises at least 90 wt. %
N-(phosphonomethyl)glycine acid equivalent, between about 0.02 wt.
% and about 0.25 wt. % N-(phosphonomethyl)iminodiacetic acid or a
salt thereof, and a byproduct selected from not more than 0.6 wt. %
N-formyl-N-(phosphonomethyl)glycine, the weight percentages being
on a dry acid equivalent basis.
[0037] In another embodiment, the glyphosate product is selected
from the group consisting of a technical grade glyphosate
composition comprising at least about 90 wt. % glyphosate acid and
a concentrated aqueous solution comprising at least about 360 grams
per liter a.e. of an agronomically acceptable salt of glyphosate.
The composition comprises less than about 0.45 wt. %
N-(phosphonomethyl)iminodiacetic acid or a salt thereof (acid
equivalent), and between about 0.05 and about 2 wt. % glyphosine or
a salt thereof (acid equivalent), on a glyphosate, a.e., basis.
[0038] The present invention also provides various processes for
the preparation of glyphosate by oxidation of
N-(phosphonomethyl)iminodiacetic acid wherein the glyphosate
product has a low N-(phosphonomethyl)iminodiacetic acid content. In
one embodiment, the process comprises contacting an aqueous
reaction medium containing N-(phosphonomethyl)iminodiacetic acid
with a gas comprising molecular oxygen in the presence of a
catalyst for the oxidation; recovering a glyphosate product from
glyphosate obtained in the resulting product reaction solution, the
recovery of the glyphosate product comprising separating such
product from an aqueous mixture wherein the ratio of total
N-(phosphonomethyl)iminodiacetic acid content to total glyphosate
content is at least 25% greater than the corresponding ratio in the
product reaction solution, oxygen having been caused to flow
through the aqueous reaction medium in the presence of the catalyst
to an extent sufficient to reduce the
N-(phosphonomethyl)iminodiacetic acid content of the product
reaction solution to a level such that the recovered glyphosate
product has an N-(phosphonomethyl)iminodiacetic acid content less
than about 600 ppm, basis glyphosate; and removing the glyphosate
product from the process.
[0039] In another embodiment, the process comprises contacting an
aqueous reaction medium containing N-(phosphonomethyl)iminodiacetic
acid with a gas comprising molecular oxygen in the presence of a
catalyst for the oxidation; recovering a glyphosate product from
glyphosate obtained in the resulting product reaction solution,
oxygen having been caused to flow through the aqueous reaction
medium in the presence of the catalyst to an extent sufficient to
reduce the N-(phosphonomethyl)iminodiacetic acid content of the
product reaction solution to a level such that the recovered
glyphosate product has an N-(phosphonomethyl)iminodiacetic acid
content less than about 600 ppm, basis glyphosate; and removing the
glyphosate product from the process.
[0040] In accordance with another embodiment, the process comprises
oxidizing N-(phosphonomethyl)iminodiacetic acid in an aqueous
reaction medium to produce a product reaction solution containing
glyphosate and unreacted N-(phosphonomethyl)iminodiacetic acid;
recovering glyphosate from the product reaction solution in a
product form having a N-(phosphonomethyl)iminodiacetic acid content
not greater than 600 ppm on a glyphosate basis, the recovery of the
product form comprising contacting an aqueous solution comprising
the product reaction solution, or a solution comprising
N-(phosphonomethyl)iminodiacetic acid derived from the product
reaction solution, with an anion exchange resin which has a
selective affinity for N-(phosphonomethyl)iminodiacetic acid in
preference to glyphosate.
[0041] In another embodiment, the process comprises oxidizing
N-(phosphonomethyl)iminodiacetic acid in an aqueous reaction medium
to produce a product reaction solution containing glyphosate and
unreacted N-(phosphonomethyl)iminodiacetic acid; crystallizing
glyphosate from a crystallizer feed solution comprising or derived
from the product reaction solution; subjecting the resulting slurry
of glyphosate crystals in mother liquor to solid/liquid separation;
purging a fraction of the mother liquor for removal of
N-(phosphonomethyl)iminodiacetic acid from the process; and
recycling another fraction of the mother liquor to a crystallizer
in which glyphosate is crystallized from the feed solution, the
volume of the purge fraction relative to the volume of the recycle
fraction being sufficient that the solid glyphosate crystals
separated in the solid/liquid separation step have an
N-(phosphonomethyl)iminodiacetic acid content lower than 600 ppm or
can be contacted with an aqueous wash medium to produce a solid
glyphosate product having such lower
N-(phosphonomethyl)iminodiacetic acid content.
[0042] In a further embodiment, the process comprises contacting an
aqueous medium containing N-phosphonomethyl-iminodiacetic acid in a
primary reaction system with a gas comprising molecular oxygen in
the presence of a particulate catalyst for the oxidation to produce
a product slurry comprising a product reaction solution comprising
glyphosate and unreacted N-(phosphonomethyl)iminodiacetic acid, and
having the particulate catalyst suspended therein; separating the
catalyst from the reaction product solution to produce a filtered
product reaction solution; and contacting an aqueous solution
comprising the filtered product reaction solution, or derived
therefrom, with an oxidizing agent in a polishing reaction zone for
further conversion of N-phosphonomethyl-iminodiacetic acid to
glyphosate.
[0043] In a further embodiment, the process comprises contacting an
aqueous reaction medium containing N-(phosphonomethyl)iminodiacetic
acid with a gas comprising molecular oxygen in the presence of a
noble metal on carbon catalyst, and in the absence of a
concentration of a non-noble metal promoter that would be effective
to either retard the oxidation of N-(phosphonomethyl)iminodiacetic
acid or causes the rate of consumption of oxygen in the oxidation
of formaldehyde or formic acid to be materially increased relative
to the rate of consumption of oxygen in the oxidation of
N-(phosphonomethyl)iminodiacetic acid; and maintaining contact of
the reaction medium with gas comprising molecular oxygen for a time
sufficient to reduce the N-(phosphonomethyl)iminodiacetic acid
content of the resulting product reaction solution to not greater
than 250 ppm.
[0044] In a further embodiment, the process comprises oxidizing
N-(phosphonomethyl)iminodiacetic acid in an aqueous reaction medium
to produce a product reaction solution containing glyphosate and
unreacted N-(phosphonomethyl)iminodiacetic acid; transferring the
product reaction solution to a product recovery process by which a
plurality of glyphosate products are produced; and operating the
product recovery process to produce at least two separate
glyphosate salt products of differing
N-(phosphonomethyl)iminodiacetic acid content, wherein the
glyphosate basis N-(phosphonomethyl)iminodiacetic acid content of
one of the products is less than about 1000 ppm one at least 25%
lower than the N-(phosphonomethyl)iminodiacetic acid content of
another of the plurality of glyphosate products.
[0045] In a still further embodiment, the process comprises
contacting N-(phosphonomethyl)iminodiacetic acid with an oxidizing
agent in an aqueous reaction medium within an oxidation reaction
zone in the presence of a catalyst for the oxidation, thereby
effecting oxidation of N-(phosphonomethyl)iminodiacetic acid and
producing a reaction solution comprising glyphosate or another
intermediate which can be converted to glyphosate; and further
processing the reaction solution to produce a glyphosate product
containing not more than about 600 ppm
N-(phosphonomethyl)iminodiacetic acid or salt thereof, the
oxidation of N-(phosphonomethyl)iminodiacetic acid in the aqueous
reaction medium being continued until the concentration of
N-(phosphonomethyl)iminodiacetic acid in the reaction medium has
been reduced to a terminal concentration such that the further
processing yields a not greater than about 600 ppm, basis
glyphosate.
[0046] The present invention further provides a programmed control
scheme for use in conjunction with the various processes for the
preparation of glyphosate by oxidation of
N-(phosphonomethyl)iminodiacetic acid. Such processes further
comprise measuring select process variables which affect the
N-(methylphosphonic)iminodiacetic acid content of one or more
glyphosate products as produced by the process; controlling the
select process variables via automated control loops to conform to
set points respectively established in the control loops;
transmitting signals to the programmed controller conveying the
values of the measurements and the set points; computing
adjustments to the set points in response to the signals in
accordance with an algorithm inscribed in software with which the
controller is programmed; and transmitting signals from the
programmed controller to the control loops for adjustment of the
set point to conform operation of the process to the algorithm.
[0047] The present invention further provides a process for the
preparation of an aqueous herbicidal concentrate composition
comprising at least about 360 grams per liter (on an acid
equivalent basis) of N-(phosphonomethyl)glycine predominantly in
the form of a salt thereof. The process comprises hydrolyzing a
dialkyl intermediate comprising dialkyl N-(phosphonomethyl)glycine,
a carboxylate salt of dialkyl N-(phosphonomethyl)glycine or other
ester intermediate produced by reaction of a dialkyl phosphite with
N-methylolglycine, to yield a solution comprising glyphosate or an
agronomically acceptable salt of glyphosate; and recovering solid
glyphosate acid or an aqueous concentrate comprising an
agronomically acceptable salt of glyphosate in a concentration of
at least about 360 grams per liter a.e.
[0048] The present invention further provides a method of supplying
a glyphosate product for applications in which it is desirable to
maintain the N-(phosphonomethyl)iminodiacetic acid content of the
product at consistently less than about 0.06 wt. % on a glyphosate
basis. The method comprises producing glyphosate in a manufacturing
facility, the production of glyphosate in such facility comprising
catalytic oxidation of N-(phosphonomethyl)iminodiacetic acid in an
aqueous medium in the presence of a catalyst for the oxidation;
during designated operations within the facility, conducting the
process under conditions effective to consistently produce a
glyphosate product having an N-(phosphonomethyl)iminodiacetic acid
content less than about 0.06 wt. %, basis glyphosate; and
segregating the glyphosate produced during the designated
operations from other glyphosate product produced during other
operations wherein the other glyphosate product has an
N-(phosphonomethyl)iminodiacetic acid content greater than about
0.06 wt. %, basis glyphosate.
[0049] In a further aspect of the invention, a method for screening
a herbicidal glyphosate formulation for use in foliar application
to a crop of transgenic glyphosate-tolerant plants subject to leaf
necrosis caused by N-(phosphonomethyl)iminodiacetic acid or a salt
thereof present in herbicidal glyphosate formulations is provided.
The method comprises (a) growing a plant of the crop until a
predetermined developmental age or for a predetermined interval of
time; (b) applying the herbicidal glyphosate formulation comprising
N-(phosphonomethyl)glycine or a salt thereof to the plant; (c)
maintaining the treated plant for a predetermined interval of time
under predetermined temperature and humidity conditions selected to
illicit a leaf necrosis injury response in the plant caused by
N-(phosphonomethyl)iminodiacetic acid or a salt thereof present in
the herbicidal glyphosate formulation; and (d) determining extent
of leaf necrosis injury to the plant.
[0050] Further aspects and embodiments of the invention are
described in the following specification and detailed in the claims
set forth below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] FIG. 1 is a schematic flow sheet illustrating a continuous
process for the manufacture of glyphosate from
N-(phosphonomethyl)iminodiacetic acid, in which the modifications
of the present invention for production of a low
N-(phosphonomethyl)iminodiacetic acid content glyphosate product
may be implemented;
[0052] FIG. 2 is a schematic flow sheet illustrating an alternative
embodiment of the process of FIG. 1 in which
N-(phosphonomethyl)iminodiacetic acid that accumulates in the
product recovery area can be removed from the process in a
controlled manner, more particularly in a manner that allocates
N-(phosphonomethyl)iminodiacetic acid removal between a solid
glyphosate acid product, a concentrated glyphosate salt solution,
and a purge stream;
[0053] FIG. 3 is a schematic flow sheet illustrating an exemplary
ion exchange system, which may be used in conjunction with the
process for the manufacture of glyphosate illustrated in FIG. 1 or
2;
[0054] FIG. 4 is a schematic flow sheet illustrating an evaporative
crystallization system modified to accommodate low
N-(phosphonomethyl)iminodiacetic acid (PMIDA) content in the feed
solution without excessive fouling of the heat exchange surfaces
and which may be used in conjunction with the process for the
manufacture of glyphosate illustrated in FIG. 1 or 2;
[0055] FIG. 5 is a graphical representation of the degree of
necrosis reduction in ROUNDUP READY FLEX cotton 2 days after
treatment (2 DAT) following field application of ROUNDUP
WEATHERMAX-type glyphosate herbicidal formulations (0.4% PMIDA)
safened with ferric sulfate addition in Example 2A.
[0056] FIG. 6 is a graphical representation of the degree of
necrosis reduction in ROUNDUP READY FLEX cotton 2 days after
treatment (2 DAT) following field application of ROUNDUP
WEATHERMAX-type glyphosate herbicidal formulations with varying
PMIDA levels and safened with fixed levels of iron in Example
2B.
[0057] FIG. 7 is a graphical representation of the average necrosis
and distribution in ROUNDUP READY FLEX cotton 2 days after
treatment (2 DAT) following field application of ROUNDUP
ORIGINALMAX-type glyphosate herbicidal formulations (0.4% PMIDA)
and varying ratios of iron to PMIDA in Example 2C.
[0058] FIG. 8 is a graphical representation of the degree of
necrosis reduction in ROUNDUP READY FLEX cotton 2 days after
treatment (2 DAT) following field application of ROUNDUP
ORIGINALMAX-type glyphosate herbicidal formulations with varying
PMIDA levels and safened with fixed levels of iron in Example
2D.
[0059] FIG. 9 is a graphical representation of the average necrosis
and distribution in ROUNDUP READY FLEX cotton 2 days after
treatment (2 DAT) following field application of: ROUNDUP
WEATHERMAX or ROUNDUP ORIGINALMAX-type glyphosate herbicidal
formulations (0.4% PMIDA) and varying ratios of iron to PMIDA; or
ROUNDUP WEATHERMAX-type glyphosate herbicidal formulations of low
PMIDA content (0.06% PMIDA) without ferric sulfate addition in
Example 2E.
[0060] FIG. 10 is the chromatogram (first isocratic solvent system)
for an iron-containing glyphosate formulation concentrate subjected
to the high-pressure liquid chromatography analytical procedure of
Example 3 to determine the concentration of PMIDA in the
formulation concentrate; and
[0061] FIG. 11 is the chromatogram (alternative isocratic solvent
system) for an iron-containing formulation concentrate subjected to
the high-pressure liquid chromatography analytical procedure of
Example 3 to determine the concentration of PMIDA in the
formulation concentrate.
DETAILED DESCRIPTION OF THE INVENTION
[0062] In accordance with the present invention, it has been
discovered that the leaf necrosis phenomenon sometimes observed in
transgenic glyphosate-tolerant cotton plants following over-the-top
application of glyphosate herbicides and under certain growing
conditions is induced, at least in part, by
N-(phosphonomethyl)iminodiacetic acid (PMIDA) and/or salts thereof
which are often present at relatively low concentrations in
glyphosate herbicidal formulations. One conventional method of
glyphosate manufacture, discussed in greater detail below, includes
liquid phase catalytic oxidative cleavage of a carboxymethyl
substituent from PMIDA (formula (1)) to produce
N-(phosphonomethyl)glycine (formula (2)) in accordance with the
following reaction:
##STR00001##
[0063] Under commercial scale conditions, high conversion of the
PMIDA to the N-(phosphonomethyl)glycine product is readily
attained. However, low concentrations (e.g., from about 0.15% to
about 0.6% by weight dry basis) of unreacted PMIDA typically remain
in the manufactured technical grade N-(phosphonomethyl)glycine
product isolated from the oxidation reaction mixture. Moreover,
PMIDA may also be present as a by-product or contaminant in
N-(phosphonomethyl)glycine manufactured by other conventional
methods known in the art. Residual PMIDA in manufactured
N-(phosphonomethyl)glycine products is thus often present in
herbicidal glyphosate compositions formulated using these products.
Given the relatively limited water solubility of the organic acid
N-(phosphonomethyl)glycine, aqueous herbicidal glyphosate
compositions are typically formulated using one or more of the more
water-soluble and agronomically acceptable salts of glyphosate and,
in such cases, the PMIDA is also predominantly present in the
composition as the corresponding salt, typically the corresponding
mono- or di-basic salt. As used herein, unless the context requires
otherwise, the term "PMIDA" includes
N-(phosphonomethyl)iminodiacetic acid and/or salts and other
derivatives thereof and the term "glyphosate" includes any
herbicidally effective form of N-(phosphonomethyl)glycine that
results in the production of the glyphosate anion in plants,
including glyphosate acid and/or salts or other derivatives
thereof.
[0064] In most applications, the low levels of PMIDA typically
present in glyphosate herbicidal formulations are not a problem.
However, as noted above, cotton, including transgenic
glyphosate-tolerant cotton varieties, is susceptible under certain
growing conditions to development of leaf necrosis induced by the
presence of even relatively low levels of PMIDA often found in
commercial herbicidal glyphosate formulations. As susceptibility to
PMIDA-induced necrosis is common to both glyphosate-tolerant cotton
(i.e., transgenic cotton) as well as non-transgenic cotton, it
appears that the PMIDA-induced leaf necrosis phenomenon in
glyphosate-tolerant cotton is unrelated to the transgene.
PMIDA-induced leaf necrosis sometimes observed in transgenic
glyphosate-tolerant cotton such as ROUNDUP READY and ROUNDUP READY
FLEX cotton varieties is characterized by a rapid onset of
symptomology, typically within about 2 days following over-the-top
application of glyphosate herbicides. Additional symptom
development beyond this period for the most part has not been
observed, indicating that this phenomenon is not a systemic effect.
Furthermore, symptom expression appears to be light activated.
[0065] Without being bound to any particular theory, these
observations suggest that PMIDA-induced necrosis may operate
through a mechanism similar to that seen with herbicides that
function through the inhibition of the protoporphyrinogen-oxidase
(PPO) enzyme. PPO is inhibited by a wide range of herbicides, such
as, the diphenylethers, oxadiazoles, cyclic imides, phenyl
pyrazoles and pyridine derivatives. PMIDA could act through the
same mechanism as those herbicides wherein membrane disruption is
initiated by the inhibition of PPO in the last stages of
chlorophyll and heme biosynthetic pathways leading to a buildup of
phytotoxic intermediates such as free radicals resulting in tissue
necrosis. More particularly, it is believed that PPO catalyzes the
oxidation of protoporphyrinogen IX (PPGIX) to protoporphyrin IX
(PPIX). PPO inhibition leads to an accumulation of PPGIX, the first
light-absorbing chlorophyll precursor. PPGIX accumulation is
apparently transitory as it overflows its normal environment in the
thylakoid membrane and oxidizes to PPIX. This oxidation may be
catalyzed by a plasmalemma enzyme that has protox activity, but is
insensitive to, it is believed, PMIDA. PPIX formed outside its
native environment probably is separated from Mg chelatase and
other pathway enzymes that normally prevent accumulation of PPIX.
Light absorption by PPIX apparently produces triplet state PPIX
which interacts with ground state oxygen to form singlet oxygen.
Both triplet PPIX and singlet oxygen can abstract a hydrogen from
unsaturated lipids, producing a lipid radical and initiating a
chain reaction of lipid peroxidation. Lipids and proteins are
attacked and oxidized, resulting in loss of chlorophyll and
carotenoids and in leaky membranes which allows cells and cell
organelles to dry and disintegrate rapidly. Quoting from Herbicide
Handbook (William K. Vencill ed., Weed Science Society of America,
8th edition, pages 69 and 329-330, (2002)).
[0066] The expression of PMIDA-induced leaf necrosis and the
severity of the resulting leaf injury are heavily dependent upon
the prevailing growing conditions and environmental factors and is
generally more severe as the PMIDA concentration in the glyphosate
herbicidal composition and application rate increase. More
particularly, conditions that favor slow metabolism in the cotton
plant or metabolic stress generally following glyphosate
application appear to be a key factor contributing to the onset and
severity of leaf necrosis. For example, it has been observed that
exposure to low temperatures is a contributor to PMIDA-induced leaf
damage observed in greenhouse and growth chamber environments. It
has been found that glyphosate-tolerant cotton plants experiencing
"cool" growing conditions (i.e., maximum temperatures of about
80.degree. F. (27.degree. C.) or less) following foliar application
of glyphosate herbicides have significantly increased tendency to
exhibit leaf injury as compared to plants experiencing "hot"
growing conditions (i.e., maximum temperatures of about 90.degree.
F. (32.degree. C.). Cotton plants experiencing maximum temperatures
of about 70.degree. F. (21.degree. C.) following glyphosate
application showed a similar amount of leaf damage as compared to
plants grown at 80.degree. F. It has been further observed that
cool growing conditions following glyphosate application produced
significantly greater leaf injury than cool growing conditions
experienced prior to glyphosate treatment. It is believed that
cotton plant metabolism at growing temperatures of at least about
90.degree. F. is sufficient to overcome the effects of PMIDA levels
typically present in the glyphosate composition, but at 80.degree.
F. and lower maximum growing temperatures, plant metabolism may be
too slow to overcome these effects, with resultant leaf damage.
[0067] If PMIDA-induced necrosis is observed, injury can range from
minor necrotic lesions affecting on average from about 1% to about
5% of the total leaf surface area of the plant to more pronounced
necrotic lesions affecting on average about 5%, 10%, 15%, 20%, 25%,
30% or more of the total leaf surface area of the affected plants.
Minor necrotic lesions generally appear as multiple, very small,
circular shaped and uniformly distributed lesions on the surface of
the treated cotton leaf having a diameter of less than about 0.5 cm
and may coalesce into larger necrotic lesions in the form of larger
circular or irregularly shaped areas or patches on the treated
cotton leaf surface having a largest dimension of greater than
about 0.5 cm. In severe cases, necrotic lesions can become
sufficiently large to result in highly visible leaf damage, or even
loss of the affected leaves. PMIDA-induced leaf necrosis or tissue
death is visibly distinct from "surfactant burn" such as "window
panes" commonly associated with the use of certain surfactants in
herbicidal formulations applied to glyphosate-tolerant crops.
[0068] In accordance with the present invention, a variety of
strategies have been devised to allow for effective weed control in
cotton production from transgenic glyphosate-tolerant cotton plants
using glyphosate herbicidal compositions while mitigating
PMIDA-induced necrosis so as to avoid significant leaf damage to
the cotton crop grown under variable environmental conditions. One
general approach is to control or limit the concentration of PMIDA
in the manufactured glyphosate product and in turn the herbicidal
glyphosate composition formulated using the product so that at the
requisite application rate necessary to attain adequate weed
control in the cotton crop, significant leaf necrosis is not
induced in the treated plants. However, in some circumstances, a
source of manufactured glyphosate having a sufficiently low
concentration of PMIDA may be unavailable or it may be cost
prohibitive or otherwise impractical to obtain or produce such a
glyphosate product. Accordingly, another aspect of the present
invention is to include in the glyphosate herbicidal composition
containing appreciable levels of PMIDA certain safening agents that
act to mitigate or inhibit PMIDA-induced necrosis in the cotton
crop.
[0069] Although susceptibility to PMIDA-induced necrosis is common
to cotton generally, this potential for leaf damage is particularly
problematic in transgenic glyphosate-tolerant cotton plants because
these varieties are engineered to allow over-the-top application of
glyphosate herbicides. Accordingly, the strategies and methods
disclosed herein for mitigating PMIDA-induced necrosis are
particularly intended for the control of weeds in cotton production
from transgenic glyphosate-tolerant cotton plants.
[0070] As used herein transgenic glyphosate-tolerant cotton plants
includes plants grown from the seed of any cotton event that
provides glyphosate tolerance and glyphosate-tolerant progeny
thereof. Such glyphosate-tolerant cotton events include, without
limitation, those that confer glyphosate tolerance by the insertion
or introduction, into the genome of the plant, the capacity to
express various native and variant plant or bacterial EPSPS enzymes
by any genetic engineering means known in the art for introducing
transforming DNA segments into plants to confer glyphosate
resistance as well as glyphosate-tolerant cotton events that confer
glyphosate tolerance by other means such as described in U.S. Pat.
Nos. 5,463,175 and 6,448,476 and International Publication Nos. WO
2002/36782, WO 2003/092360 and WO 2005/012515.
[0071] Non-limiting examples of transgenic glyphosate-tolerant
cotton events include the current commercial ROUNDUP READY cotton
event designated 1445 and described in U.S. Pat. No. 6,740,488. Of
particular interest in the practice of the present invention are
methods for weed control in a crop of transgenic
glyphosate-tolerant cotton plants in which glyphosate resistance is
conferred in a manner that allows later stage application of
glyphosate herbicides without incurring significant
glyphosate-mediated reproductive injury. Non-limiting examples of
such transgenic glyphosate-tolerant cotton plants include those
grown from the seed of the ROUNDUP READY FLEX cotton event
(designated MON 88913 and having representative seed deposited with
American Type Culture Collection (ATCC) with Accession No.
PTA-4854) and similar glyphosate-tolerant cotton events and progeny
thereof as described in International Publication No. WO
2004/072235. ROUNDUP READY FLEX cotton event MON 88913 and similar
glyphosate-tolerant cotton events may be characterized in that the
genome comprises one or more DNA molecules selected from the group
consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, and SEQ ID
NO:4; or the genome in a DNA amplification method produces an
amplicon comprising SEQ ID NO:1 or SEQ ID NO:2; or the transgenic
glyphosate-tolerant cotton plants comprise a glyphosate tolerant
trait that is genetically linked to a complement of a marker
polynucleic acid, and the marker polynucleic acid molecule is
homologous or complementary to a DNA molecule selected from the
group consisting of SEQ ID NO:1 and SEQ ID NO:2 as described in
International Publication No. WO 2004/072235, the entire contents
of which are incorporated herein by reference.
[0072] As noted above, the ROUNDUP READY FLEX cotton event MON
88913 allows for over-the-top application of glyphosate herbicides
at advanced stages of plant development without incurring
significant glyphosate-mediated reproductive injury (e.g., as
quantified, for example, by flower pollen shed and/or lint yield).
As compared to the previous commercial ROUNDUP READY cotton event
designated 1445, ROUNDUP READY FLEX cotton event MON 88913 is
particularly advantageous in allowing foliar application of
glyphosate herbicide for weed control at a developmental age
characterized by at least five leaf nodes present on a cotton plant
of the crop. As used herein, a node having a leaf branch is
referred to as a leaf node in accordance with the conventional node
method used in assessing cotton plant developmental age.
Furthermore, cotyledons are leaves originally contained in the seed
and are not considered as plant leaves or nodes for purposes of
determination of the stage of cotton development. That is, as
generally accepted by those skilled in the art and as used herein,
the stem point of cotyledon attachment is referenced as Node 0. The
fifth and subsequent leaf nodes are typically the first
reproductive (i.e., fruiting) branches and may develop a fruiting
bud and associated leaf. A leaf node having a reproductive branch
may be referred as a reproductive node. Cotton plants can develop
as many as about 25 leaf nodes, with nodes 5-25 potentially
developing into reproductive nodes. In practicing weed control in a
crop of transgenic glyphosate-tolerant cotton grown from seed of
ROUNDUP READY FLEX cotton event MON 88913 or similar cotton events
and progeny thereof, glyphosate herbicidal formulations can be
applied over-the-top of the crop at more advanced developmental
ages characterized, for example, by six, ten, twelve, fourteen or
more leaf nodes present on a cotton plant of the crop and up to and
including layby without incurring significant glyphosate-mediated
reproductive injury to the crop. The herbicidal glyphosate
formulation may be applied over-the-top of the cotton crop at
various intervals of advanced development, characterized, for
example, by six or more leaf nodes and no more than ten, twelve,
fourteen, sixteen, eighteen, twenty or twenty-five leaf nodes on a
cotton plant of the crop. The strategies and methods disclosed
herein for mitigating PMIDA-induced necrosis are particularly
advantageous in weed control methods used in cultivation of ROUNDUP
READY FLEX cotton and similar events that permit such later stage
over-the-top application of glyphosate herbicides since the
appearance of necrotic lesions on the treated cotton plants may
appear to be more pronounced due to the more fully developed canopy
and greater available leaf area.
[0073] By employing the various strategies discussed in detail
below, PMIDA-induced leaf necrosis in transgenic
glyphosate-tolerant cotton can be substantially avoided under the
relevant growing conditions or at least sufficiently mediated or
inhibited. The extent of leaf necrosis is readily quantified by
plant biologists and technicians through visual assessment of the
area of any necrotic lesions relative to the total leaf surface
area of the cotton plants following treatment with a glyphosate
herbicide. In the practice of the weed control methods of the
present invention, PMIDA-induced necrotic lesions on the surface of
the leaves of the transgenic glyphosate-tolerant cotton plants are
generally inhibited so as on average to account for no more than
about 25% of the total leaf area of the plants of the treated crop.
Preferably, necrotic lesions on the surface of the leaves of the
cotton plants treated in accordance with the present invention on
average account for no more than about 20%, and even more
preferably no more than about 15% of the total leaf area of the
plants of the treated crop. By practicing the more preferred
embodiments of the present invention disclosed herein,
PMIDA-induced necrotic lesions on the surface of the leaves of the
cotton plants may be advantageously inhibited so as to on average
account for no more than about 10% or no more than about 5% of the
total leaf area of the plants of the treated crop. In accordance
with especially preferred embodiments of the present invention,
onset of PMIDA-induced necrosis is substantially avoided under all
relevant growing conditions including those noted above and
discussed below that might otherwise tend to enhance the onset and
severity of PMIDA-induced necrosis.
[0074] As noted above, the onset and severity of PMIDA-induced leaf
necrosis in transgenic glyphosate-tolerant cotton plants is
dependent on the prevailing growing conditions as well as the
concentration of PMIDA in the glyphosate herbicide applied to the
plants. In accordance with the present invention, it has been
determined that under many growing conditions and at typical
glyphosate application rates necessary for adequate weed control
(e.g., at rates of from about 0.75 to about 1.125 lb glyphosate
a.e./A or about 0.84 to about 1.26 kg glyphosate a.e./ha)
significant PMIDA-induced leaf necrosis can generally be avoided by
controlling the concentration of PMIDA in the herbicidal glyphosate
composition such that the application rate of PMIDA is no more than
about 2.5 g PMIDA acid equivalent per hectare, preferably no more
than about 2.2 g PMIDA acid equivalent per hectare, more preferably
no more than about 2 g PMIDA acid equivalent per hectare, and even
more preferably no more than about 1.7 g PMIDA acid equivalent per
hectare. However, because cotton plant susceptibility to
PMIDA-induced necrosis is dependent upon environmental conditions
that may vary widely from one growing location to another and
throughout the growing season, in order to provide a safety factor
and more consistently avoid the risk of expression of leaf injury,
it is preferred to control the concentration of PMIDA in the
herbicidal glyphosate composition and the application rate of the
composition to the cotton plants to further reduce the application
rate of PMIDA to no more than about 1.5 g PMIDA acid equivalent per
hectare, even more preferably no more than about 1.2 g PMIDA acid
equivalent per hectare, and still more preferably no more than
about 1 g PMIDA acid equivalent per hectare. In accordance with
even more preferred embodiments of the present invention, the
concentration of PMIDA in the herbicidal glyphosate composition and
the application rate of the composition are controlled such that
the application rate of PMIDA is no more than about 0.7 g PMIDA
acid equivalent per hectare, even more preferably no more than
about 0.5 g PMIDA acid equivalent per hectare and especially no
more than about 0.25 g PMIDA acid equivalent per hectare.
[0075] As apparent to those skilled in the art, based on typical
glyphosate application rates necessary for adequate weed control in
transgenic glyphosate-tolerant cotton (e.g., at rates of from about
0.75 to about 1.125 lb glyphosate a.e./A or about 0.84 to about
1.26 kg glyphosate a.e./ha), the composition including the
concentration of PMIDA in the herbicidal glyphosate formulation
applied to the plants, concentrates from which such formulations
are prepared and ultimately the composition of the manufactured
technical grade glyphosate product from which such compositions are
prepared can be readily determined. Glyphosate manufacturing
processes such as those including the oxidative cleavage of a PMIDA
substrate or those utilizing glycine can be readily practiced or
modified to produce a technical grade N-(phosphonomethyl)glycine
product of sufficient glyphosate assay and having a PMIDA
concentration suitable for producing herbicidal glyphosate
compositions capable of achieving PMIDA application rates so as to
not induce significant leaf necrosis in the treated plants.
Exemplary process strategies for producing manufactured technical
grade glyphosate products having sufficiently low PMIDA content are
described in detail below.
[0076] In some situations, a source of manufactured glyphosate
having a sufficiently low concentration of PMIDA may be unavailable
or it may be cost prohibitive or otherwise impractical to obtain or
produce such a glyphosate product. That is, it may not always be
feasible or economically practical to control the concentration of
PMIDA in the herbicidal glyphosate composition applied to the
cotton plants at the rate necessary to attain adequate weed control
while minimizing the PMIDA application rate to an extent sufficient
to avoid inducing significant leaf necrosis in the treated plants.
However, in accordance with another aspect of the present
invention, glyphosate herbicidal composition containing appreciable
levels of PMIDA (e.g., corresponding to an application rate in
excess of about 2.5 g PMIDA acid equivalent per hectare and up to
about 5 g or 10 g PMIDA acid equivalent per hectare or higher) that
might otherwise lead to leaf necrosis can be safened by the
inclusion of certain PMIDA safening agents or safeners that act to
mitigate or inhibit PMIDA-induced necrosis in the cotton crop.
Furthermore, even glyphosate herbicidal formulations containing
reduced levels of PMIDA sufficient to attain a PMIDA application
rate of no more than about 2.5 g PMIDA acid equivalent per hectare
may further include a safening agent as an added measure of
protection against PMIDA-induced necrosis.
[0077] Several classes of PMIDA safening agents suitable for
inclusion in glyphosate herbicidal compositions containing PMIDA
have been discovered. Some of these safening agents are believed to
inhibit significant PMIDA-induced leaf necrosis by inhibiting
buildup of phytotoxic free radicals in the tissues of cotton plants
that might otherwise lead to membrane disruption and tissue death.
Non-limiting examples of safening agents that interrupt free
radical formation resulting from uptake of PMIDA in the foliar
tissues of the treated cotton plants include antioxidants, certain
metal ions and light absorbing compounds.
[0078] Antioxidants are believed to mitigate PMIDA-induced leaf
necrosis by scavenging and destroying free radicals generated in
the treated cotton plants. Indeed, observed reduction of
PMIDA-induced necrosis through the use of antioxidants in
accordance with the present invention is further evidence that the
necrosis phenomenon is at least in part the result of free radical
formation. More particularly, antioxidants added to glyphosate
formulations of the present invention are believed to scavenge free
radicals and retard the oxidation of organic plant materials such
as lipids and proteins that can result in plant tissue damage such
as by loss of chlorophyll and carotenoids and in leaky cell
membranes with concomitant cell and cell organelle drying and
disintegration.
[0079] Suitable antioxidants or free radical scavengers include
those considered as generally recognized as safe (GRAS) as
specified in 21 C.F.R. .sctn.182. For example, safening
antioxidants may be selected from ascorbic acid, dehydroascorbic
acid, ascorbyl palmitate, ascorbyl stearate, sodium ascorbate,
sorbic acid, sodium sorbate, potassium sorbate, anoxomer, retinol,
resorcinol, the various tocopherols and tocophatrienes (e.g.,
D-.alpha.-tocopheryl acetate, D-.alpha.-tocopheryl acid succinate,
D-.beta.-tocopherol, D-.gamma.-tocopherol, D-6-tocopherol,
D-.alpha.-tocotrienol, D-.beta.-tocotrienol, D-.gamma.-tocotrienol,
DL-.alpha.-tocopherol, DL-.alpha.-tocopheryl acetate,
DL-.alpha.-tocopheryl calcium succinate, DL-.alpha.-tocopheryl
nicotinate, DL-.alpha.-tocopheryl linoleate/oleate and derivatives
or stereo isomeric forms thereof), hydroquinone, butylated
hydroxytoluene (BHT), butylated hydroxyanisole (BHA), t-butyl
hydroquinone (TBHQ), propyl gallate, dodecyl gallate, isoamyl
gallate, octyl gallate, reduced coenzyme-Q, flavones and
isoflavones such as apigenin, quercetin, genistein and daidzein,
pycnogenol, ubiquinone, ubiquinol, monosodium glutamate, butylated
hydroxymethylphenol, dilauryl thiodipropionate, disodium
ethylenediamine tetraacetate, tartaric acid, erythorbic acid,
sodium erythorbate, ethoxyquin, ethyl protocatechuate, guaiac
resin, gum guaiac, isopropyl citrate, monoglyceride citrate,
lecithin, nordihydroguaiaretic acid, phosphoric acid, potassium
lactate, potassium metabisulfite, potassium sulfite, sodium
hypophosphite, sodium lactate, sodium metabisulfite, sodium
sulfite, sodium thiosulfate, stannous chloride, tertiary
butylhydroquinone, 3-t-butyl-4-hydroxyanisole, calcium ascorbate,
calcium disodium EDTA, catalase, cetyl gallate, clove extract,
coffee bean extract, 2,6-di-t-butylphenol, disodium citrate, edetic
acid, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, ethyl gallate,
ethyl maltol, eucalyptus extract, fumaric acid, gentian extract,
glucose oxidase, heptyl paraben, hesperetin,
4-hydroxymethyl-2,6-di-t-butylphenol, N-hydroxysuccinic acid, lemon
juice, lemon juice solids, maltol, methyl gallate, methylparaben,
phosphatidylcholine, pimento extract, potassium bisulfate,
potassium sodium tartrate anhydrous, rice bran extract, rosemary
extract, sage extract, sodium ascorbate, sodium erythorbate, sodium
hypophosphate, sodium hypophosphate, sodium thiosulfate
pentahydrate, soy flour, sucrose, .alpha.-terpineol, tocopherol,
D-.alpha.-tocopherol, DL-.alpha.-tocopherol, tocopheryl acetate,
D-.alpha.-tocopheryl acetate, DL-.alpha.-tocopheryl acetate,
2,4,5-trihydroxybutyrophenone, wheat germ oil, thiodipropionic acid
and mixtures thereof. In some cases, a combination of antioxidants
is used as the safening agent wherein the antioxidants work
together to produce an effect in mitigating PMIDA-induced necrosis
that is greater than that achieved using a comparable amount of
each antioxidant individually.
[0080] Experimental results indicate that all antioxidants
evaluated showed some ability to counteract PMIDA-induced necrosis
in glyphosate treated cotton. In accordance with a preferred
embodiment, the antioxidant safening agent is selected from
hydroquinone, resorcinol, BHA, BHT and mixtures thereof.
[0081] The requisite amount of antioxidant to add to the herbicidal
glyphosate compositions to avoid significant PMIDA-induced necrosis
in the treated cotton plants depends on the PMIDA concentration,
the selected antioxidant or combination of antioxidants and the
relative ability of the antioxidant safening agent to scavenge free
radicals and may be readily determined empirically by one skilled
in the art through routine experimentation. The safening agent
comprising one or more antioxidants is preferably added to
herbicidal glyphosate compositions, including concentrates and tank
mixes, at a molar ratio to PMIDA of from about 50:1 to about 1:1,
from about 40:1 to about 1:1, from about 30:1 to about 1:1, from
about 20:1 to about 1:1, from about 15:1 to about 1:1, from about
10:1 to about 1:1, from about 5:1 to about 1:1, from about 3:1 to
about 1:1, or even from about 2:1 to about 1:1.
[0082] Certain metal ions present in the herbicidal glyphosate
compositions may also act as a safening agent to mitigate
PMIDA-induced leaf necrosis in the treated cotton plants. PMIDA, by
virtue of the presence of carboxyl and a phosphonomethyl groups or
ligands, can function as a strong complexing agent and can chelate
or otherwise bind with free metal ions in solution and thereby be
sequestered (e.g., not taken up into the foliar tissues of the
cotton plant) or otherwise rendered bio-inactive to the cotton
plant. PMIDA present in glyphosate compositions is believed to
selectively bind or otherwise form a complex (e.g., a (II) or (III)
coordination complex or chelate) or salt with metal ions and
thereby render it biologically unavailable in the formation of free
radicals in the cotton plant. That is, the metal ion added to the
composition is subject to formation of a complex or salt with PMIDA
(e.g., N-(phosphonomethyl)iminodiacetic acid or an anion formed by
deprotonation or partial deprotonation thereof). Importantly, PMIDA
forms more stable complexes with such metal ions than does
glyphosate such that the PMIDA and not the glyphosate selectively
complexes or binds with the metal ions, thereby avoiding
significant negative impact on herbicidal activity that would occur
if a significant amount of glyphosate were rendered inactive by
complexing or binding with the metal ion.
[0083] The metal ion added to the glyphosate composition as a PMIDA
safening agent may be any transition metal or other metal and is
preferably agronomically acceptable and recognized as inert for
permitted use in agricultural herbicide compositions. Suitable
non-limiting examples of metal ion safening agents include
aluminum, antimony, iron, chromium, nickel, manganese, cobalt,
copper, zinc, vanadium, titanium, molybdenum, tin, barium and
mixtures thereof. In one preferred embodiment, the metal ion is
selected from aluminum, copper, iron, zinc and mixtures thereof. In
another preferred embodiment, the safening agent comprises iron
ions or a mixture of iron ions and zinc ions or a mixture of iron
ions and copper ions. In one preferred embodiment, the metal ion
safening agent added to the herbicidal composition for selective
complexing or binding with PMIDA comprises a polyvalent metal ion
(e.g., Fe(III), Al(III), Zn(II), and Cu(II)).
[0084] The metal ion introduced into herbicidal glyphosate
compositions may be derived from various salts (e.g., the salt of a
strong acid such as a metal chloride or metal sulfate or the salt
of a di-, tri- or other polycarboxylic acid or derivative) or other
compounds by dissociation or dissolution in the composition or from
the elemental metal. Suitable source compounds for the metal ions
include, without limitation, aluminum chloride, aluminum hydroxide,
aluminum oxide, aluminum sulfate, antimony trioxide, barium
carbonate, barium sulfate, cobalt carbonate, cobalt sulfate, copper
acetate, copper carbonate, copper hydroxide, copper nitrate, copper
sulfate, cupric oxide, cuprous oxide, ferric ammonium sulfate,
ferric chloride, ferric oxide, ferric oxide hydrate, ferric
sulfate, ferrous ammonium sulfate, ferrous oxide, ferrous sulfate,
iron, iron salts of di-, tri- or other polycarboxylic acids such as
iron citrate, iron hydroxide oxide, ferosoferric oxide, nickel
chloride, nickel acetate, nickel sulfate, potassium aluminum
sulfate, potassium permanganate, sodium aluminate, sodium aluminum
phosphate, sodium chromate, sodium iron(III)
ethylenediaminetetraacetate, sodium molybdate, sodium permanganate,
sodium potassium aluminum silicate, tin oxide, titanium sulfate,
vanadyl sulfate, zinc acetate, zinc chloride, zinc hydroxide, zinc
iron oxide, zinc naphthenate, zinc oxide, zinc oxide sulfate
(Zn.sub.4O.sub.3(SO.sub.4)), zinc sulfate (basic), zinc sulfate
(monohydrate) and mixtures thereof.
[0085] In one preferred embodiment, the metal ion safening agent
added to the herbicidal composition for selective complexing or
binding with PMIDA comprises polyvalent iron (e.g., Fe(III)) and is
derived from ferric ammonium sulfate, ferric chloride, ferric
oxide, ferric oxide hydrate, ferric sulfate, ferrous ammonium
sulfate, ferrous oxide, ferrous sulfate and/or iron salts of di-,
tri- or other polycarboxylic acids such as iron citrate. In one
preferred embodiment, a safening agent comprising polyvalent iron
ions in the herbicidal glyphosate composition is derived from
ferric sulfate, ferric chloride and/or iron citrate.
[0086] When preparing glyphosate concentrate compositions
containing certain metal ion safening agents such as iron derived
from iron oxide, ferric chloride or ferric sulfate, it may be
necessary to first mix the metal ion with a suitable solubilizing
or stabilizing ligand (sL) in an aqueous solution before combining
it with the PMIDA-containing glyphosate. For example, aqueous
solutions of the metal ion and solubilizing ligand may be mixed and
then the mixture combined with glyphosate and other components of
the composition. This practice inhibits precipitation of a metal
salt of glyphosate and/or the precipitation of metal hydroxide in
the composition thereby rendering the metal ion unavailable for
complexing or binding with PMIDA. The severity of these solubility
issues appears to be somewhat dependent upon the identity of the
metal salt of glyphosate included in the concentrate composition
and, for example, is more problematic when preparing iron safened
concentrate compositions containing the potassium salt of
glyphosate as compared to the isopropylamine salt of glyphosate.
The solubilizing or stabilizing ligand, is selected to (1) form a
complex with the metal ion with sufficient stability to be
competitive with glyphosate's metal complex stability and
sufficiently stable to prevent any metal salt hydrolysis to metal
hydroxides at the pH of the composition (typically pH of 4 to 5);
and (2) form a complex weaker than that formed by PMIDA, thereby
allowing PMIDA to displace and replace this solubilizing ligand
from the metal in the final composition. The metal-ligand formation
constants are used to quantify the complex's stability, and can be
readily determined by potentiometric titration or found in the
literature. The complex stability for the solubilizing ligand can
also be controlled by adjusting the amount used relative to the
metal ion. Specifically, the molar ratio of solubilizing ligand to
metal ion is optimized to eliminate the adverse effects that are
observed on herbicidal activity and formulation homogeneity,
detailed above, when simple, aqueous metal ions are used. This
molar ratio is typically greater than 1, and is usually from about
1.5 to about 4 (sL/metal). The composition will thus contain three
primary materials capable of complexing or binding with the metal
ion (i.e., in order of decreasing stability, decreasing
metal-ligand formation constant PMIDA>sL.apprxeq.glyphosate).
Examples of suitable solubilizing ligands include polyacids (e.g.,
polycarboxylic acids) and hydroxyl acids like citric acid, gluconic
acid, oxalic acid, malonic acid, succinic acid, malic acid,
tartaric acid, fumaric acid, maleic acid, glutaric acid,
dimethylglutaric acid, adipic acid, trimethyladipic acid, pimelic
acid, tartronic acid, suberic acid, azelaic acid, sebacic acid,
1,12-dodecanedioic acid, 1,13-tridecanedioic acid, glutamic acid,
phthalic acid, isophthalic acid, lactic acid, terephthalic acid, or
an anhydride, ester, amide, halide, salt or precursor of any of
these acids, polyhydroxy compounds like fructose and catechol,
amino acids, proteins and polysaccharides. In accordance with one
preferred embodiment, the solubilizing ligand comprises a
polycarboxylic acid such as citric acid.
[0087] An additional complication exists with aqueous solutions of
iron (III). At a pH of up to about 2, ferric iron has a strong
tendency to hydrolyze to form a binuclear species,
[Fe(H.sub.2O)4(OH)2Fe(H.sub.2O)4].sup.4+ and at a pH above about 2
to 3 polynuclear Fe--OH species. The latter results in the
precipitation of colloidal or hydrous ferric oxide. Glyphosate
compositions have a pH around 4.5 units. However, this problem can
likewise be overcome by employing a suitable solubilizing ligand as
described above. The solubilizing ligand selected (e.g., citric
acid, fructose) possesses a metal stability constants less than
that of PMIDA, to allow PMIDA to displace the solubilizing ligand,
but stable enough to prevent hydrolysis of Fe(III) as described
above. As an alternative to or in addition to using a solubilizing
ligand to overcome solubility and precipitation issues that might
arise when preparing glyphosate concentrate compositions containing
certain metal ion safening agents, it may be advantageous to use a
mixture of metal ions to prepare a suitable safened concentrate.
For example, a combination of iron ions and zinc ions or a
combination of iron ions and copper ions may be employed.
[0088] The amount of metal ion safening agent introduced into the
composition relative to PMIDA is selected to ensure the reduction
of free (i.e., non-bound or non-complexed) PMIDA to a level
sufficiently low so as to not induce significant leaf necrosis in
the cotton crop and can be readily determined through routine
experimentation. The minimally effective molar ratio of metal ion
safening agent to PMIDA in the herbicidal glyphosate composition
depends upon the PMIDA concentration. As the concentration of PMIDA
in the manufactured glyphosate product from which herbicidal
glyphosate compositions such as concentrates and tank mixes are
prepared decreases, a lower molar ratio of metal ion safening agent
to PMIDA (e.g., even less than 1:1) may be effectively utilized in
the composition and satisfactory results obtained since free,
biologically active PMIDA in the composition may be reduced by the
safening agent to a level that prevents significant PMIDA-induced
necrosis in the treated cotton plants at the designated application
rate. The safening agent comprising one or more metal ions is
generally added to herbicidal glyphosate compositions, including
concentrates and tank mixes, at a molar ratio to PMIDA of at least
about 0.15:1, at least about 0.2:1, at least about 0.25:1, at least
about 0.3:1, at least about 0.35:1, at least about 0.4:1 and
preferably at a molar ratio to PMIDA of at least about 0.45:1, at
least about 0.5:1, at least about 0.55:1, at least about 0.6:1, at
least about 0.65:1, at least about 0.7:1, at least about 0.75:1, at
least about 0.8:1, at least about 0.85:1, at least about 0.9:1 or
even at least about 0.95:1. Typically, the molar ratio of the metal
ion safening agent to PMIDA in the herbicidal glyphosate
composition is no greater than about 25:1, no greater than about
20:1, no greater than about 15:1, no greater than about 10:1, no
greater than about 5:1, no greater than about 4:1, no greater than
about 3:1 and preferably no greater than about 2.5:1. Often the
concentration of PMIDA in the manufactured glyphosate product is
sufficiently high such that the molar ratio of the metal ion
safening agent to PMIDA in the herbicidal glyphosate composition
including concentrates and tank mixes is at least about 0.5:1,
typically from about 0.5:1 to about 25:1, from about 0.5:1 to about
20:1, from about 1:1 to about 25:1, from about 1:1 to about 20:1,
from about 1:1 to about 15:1, from about 1:1 to about 10:1, from
about 1:1 to about 9:1, from about 1:1 to about 8:1, from about 1:1
to about 7:1, from about 1:1 to about 6:1, from about 1:1 to about
5:1, from about 1:1 to about 4:1, preferably from about 1:1 to
about 3:1, more preferably from about 1:1 to about 2.5:1, and even
more preferably from about 1:1 to about 2:1. Utilizing a metal ion
safening agent in the glyphosate herbicidal compositions of the
present invention allows the application rate of free, biologically
active PMIDA to be reduced to no more than about 2.5 g PMIDA acid
equivalent per hectare and lower (e.g., as noted above and
preferably no more than about 1.5 g, more preferably no more than
about 1.2 g, more preferably no more than about 1 g, even more
preferably no more than about 0.7 g, still more preferably no more
than about 0.5 g and especially no more than about 0.25 g PMIDA
acid equivalent per hectare) and thereby inhibit significant
PMIDA-induced necrosis in the treated cotton plants.
[0089] In practicing the various embodiments of the present
invention, it may be necessary to determine the PMIDA content of a
material such as manufactured glyphosate product used in
formulation of concentrates, tank mixes or other forms of
herbicidal compositions or the PMIDA content of the formulated
herbicidal compositions themselves, for example, to determine
whether a safening agent is necessary, the quantity of safening
agent to be employed as well as to assure compliance with the
established compositional specifications. Analytical methods for
determining PMIDA content are available to those skilled in the
art. One such method using a high-pressure liquid chromatography
procedure (HPLC) is described in Example 3 below.
[0090] Similarly, in practicing the embodiment described herein
calling for use of certain metal ion safening agents, it may be
necessary to accurately determine the metal ion content of an
herbicidal glyphosate composition. Methods for analyzing a product
or material to determine the concentration of metal ions such as
those disclosed herein suitable for use as a safening agent are
likewise available to those skilled in the art. By way of example,
trace concentrations of iron in materials used and produced in the
practice of the present invention may be measured using the test
method based on photometric determination of the
1,10-phenanthroline complex formed with the iron(II) ion described
in ASTM E 394-94.
[0091] In accordance with another embodiment of the invention, the
safening agent included in the herbicidal glyphosate composition
comprises a light absorbing compound that acts to protect the
treated cotton plant from particular light spectra to inhibit free
radical production associated with photo-activated PMIDA-induced
necrosis. Generally, the light absorbing compound is selected so as
to preferentially block at least a portion of the visible light
spectrum near the wavelength(s) associated with PMIDA-induced free
radical production in the treated cotton plant and to transmit
other portions of the visible light spectrum necessary for adequate
photosynthesis and plant health.
[0092] Suitable light absorbing compounds include certain dyes such
as FD&C yellow dye #5 (commonly known as tartrazine and having
the chemical name
3-carboxy-5-hydroxy-1-p-sulfophenyl-4-p-sulfophenylazopyrazole
trisodium salt), FD&C Blue #1, FD&C Red #40, FD&C Red
#33, FD&C Violet #1, Fast Green FCF, methylene blue and
mixtures thereof. Tartrazine having a maximum light absorbance at a
wavelength of about 425 nm, was tested as a safening agent in
glyphosate spray solutions and found to significantly decrease
PMIDA-induced necrosis in the treated cotton plants. The amount of
tartrazine or other light absorbing compound introduced into the
composition as a safening agent is selected to ensure absorbance of
at least a portion of the visible light spectrum near the
wavelength(s) associated with PMIDA-induced free radical production
in the treated cotton plant so as to reduce the formation of free
radicals to a level sufficient to not induce significant leaf
necrosis in the cotton crop and can be readily determined through
routine experimentation. For example, the safening agent comprising
tartrazine or other dye is generally added to herbicidal glyphosate
compositions, including concentrates and tank mixes, in an amount
sufficient such that at least about 50, 60, 70, 80 or 90% or more
of the incident light at the relevant wavelength(s) is absorbed.
The preferred amount depends on the identity of the dye or other
light absorbing compound and the relative ability of the material
to absorb incident light at the relevant wavelength(s) associated
with PMIDA-induced free radical production. Some dyes and other
light absorbing compounds have a tendency to degrade or fade over
time or upon exposure to light. Accordingly, in practicing this
embodiment of the invention, it may be useful to incorporate the
dye or other light absorbing compound into the glyphosate
composition just prior to use or to take other measures to ensure
the safening activity of the dye is not significantly
diminished.
[0093] Humectants are another class of safening agents that may be
employed in the practice of the present invention to inhibit
PMIDA-induced necrosis in treated cotton plants. Humectants are
believed to mitigate PMIDA-induced necrosis by protecting or aiding
in the repair of cell membranes in the foliar tissues of the cotton
plants damaged by free radicals and/or by modifying or altering the
leaf surface/herbicidal formulation interface, thus affecting the
uptake of PMIDA. Without being bound by any particular theory, it
is postulated that humectants can be entrapped in the interstices
of the cell wall surfaces, where they act as a hygroscopic agent,
thus increasing the amount of water held in this area. The
humectants employed in the compositions of this invention are
preferably water-soluble and are substantially non-ionizable. By
substantially non-ionizable it is meant that no significant or
detectable disassociation in water occurs. Such humectants can be
employed in addition to or substituted partially for, the water
component of the inventive herbicidal glyphosate compositions.
[0094] Examples of suitable humectants include, without limitation,
materials selected from the group consisting of glycerin, urea,
guanidine, glycolic acid and glycolate salts (e.g., ammonium and
quaternary alkyl ammonium), lactic acid and lactate salts (e.g.,
ammonium and quaternary alkyl ammonium), polyhydroxy alcohols such
as sorbitol, xylitol, inositol, mannitol, pantothenol, glycerol,
hexanetriol (e.g., 1,2,6-hexanetriol), 1,4-butanediol,
tetramethyl-6-decyne-4,7-diol, PEG-5 pentaerythritol ether,
polyglyceryl sorbitol, diethylene glycol, propylene glycol,
butylene glycol, hexylene glycol and the like, polyethylene
glycols, sugars and starches (e.g. sucrose), sugar and starch
derivatives (e.g., alkoxylated glucose, hydrogenated partially
hydrolyzed polysaccharides and hydrogenated starch hydrolysate),
hyaluronic acid, lactamide monoethanolamine, acetamide
monoethanolamine, sodium 2-pyrrolidone-5-carboxylate, collagen,
gelatin, 10 to 20 mole ethoxylates or propoxylates of glucose
(e.g., GLUCAM E-20) and mixtures thereof. Preferred humectants
include sorbitol, xylitol, inositol, mannitol, pantothenol,
glycerol and derivatives and mixtures thereof.
[0095] The humectant is preferably added to the glyphosate
compositions, including concentrates and tank mixes, in a molar
excess to PMIDA, for example, at a molar ratio to PMIDA of from
about 1000:1 to about 1:1, from about 500:1 to about 1:1, from
about 250:1 to about 1:1, from about 100:1 to about 1:1, from about
50:1 to about 1:1, from about 40:1 to about 1:1, from about 30:1 to
about 1:1, from about 20:1 to about 1:1, from about 15:1 to about
1:1, from about 10:1 to about 1:1, from about 5:1 to about 1:1,
from about 3:1 to about 1:1 or even from about 2:1 to about 1:1.
The preferred ratio depends on the PMIDA concentration, the
humectant and the relative ability the humectant safening agent to
mitigate PMIDA-induced tissue damage and may be readily determined
by one skilled in the art using routine experimentation.
[0096] It should be understood that in the practice of the present
invention wherein a safening agent is used in a herbicidal
glyphosate composition containing PMIDA to mitigate leaf necrosis
in the treated cotton plants, the safening agent may comprise any
combination of two or more materials selected from the various
classes of safening agents disclosed herein and including
combinations of antioxidants, metal ions, light absorbing
compounds, humectants and/or certain surfactants effective in
mitigating PMIDA-induced necrosis as disclosed in greater detail
below. Moreover, it should be understood that many of the specific
safening agents disclosed herein may be multifunctional and,
although identified within a particular class of safening agents,
may provide safening against PMIDA-induced necrosis through one or
more mechanisms common to other classes of safening agents.
[0097] In another embodiment of the present invention, an adjuvant
is selected to control, or moderate, the rate of PMIDA uptake into
the cotton plant such that the plant can metabolize the PMIDA
without development of significant leaf necrosis. Alternatively,
the adjuvant can render the PMIDA less biologically active before
cellular uptake and translocation of the PMIDA in the plant.
[0098] In one embodiment, the adjuvant is a compound having at
least two hydroxyl substituents that are oriented no more than 6
atoms apart and in the same spatial orientation within the
molecule. Such adjuvants include diols, triols, polyols, and the
like, such as alkanediols, alkenediols, alkynediols, benzenediols,
dialkanolamines, trialkanolamines, polyalkylene glycols, dialkylene
glycols, trialkylene glycols, and alkylpolyglucosides. Some
suitable adjuvants are nonionic surfactants, such as esters of
polyhydric alcohols, alkoxylated amides, alkoxylated alkylphenols,
alkoxylated arylphenols, fatty alcohol alkoxylates, alcohol
alkoxylates, and alkylpolyglucosides. Commercially available
alkylpolyglucosides include AGRIMUL APG 2067, APG 2069 (nonyl/decyl
polyglucoside having an average of 1.6 polyglucoside units) and APG
2076 all from Cognis, BEROL AG6202 (2-ethyl-1-hexylglycoside from
Akzo Nobel) and AL2042 (octyl/decyl with an average of 1.7
glycoside units available from Imperial Chemical Industries
PCL).
[0099] In an embodiment of the invention, the glyphosate
composition is formulated such that the weight ratio of the PMIDA
uptake-moderating adjuvant to PMIDA present in the glyphosate
composition is selected so that the rate of transfer of PMIDA into
the foliar tissues of the plant is sufficiently low enough to
inhibit significant leaf necrosis. Stated another way, the
adjuvant, when applied as part of an aqueous glyphosate spray
composition, is of the type and present in a sufficient
concentration to prohibit the crop of transgenic
glyphosate-tolerant cotton plants from cellularly uptaking and
translocating an amount of PMIDA thereof sufficient to induce
significant leaf necrosis in the cotton plant. One way to
accomplish this is to select an adjuvant which, when compared to an
equivalent amount by weight of an alkoxylated alkylamine surfactant
(e.g., ethoxylated tallowamine), provides less intimate contact
between the applied herbicidal composition and the
microtopographically rough surface of the cotton plant, for example
by increasing the contact angle of the composition, so as to
minimize spreading of the composition into crevices and pores in
the plant. Another means for decreasing the rate of PMIDA uptake is
to select an adjuvant that minimizes sticking or adhesion to a
plant surface when used in an aqueous spray composition as compared
to the same composition containing the alkoxylated alkylamine
rather than the selected adjuvant. Yet another way of reducing the
rate of PMIDA uptake is to select an adjuvant that causes the spray
composition to dry faster, minimizing penetration through the leaf
cuticle relative to the same composition containing the alkoxylated
alkylamine rather than the selected adjuvant. These various
adjuvant selection strategies may also negatively impact the
herbicidal activity of glyphosate and therefore are preferably
employed so as to provide a differential effect to obtain the
desired reduction in PMIDA-induced necrosis in the treated cotton
plant without significantly undermining glyphosate herbicidal
activity under the relevant growing conditions.
[0100] The PMIDA uptake-moderating adjuvant is preferably added to
the glyphosate composition at a weight ratio to PMIDA of between
about 200:1 to 1:1, 150:1 to 1:1, 100:1 to 1:1, 75:1 to 1:1, 50:1
to 1:1, 40:1 to 1:1, 30:1 to 1:1, 20:1 to 1:1 or even 10:1 to 1:1.
A preferred ratio depends on the PMIDA concentration, the identity
of the adjuvant and the relative ability of that adjuvant to
control, or moderate, the rate of PMIDA uptake into the cotton
plant. A preferred ratio may be readily determined by one skilled
in the art using routine experimentation.
[0101] It is to be noted that the present invention encompasses any
glyphosate formulation disclosed herein (e.g., concentrate, solid
or tank mix) which comprises reduced amounts of PMIDA or any one of
the PMIDA safening agents or safeners described above, as well as
any combination or mixture which includes any one, two, three,
four, five or six of these safeners. Exemplary combinations are set
forth in greater detail in Formulation Tables A-E, below (which
illustrate that glyphosate acid and/or salts or other derivatives
thereof, can be combined with a safening agent or a reduced amount
of PMIDA to form a herbicidal composition comprising two to seven
components, wherein: G=glyphosate; AO=antioxidant; MI=metal ion;
LA=light absorbing compound; H=humectant; CU=adjuvant for
mitigating cellular uptake of PMIDA or biological activity of
PMIDA; P=reduced amount of PMIDA; and Active No. is a herbicide
combination reference number):
TABLE-US-00001 TABLE A Glyphosate in Combination with One Safener
or a Reduced Amount of PMIDA Active No. Herbicides 1 G + AO 2 G +
MI 3 G + LA 4 G + H 5 G + CU 6 G + P
TABLE-US-00002 TABLE B Glyphosate in Combination with Two Safeners
or One Safener and a Reduced Amount of PMIDA Active No. Herbicides
7 G + AO + P 8 G + AO + MI 9 G + AO + H 10 G + AO + CU 11 G + AO +
LA 12 G + P + MI 13 G + P + H 14 G + P + CU 15 G + P + LA 16 G + MI
+ H 17 G + MI + CU 18 G + MI + LA 19 G + H + CU 20 G + H + LA 21 G
+ CU + LA
TABLE-US-00003 TABLE C Glyphosate in Combination with Three
Safeners or Two Safeners and a Reduced Amount of PMIDA Active No.
Herbicides 22 G + AO + P + MI 23 G + AO + P + H 24 G + AO + P + CU
25 G + AO + P + LA 26 G + AO + MI + H 27 G + AO + MI + CU 28 G + AO
+ MI + LA 29 G + AO + H + CU 30 G + AO + H + LA 31 G + AO + CU + LA
32 G + P + MI + H 33 G + P + MI + CU 34 G + P + MI + LA 35 G + P +
H + CU 36 G + P + H + LA 37 G + P + CU + LA 38 G + MI + H + CU 39 G
+ MI + H + LA 40 G + MI + CU + LA 41 G + H + CU + LA
TABLE-US-00004 TABLE D Glyphosate in Combination with Four Safeners
or Three safeners and a Reduced Amount of PMIDA Active No.
Herbicides 42 G + AO + P + MI + H 43 G + AO + P + MI + CU 44 G + AO
+ P + MI + LA 45 G + AO + P + H + CU 46 G + AO + P + H + LA 47 G +
AO + P + CU + LA 48 G + AO + MI + H + CU 49 G + AO + MI + H + LA 50
G + AO + MI + CU + LA 51 G + AO + H + CU + LA 52 G + P + MI + H +
CU 53 G + P + MI + H + LA 54 G + P + MI + CU + LA 55 G + P + H + CU
+ LA 56 G + MI + H + CU + LA -- --
TABLE-US-00005 TABLE E Glyphosate in Combination Five Safeners or
Four Safeners and a Reduced Amount of PMIDA Active No. Herbicides
57 G + AO + P + MI + H + CU 58 G + AO + P + MI + H + LA 59 G + AO +
P + MI + CU + LA 60 G + AO + P + H + CU + LA 61 G + AO + MI + H +
CU + LA 62 G + P + MI + H + CU + LA
[0102] The safeners as described above can be added to any
glyphosate liquid concentrate, solid concentrate, technical grade
glyphosate product, ready-to-use concentrate, or spray composition.
Glyphosate is typically formulated as a salt in an aqueous liquid
concentrate, a solid concentrate, an emulsion or a microemulsion.
Suitable salt forms of glyphosate which may be used in accordance
with any of the formulations of the present invention include, for
example, alkali metal salts, for example sodium and potassium
salts, ammonium salts, di-ammonium salts such as dimethylammonium,
alkylamine salts, for example dimethylamine and isopropylamine
salts, alkanolamine salts, for example ethanolamine salts,
alkylsulfonium salts, for example trimethylsulfonium salts,
sulfoxonium salts, and mixtures or combinations thereof. Examples
of commercial formulations of glyphosate include, without
restriction: ROUNDUP ULTRA, ROUNDUP ULTRAMAX, ROUNDUP CT, ROUNDUP
EXTRA, ROUNDUP BIOACTIVE, ROUNDUP BIOFORCE, RODEO, POLARIS, SPARK
and ACCORD, all of which contain glyphosate as its
isopropylammonium salt (IPA); ROUNDUP DRY and RIVAL which contain
glyphosate as its ammonium salt; ROUNDUP GEOFORCE, a sodium
glyphosate formulation; TOUCHDOWN, a glyphosate trimesium salt
formulation, TOUCHDOWN IQ, a glyphosate diammonium salt
formulation, TOUCHDOWN TOTAL IQ, a potassium glyphosate
formulation, and ROUNDUP WEATHERMAX, a potassium glyphosate
formulation.
[0103] The relative amount of glyphosate present in a contemplated
herbicidal composition (i.e., a particulate solid concentrate, or
liquid concentrate, or alternatively a ready-to-use, or tank-mix,
composition) may vary depending upon many factors, including for
example the weed species to be controlled and the method of
application. Generally speaking, however, the concentration of
glyphosate, and optionally a surfactant and/or some other adjuvant
or additive (as described elsewhere herein), in the herbicidal
compositions of the invention is sufficient to provide at least
about 70% control (as determined by means known in the art) within
about 50 days, preferably about 40 days, more preferably about 30
days, still more preferably about 20 days, still more preferably
about 15 days, still more preferably about 10 days, still more
preferably about 5 days, and even still more preferably about 1
day, or less, after application of the composition to a weed. In a
more preferred embodiment, the concentration of glyphosate, and
optionally a surfactant and/or some other additive, in the
herbicidal compositions of the invention is sufficient to provide
at least about 80%, more preferably at least about 85%, still more
preferably at least about 90%, and still more preferably at least
about 95%, control, or more, within about 50 days, preferably about
40 days, more preferably about 30 days, still more preferably about
20 days, still more preferably about 15 days, still more preferably
about 10 days, still more preferably about 5 days, and even still
more preferably about 1 day, or less, after application of the
composition to a weed.
[0104] Additionally, the concentration of glyphosate, and
optionally a surfactant and/or some other adjuvant or additive (as
described elsewhere herein), in the herbicidal compositions of the
invention is sufficient to provide at least about 70% control of
weed regrowth (as determined by means known in the art) for at
least about 20, preferably at least about 30, more preferably at
least about 40, still more preferably at least about 50, still more
preferably at least about 60, still more preferably at least about
70, still more preferably at least about 80, or even still more
preferably at least about 90, days after application of the
composition to a weed. In a more preferred embodiment, the
concentration of glyphosate, and optionally a surfactant and/or
some other adjuvant or additive, in the herbicidal compositions of
the invention is sufficient to provide at least about 80%, more
preferably at least about 85%, still more preferably at least about
90%, or still more preferably at least about 95% control, or more,
for at least about 20, more preferably at least about 30, still
more preferably at least about 40, still more preferably at least
about 50, still more preferably at least about 60, still more
preferably at least about 70, still more preferably at least about
80, or even still more preferably at least about 90, days after
application to the weed.
[0105] Accordingly, liquid concentrate compositions of the
invention are formulated to include glyphosate in a concentration
of at least about 50 grams, preferably at least about 75 grams, and
more preferably at least about 100, 125, 150, 175, 200, 225, 250,
275, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410,
420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540,
550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670,
680, 690 or 700 grams (acid equivalent or a.e.) per liter, or more.
The glyphosate concentration ranges, for example, from about 50 to
about 680 grams (a.e.) per liter, from about 100 to about 600 grams
(a.e.) per liter (gpl), from about 250 to about 600 grams (a.e.)
per liter, or from about 360 to about 540 grams (a.e.) per liter.
When expressed as a weight percentage based on the total weight of
the glyphosate concentrate, a liquid concentrate of the invention
comprises at least about 10 wt. % glyphosate (acid equivalent or
a.e.), preferably at least about 15 wt. %, and more preferably at
least about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50,
51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 62, 63, 64, 65, 66, 67, or
68 wt. % a.e., or more. The glyphosate concentration ranges, for
example, from about 10 wt. % to about 70 wt. % a.e., more
preferably from about 20 wt. % to about 68 wt. % a.e., and even
more preferably from about 25 wt. % to about 45 wt. % a.e. If the
concentrate is applied as a ready-to-use composition, the
glyphosate concentration is typically from about 1 wt. % to about 3
wt. % a.e., and more preferably from about 1 wt. % to about 2 wt. %
a.e.
[0106] When expressed as a weight percentage based on the total
weight of the glyphosate concentrate, solid concentrate
compositions of the invention are formulated to include glyphosate
in a concentration of at least about 5 wt. % glyphosate (acid
equivalent or a.e.), preferably at least about 20 wt. % a.e., and
more preferably at least about 25, 30, 35, 40, 45, 50, 55, 60, 65,
70, 75, 80, 85, 90, or 95 wt. % a.e., or more. The glyphosate
concentration ranges, for example, from about 5 wt. % to about 97
wt. % a.e., more preferably from about 30 wt. % to about 85 wt. %
a.e., and even more preferably from about 50 wt. % to about 75 wt.
% a. e.
[0107] Spray compositions of the invention are formulated for
application of at least about 1 gallon of spray composition per
acre, preferably at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, or 20 gallons per acre, or more. The
spray volume of the spray composition ranges, for example, from
about 1 gallon to about 100 gallons per acre, more preferably from
about 2 gallons to about 40 gallons per acre, and more preferably
from about 2 gallons to about 5 gallons per acre for an aerial
application and from about 5 gallons to about 20 gallons per acre
for a ground application. The glyphosate in such spray compositions
is applied to glyphosate-tolerant transgenic cotton plants at rates
of from about 0.75 to about 1.125 lb glyphosate a.e./A or about
0.84 to about 1.26 kg glyphosate a.e./ha.
Preparation of Glyphosate Compositions
[0108] Unless otherwise noted herein, the herbicidal compositions
of the invention that include one or more PMIDA safening agents or
safeners can be prepared on site by the end-user shortly before
application to the foliage of the vegetation to be killed or
controlled by mixing in an aqueous solution (i) a glyphosate
composition, (ii) a safener, and (iii) any optional components,
such as a suitable surfactant or other adjuvant(s). Such
compositions are typically referred to as "tank-mix" compositions.
Typically, herbicidal compositions of the present invention that
are ready to be applied directly to foliage can be made with a
glyphosate concentration as described elsewhere herein. In one
embodiment, an additive composition or mixture is provided for the
end-user to provide the PMIDA safener to be added to the tank mix.
The additive composition or mixture can optionally include
surfactant and/or other adjuvant components typical in a glyphosate
tank mix, and can be provided as a liquid or solid. For example,
the end-user can be provided with a sachet of solid material that
can be added to the aqueous solution and mixed to dissolve the
material.
[0109] Alternatively, the herbicidal compositions of the invention
may be provided to the end-user already formulated, either at the
desired dilution for application (i.e., "ready-to-use"
compositions) or requiring dilution, dispersion, or dissolution in
water by the end-user (i.e., "concentrate" compositions). Such
pre-formulated concentrates can be liquids or particulate
solids.
[0110] With respect to the particulate solids, or dry formulations,
of the present invention, it is to be noted that these may be in
the form of powders, pellets, tablets flakes or granules. These dry
formulations are typically dispersed or dissolved into water prior
to use. Preferably, there are no substantially water insoluble
constituents present at substantial levels in such formulations
such that the formulations are substantially water soluble. In dry
formulations of the present invention, the glyphosate itself may
provide the support for other formulation constituents, or there
may be additional inert ingredients which provide such support. One
example of an inert support ingredient that may be used in
accordance with the present invention is ammonium sulfate. It will
be recognized by one skilled in the art that as used herein, the
term "dry" does not imply that dry formulations of the present
invention are 100% free of water. Typically, dry formulations of
the present invention comprise from about 0.5% to about 5% (by
weight) water. It is preferred that the dry formulations of the
present invention contain less than about 1% (by weight) water.
Additionally, it is preferred for at least some embodiments that
the particulate solid exhibits a dissolution rate of not more than
about 5 minutes, about 4 minutes, about 3 minutes, about 2 minutes,
or even about 1 minute.
[0111] Dry, water-soluble or water-dispersible formulations in
accordance with the present invention can be produced by any
process known in the art, including spray drying, fluid-bed
agglomeration, pan granulation, or extrusion. In dry formulations,
glyphosate may be present as a salt, or as an acid. Formulations
containing glyphosate acid may optionally contain an acid acceptor
such as an ammonium or alkali metal carbonate or bicarbonate,
ammonium dihydrogen phosphate or the like so that upon dissolution
or dispersion in water by the user a water-soluble salt of
glyphosate is produced.
[0112] Also embraced by the present invention are liquid
concentrate formulations having an aqueous phase wherein glyphosate
is present predominantly in the form of a salt, and a non-aqueous
phase optionally containing a second herbicidal active ingredient
that is relatively water-insoluble. Such formulations
illustratively include emulsions (including macro- and
microemulsions, water-in-oil, oil-in-water and
water-in-oil-in-water types), suspensions and suspoemulsions. The
non-aqueous phase can optionally comprise a microencapsulated
component, for example a microencapsulated herbicide. In
formulations of the invention having a non-aqueous phase, the
concentration of glyphosate a.e. in the composition as a whole is
nonetheless within the ranges recited herein for aqueous
concentrate formulations.
[0113] It is to be noted that the herbicidal spray compositions of
the present invention are applied as aqueous solutions or
dispersions, whether they are manufactured ready for application or
result from the further dilution of a liquid glyphosate concentrate
or the addition of water to a particulate solid glyphosate
concentrate. However, the term "aqueous," as used herein, is not
intended to exclude the presence of some small amount of
non-aqueous solvent, so long as the predominant solvent present, is
water. Herbicidal spray compositions, also known as tank-mixes,
typically contain from about 0.5% to about 2% by weight per volume
(w/v) percent glyphosate a.e. and more typically about 1% w/v
a.e.
Application
[0114] Generally speaking, the present invention is additionally
directed to a method of killing or controlling weeds or unwanted
vegetation in a field containing a crop (e.g., of transgenic
glyphosate-tolerant cotton plants having increased glyphosate
tolerance in vegetative and reproductive tissues). In one
embodiment, the method comprises the steps of diluting an aqueous
glyphosate concentrate or diluting a solid particulate glyphosate
concentrate in a suitable volume of water to form a tank mix, and
applying a herbicidally effective amount of the tank mix to foliage
of cotton plants genetically transformed to tolerate glyphosate,
and simultaneously to foliage of weeds growing in close proximity
to such plants. This method of use results in control of the weeds
or unwanted vegetation while leaving the cotton plants
substantially unharmed.
[0115] It should be understood that while the present invention is
particularly directed to killing or controlling weeds or unwanted
vegetation in a crop of transgenic glyphosate-tolerant cotton
plants such as ROUNDUP READY and ROUNDUP READY FLEX cotton that are
susceptible to PMIDA-induced leaf necrosis following over-the-top
foliar application of glyphosate herbicides, the herbicidal
glyphosate compositions and methods of weed control disclosed
herein are not limited to such application and may be effectively
employed generally in weed management to kill or control the growth
of unwanted vegetation in cultivated crop lands as well as in other
industrial and residential applications.
[0116] The practice of the present invention can be employed to
kill or control the growth of a wide variety of unwanted plants,
including annual and perennial grass and broadleaf weed species, by
applying to the foliar tissues of the plants aqueous glyphosate
compositions of the present invention. Particularly important
annual dicotyledonous plant species include, without limitation,
velvetleaf (Abutilon theophrasti), pigweed (Amaranthus spp.),
buttonweed (Borreria spp.), oilseed rape, canola, indian mustard,
etc. (Brassica spp.), commelina (Commelina spp.), filaree (Erodium
spp.), sunflower (Helianthus spp.), morningglory (Ipomoea spp.),
kochia (Kochia scoparia), mallow (Malva spp.), wild buckwheat,
smartweed, etc. (Polygonum spp.), purslane (Portulaca spp.),
Russian thistle (Salsola spp.), sida (Sida spp.), wild mustard
(Sinapis arvensis) and cocklebur (Xanthium spp.).
[0117] Particularly important annual monocotyledonous plant species
that may be killed or controlled using the compositions of the
present invention include, without limitation, wild oat (Avena
fatua), carpetgrass (Axonopus spp.), downy brome (Bromus tectorum),
crabgrass (Digitaria spp.), barnyardgrass (Echinochloa crus-galli),
goosegrass (Eleusine indica), annual ryegrass (Lolium multiflorum),
rice (Oryza sativa), ottochloa (Ottochloa nodosa), bahiagrass
(Paspalum notatum), canarygrass (Phalaris spp.), foxtail (Setaria
spp.), wheat (Triticum aestivum) and corn (Zea mays).
[0118] Particularly important perennial dicotyledonous plant
species for control of which a composition of the invention can be
used include, without limitation, mugwort (Artemisia spp.),
milkweed (Asclepias spp.), Canada thistle (Cirsium arvense), field
bindweed (Convolvulus arvensis) and kudzu (Pueraria spp.).
[0119] Particularly important perennial monocotyledonous plant
species for control of which a composition of the invention can be
used include, without limitation, brachiaria (Brachiaria spp.),
bermudagrass (Cynodon dactylon), yellow nutsedge (Cyperus
esculentus), purple nutsedge (C. rotundus), quackgrass (Elymus
repens), lalang (Imperata cylindrica), perennial ryegrass (Lolium
perenne), guineagrass (Panicum maximum), dallisgrass (Paspalum
dilatatum), reed (Phragmites spp.), johnsongrass (Sorghum
halepense) and cattail (Typha spp.).
[0120] Other particularly important perennial plant species for
control of which a composition of the invention can be used
include, without limitation, horsetail (Equisetum spp.), bracken
(Pteridium aquilinum), blackberry (Rubus spp.) and gorse (Ulex
europaeus).
[0121] The herbicidal composition of the present invention is
applied to plants at a rate sufficient to give the desired
biological effects: control of weed growth without inducing
significant leaf necrosis in cotton plants. These application rates
are usually expressed as amount of glyphosate per unit area
treated, e.g. grams per hectare (g/ha). What constitutes a "desired
effect" varies according to the standards and practice of those who
investigate, develop, market and use compositions and the selection
of application rates that are herbicidally effective for a
composition of the invention is within the skill of those skilled
in the art. Typically, the amount of the composition applied per
unit area to give 85% control of a weed species as measured by
growth reduction or mortality is often used to define a
commercially effective rate.
[0122] The selection of application rates that are herbicidally
effective for a composition of the invention is within the skill of
the ordinary agricultural scientist. Those of skill in the art will
likewise recognize that individual plant conditions, weather and
growing conditions, as well as the specific active ingredients and
their weight ratio in the composition, will influence the degree of
herbicidal effectiveness achieved in practicing this invention.
[0123] The herbicidal spray compositions included in the present
invention can be applied to the foliage of the plants to be treated
through any of the appropriate methods that are well known to those
having skill in the art, including aerial application, and ground
application techniques (e.g., a ground boom, a hand sprayer,
rope-wick, etc.).
[0124] If desired, the user can mix one or more adjuvants with a
composition of the invention and the water of dilution when
preparing the application composition. Such adjuvants can include
additional surfactant and/or an inorganic salt such as ammonium
sulfate with the aim of further enhancing herbicidal efficacy.
Optional Formulation Components
[0125] Glyphosate formulations typically comprise adjuvants that
enhance glyphosate herbicidal efficacy or otherwise enhance
stability of the formulation. For example, glyphosate salts
generally require the presence of a suitable surfactant to optimize
uptake into the plant. As used herein, "surfactant" is intended to
include a wide range of adjuvants that can be added to herbicidal
glyphosate formulations to enhance the herbicidal efficacy thereof
as compared to the efficacy of the glyphosate salt in the absence
of such adjuvant. In particular, surfactants facilitate the
translocation of glyphosate through the waxy leaf surface and into
the plant. The surfactant can be provided in the formulation and/or
can be added by the end user to a diluted spray composition.
[0126] Surfactant classes that have been formulated with glyphosate
include cationics, nonionics, anionics, amphoterics, zwitterionics
and mixtures thereof. Surfactants typically tending to provide the
most useful glyphosate enhancement are generally, but not
exclusively, cationic surfactants. Examples of cationic surfactant
classes include alkylamine alkoxylates (including etheramines and
diamines) such as tallowamine alkoxylate, cocoamine alkoxylate,
etheramine alkoxylate, tallow ethylenediamine alkoxylate and
amidoamine alkoxylates; alkylamine quaternary amines such as
alkoxylated quaternary alkyl amines (e.g., ethoxylated quaternary
alkyl amines or propoxylated quaternary alkyl amines); alkylamine
acetates such as tallowamine acetate or octylamine acetate; amine
oxides such as ethoxylated amine oxides (e.g.,
N,N-bis(2-hydroxyethyl)cocoamine-oxide), nonethoxylated amine
oxides (e.g., cetyldimethylamine-oxide) and amidoamine oxides; and
quaternary ammonium salts. Suitable cationic surfactants are
described, for example, in U.S. Pat. Nos. 3,853,530, 5,750,468,
5,668,085, 5,317,003 and 5,464,807, European Patent No. 0274369,
International Publication No. WO 95/33379, and U.S. Application
Publication No. 2003/0104943 A1, the entire disclosures of which
are incorporated herein by reference.
[0127] A preferred class of cationic surfactants commonly used in
glyphosate formulations is ethoxylated alkylamines of formula
(3):
##STR00002##
wherein m+n is between about 2 and about 25 and R is a branched or
straight chain alkyl group having from about 12 to about 22 carbon
atoms. Preferably, R is a coco or tallow group. Examples of such
alkylamines include TRYMEEN 6617 (from Cognis) and ETHOMEEN C/12,
C/15, C/20, C/25, T/12, T/15, T/20 and T/25 (from Akzo Nobel) where
"C" indicates R being coco and "T" indicates R being tallow.
[0128] Another preferred class of cationic surfactants commonly
used in glyphosate formulations are etheramines such as those
described in U.S. Pat. No. 5,750,468 including those of the
following formulae (4) to (6):
##STR00003##
wherein R.sub.1 is a straight or branched chain C.sub.6 to about
C.sub.22 alkyl, aryl or alkylaryl group, m is an average number
from 1 to about 10, R.sub.2 in each of the m (O--R.sub.2) groups is
independently C.sub.1-C.sub.4 alkylene, R.sub.3 groups are
independently C.sub.1-C.sub.4 alkylene, and x and y are average
numbers such that x+y is in the range from 2 to about 60;
##STR00004##
wherein R.sub.1 is a straight or branched chain C.sub.6 to about
C.sub.22 alkyl, aryl or alkylaryl group, m is an average number
from 1 to about 10, R.sub.2 in each of the m (O--R.sub.2) groups is
independently C.sub.1-C.sub.4 alkylene, R.sub.3 groups are
independently C.sub.1-C.sub.4 alkylene, R.sub.4 is C.sub.1-C.sub.4
alkyl, x and y are average numbers such that x+y is in the range
from 0 to about 60, and A- is an agriculturally acceptable
anion;
##STR00005##
wherein R.sub.1 is a straight or branched chain C.sub.6 to about
C.sub.22 alkyl, aryl or alkylaryl group, m is an average number
from 1 to about 10, R.sub.2 in each of the m (O--R.sub.2) groups is
independently C.sub.1-C.sub.4 alkylene, R.sub.3 groups are
independently C.sub.1-C.sub.4 alkylene, and x and y are average
numbers such that x+y is in the range from 2 to about 60.
[0129] Examples of preferred nonionic surfactants include
alkylpolyglucosides, glycerol esters, ethoxylated glycerol esters,
ethoxylated castor oil, ethoxylated reduced sugar esters,
polyhydric alcohol esters, ethoxylated amides, ethoxylated
polyethylene glycol esters, ethoxylated alkyl phenols, ethoxylated
arylphenols, fatty alcohol ethoxylates, ethylene oxide copolymers,
propylene oxide copolymers, organosilicones, fluoro-organics and
mixtures thereof.
[0130] Examples of preferred anionic surfactants include
polyalkoxylated phosphate esters and diesters; fatty soaps such as
ammonium tallowate and sodium stearate; alkyl sulfates such as
sodium C.sub.8-10 alcohol sulfate, sodium oleyl sulfate, and sodium
lauryl sulfate; sulfated oils such as sulfated castor oil; ether
sulfates such as sodium lauryl ether sulfate, ammonium lauryl ether
sulfate, and ammonium nonylphenol ether sulfate; sulfonates such as
petroleum sulfonates, alkylbenzene sulfonates (e.g., sodium
(linear) dodecylbenzene sulfonate or sodium (branched)
dodecylbenzene sulfonate), alkylnapthalene sulfonates (e.g., sodium
dibutylnapthalene sulfonate), alkyl sulfonates (e.g., alpha olefin
sulfonates), sulfosucinnates such as dialkylsulfosuccinates (e.g.,
sodium dioctylsulfosuccinate) and monoalkylsulfosuccinate and
succinamides (e.g., disodium laurylsulfosuccinate and disodium
N-alkylsulfosuccinamate); sulfonated amides such as sodium N-methyl
N-coco taurate; isethionates such as sodium cocoyl isethionate;
N-acyl sarcosinates such as N-lauroyl sarcosine, sodium lauryl
sarcosinate, sodium cocoyl sarcosinate and sodium myristoyl
sarcosinate; and phosphates such as alkylether ethoxylate
phosphates and alkylarylether ethoxyated phosphates; saturated
carboxylic and fatty acids such as butyric, caproic, caprylic,
capric, lauric, palmitic, myristic or stearic acid; and unsaturated
carboxylic acids such as palmitoleic, oleic, linoleic or linoleic
acid.
[0131] Exemplary amphoteric surfactants include betaines such as
simple betaines (e.g., cocodimethylbetaine), sulfobetaines,
amidobetaines, and cocoamidosulfobetaines; imidazolinium compounds
such as disodium lauroamphodiacetate, sodium cocoamphoacetate,
sodium cocoamphopropionate, disodium cocoaminodipropionate, and
sodium cocoamphohydoxypropyl sulfonate; and other amphoteric
surfactants such as alkyl hydroxyethylglycines (e.g., N-alkyl,
N,-bis(2-hydroxyethyl)glycine) and alkylaminedipropionates.
[0132] A glyphosate formulation of the invention can comprise any
combination of the surfactants described above so long as the
surfactant does not induce significant leaf necrosis in cotton
plants when it is formulated in the glyphosate composition. In one
combination described in International Publication No. WO 00/15037,
an alkylpolyglycoside surfactant is combined with an alkoxylated
alkylamine surfactant. Such a surfactant combination can be used in
a glyphosate composition of the present invention and applied to
transgenic glyphosate-tolerant cotton plants without inducing
significant leaf necrosis if the PMIDA content of the composition
is controlled and/or a PMIDA safener is added to the glyphosate
composition (e.g., a humectant, metal ions, light absorber, or
antioxidant).
[0133] Other additives and adjuvants typically employed in
glyphosate formulations can be combined with or included in the
glyphosate compositions of the present invention. For instance,
urea, ammonium sulfate, viscosity modifiers, dispersants, organic
solvents, glycols, buffers, antifoam agents, di-carboxylic acids
and/or polycarboxylic acids are all suitable additives.
[0134] Optionally, one or more of the compositions of the present
invention may further comprise one or more additional pesticides,
such as for example, water-soluble herbicidal active ingredients or
water-insoluble herbicidal active ingredients, including without
restriction acifluorfen, asulam, benazolin, bentazon, bialaphos,
bispyribac, bromacil, bromoxynil, carfentrazone, chloramben, 2,4-D,
2,4-DB, dalapon, dicamba, dichlorprop, diclofop, difenzoquat,
diquat, endothall, fenac, fenoxaprop, flamprop, fluazifop,
fluoroglycofen, fomesafen, fosamine, glufosinate, haloxyfop,
imazameth, imazamethabenz, imazamox, imazapic, imazapyr, imazaquin,
imazethapyr, ioxynil, MCPA, MCPB, mecoprop, methylarsonic acid,
naptalam, nonanoic acid, paraquat, sulfamic acid, 2,3,6-TBA, TCA,
acetochlor, aclonifen, alachlor, ametryn, amidosulfuron, anilofos,
atrazine, azafenidin, azimsulfuron, benfluralin, benfuresate,
bensulfuron-methyl, bensulide, benzofenap, bifenox, bromobutide,
bromofenoxim, butachlor, butamifos, butralin, butroxydim, butylate,
cafenstrole, carbetamide, carfentrazone-ethyl, chlomethoxyfen,
chlorbromuron, chloridazon, chlorimuron-ethyl, chlornitrofen,
chlorotoluron, chlorpropham, chlorsulfuron, chlorthal-dimethyl,
chlorthiamid, cinmethylin, cinosulfuron, clethodim,
clodinafop-propargyl, clomazone, clomeprop, cloransulam-methyl,
cyanazine, cycloate, cyclosulfamuron, cycloxydim, cyhalofop-butyl,
daimuron, desmedipham, desmetryn, dichlobenil, diclofop-methyl,
diflufenican, dimefuron, dimepiperate, dimethachlor, dimethametryn,
dimethenamid, dinitramine, dinoterb, diphenamid, diuron, EPTC,
esprocarb, ethalfluralin, ethametsulfuron-methyl, ethofumesate,
ethoxysulfuron, etobenzanid, fenoxaprop-ethyl, fenuron,
flamprop-methyl, flazasulfuron, fluazifop-butyl, fluchloralin,
flumetsulam, flumiclorac-pentyl, flumioxazin, fluometuron,
fluorochloridone, fluoroglycofen-ethyl, flupoxam, flurenol,
fluridone, flurtamone, fluthiacet-methyl, fomesafen, halosulfuron,
haloxyfop-methyl, hexazinone, imazosulfuron, indanofan,
isoproturon, isouron, isoxaben, isoxaflutole, isoxapyrifop,
lactofen, lenacil, linuron, mefenacet, metamitron, metazachlor,
methabenzthiazuron, methyldymron, metobenzuron, metobromuron,
metolachlor, metosulam, metoxuron, metribuzin, metsulfuron,
molinate, monolinuron, naproanilide, napropamide, naptalam,
neburon, nicosulfuron, norflurazon, orbencarb, oryzalin,
oxadiargyl, oxadiazon, oxasulfuron, oxyfluorfen, pebulate,
pendimethalin, pentanochlor, pentoxazone, phenmedipham, piperophos,
pretilachlor, primisulfuron, prodiamine, prometon, prometryn,
propachlor, propanil, propaquizafop, propazine, propham,
propisochlor, propyzamide, prosulfocarb, prosulfuron,
pyraflufen-ethyl, pyrazolynate, pyrazosulfuron-ethyl, pyrazoxyfen,
pyributicarb, pyridate, pyriminobac-methyl, quinclorac, quinmerac,
quizalofop-ethyl, rimsulfuron, sethoxydim, siduron, simazine,
simetryn, sulcotrione, sulfentrazone, sulfometuron, sulfosulfuron,
tebutam, tebuthiuron, terbacil, terbumeton, terbuthylazine,
terbutryn, thenylchlor, thifensulfuron, thiobencarb, tiocarbazil,
tralkoxydim, triallate, triasulfuron, tribenuron, trietazine,
trifluralin, triflusulfuron and vernolate.
[0135] In one embodiment, a glyphosate concentrate or spray
composition is prepared from a manufactured technical grade
glyphosate product comprising at least about 90, 91, 92, 93, 94,
95, 96, 97, 98 or 99 wt. % glyphosate acid equivalent (a.e.); less
than about 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.20, 0.30, 0.40,
0.50 or 0.60 wt. % PMIDA (on an acid equivalent basis); and
aminomethylphosphonic acid (AMPA), wherein the weight ratio of
PMIDA to AMPA is not more than 0.18:1, 0.19:1, 0.20:1, 0.21:1,
0.22:1, 0.23:1, 0.24:1, or 0.25:1, the weight percentages being on
a dry basis. Preferably the glyphosate concentration is at least
about 95 wt. % on an acid equivalent basis.
[0136] In another embodiment, a glyphosate concentrate or spray
composition is prepared from a manufactured technical grade
glyphosate product comprising at least about 90, 91, 92, 93, 94,
95, 96, 97, 98 or 99 wt. % glyphosate acid equivalent (a.e.); less
than about 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13,
0.14 or 0.15 wt. % PMIDA (on an acid equivalent basis); and a
by-product selected from not more than about 0.2, 0.3, 0.4, 0.5,
0.6, or 0.7 wt. % N-formyl glyphosate (NFG) or not more than about
0.01, 0.02 or 0.03 wt. % N-methyl iminodiacetic acid (NMIDA), the
weight percentages being on a dry basis. Preferably the glyphosate
concentration is at least about 95 wt. % on an acid equivalent
basis.
[0137] An aqueous herbicidal concentrate composition of the
invention, for example, comprises at least about 360, 370, 380,
390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510,
520, 530, 540, 550, 560, 570, 580, 590 or 600 or more grams
glyphosate per liter (on an acid equivalent basis), less than about
0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4 or 5 grams per
liter (on an acid equivalent basis) of PMIDA, and AMPA, wherein the
weight ratio of PMIDA to AMPA is not more than 0.25:1.
[0138] In another embodiment, an aqueous herbicidal concentrate
composition comprises at least about 360, 370, 380, 390, 400, 410,
420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540,
550, 560, 570, 580, 590 or 600 or more grams glyphosate per liter
(on an acid equivalent basis), less than about 0.3, 0.35, 0.4, 0.5,
0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4 or 5 grams per liter (on an acid
equivalent basis) of PMIDA, and at least one surfactant other than
an alkoxylated alkyl amine or an alkoxylated phosphate ester.
[0139] In one embodiment, the glyphosate herbicidal composition in
accordance with the present invention is in the form of an aqueous
concentrate and comprises glyphosate (e.g.,
N-(phosphonomethyl)glycine or an agronomically acceptable salt
thereof), PMIDA, a surfactant component comprising a cationic
surfactant and a metal ion safening agent which forms a complex or
salt in the composition with PMIDA or an anion formed by
deprotonation or partial deprotonation thereof. The molar ratio of
the metal ion safening agent comprising one or more metal ions to
PMIDA acid equivalent is typically at least about 0.4:1, at least
about 0.45:1, at least about 0.5:1, at least about 0.55:1, at least
about 0.6:1, at least about 0.65:1, at least about 0.7:1, at least
about 0.75:1, at least about 0.8:1, at least about 0.85:1, at least
about 0.9:1 or at least about 0.95:1. Preferably, the concentration
PMIDA in the manufactured technical grade glyphosate product from
which such concentrates are formulated is managed below about 3000
ppm, more preferably from about 1200 to about 2500 ppm, such that
effective safening of the concentrate composition is achieved at
molar ratio of metal ion safening agent to PMIDA acid equivalent of
from about 1:1 to about 6:1, from about 1:1 to about 5:1, from
about 1:1 to about 4:1, from about 1:1 to about 3:1, from about 1:1
to about 2.5:1 and preferably from about 1:1 to about 2:1.
[0140] In such aqueous concentrate formulations, the glyphosate is
preferably predominantly present in the form of an agronomically
acceptable salt of N-(phosphonomethyl)glycine selected from the
group consisting of alkali metal salts, alkylamine salts, and
mixtures or combinations thereof. In accordance with one especially
preferred embodiment, the glyphosate is predominantly present in
the form of the potassium salt and the concentration of the
glyphosate salt is at least about 360, 370, 380, 390, 400, 410,
420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540,
550, 560, 570, 580, 590 or 600 or more grams per liter on an acid
equivalent basis. Examples of preferred cationic surfactant
components for use in such concentrates include the ethoxylated
alkylamines of formula (3) and the etheramines of formulae (4) to
(6). Preferably, the metal ion safening agent comprises polyvalent
iron (e.g., Fe(III)) and may be suitably derived from ferric
sulfate and combined with citric acid as a solubilizing ligand in
the concentrate composition as described above. Alternatively, iron
citrate may be used in the formulation of such iron ion-safened
concentrates.
Glyphosate Manufacturing Processes
[0141] In a preferred process for the manufacture of glyphosate, an
aqueous solution of N-(phosphonomethyl)iminodiacetic acid (PMIDA)
is contacted with an oxidizing agent in the presence of a catalyst.
The catalyst may be, for example, a particulate activated carbon as
described by Chou in U.S. Pat. No. 4,624,937, a noble metal on
carbon catalyst as described by Ebner et al. in U.S. Pat. No.
6,417,133, or a transition metal/nitrogen composition on carbon as
described in U.S. Application Publication No. U.S. 2004/0010160 A1;
International Publication No. WO 2005/016519 A1; and in copending
and co-assigned U.S. application Ser. No. 11/357,900, filed Feb.
17, 2006, now issued as U.S. Pat. No. 8,198,479, all of which are
expressly incorporated herein by reference.
[0142] Conventionally, the oxidation reaction is conducted in one
or more stirred tank reactors wherein the catalyst is slurried in
an aqueous solution of PMIDA. The reactor(s) may be operated in
either a batch or continuous mode. Where reaction is conducted in a
continuous mode, the aqueous reaction medium may be caused to flow
through a plurality of continuous stirred tank reactors (CSTRs) in
series. The oxidizing agent is preferably molecular oxygen, though
other oxidants such as, for example, hydrogen peroxide or ozone,
may also be used. Where molecular oxygen is used, the reaction is
conveniently conducted at a temperature in the range from about
70.degree. C. to about 140.degree. C., more typically in the range
from about 80.degree. C. to about 120.degree. C. Where a
particulate noble metal catalyst is used, it is typically slurried
in the reaction solution at a concentration of from about 0.5% to
about 5% by weight.
[0143] In a series of CSTRs, the temperature of each reactor is
independently controlled, but typically each reactor is operated in
substantially the same temperature range as the other(s).
Preferably, the temperature is controlled at a level which
maintains glyphosate in solution and achieves substantial oxidation
of by-product formaldehyde and formic acid, without excessive
formation of either by-product iminodiacetic acid (IDA), which
typically results from oxidation of PMIDA, or by-product
aminomethylphosphonic acid (AMPA), which typically results from
oxidation of glyphosate. Formation of each of these by-products
tends to increase with temperature, with IDA formation occurring
principally in the first or second reactor where PMIDA
concentration is high, and AMPA being formed principally in the
last or penultimate reactor where glyphosate concentration is
relatively high. Where the oxidant is molecular oxygen, it may be
introduced independently into one or more, preferably all, of the
series of CSTRs. Typically, the oxygen pressure may be in the range
of from about 15 to about 300 psig, more typically in the range of
from about 40 to about 150 psig. Where CSTRs are arranged for
cascaded flow without intermediate transfer pumps, the pressure in
each successive CSTR is preferably lower than the pressure in the
immediately preceding CSTR so as to assure a positive differential
for promoting forward flow. Typically, oxygen pressure in the first
of a series of CSTRs is operated an a level approximating its
pressure vessel rating, while each of the remaining reactors in the
series are operated at a pressure that is within its rating but
also sufficiently below the pressure prevailing in the immediately
preceding reactor to ensure forward flow. For example, in a system
comprising three such reactors in series, the first reactor might
be operated at a pressure in the range of from about 105 to about
125 psig, the second reactor at from about 85 to about 100 psig and
the third reactor at from about 60 to about 80 psig.
[0144] A process comprising a series of CSTRs for production of
glyphosate is illustrated in FIG. 1. Catalytic oxidation of PMIDA
is conducted in a series of CSTRs 101 to 105 in each of which an
aqueous solution of PMIDA is contacted with molecular oxygen in the
presence of a particulate catalyst slurried in the aqueous medium.
A reaction slurry exiting the final CSTR 105 is directed to a
catalyst filter 107 wherein particulate catalyst is removed for
recycle to the reaction system. For recovery of glyphosate product,
filtered reaction solution is divided between a vacuum crystallizer
109, typically operated without substantial heat input (i.e.,
adiabatically) and an evaporative crystallizer 111 wherein water is
driven off the aqueous phase by transfer heat from a heat transfer
fluid such as steam. A crystallization slurry 113 produced in
vacuum crystallizer 109 is allowed to settle, and the supernatant
mother liquor 115, which contains some unreacted PMIDA, is decanted
and may be recycled to the reaction system, typically to CSTR 101.
A solid technical grade glyphosate product may be recovered from
the underflow slurry 117 exiting the decantation step. According to
the optional process alternative illustrated in FIG. 1, the
concentrated vacuum crystallizer slurry 117 underflowing from the
decantation is divided into two fractions. One fraction 119 is
mixed with the crystal slurry exiting the evaporative crystallizer
111 and directed to a centrifuge 121 which separates a solid,
crystalline technical grade glyphosate acid product that may be
used or sold in the form of the solid wet centrifuge cake. The
other vacuum crystallizer underflow slurry fraction 123 is directed
to another centrifuge 125 which separates a solid crystalline
product that is used to prepare a concentrated glyphosate salt
solution. For this purpose, solids exiting centrifuge 125 are
directed to a salt makeup tank 127 where they are neutralized with
a base such as potassium hydroxide (KOH) or isopropylamine in an
aqueous medium to a typical concentration of from about 400 to 650
grams per liter, acid equivalent.
[0145] Mother liquor 129 from centrifuge 125 typically contains
PMIDA in a proportion sufficient to justify recycle thereof to
reactor 101. Mother liquor 131 from centrifuge 121 is divided into
a purge fraction 133 which is removed from the process, and a
recycle fraction 135 which is returned to evaporative crystallizer
111.
[0146] In addition to unreacted PMIDA, the reaction solution
typically contains small proportions of other impurities that are
innocuous but generally ineffective as herbicides, and which can
compromise the crystallization step and/or reduce productivity.
These must ultimately be removed from the process, in part via
purge 133 and in part as minor components of glyphosate products.
To balance the proportion of impurities purged in fraction 133 with
those removed in the concentrated aqueous salt product, a mother
liquor transfer line 139 is provided for optional transfer of
mother liquor from line 135 to neutralization tank 127.
[0147] FIG. 2 illustrates a modest refinement of the process of
FIG. 1 wherein the crystal slurry exiting evaporative crystallizer
111 is divided between centrifuge 121 and a parallel centrifuge
137. The centrifuge wet-cake from centrifuge 121 is removed from
the process and may be utilized or sold as a solid technical grade
glyphosate product, but the wet-cake from centrifuge 137 is
directed to tank 127 for use in preparing a glyphosate salt
concentrate. The mother liquor draining from both centrifuges 121
and 137 is combined as stream 131 which is divided between purge
stream 133 and stream 135 which is recycled to the evaporative
crystallizer.
[0148] In operation of the continuous oxidation process depicted in
FIGS. 1 and 2, a slurry comprising an aqueous solution typically
comprising from about 6.5% to about 11% by weight PMIDA is
introduced continuously into CSTR 101. The aqueous reaction medium
formed in CSTR 101 may typically contain from about 2% to about 5%
by weight of a particulate noble metal catalyst suspended therein.
For example, the catalyst may comprise a bifunctional noble metal
on carbon catalyst as described in U.S. Pat. Nos. 6,417,133,
6,603,039, 6,586,621, 6,963,009, and 6,956,005 and published U.S.
Application Publication No. 2006/0020143, which are expressly
incorporated herein by reference. A source of oxygen, e.g., air, or
preferably oxygen enriched air or substantially pure oxygen, is
sparged into the aqueous reaction medium within reactor 101 at
pressure in the range from about 105 to about 125 psig and reaction
is typically conducted at a temperature in the range from about
90.degree. to about 115.degree. C. Typically, a PMIDA conversion to
glyphosate in the range of about 82% to about 85% is realized in
reactor 101. Reaction solution containing slurried catalyst exiting
CSTR 101 flows to second stage CSTR 103 which is operated under
substantially the same temperature conditions as CSTR 101, but with
oxygen sparged at an oxygen pressure in the range from about 85 to
about 100 psig. PMIDA conversion achieved at the exit of reactor
103 is typically in the range from about 90% to about 97% (i.e.,
conversion within the second reactor is from about 8% to about 15%,
basis, the PMIDA charged to reactor 101).
[0149] Reaction solution with slurried catalyst exiting CSTR 103
flows to a third CSTR 105. Oxygen is sparged into reactor 105 at a
pressure in the range of from about 60 to about 80 psig. Typically,
the temperature of the reaction solution in reactor 105 is
maintained in substantially the same range as in reactors 101 and
103. PMIDA conversion in reactor 103 is typically 3% to 5%, basis
the PMIDA entering reactor 101, resulting in an overall PMIDA
conversion in the continuous reaction system from about 97% to
about 99.5%.
[0150] Reactors 101 through 105 are vented under feed back pressure
control. In a preferred mode of operation, the flow rate of oxygen
to each reactor is controlled to establish and maintain a target
consumption of the oxygen that is introduced into the reactor in
the oxidation of PMIDA and reaction by-products such as
formaldehyde and formic acid. The proportionate consumption of
oxygen introduced into the reactor is referred to herein as the
oxygen utilization. In conventional operation, the pressure is
preferably established at a level that provides an oxygen
utilization of at least 60%, preferably at least about 80%, more
preferably at least about 90%. Consistent with the preferred oxygen
utilization, the oxygen feed is divided among a series of CSTRs
generally in proportion to the reaction rate prevailing in each of
the reactors. Preferably, the reactors are sized to provide a
residence time effective to accomplish a substantial fraction of
the conversion in the first of a series of, e.g., three CSTRs. For
example, 65% to 80% of the oxygen may be fed to the first of three
reactors, 20% to 30% to the second, and 1% to 5% to the third.
Typically, reaction in all but the last of a series of CSTRs is
mass transfer limited, i.e., pseudo zero order. Under finishing
conditions in the last reactor, the reaction is non-zero order,
e.g., approximately first order. As discussed hereinbelow, as the
catalyst mass ages, deactivates, conversion may be maintained by
increasing the oxygen flow rates, at the same or different
allocations of oxygen among reactors (e.g., in the process of FIGS.
1 and 2 by increasing the proportion of oxygen introduced into
reactor 101 or 103), to accomplish more of the conversion in the
reactors upstream of the last reactor.
[0151] Where the oxygen utilization is relatively high, especially
where it is greater than about 80% or about 90%, it has been found
that the PMIDA content of the effluent from the final reactor is
typically in the range of from about 800 to 1300 ppm on a total
reaction solution basis. Where glyphosate is recovered by
crystallization from the reaction solution in the manner described
above, the PMIDA content of the glyphosate product(s) is generally
substantially higher than in the product reaction solution exiting
reactor 105. Due to recycle of mother liquor containing PMIDA, the
aqueous crystallizer feed solutions from which glyphosate is
crystallized generally contain PMIDA in a ratio to glyphosate that
is at least 25% higher, or in various steady state operations at
least 50% higher, than the ratio of PMIDA to glyphosate in the
product reaction solution. The extent of PMIDA buildup is limited
by the volume of purge fraction 133. However, when a process of the
type illustrated in FIGS. 1 and 2 has reached substantially steady
state operation, a PMIDA range of from about 800 to about 2500 ppm
in the final reaction solution may typically translate into a
concentration of 2000 to 6000 ppm in the final glyphosate product,
provided that a purge stream is provided in which a reasonable
fraction, perhaps up to 10%, of the PMIDA contained in the reaction
solution is purged from the process. Where more than one form of
product is produced (e.g., where product is provided in both the
form of solid technical grade glyphosate product and a concentrated
solution of a glyphosate salt) the PMIDA content may vary between
the plural products, depending in part on the direction and
division of various process streams in the product recovery
scheme.
[0152] It will be understood that a variety of other schemes may be
used for the preparation of a glyphosate reaction solution by the
catalyzed oxidation of a PMIDA substrate and for recovery of a
technical grade glyphosate product(s) from a glyphosate reaction
solution in the form of a solid and/or a concentrated glyphosate
salt solution. For example, the filtered reaction solution may all
be directed to an evaporative crystallizer and the product
recovered from the crystallizer slurry in a filter or centrifuge
for use either as glyphosate acid or in the preparation of a
concentrated salt solution. In such process, the mother liquor may
be divided into a purge fraction and a fraction which is recycled
to the evaporative crystallizer. Alternatively, all or a portion of
the mother liquor which is not purged may be recycled to the
reaction system. Various oxidation reaction systems for the
catalytic oxidation of a PMIDA substrate and alternative process
schemes for recovering technical grade glyphosate product from the
oxidation reaction solution, including schemes utilizing adiabatic
vacuum crystallization, are known and described, for example, by
Haupfear et al. in U.S. Application Publication Nos. U.S.
2002/0068836 A1 and U.S. 2005/0059840 A1, the entire contents of
which are expressly incorporated herein by reference.
Modifications in PMIDA Oxidation Reaction Conditions and
Systems
[0153] In accordance with the present invention, it has been
discovered that oxygen flow to the reactor(s) may be optionally
adjusted in a manner that reduces the concentration of PMIDA in the
final reaction solution, resulting in a generally proportionate
decrease in the PMIDA content of the recovered glyphosate product
or products. Generally, it has been found that increasing oxygen
flow in one or more of the reactors enhances the conversion of
PMIDA to glyphosate. The exact relationship of oxygen flow to PMIDA
conversion varies significantly with the other conditions of the
process, with the nature of the catalyst, with catalyst age and
concentration, with batch vs. continuous operation, with product
throughput, and with the peculiarities of the configuration a
specific reactor, its oxygen feed point, agitation system and gas
flow patterns. However, those skilled in the art can readily adjust
the oxygen flow rate for a specific reactor or series of reactors
to obtain a desired response in increased conversion of PMIDA. By
way of example, where a continuous reaction system of the type
illustrated in FIG. 1 is operating at a residual PMIDA level of 800
to 1500 ppm in the reaction solution exiting CSTR 105, the PMIDA
content of the product reaction solution may be reduced to from
about 150 to about 250 ppm by a proportionate increase in the sum
of the oxygen flow rates to reactors 101 to 105 of roughly from
about 0.1 to about 2% relative to the sum of flow rates that yields
a PMIDA content of 800 ppm under otherwise identical process
conditions. Alternatively, such reduction in PMIDA content of the
product reaction solution may be achieved by increasing the flow
rate of oxygen to the last of the series of reactors, reactor 105,
by at least about 5%, typically from about 10% to about 30%
relative to the flow rate which yields a PMIDA content of 800 ppm
under otherwise identical reaction conditions.
[0154] Over an extended period of operations, the catalyst may
deactivate to the extent that desired conversion can no longer be
achieved by adjustment of oxygen flow to the last of a series of
CSTRs. However, up to a limit defined by useful catalyst life (or
at augmentation or partial replacement with fresh catalyst), the
desired conversion can still be maintained by progressively
increasing the oxygen flow to the earlier reactors, e.g., reactors
101 and 103 in FIGS. 1 and 2. Preferably, the oxygen flow rate is
increased sufficiently to actually increase the conversion in the
reaction solution exiting the penultimate reactor, so that the duty
imposed on the last reactor is reduced. Thus, the desired ultimate
conversion is obtained even though the productivity of the last
reactor per se has declined. Conversion can also be increased by
increasing residence time in the reactors. As those skilled in the
art will appreciate, an infinite number of combinations of flow
rates to the respective reactors may be available to achieve the
desired level of PMIDA in the product reaction solution.
[0155] It has further been discovered that maintaining a desired
PMIDA content in the reaction solution exiting the final reactor
can be facilitated by selection of the system for monitoring the
composition of the reaction solution. In a particularly preferred
embodiment of the invention, the composition of the reaction
solution exiting the final reactor is monitored by passing the
reaction solution, or a sample of such solution, through a device
of the type described in co-assigned U.S. provisional application
Ser. No. 60/667,783, filed Apr. 1, 2005, entitled CONTROL OF PMIDA
CONVERSION IN MANUFACTURE OF GLYPHOSATE (attorney's docket number
MTC 6911). For example, the conversion can be estimated by
cumulative heat generation arising from the oxidation of PMIDA, by
the instantaneous rate of heat generation, or combination of both.
From the instantaneous rate, the conversion and rate constant may
also be inferred in the manner described in the aforesaid
application, particularly if analyzed in combination with
laboratory kinetic data and historical operational process data.
Other methods for monitoring conversion include measuring the
cumulative or instantaneous oxygen consumption, and/or the
cumulative and/or instantaneous rate of carbon dioxide generation,
and/or a function of the power consumed in maintaining a select
current density, or a select potential difference between
electrodes immersed in the reaction solution. A device useful for
the latter purpose comprises a pair of electrodes immersed in the
reaction solution or a sample thereof, and is controlled to
maintain a select current density or impose a select voltage or
schedule of voltages between the electrodes. In the latter
instance, the device typically comprises a third electrode function
as a reference electrode for use in maintaining the desired
voltage. Where the device is controlled to maintain a select
current density, the voltage required to maintain the current is
indicative of the residual PMIDA content in the solution. As long
as PMIDA is present, and the current is established at a level
sufficient to consume C.sub.1s such as formaldehyde and formic
acid, the requisite voltage may approximate that required for the
electrochemical oxidation of PMIDA. As PMIDA is exhausted, the
voltage increases to a level effective for electrochemical
oxidation of glyphosate. Where a select voltage or schedule of
voltages is applied, the current observed at a voltage effective
for electrochemical oxidation of PMIDA is indicative of residual
PMIDA content. In the process of FIGS. 1 and 2, such an
electrochemical oxidation probe is conveniently located in the
stream exiting the catalyst filter 107, preferably following a
polishing filter downstream of the catalyst filter which is
effective for removal of catalyst fines.
[0156] In a further advantageous embodiment of the process of the
invention, cumulative or instantaneous heat generation, oxygen
consumption, or carbon dioxide generation, or an electrochemical
oxidation probe are monitored and used to estimate the conversion
in and/or composition of the reaction solution exiting the next to
last reactor (reactor 103 in FIGS. 1 and 2), and/or the third last
reactor (i.e., reactor n-2 in a series of n reactors; e.g., reactor
101 in FIGS. 1 and 3). Where an electrochemical oxidation probe is
used in the third last reactor, it is preferably operated to
maintain a target current density. By periodically reversing the
polarity, the electrodes are kept clean in the catalyst slurry
environment. Optionally, further intelligence for controlling PMIDA
levels exiting the reaction system may be provided by application
of mathematical models which project conversions based on input of
current process signals into a program based on first principles
and/or historical operating data. By these means, the process
operator, or a process management control system, can increase the
oxygen flow to the earlier reactor or reactors as the catalyst mass
deactivates, thereby reducing the demand on the final reactor and
achieving the desired conversion and residual PMIDA content in the
solution exiting the last reactor.
[0157] In a batch reaction system, the PMIDA content of the
reaction solution may optionally be reduced by extending the cycle
during which a source of oxygen is sparged into the aqueous
reaction medium. For a given operation, a conventional oxygen flow
cycle may be identified by any convenient conventional means, as,
for example, by periodic analysis of samples from the reactor.
Where performance as a function of time is reasonably consistent,
timing of the batch may be sufficient and sampling may not be
necessary. In any case, it has been discovered that, by extending
the oxygen sparging cycle by from about 2 to about 15 minutes, more
typically from about 5 to about 10 minutes, PMIDA conversion can be
increased to reduce residual PMIDA content from a range from about
275 to about 350 ppm to a range from about 50 to about 100 ppm or
even lower.
[0158] Because the oxidation reaction is exothermic, means are
provided for transfer of reaction heat from the reaction mixture in
the reactor(s) under feedback temperature control. Thus, if a
cooling fluid such as cooling tower water is passed through a heat
exchanger (e.g., cooling coils) for controlling the reaction
temperature, the extent of reaction can be estimated from the
cumulative heat dissipation over the batch cycle, as may be
determined from an integrated average of the product of cooling
fluid flow rate and temperature rise through the heat exchanger
during the course of the batch. Since the oxidation reaction is
between zero order and first order for PMIDA (Langmuir-Hinshelwood
kinetics), and the first order region is generally below 1000 ppm
PMIDA, the residual PMIDA content may also be inferred from the
residual rate of reaction at the end of the batch. As the catalyst
ages and its activity declines, the effect on first order rate
constants can be periodically tracked by sampling near the end of
the batch. In operation of a batch process, the rate and extent of
catalyst deactivation may be monitored by keeping track of "oxygen
practice," as measured by the ratio to glyphosate produced of
cumulative quantity of oxygen used to reach the target conversion.
This index, which may be expressed in kg oxygen per metric ton of
glyphosate (or alternatively in lbs. per hundredweight), increases
as the catalyst deactivates for a given PMIDA payload. A similar
index may be used for a series of CSTRs, but at higher starting and
ending values.
[0159] The achievement of a low PMIDA content in the filtered
aqueous reaction product stream by increased oxygen flow or
extended batch cycle typically involves a modest penalty in
glyphosate yield and an increase in the concentration of certain
impurities, prominently aminomethylphosphonic acid (AMPA). Where a
noble metal on carbon catalyst is used for the reaction, these
schemes may also typically result in an increased rate of
deactivation of catalyst, resulting in increased catalyst
consumption. However, the reduced PMIDA content generally affords a
benefit in the preparation of herbicidal glyphosate compositions
for the control of weeds in genetically-modified cotton crops that
outweighs the adverse effects on yield, catalyst consumption and
the minor increase in impurities.
[0160] In accordance with the invention, several additional
modifications to the oxidation reaction system have been identified
that can be used in lieu of, or in combination with increased
oxygen flow and/or extended batch cycle as described above.
[0161] Alternatively, or in addition to increasing oxygen flow to
the reactor(s), enhanced conversion of PMIDA can be achieved by
operation at relatively high reaction temperature within the
aforesaid range of from about 70.degree. to 140.degree. C., and/or
by modification of the catalyst system.
[0162] Conversion of PMIDA is promoted by operation at elevated
temperature (e.g., in the range of about 110.degree. C. or above)
typically from about 110.degree. to about 125.degree. C. Because
higher temperature leads to increased by-product formation, such as
by oxidation of glyphosate to AMPA, the temperature is preferably
not increased to more than the extent that may be necessary, either
alone or in combination with other modifications such as oxygen
flow rate, to achieve the target level of PMIDA. A significant
effect on PMIDA conversion can be achieved by operation in the
range of from about 115.degree. to about 125.degree. C., or perhaps
optimally in the range of from about 118.degree. to about
125.degree. C.
[0163] The catalyst system may be modified by an increased charge
of noble metal on carbon catalyst, by adding activated carbon to
the catalyst system, and/or by altering the selection of promoter
for the noble metal on carbon catalyst. If a fresh catalyst charge
is increased beyond a threshold level (e.g., above a concentration
in the range of from about 1.5% to about 2% by weight) the effect
may be to increase the oxidation of PMIDA to IDA rather than
glyphosate. However, while PMIDA may oxidize to IDA resulting in an
overall selectivity loss, the net effect is still to reduce the
PMIDA content of the final glyphosate product. Moreover, when a
catalyst mass has been used through a substantial number of
recycles, activity of the catalyst mass may usefully be increased
by purging some fraction of the spent catalyst and adding fresh
catalyst in its place. When this method is followed, PMIDA
conversion may be significantly enhanced without significant
formation of IDA (i.e., selectivity to glyphosate may be
substantially preserved).
[0164] An activated carbon catalyst such as the catalyst that is
described by Chou in U.S. Pat. No. 4,624,937, is highly effective
for oxidation of PMIDA to glyphosate, even if not as effective for
oxidation of by-product C.sub.1 species such as formaldehyde and
formic acid. The carbon catalyst is also relatively inexpensive
compared to the noble metal on carbon catalyst, though it is
typically consumed at a substantially higher rate. Thus, a fairly
liberal addition of carbon catalyst to either a batch reactor, or
to the last of a series of cascaded CSTRs, (e.g., in a proportion
of at least about 1.5% by weight, typically from about 2.5% to
about 3.5% by weight, basis, the noble metal on carbon catalyst
charge) can materially reduce the residual PMIDA content in the
final reaction solution.
[0165] Certain transition metals such as Bi and Te are effective as
promoters to improve the effectiveness of a noble metal on carbon
catalyst for oxidation of by-product C.sub.1 species such as
formaldehyde and formic acid. However, data indicate that the
oxidation of PMIDA may be marginally retarded by such promoters,
perhaps by directing oxygen to contact and react with C.sub.1
species in preference to PMIDA. When used either alone or in
combination with activated carbon for preparation of low PMIDA
content glyphosate, a noble metal on carbon catalyst can either
have no promoter, or have a promoter whose identity and loading is
selected to minimize any negative effect on the kinetics of the
PMIDA oxidation. In this connection, a particular reactor, such as
the final reactor in a series of CSTRs, can be dedicated to
substantial extinction of PMIDA, and the use of a catalyst which
has no promoter, or in which the promoter is selected to be
favorable to PMIDA oxidation, can be limited to the dedicated
reactor.
[0166] Because further thermal effects are minimal once a
relatively high conversion has been achieved, a finishing reactor,
such as the final reactor in a series of continuous reactors, can
readily be operated as a flow reactor (e.g., with a fixed catalyst
bed) rather than a back-mixed reactor, so as to enhance the driving
force for extinction of PMIDA. Moreover, such finishing reactor can
be added, for example, as reactor n+1 after a series of n CSTRs,
for example as the fourth reactor following reactor 105 of FIG. 1.
Optionally, the catalyst loaded in such reactor can predominantly
or exclusively comprise activated carbon.
[0167] In order to minimize residual PMIDA in the product reaction
solution exiting the final stage of a cascaded continuous stirred
tank reaction system, it is helpful to minimize short circuiting of
aqueous medium from the reactor inlet to the reactor exit. Thus, in
accordance with principles known to the art, the feed point, exit
point, baffle array, agitation pattern and agitation intensity may
be selected to minimize the extent of short circuiting. Where a
CSTR is provided with an external heat exchanger through which the
reaction mixture is circulated for removal of the heat of reaction,
the reaction mixture may conveniently be withdrawn from the reactor
at a forward flow port in the circulating line. Advantageously, the
inlet for reaction medium can be positioned in the same circulating
line downstream of the exit port by a distance sufficient to avoid
any short circuiting due to axial backmixing. For example, the exit
port can be placed in the circulating line upstream of the heat
exchanger and the inlet port can be located immediately downstream
of the heat exchanger.
[0168] In accordance with the invention, further process
modifications outside the principal PMIDA oxidation system, may be
used to reduce the PMIDA content of the finished glyphosate
product(s). Such additional modifications, as described
hereinbelow, may be used together with or lieu of any combination
of the modifications to the reaction system that are described
above.
PMIDA Purge
[0169] For example, in the process of FIG. 1, the volume of purge
stream fraction 133 can be increased relative to evaporative
crystallizer mother liquor recycle fraction 135, thus reducing the
steady state inventory of PMIDA in the glyphosate product recovery
area of the process. The extent of purge required to obtain a given
specification for a given form of glyphosate product varies
depending on the PMIDA content of the filtered reaction product
stream and the exact material balance of the overall process, and
especially the material balance of the glyphosate recovery area.
The effect of increased purge may be augmented by a more extended
wash of the separated glyphosate solids that are obtained as a
centrifuge wet-cake in centrifuges 121 and 125, or in filters or
centrifuges that may be used in alternative schemes for product
recovery. Increased wash volume is ordinarily integrated with the
purging scheme because either the wash liquor itself must be
purged; or, if the wash liquor is combined with one or more of the
recycle mother liquor streams, it marginally increases the amount
of PMIDA that must be purged from the process. In either case, the
net purge volume is generally increased by an increment
corresponding to the volume of the wash liquor. An increase of wash
volume might be achieved independently of the purge fraction where
the quality of the wash solution permits its use in preparing the
aqueous solution of PMIDA which is introduced into the reaction
system.
Allocation of PMIDA Among Plural Grades of Glyphosate
[0170] The processes as illustrated in FIGS. 1 and 2 are also
adapted for the production of different grades of glyphosate, e.g.,
one grade that has a PMIDA content less than 600 ppm for use in
glyphosate compositions for application to genetically-modified
cotton crops to inhibit PMIDA-induced necrosis, and another grade
of higher PMIDA content that is quite satisfactory for multiple
other applications. Generally, the centrifuge wet-cake produced in
centrifuge 125 has a lower PMIDA content than the wet-cake produced
in centrifuge 121 (or 137) because the mother liquor from the
vacuum crystallizer is less concentrated than the mother liquor
from the evaporative crystallizer, and because no recycle mother
liquor stream is introduced into vacuum crystallizer 109. The PMIDA
content of the solid glyphosate acid product removed from the
process by centrifuge 121 can be balanced with the PMIDA content of
the salt concentrate exiting the process from neutralization tank
127 by increasing the fraction of vacuum crystallizer slurry
underflow 117 from the decantation step that is directed to
evaporative crystallizer centrifuges 121 relative to that which is
directed to centrifuge 125 and/or by increasing the fraction of
evaporative crystallizer slurry that is directed to centrifuge 137
for production of evaporative crystallizer centrifuge wet-cake to
be incorporated into the concentrated glyphosate salt solution in
salt makeup tank 127. If desired, the PMIDA content can be
unbalanced, and a disproportionately low PMIDA content salt
concentrate prepared by minimizing the fraction of vacuum
crystallizer slurry 117 directed to centrifuge 121, and
transferring mother liquor from the evaporative crystallizer
circuit to the neutralization tank via mother liquor transfer line
139 and/or by eliminating the fraction of evaporative crystallizer
slurry that is directed to centrifuge 137.
[0171] Alternatively, a low PMIDA content solid glyphosate acid
product can be prepared by diverting PMIDA to the salt makeup tank
127. In this case, a relatively high fraction of the vacuum
crystallizer slurry underflowing the decantation step is directed
to centrifuge 121, and a high fraction of the evaporative
crystallizer slurry is sent to centrifuge 137. According to these
various process schemes, the process material balance can be
managed to contemporaneously, or indeed simultaneously, to produce
two separate glyphosate products of distinctly different glyphosate
basis PMIDA content.
[0172] As a further alternative to the preparation of low PMIDA
content glyphosate product, the product obtained during process
startup can be segregated and dedicated for use in glyphosate
composition for application to and weed control in
genetically-modified cotton crops. By starting up with water in the
evaporators, neutralization tank and process storage vessels (not
shown), the impact of PMIDA in recycle mother liquor can be avoided
immediately after startup, and kept to a modest level during the
early portion of the transient period in which the product recovery
area gravitates to steady state operation.
[0173] Further alternative process schemes for allocating residual
PMIDA among two or more glyphosate products are described by
Haupfear et al. in U.S. Application Publication No. U.S.
2005/0059840 A1, the entire text of which is expressly incorporated
herein by reference.
[0174] Whether by sequential operation, segregated operations, or
control of process material balance to simultaneously yield
different grade products, the processes of the invention can be
implemented to yield a plurality of differing grade products,
including a low PMIDA product having a glyphosate basis PMIDA
content typically less than about 1000 ppm, preferably less than
about 600 ppm, and at least 25% lower than at least one other, or
preferably any other, of such plurality. Moreover, using any one or
more of the various process stratagems described above (or below),
a low PMIDA product may be produced having a glyphosate basis PMIDA
content that is less than about 1000 ppm, or less than about 600
ppm, and at least about 50% lower, or even at least about 75%
lower, than the PMIDA content of another of the plurality of
products, or preferably any such plurality.
Ion Exchange
[0175] In a further alternative embodiment of the invention, PMIDA
may be removed from one or more process streams by ion exchange. A
variety of options may be followed in providing for removal of
PMIDA by ion exchange. For example, an ion exchange column could be
used to remove PMIDA from mother liquor as it is recycled from the
evaporative crystallizer centrifuge 121 (and/or 137) before
separation of purge fraction 133, or in recycle mother liquor
fraction 135 after separation of the purge fraction, or in stream
129 from centrifuge 125. Alternatively, or additionally, an ion
exchanger could be positioned in the filtered reaction solution
stream ahead of the point where it is divided between the vacuum
crystallizer 109 and the evaporative crystallizer 111 in FIG.
1.
[0176] In an ion exchanger, the PMIDA-bearing process stream is
contacted with an anion exchange resin, preferably an anion
exchange resin that has a greater affinity for the more strongly
acidic PMIDA anion than for the relatively more weakly acidic
glyphosate anion and for many of the other compounds in this
stream. Because the process stream from which PMIDA is to be
removed typically has a high ratio of glyphosate to PMIDA, the
resin's affinity for PMIDA should be significantly greater than its
affinity for glyphosate. Efficient separation of PMIDA is enhanced
where the affinity of the resin for PMIDA is at least two times,
three times, four times, five times, 10 times, 20 times or as much
as 100 times its affinity for glyphosate. Weakly basic exchange
resins are preferred. Functional sites of conventional weak base
anion exchange resins typically comprise secondary amine or
tertiary amines. Available anion exchange resins typically
comprise, for example, a styrene butadiene polymer having a
secondary or tertiary amine site which may be protonated in acidic
solution to function as an anion exchanger. Suitable commercially
available resins include, for example: AMBERLYST A21, AMBERLITE
IRA-35, AMBERLITE IRA-67, AMBERLITE IRA-94 (all from Rohm &
Haas, Philadelphia, Pa.), DOWEX 50.times.8-400 (Dow Chemical
Company, Midland, Mich.), LEWATIT MP-62, IONAC.TM. 305, IONAC.TM.
365 and IONAC.TM. 380 (Sybron Chemicals, Birmingham, N.J.), and
DUOLITE a-392 (Diamond Shamrock Corp., Dallas, Tex.).
[0177] A complication in removal of PMIDA by ion exchange can arise
from the presence of a substantial fraction of chlorides in the
filtered reaction solution, which tend to be concentrated somewhat
in the solution ultimately subjected to ion exchange such as
evaporative crystallizer mother liquor 131. When an acidic solution
such as mother liquor recycle solution 131 is passed over an anion
exchange resin, chloride ions are retained at the protonated amine
sites preferentially to PMIDA. Where this is the case, two columns
may typically be provided in series, with the first column
dedicated to removal of chloride ions, with either a strong or weak
base anion exchange resin, and the effluent from the first column
passed through a second column comprising a weak base exchange
resin wherein PMIDA anions are removed. Each column may be eluted
and the anion exchange resin regenerated by passage of a caustic
solution, typically sodium hydroxide (NaOH), through the
column.
[0178] The solution from which PMIDA and/or chlorides are to be
removed is passed through the column in which the desired exchange
occurs until breakthrough of the ion to be removed is observed in
the effluent from the column. Breakthrough may occur when the
entire column has reached an equilibrium level of chloride ion or
PMIDA as the case may be. As saturation is approached, the capacity
of the column for the target anion may be reduced to some extent by
the presence of the anions of components that are of comparable
acidity as the target anion, e.g., phosphate and N-formylglyphosate
(NFG). Breakthrough may be determined by any conventional means of
detection, including, for example, conductivity, absorbance of
light (254 nm), pH and the like. In a preferred method, PMIDA
breakthrough is detected by monitoring conductivity of the column
eluate. For example, as described in U.S. provisional application
Ser. No. 60/667,783 (attorney's docket number MTC 6911), a
potential may be applied between a working electrode and another
electrode immersed in the column eluate or a sample thereof, and
measurement made of a function of the power consumed in maintaining
a select current density, or a select potential difference between
the electrodes. Alternatively, the end point of an ion exchange
cycle can be practiced by volumetric control of the quantity of
aqueous solution passed through the column (i.e., the cumulative
quantity of mother liquor or other PMIDA-containing stream passed
through the anion exchange bed relative to the volume of the bed,
typically expressed in "bed volumes.").
[0179] After an ion exchange cycle is complete, the column can be
eluted to remove the anion that has been collected therein.
[0180] A column in which chlorides have been collected from a
process stream may be eluted with a caustic solution (e.g., NaOH)
to regenerate free amine sites and produce an eluate salt solution
that may typically be discarded. Interstitial caustic is removed by
washing the column with water. Unless interstitial caustic is
removed, it is recycled to the crystallizer with adverse impact on
the crystallization.
[0181] A column in which PMIDA has been collected from a process
stream may first be washed with water to displace process liquid
from the column. Thereafter, the column may be eluted with a strong
acid to remove PMIDA for recovery; and then regenerated, typically
with a caustic solution such as NaOH, and then washed with water to
remove interstitial caustic. Eluate comprising PMIDA can be
recycled to the oxidation reaction system for further conversion of
the PMIDA to glyphosate. Illustrative examples of acids that can be
used for elution of PMIDA from an ion exchange column include
strong mineral acids such as hydrochloric acid or sulfuric acid. In
various embodiments, the ion exchange resin may be contacted with a
wash solution or multiple wash solutions during a series of wash
steps subsequent to elution. Suitable wash solutions include, for
example, water, a buffer solution, a strong base such as KOH, NaOH,
or NH.sub.4OH or a weaker base such as Na.sub.2CO.sub.3.
[0182] During elution of an ion exchange column loaded with PMIDA,
the column effluent is monitored for the conjugate base of the
strong acid (e.g., chloride ion when Cl is detected in the
effluent). Upon appearance of chlorides, recycle of eluate to the
PMIDA oxidation step is terminated, and the column is washed with
water, then caustic and then again water to return it to the free
amine state. If desired, buffers and/or solvents may be used in
washing of the column after elution, but this is not ordinarily
necessary or useful.
[0183] Ion exchange can be conducted at ambient or elevated
temperature. More particularly, the mother liquor from the
evaporative crystallizer centrifuge 121 (and/or 137) may be treated
by ion exchange resin without heating or cooling prior to
introduction into the ion exchange column. Typically, this stream
has a temperature in the range of from about 45.degree. to about
85.degree. C., more typically from about 55.degree. to about
75.degree. C. Column dimensions and flow rates through the column
are governed by standard column design principles and can be
readily determined by one skilled in the art.
[0184] If desired, a third column can be provided downstream of the
PMIDA column for recovery of glyphosate by ion exchange. See, for
example, the process as described in U.S. Pat. No. 5,087,740, which
is expressly incorporated by reference herein.
[0185] In various embodiments, a still further ion exchange column
may be provided for recovery of platinum or other noble metal that
may have been leached from the catalyst used in the oxidation of
PMIDA. Such a process for recovery of noble metal by ion exchange
is described in copending and co-assigned U.S. application Ser. No.
11/273,410, filed Nov. 14, 2005, entitled RECOVERY OF NOBLE METALS
FROM AQUEOUS PROCESS STREAMS (attorney's docket number MTC 6909.1),
which is also expressly incorporated herein by reference.
Preferably, ion exchange for recovery of noble metal is conducted
upstream of the ion exchanger used for separation of PMIDA or
removal of chlorides.
[0186] In a continuous process such as that illustrated in FIG. 1,
a pair of ion exchange columns can be provided in parallel for each
ion exchange operation that is conducted as part of the process. In
this manner, one column can be used for removal of target anion
while the other is being eluted and regenerated.
[0187] Although ion exchange has been described above with
reference to ion exchange columns, the resin may alternatively be
added directly with agitation as a solid phase reagent to the
process stream from which the PMIDA (or other target anion) is to
be removed. Ion exchange operations have been described above with
reference to the continuous processes depicted in FIGS. 1 and 2.
Removal of excess PMIDA by ion exchange is also useful in a
simplified glyphosate product recovery scheme in which all product
reaction solution is directed to a single glyphosate recovery stage
such as a single evaporative crystallizer. A single crystallizer
typically may be used where the oxidation reaction is conducted in
a batch mode. In such a process, glyphosate crystals are separated
from the crystallization slurry by filtration or centrifugation,
and the mother liquor typically recycled to the crystallizer. In
extended operations, a fraction of mother liquor is purged to
remove impurities. Ion exchange for removal of PMIDA from the
mother liquor allows reduction of the purge fraction necessary to
provide a given PMIDA specification in the glyphosate product.
Also, the PMIDA which is removed can be recovered by elution as
described above and recycled to the oxidation reactor.
[0188] FIG. 3 illustrates an exemplary ion exchange system,
located, for example, in stream 131 of FIG. 1 or 2, upstream of the
purge 133. As illustrated, the system comprises three columns in
series, a platinum (or other noble metal) recovery column 201, a
chloride removal column 203 and a PMIDA removal column 205. Column
201 comprises an adsorption zone which may comprise activated
carbon, or more typically a weak base anion exchange resin, strong
base anion exchange resin, strong acid cation exchange resin weak
acid cation exchange resin, chelating resin, or in some instances,
mixtures thereof. Specific resins useful in the recovery of
solubilized platinum are described in U.S. Ser. No. 11/273,410
(attorney's docket no. MTC 6909.1), expressly incorporated herein
by reference. Preferably, a chelating resin is used. Column 203
comprises an anion exchange zone containing a resin of the type
described hereinabove for removal of chlorides, and column 205
comprises an anion exchange zone containing a resin of the type
described for the removal of PMIDA.
[0189] Although only a single column is depicted for each recovery
or removal operation in FIG. 3, typically at least a pair of
columns is provided in parallel at each stage to allow one column
to be eluted, regenerated, and washed while the other is in
operation for removal of Pt, Cl.sup.- or PMIDA, respectively.
Operating conditions for column 201 are described in U.S. Ser. No.
11/273,410. As further described in the '410 application,
breakthrough of noble metal from column 201 may be detected by
ICP-MS, ICP-OES, or AA. A simple conductivity device is effective
for determining breakthrough of chlorides from column 203 or
205.
[0190] While FIG. 3 depicts separate columns (or column pairs) in
series for chloride removal and PMIDA removal, respectively, the
two columns function as a single adsorption system so far as
adsorption phenomena are concerned, at least in the case where the
ion exchange properties of the resins used in columns 203 and 205
are substantially the same. In any case, all adsorbable components
of the solution are initially adsorbed on column 203 but PMIDA is
progressively displaced by as the column becomes loaded. PMIDA
desorbed from or passing through column 203 is adsorbed on the
anion exchange resin in column 205. When column 203 (or a
corresponding adsorption zone within a single column) becomes
loaded with chloride, the latter ions eventually break through in
the effluent from column 203 (or corresponding zone) and begin
displacing the PMIDA from column 205 (or a corresponding downstream
adsorption zone of a single column). Separating the adsorption bed
into two columns facilitates monitoring the chloride wave and
scheduling regeneration of anion exchange resin for sustained
operations. Breakthrough from column 205 may result from either
saturation of the resin therein with PMIDA or displacement of PMIDA
by chloride. In either case, breakthrough may occur before maximum
PMIDA loading is realized, with the PMIDA content of the effluent
progressively increasing as column saturation is approached, rising
to the level in the inlet mother liquor stream when saturation is
reached. Where chloride displaces PMIDA, the PMIDA loading reaches
a maximum and then begins to decline as it is displaced by
chloride. In the system depicted in FIG. 3, this conditions can be
avoided if column 203 is regenerated as soon as chloride
breakthrough is observed. In either case, process operators can
identify an optimum balance between PMIDA removal efficiency and
column loading.
[0191] Regardless of whether the chloride and PMIDA ions are
removed in physically separate adsorption beds in series or in a
single adsorption bed, the adsorption system may be considered to
comprise two distinct adsorption zones, one in which chlorides are
being adsorbed and another in which PMIDA is being adsorbed.
However, the size and location of these adsorption zones are not
static. The boundary between the zones moves as the chloride wave
advances in displacing PMIDA from the resin.
[0192] Shown at 207 is a device effective to sense breakthrough of
PMIDA from column 205. The device comprises a pair of electrodes
immersed in the stream exiting the column or a sample thereof, and
is controlled to maintain a select current density or impose a
select voltage or schedule of voltages between the electrodes.
Where the device is controlled to maintain a select current
density, breakthrough of PMIDA is reflected in a drop, typically a
relatively sharp drop in the voltage required to maintain the
select current density. Where a select voltage, or programmed
series of voltages is imposed, breakthrough of PMIDA is indicated
by a significant increase in current at a voltage that is
sufficient for electrolytic oxidation of C.sub.1s and PMIDA but not
residual glyphosate. Detailed descriptions of devices which
function on these bases are set forth in co-assigned U.S.
provisional application Ser. No. 60/667,783 (attorney's docket
number MTC 6911), which is expressly incorporated herein by
reference.
[0193] Whenever any of columns 201, 203 or 205 reaches a
breakthrough condition, introduction of mother liquor is terminated
and the adsorbed component recovered. In the case of column 205,
PMIDA may be eluted with a strong acid such as HCl. Both columns
203 and 205 may be regenerated using a caustic eluant, followed by
a water wash, as described above. The aqueous NaCl eluate may be
discarded. In the case of column 201, the noble metal component may
optionally be eluted with an eluant, e.g., an acidic eluant where
the noble metal species is present in the form of cation, or a
caustic eluant where the noble metal is present in an anion.
However, in the case of column 201, more quantitative recovery can
generally be achieved by removing the loaded resin from the column,
incinerating the resin, and recovering noble metal from the
ash.
[0194] Recovery of noble metal in column 201 is typically in the
range between about 60% and about 85%. Thus, in monitoring
operation of this column "breakthrough" is a relative term, and the
breakthrough detection device is calibrated to detect an increase
in signal above a steady state level. In any event, a portion of
the noble metal is typically lost in purge stream 133 or in the
product glyphosate salt concentrate. Where PMIDA is removed by ion
exchange via column 205, it has been found that a portion of the
noble metal passing through columns 201 and 203 is adsorbed on the
resin contained in column 205. If this column is regenerated or
washed with aqueous ammonia, the platinum is desorbed, and
ultimately lost either in the purge stream or by incorporation into
the aqueous glyphosate salt product. However, it has been
discovered that if the column is regenerated with a strong base
such as an alkali metal hydroxide, e.g., NaOH or KOH, and washed
with strong base or water, platinum species are typically not
desorbed, but remain on the column, thus allowing ultimate recovery
of this fraction of the platinum by removal and incineration of the
resin.
[0195] Disposition of the eluates from columns 203 and 205,
respectively, is as described above. The acidic eluate comprising
PMIDA is typically recycled to the reaction system. As regeneration
proceeds, the chloride content typically declines in the caustic
regeneration solution exiting the column. Advantageously, a portion
of the caustic regeneration solution, particularly that exiting the
column toward the end of the regeneration cycle, may be preserved
and used in a subsequent regeneration cycle in the same or a
parallel PMIDA removal column.
[0196] Although an anion exchange resin which has a substantially
higher affinity for PMIDA than for glyphosate is preferably
selected for column 205, some glyphosate is typically removed along
with PMIDA from the mother liquor or other solution that is
processed in the column. The incidence of glyphosate removal may be
relatively significant when the column contains fresh or freshly
regenerated resin. As PMIDA accumulates in the column, the
glyphosate fraction moves down (or in any event toward the column
exit) in a manner similar to the operation of a chromatographic
column. In an alternative embodiment of the process, the effluent
from column 205 may be monitored not only for PMIDA but also for
glyphosate. As the column becomes loaded with PMIDA, glyphosate
breaks through first. When the column is eluted, a glyphosate
fraction comes off first and may be segregated for recycle, e.g.,
to the evaporative crystallizer. Prior to elution, the column is
washed for removal of residual glyphosate caught in the
interstitial spaces between the resin beads. The glyphosate content
of the wash solution may also be sufficient to justify recycle to
the evaporative crystallizer.
[0197] Where the operation of column 205 is monitored by use of
device 207, the threshold voltage at which a significant current
density is realized may first be observed to decline to a value
reflective of the oxidation of glyphosate. Such threshold voltage
substantially prevails until PMIDA breakthrough approaches. During
elution, a similar voltage response or requirement should be
observed during elution of the glyphosate fraction which may be
directed, e.g., to a feed tank for the evaporative crystallizer.
When the voltage required to sustain a target current density
declines to a value reflective of the oxidation of PMIDA, the
eluate may be redirected for recycle to the reactor, or
alternatively to the purge.
[0198] According to a further alternative for recovery of
glyphosate, a column loaded with both glyphosate and PMIDA may be
initially eluted with a relatively weak base such as isopropylamine
("IPA") to remove the relatively weakly sorbed glyphosate in the
form of the salt. Optionally and preferably, neat liquid IPA can be
used for the elution, which produces an eluate consisting of a
relatively concentrated solution of the IPA salt of glyphosate.
This eluate may directed to neutralization and mixing tank 127 and
used directly in producing aqueous IPA glyphosate concentrates.
[0199] In accordance with a further process alternative, as
mentioned above, another column comprising an ion exchange zone
comprising a resin effective for sorption of glyphosate, typically
a further ion exchange column, can be provided downstream of column
205. This column is not shown in FIG. 3 but may be positioned to
receive the process stream that has been passed in series through
columns 203 and 205, or in series through columns 201, 203 and
205.
Finishing Reactor in Product Recovery Process
[0200] According to a further alternative, PMIDA can be removed
from product recovery process streams by catalytic oxidation to
glyphosate. In addition to or in lieu of a finishing reactor as
described above in the principal reaction train, polishing
reactor(s) can be positioned in one or more process streams within
a product recovery system of the type illustrated in FIG. 1. For
example such a reactor could be positioned in the feed stream to
evaporative crystallizer 111 (as a pre-recovery polishing reactor),
in mother liquor stream 131 exiting evaporative crystallizer
centrifuge 121 (and/or 137), or elsewhere in the process.
[0201] Such further finishing reactor can optionally be operated
with only a carbon catalyst. Moreover, since only marginal
oxidation is involved, thermal effects are minimal, making it at
least potentially advantageous to operate the reactor as a flow
reactor with a fixed bed of catalyst, thus enhancing the driving
force for substantial extinction of PMIDA. Where the reactor is
placed in stream 131, ahead of the purge stream, the effect on
overall yield of the marginal oxidation of glyphosate to AMPA is
minimal. Oxidation reaction systems for preparation of glyphosate
reaction solutions by catalytic oxidation of a PMIDA substrate
including finishing or pre-recovery polishing reactors are
described by Haupfear et al. in U.S. Application Publication No.
U.S. 2002/0068836 A1, the entire contents of which is incorporated
herein by reference.
Crystallizer Operations
[0202] Process options effective to produce a product of relatively
low PMIDA content have implications for the operation of
evaporative crystallizer 111. PMIDA has been found to function as a
solubilizer for glyphosate. Thus, where the reaction system is
operated under such conditions as to yield a filtered product
reaction solution of relatively low PMIDA content, and/or where the
filtered reaction solution is passed through a finishing reactor
for further conversion of PMIDA to glyphosate, and/or where PMIDA
is removed from recycle mother liquor by ion exchange, solubility
of glyphosate in the recycle mother liquor can be lowered. At a
given system pressure, a lower PMIDA/glyphosate ratio causes
crystallization to commence at relatively lower temperature, which
can result in fouling of process side heat exchanger surfaces in or
associated with the evaporative crystallizer.
[0203] FIG. 4 illustrates an evaporative crystallization system
modified to accommodate low PMIDA content in the feed solution
without excessive fouling of the heat exchange surfaces. In the
system of FIG. 4, crystallizer 109 comprises a vapor liquid
separator 301, an external heat exchanger 303, and an axial or
centrifugal circulation pump 305 and line 307 for circulation of
the crystallization slurry between the vapor liquid separator
through the heat exchanger. A mist eliminator 309 in the upper
portion of the vapor liquid separator helps to collect entrained
liquid and return it to the liquid phase within the separator body.
Crystallization slurry is drawn off through port 311 in the
circulation line for delivery to centrifuge 121 and optionally
centrifuge 137. Fouling of heat exchanger 303 is potentially
attributable to accumulation of glyphosate on the process side tube
surfaces, but may also be attributable to plugging of the heat
exchanger tubes with large chunks of crystalline material which may
calve off the walls of separator 301.
[0204] It may further be noted that the commencement of
crystallization at lower temperature results in an enhanced
crystallization yield. While this effect may be advantageous from
the standpoint of initial crystallizer productivity, and marginally
beneficial with regard to yield on raw materials, the higher solids
content of the circulating slurry is believed to have an adverse
effect on heat transfer. Increased solids content increases the
effective viscosity of the circulating slurry, thereby increasing
pressure drop through the heat exchanger. At a given limiting pump
head, this results in a decreased flow rate, decreased velocity
along the process side of the tube wall, and consequently decreased
heat transfer coefficients. Thus, even without any fouling or
plugging of tubes, heat transfer rates and productivity can be
compromised by the higher solids content obtained as the
crystallization temperature drops with PMIDA content.
[0205] In any event, injection of water into the circulating pump
suction imposes a sensible heat load that tends to reduce the rate
of precipitation in the tubes. Although water injection does not
reduce the steady state composition of the liquid phase in the
vapor/liquid separator, it marginally reduces the degree of
supersaturation in the liquid phase entering the heat exchanger,
and may thus marginally reduce the tendency of the tubes to foul by
further encrustation with glyphosate. Perhaps more significantly,
it reduces the solids content of the slurry passing through the
heat exchanger, thus reducing the viscosity, and contributing to
increased process side velocity and heat transfer coefficients.
[0206] Injection of water above the mist eliminator is useful in
minimizing pressure drop through the mist eliminator and
controlling the extent of crystallization on the walls of the
separator. Increasing the slurry circulation rate via pump 303
serves to reduce the temperature rise in the heat exchanger and
enhance the scouring action of the circulating slurry, further
contributing to control of fouling.
[0207] Aside from the complications which it can create in the
operation of the evaporative crystallizer, ion exchange also
functions to reduce the chloride and phosphate content of the
mother liquor circulating in the evaporative crystallization
system. Whether as a result of lower chloride and phosphate content
or otherwise, it has been found that enhanced crystal growth is
achieved in the evaporative crystallizer in operations wherein
PMIDA, and necessarily also chloride and phosphate, is removed by
ion exchange. The larger crystals thus produced have superior
dewatering properties as compared to the crystals obtained in an
evaporative crystallization system wherein a mother liquor of
relatively high PMIDA, and/or phosphate concentration circulates
between the evaporative crystallizer and centrifuge 121 or 121 and
137. Production of relatively larger crystals is advantageous in
removal of residual impurities, including PMIDA, by separation of
solids from mother liquor in the centrifuge(s) and washing of the
centrifuge cake. It has further been observed that, where the
crystallizer is operated to consistently generate relatively large
glyphosate particles, the fouling effect of reduced PMIDA content
is at least partially offset. Heat exchange surfaces are generally
less prone to fouling in an operation wherein heat is transferred
to a slurry comprising relatively large particles than in an
operation where relatively fine crystals are produced.
Programmed Control Scheme
[0208] The present invention contemplates the use of essentially
all combinations and permutations of the various measures that are
described hereinabove for reducing the PMIDA content of a
glyphosate product. In some instances, it may not be technically
feasible or economically attractive to achieve a target PMIDA
concentration by resort solely to increased oxygen flow rate,
solely to increased purge, or solely to another single process
stratagem outlined herein. Although certain process modifications
such as ion exchange, where justified, may be quite sufficient to
achieve any desired PMIDA level, there can still be advantages in
adopting ion exchange in combination with other operational
variations.
[0209] In practicing the various methods of the invention,
operational stability, economic optimization, product and emission
specification and/or other advantages and constraints may be met or
achieved by a programmed control scheme under which a combination
of various measures such as increased oxygen flow, purge
adjustment, allocation of PMIDA among plural product forms, ion
exchange conditions, process flows, reactor and crystallizer
temperatures, reactor and crystallizer pressures, etc., may be
monitored and controlled at values which achieve a target PMIDA
specification in one or more glyphosate product forms according to
an optimal or otherwise desirable operational mode. In accordance
with such a control scheme, signals conveying the current values of
various parameters and the control set points for the control loops
for such parameters may be transmitted to a programmed controller
which, in response to these inputs, may generate out put signals to
adjust the various set points according to an algorithm inscribed
in controller software. For example, the algorithm may be adapted
to achieve a target PMIDA content in a specified glyphosate product
form at minimum cost, and/or at maximum throughput, and/or to meet
other product specifications, and/or to conform to emission
standards, etc.
[0210] Such a program may be periodically adjusted as necessary to
reflect changes in raw material prices, product demand, production
scheduling, environmental conditions, etc.
Glyphosate Product
[0211] By implementation of one or more of the process
modifications and stratagems as described above, a manufactured
glyphosate product may be recovered and removed from the process in
a desired form with a PMIDA content of less than, 6,000 ppm, 5,000
ppm, 4,000 ppm, 3,000 ppm, 2,000 ppm, 1,000 ppm, 600 ppm or even
significantly lower. A glyphosate product of such low PMIDA level
can be produced, for example, in the form of a solid crystalline
glyphosate acid, or in the form of an aqueous concentrate of
glyphosate salt, such as a potassium or isopropylamine salt having
a glyphosate content of at least about 360 gpl, a.e., preferably at
least about 500 gpl, a.e., more preferably at least about 600 gpl,
a.e.
[0212] Glyphosate having a relatively low PMIDA content, e.g., not
greater than about 0.45 wt. % acid equivalent on a glyphosate,
a.e., basis, can be prepared by any of a variety of manufacturing
processes. Significant commercial advantages result from the
preparation of glyphosate by a process comprising the catalytic
oxidation of a PMIDA substrate as described in detail hereinabove.
Glyphosate obtained in this manner has a very low glyphosine
content, typically less than about 0.010 wt. % acid equivalent on a
glyphosate a.e. basis. It generally has a small but acceptable
glycine content, i.e., at least about 0.02 wt. % acid equivalent as
also computed on a glyphosate, a.e., basis. PMIDA-derived
glyphosate product may also include small, but acceptable
concentrations of a number of other by-products and impurities.
These may include for example: iminodiacetic acid or salt thereof
(IDA) in a concentration of at least about 0.02 wt. % acid
equivalent on a glyphosate, a.e., basis; N-methyl glyphosate or a
salt thereof (NMG) in a concentration of at least about 0.01 wt. %
on a glyphosate, a.e., basis; N-formyl glyphosate or a salt thereof
(NFG) in a concentration of at least about 0.010 wt. % acid
equivalent on a glyphosate, a.e., basis; iminobis
(methylenephosphonic acid) or a salt thereof (iminobis) in a
concentration of at least about 0.010 wt. % acid equivalent on a
glyphosate, a.e., basis; and N-methylaminomethylphosphonic acid
(MAMPA) or a salt thereof in a concentration of at least about
0.010 wt. % acid equivalent on a glyphosate, a.e., basis.
[0213] These relative proportions generally apply regardless of the
form of the glyphosate product, i.e., regardless of whether it is
in the form of solid state glyphosate acid or a concentrated
aqueous liquid solution comprising a glyphosate salt such as, for
example, a potassium, isopropylamine, monoammonium or diammonium
salt. Preferred aqueous concentrates comprise at least about 360
grams per liter glyphosate on an acid equivalent basis, with
proportionate minor concentrations of the common by-products and
impurities as listed above.
[0214] Further detailed limits and ranges for IDA, NMG, AMPA, NFG,
iminobis, and MAMPA are set out below. All are expressed on an acid
equivalent basis relative to glyphosate, a.e.
[0215] More typically, the IDA content may be between about 0.02
wt. % and about 1.5 wt. %, e.g., between about 0.05 wt. % and about
1.0 wt. %, on a glyphosate a.e. basis. Preferably, the IDA content
is not greater than about 0.58 wt. %, not greater than about 0.55
wt. %, or not greater than about 0.50 wt. % on the same basis. In
most operations, the product obtained has an IDA content between
about 0.1 and about 0.58 wt. %, between about 0.1 and about 0.55
wt. %, between about 0.02 and about 0.55 wt. %, or between about
0.1 and about 0.50 wt. %.
[0216] Generally, the NMG content is between about 0.02 and about
1.5 wt. %, for example, between about 0.02 and about 1.0 wt. %, or
between about 0.070 and about 1 wt. % on a glyphosate, a.e., basis.
Preferably, the NMG content is not greater than about 0.55 wt. % or
not greater than about 0.50 wt. %.
[0217] The glyphosate product also typically contains
aminomethylphosphonic acid or a salt thereof (AMPA) in a
concentration that may be incrementally higher than that of
glyphosate products which have relatively higher residual PMIDA
content. For example, the AMPA content may range between about 0.15
and about 2 wt. %, more typically between about 0.2 and about 1.5
wt. % aminomethylphosphonic acid or a salt thereof on a glyphosate,
a.e., basis. In most instances, the AMPA content is at least about
0.30 wt. % on the same basis.
[0218] The NFG content is ordinarily between about 0.01 and about
1.5 wt. %, e.g., between about 0.03 and about 1.0 wt. %, more
typically between about 0.010 and about 0.70 wt. % on a glyphosate,
a.e., basis. It is generally preferred that the NFG content be not
greater than about 0.70 wt. %, not greater than about 0.60 wt. %,
not greater than about 0.50 wt. %, not greater than about 0.40 wt.
%, or not greater than about 0.30 wt. % on the same basis.
[0219] Typically the iminobis content of the glyphosate product is
between about 0.1 and about 1.5 wt. %, e.g., between about 0.2 and
about 1.0 wt. % on a glyphosate, a.e., basis. Preferably, the
iminobis content is not greater than about 0.8 wt. %
iminobis(methylenephosphonic acid), normally between about 0.2 and
about 0.8 wt. % on the same basis.
[0220] The MAMPA content is ordinarily between 0.1 about and about
2 wt. %, e.g., between 0.15 about and about 1.0 wt. % on a
glyphosate, a.e., basis. Most typically, the MAMPA content is at
least about 0.25 wt. % MAMPA on the same basis. Most PMIDA-derived
product comprises between about 0.25 and about 0.6 wt. % MAMPA.
[0221] Although the typical levels of these various impurities and
by-products are inconsequential so far as the function, use and
handling of the glyphosate product is concerned, they serve as
markers which distinguish a product produced by catalytic oxidation
of PMIDA from glyphosate product as produced by other processes.
The presence of such impurities and by-products in the upper
portions of the above described ranges have some measurable impact
on manufacturing process yields, and thus on product manufacturing
cost.
Other Glyphosate Manufacturing Processes
[0222] Glyphosate product of low PMIDA content may also be
manufactured by processes that use substrates such as AMPA or
glycine. Each of these processes generates a profile of by-products
and impurities that is somewhat different from that of the PMIDA
oxidation process. For example, the product of the glycine process
most typically contains glyphosine in a concentration greater than
about 0.010 wt. %, more typically at least about 0.1 wt. %, and
most typically in the range of about 0.3 to about 1 wt. %, all on a
glyphosate, a.e., basis. The product of the AMPA-based process may
have a modest to significant fraction of unreacted AMPA, though the
product of the PMIDA process can have a comparable AMPA content,
especially when latter is operated to minimize residual PMIDA and
the former to minimize residual AMPA. The glycine content of the
AMPA process product is generally significantly lower than 0.02 wt.
% on a glyphosate, a.e., basis.
[0223] According to an alternative embodiment of the present
invention, glyphosate of low PMIDA content may be produced from
glycine, e.g., by a process as described in U.S. Pat. No.
4,486,359, which is expressly incorporated in its entirety herein
by reference. In this process, glycine is initially reacted with
paraformaldehyde in the presence of triethylamine to produce
N,N-bis(hydroxymethyl)glycine. The reaction is conducted in a
methanol medium, typically at MeOH reflux temperature (i.e., about
65.degree. C.). The N,N-bis(hydroxymethyl)glycine intermediate is
reacted with dimethyl phosphite to yield an ester, which the
above-mentioned patent characterizes as the methyl ester of
glyphosate. The ester is hydrolyzed in HCl to glyphosate acid. This
product generally has a glyphosine content in excess of 0.010 wt.
%, more typically between about 0.05% and about 2% on a glyphosate,
a.e., basis. Commercial sources of glycine process glyphosate may
commonly contain between about 0.2% and about 1.5% by weight
glyphosine and between about 0.05% and about 0.5% by weight
glycine, more typically between about 0.3 and about 1% by weight
glyphosine and between about 0.1 and about 0.3% by weight glycine,
all on a glyphosate, a.e., basis.
[0224] In an alternative to the process of U.S. Pat. No. 4,486,359,
Japanese Published Application Hei 9-227583 (application no.
Hei-9-6881) describes a process in which the reaction between
paraformaldehyde and glycine may be conducted in the presence of
tributylamine rather than triethylamine, and the ester intermediate
may be hydrolyzed in an alkaline medium such as NaOH rather than in
acidic medium such as HCl. The Japanese patent publication reports
that the base hydrolysis may produce a product of lower glyphosine
content than the product of the process of U.S. Pat. No.
4,486,359.
[0225] In conducting the process, a source of formaldehyde,
preferably paraformaldehyde is mixed with a reaction medium
comprising C.sub.1 to C.sub.4 alcohol at moderately elevated
temperature, tributylamine is added to the resulting solution and
the mixture preferably agitated at about 35.degree. to 50.degree.
C. for typically 30 to 60 minutes. Glycine is added to the alcohol
medium in a proportion which preferably assures a formaldehyde to
glycine molar ratio from about 1 to 5, and the glycine is
preferably completely dissolved in the medium. Preferably, the
molar ratio of tributylamine to glycine is from about 0.5 to about
3. The temperature is maintained at least about 30.degree. C.,
preferably between about 50.degree. and about 60.degree. C. for
typically about 10 to 60 minutes, resulting in reaction of glycine
with formaldehyde to form the tributylamine salt of
N-methylolglycine. A dialkylphosphite, e.g., dimethylphosphite, is
then added to the solution under agitation at elevated temperature,
preferably at least about 50.degree. C., more typically about
65.degree. to about 80.degree. C., conveniently under alcohol
reflux, preferably at a molar ratio to N-methylolglycine from about
0.6 to about 2.0. Dialkylphosphite condenses with the tributylamine
salt of N-methylolglycine to yield an ester intermediate depicted
in the Japanese patent publication as the dialkyl ester of the
tributylamine carboxylate salt of glyphosate. Addition of a strong
base such as NaOH, to this solution saponifies the ester, liberates
tributylamine and forms the Na salt of glyphosate. The reaction
mixture separates into two liquid phases, yielding an upper layer
containing tributylamine and a lower layer comprising a solution of
Na or K salt of glyphosate. Tributylamine may be recovered from the
upper layer for recycle. The lower layer may be acidified to
crystallize glyphosate acid.
[0226] In accordance with the present invention, the alkaline
hydrolysis may be conducted with a strong base comprising a desired
countercation such as, e.g., KOH, as a step in the preparation of
an aqueous concentrate of the potassium salt of glyphosate. Where
the phase separation is carried out under conditions that assure
substantially quantitative partition of tributylamine to the upper
layer, the lower layer may be used directly in the preparation of
an aqueous glyphosate concentrate comprising the potassium salt.
Alternatively, the glyphosate salt may be acidified to precipitate
glyphosate acid, and the glyphosate acid separated by filtration or
centrifugation and washed, and the washed glyphosate wet-cake
reslurried with water and base to produce the desired salt. In the
latter process, the advantage of using KOH for the conversion of
intermediate ester to glyphosate salt is diminished. Where
triethylamine is used as the alkylamine, it can be quantitatively
removed by distillation of the hydrolyzate, which may in certain
instances facilitate direct preparation of a concentrate of the
glyphosate salt of the base used for the conversion of the
intermediate ester. Preferably, the concentrate comprises at least
about 360 gpl glyphosate on an acid equivalent basis.
[0227] Regardless of whether the aqueous or solid glyphosate
concentrate is prepared from glyphosate produced by oxidation of
PMIDA or from glyphosate produced from glycine or other starting
material, the concentrates of the invention include mixed
countercation concentrates comprising any combination of
monoammonium, diammonium, isopropylamine, potassium, dipotassium,
sodium, monoethanolamine, ethylamine, ethylenediamine,
n-propylamine, hexamethylenediamine, or trimethylsulfonium salt. A
preferred combination may comprise potassium, or a mixture of
potassium and isopropylamine salts, wherein each of potassium and
isopropylamine is in a mole ratio to glyphosate between about 0.1
and about 0.9. In such a concentrate, the mole ratio of
isopropylamine to potassium may be between about 0.1 and about 0.9,
in certain embodiments between about 0.2 and about 0.8, and in
certain particular embodiments between about 0.3 and about 0.7. In
such mixed countercation concentrates, the mole ratio of the sum of
isopropylamine and potassium to glyphosate may typically be between
about 0.7 and about 1.2.
[0228] As far as is known, glyphosate has not been manufactured on
a commercial scale in the United States using tributylamine and/or
an alkaline hydrolysis process. However, it is understood that this
process may be capable of producing a glyphosate product of the
present invention, preferred embodiments of which contain
relatively low concentrations of glyphosine. For example, it is
understood that the alkaline hydrolysis process may be conducted in
a manner effective to yield a glyphosate product containing
glyphosine in a proportion between about 0.05 to about 0.8 wt. %,
about 0.05 to about 0.6 wt. %, about 0.05 to about 0.5 wt. % or
about 0.05 to about 0.4 wt. %, about 0.1 to about 0.8 wt. %, about
0.1 to about 0.6 wt. %, 0.1 to 0.5 wt. %, 0.1 to 0.4 wt. % or about
0.1 to 0.3 wt. %, basis glyphosate a.e. Such product may typically
contain glycine in a concentration between about 0.05 and about 4
wt. %, more typically between about 0.05 and about 2 wt. %, or
between about 0.1 and about 0.5 wt. %, on a glyphosate, a.e.,
basis.
[0229] As noted above, aqueous liquid concentrates comprising
agronomically acceptable salts of glyphosate preferably contain a
surfactant that promotes penetration of the herbicide into the
foliage of the plant. Cationic surfactants are generally preferred,
but nonionic surfactants and combinations of cationic and nonionic
surfactants are also advantageous. Particularly preferred cationic
surfactants include alkoxylated alkylamines, alkoxylated
etheramines, alkoxylated phosphate esters, and combinations
thereof. It will be understood that the present invention
encompasses each all of the various PMIDA-based, glycine-based and
other glyphosate products described or referred to above in
combination with such surfactants or combinations of
surfactants.
[0230] To provide a reliable commercial source of glyphosate having
a relatively low residual PMIDA content, it is necessary to either
operate the manufacturing process on a sustained basis to
consistently produce glyphosate product of low PMIDA content, or to
segregate product from designated operations in order to accumulate
commercial quantities of low PMIDA product.
[0231] Although glyphosate products having a low PMIDA content have
been incidentally produced on a transient basis during startup of a
manufacturing facility for the catalytic oxidation of PMIDA to
glyphosate, or in operation well below rated capacity, the
processes of the prior art have not been effective for the
preparation of a low PMIDA glyphosate product on a continuing basis
during steady state operations at or near capacity. Thus, each of
the various glyphosate products of the invention encompasses a lot,
run, shipment, segregate, campaign or supply of glyphosate product
as produced by a process capable of maintaining a low PMIDA content
on a continuing basis. According to the present invention, such a
lot, run, shipment, campaign, segregate or supply comprises a
quantity of solid state glyphosate acid, or concentrated aqueous
solution of glyphosate salt, comprising at least 1500 metric tons,
preferably at least about 3000 metric tons, glyphosate on a
glyphosate a.e. basis.
[0232] For purposes of this invention, a "lot" may be considered a
designated quantity of glyphosate product that is produced under
substantially consistent process conditions in a particular
manufacturing facility during a defined period of operations or
over a designated period of time. Production of the lot may be
interrupted for production of other glyphosate product or
non-glyphosate product, or purge of impurities from the process,
but not otherwise by catalyst replacement, turnaround or startup
operations. Glyphosate may be produced according to various
different processes, some of which (e.g., a process comprising the
aqueous phase catalytic oxidation of PMIDA) can be conducted in
either a batch or continuous mode in the oxidation step and/or or
in the recovery of glyphosate by crystallization thereof from an
aqueous medium. With reference to a process comprising a batch
reaction and/or batch glyphosate crystallization operation, it is
understood that a lot may comprise the product of a plurality of
batches.
[0233] A "run" is quantity of glyphosate product made in a
particular manufacturing facility in continuing or consecutive
operations over a designated period without interruption for
maintenance, catalyst replacement, or catalyst loading. It may
include both startup and steady state operations. With reference to
a batch reaction and/or batch glyphosate crystallization operation,
it is understood that a run may comprise the product of a plurality
of batches.
[0234] A "campaign" is a series of runs conducted over an
identifiable period of time during which the runs may be
interrupted by other runs not part of the campaign or by purge of
impurities, or for maintenance, but not by turnaround or catalyst
replacement. No more than one of the runs may include startup
operations; provided, however, that more than one of the runs may
comprise operation at a rate more than 30% below established
capacity. Compare the description of startup operations as set out
hereinbelow.
[0235] A "shipment" is a commercial quantity of glyphosate product
transported to a particular customer or user in either a single
unit, single combination of units, consecutive units, or
consecutive combinations of units without interruption by transport
of a commercial quantity of a glyphosate product of materially
different average PMIDA content on a glyphosate, a.e., basis to the
same user or customer. A materially different PMIDA content is
PMIDA content that is either more than 0.15 wt. % higher than the
average PMIDA content of the shipment on a glyphosate, a.e., basis,
more than 35% higher than the average PMIDA content of the shipment
on a PMIDA basis, or is above 4500 ppm on a glyphosate a.e.
basis.
[0236] A "supply" is a series of shipments that may be interrupted
by other shipments of glyphosate product to other customers or
users.
[0237] A "segregate" is a quantity of glyphosate product that is
isolated from other glyphosate product produced in the same
manufacturing facility over the same period of time (i.e., the time
during which the segregate is produced). The segregate may be
produced in different runs, and may be allocated among different
shipments or different supplies.
[0238] Startup operations are operations that are conducted in a
manufacturing facility in which glyphosate product has not
previously been produced, or directly following interruption of the
production of glyphosate product and removal of a substantial
fraction of the inventory of process liquids contained in process
equipment, with the effect of lowering the total inventory of
by-products and impurities in the process facility by at least 25
wt. %. Impurities and by-products include PMIDA, IDA, AMPA, NMG,
NFG, iminobis(methylenephosphonic acid), MAMPA, formic acid, NMIDA,
glycine and glyphosine. For purposes of this invention, operations
at a rate that is more than 30% below currently established
capacity of a manufacturing facility is also deemed within the
ambit of startup operations.
Other Definitions
[0239] Unless otherwise noted, terms and abbreviations are to be
understood according to conventional usage by those of ordinary
skill in the relevant art. Definitions of common terms in molecular
biology may also be found in Rieger et al., Glossary of Genetics:
Classical and Molecular, 5th edition, Springer-Verlag: New York,
1991; and Lewin, Genes V, Oxford University Press: New York, 1994.
The nomenclature for DNA bases as set forth at 37 CFR .sctn.1.822
is used.
[0240] "Affinity" as used herein means the tendency of an ion
exchange resin to complex with another species, such as PMIDA or
glyphosate, under the existing process conditions, including the
particular combination of acids, solvents, and other ingredients
that are present.
[0241] When a maximum or minimum "average number" is recited herein
with reference to a structural feature such as oxyethylene units or
glucoside units, it will be understood by those skilled in the art
that the integer number of such units in individual molecules in a
surfactant preparation typically varies over a range that can
include integer numbers greater than the maximum or smaller than
the minimum "average number". The presence in a composition of
individual surfactant molecules having an integer number of such
units outside the stated range in "average number" does not remove
the composition from the scope of the present invention, so long as
the "average number" is within the stated range and other
requirements are met.
[0242] A transgenic "event" is produced by transformation of a
plant cell with heterologous DNA, e.g., a nucleic acid construct
that includes a transgene of interest; regeneration of a population
of plants resulting from the insertion of the transgene into the
genome of the plant cell, and selection of a particular plant
characterized by insertion into a particular genome location. The
term "event" also refers to the original transformant plant and
progeny of the transformant that include the heterologous DNA.
[0243] "Exogenous" refers to materials originating from outside of
an organism or cell. This typically applies to nucleic acid
molecules used in producing transformed or transgenic host cells
and plants.
[0244] "Fruiting branch" refers to a reproductive branch of a
cotton plant upon which the fruit (boll) appears and typically
arises at the fourth through eighth plant node.
[0245] The term "gene" refers to chromosomal DNA, plasmid DNA,
cDNA, synthetic DNA, or other DNA that encodes a peptide,
polypeptide, protein, or RNA molecule, and regions flanking the
coding sequence involved in the regulation of expression.
[0246] "Glyphosate-tolerant" refers to a plant exhibiting reduced
phytotoxic effects from application of glyphosate (e.g.,
N-(phosphonomethyl)glycine or a salt thereof) on the plant.
[0247] Herbicidal effectiveness is one of the biological effects
that can be enhanced through this invention. "Herbicidal
effectiveness," as used herein, refers to any observable measure of
control of plant growth, which can include one or more of the
actions of (1) killing, (2) inhibiting growth, reproduction or
proliferation, and (3) removing, destroying, or otherwise
diminishing the occurrence and activity of plants. The herbicidal
effectiveness data set forth herein report "control" as a
percentage following a standard procedure in the art which reflects
a visual assessment of plant mortality and growth reduction by
comparison with untreated plants, made by technicians specially
trained to make and record such observations. In all cases, a
single technician makes all assessments of percent control within
any one experiment or trial. Such measurements are relied upon and
regularly reported by Monsanto Company in the course of its
herbicide business.
[0248] "Heterologous DNA" refers to DNA from a source different
than that of the recipient cell.
[0249] "Homologous DNA" refers to DNA from the same source as that
of the recipient cell.
[0250] "Layby" refers to the growth point at which a final
herbicide ground application is made that is designed to eliminate
or suppress weeds until harvest.
[0251] "Node" refers to a point along the main cotton plant stem
from which vegetative and fruiting branches originate.
[0252] When used in the context of a surfactant or a glyphosate
salt, "predominantly" means at least about 50%, preferably at least
about 75% and more preferably at least about 90%.
[0253] A "recombinant" nucleic acid is made by an artificial
combination of two otherwise separated segments of sequence, e.g.,
by chemical synthesis or by the manipulation of isolated segments
of nucleic acids by genetic engineering techniques.
[0254] The term "recombinant DNA construct" or "recombinant vector"
refers to any agent such as a plasmid, cosmid, virus, autonomously
replicating sequence, phage, or linear or circular single-stranded
or double-stranded DNA or RNA nucleotide sequence, derived from any
source, capable of genomic integration or autonomous replication,
comprising a DNA molecule that one or more DNA sequences have been
linked in a functionally operative manner. Such recombinant DNA
constructs or vectors are capable of introducing a 5' regulatory
sequence or promoter region and a DNA sequence for a selected gene
product into a cell in such a manner that the DNA sequence is
transcribed into a functional mRNA that is translated and therefore
expressed. Recombinant DNA constructs or recombinant vectors may be
constructed to be capable of expressing antisense RNAs, in order to
inhibit translation of a specific RNA of interest.
[0255] "Regeneration" refers to the process of growing a plant from
a plant cell (e.g., plant protoplast or explant).
[0256] "Transcription" refers to the process of producing an RNA
copy from a DNA template.
[0257] "Transformation" refers to a process of introducing an
exogenous nucleic acid sequence (e.g., a vector, recombinant
nucleic acid molecule) into a cell or protoplast that exogenous
nucleic acid is incorporated into a chromosome or is capable of
autonomous replication.
[0258] "Transformed" or "transgenic" refers to a cell, tissue,
organ, or organism into that has been introduced a foreign nucleic
acid, such as a recombinant vector. A "transgenic" or "transformed"
cell or organism also includes progeny of the cell or organism and
progeny produced from a breeding program employing such a
"transgenic" plant as a parent in a cross and exhibiting an altered
phenotype resulting from the presence of the foreign nucleic
acid.
[0259] The term "transgene" refers to any nucleic acid sequence
nonnative to a cell or organism transformed into said cell or
organism. "Transgene" also encompasses the component parts of a
native plant gene modified by insertion of a nonnative nucleic acid
sequence by directed recombination.
[0260] "Vector" refers to a plasmid, cosmid, bacteriophage, or
virus that carries foreign DNA into a host organism.
[0261] Following are Examples presented to illustrate the present
invention and are not intended to limit the scope of this
invention. The examples will permit better understanding of the
invention and perception of its advantages and certain variations
of execution.
EXAMPLES
[0262] The following Examples are presented to illustrate the
present invention and are not intended to limit the scope of this
invention. The examples will permit better understanding of the
invention and perception of its advantages and certain variations
of execution. All glyphosate concentrations are on a glyphosate
acid equivalent (a.e.) basis and all concentrations are on a weight
basis unless stated otherwise.
[0263] In the following Examples 1, M1-M4, AO1, H1, H2, D1, M9 and
M10, greenhouse tests were conducted to evaluate the relative
effectiveness of compositions in reducing PMIDA-induced necrosis in
ROUNDUP READY FLEX cotton. Compositions for comparative purposes
included the following: [0264] Composition A: which consists of
approximately 37.2% a.e. by weight of glyphosate IPA salt in
aqueous solution together with approximately 11.7% surfactant. The
surfactant was a blend of an alkoxylated alkylamine and an
alkoxylated phosphate ester. The IPA salt of glyphosate was made
from a technical grade glyphosate having <100 ppm PMIDA (dry
weight basis) resulting in non-detectable levels of PMIDA level in
the composition. [0265] Composition B: which consists of
approximately 39.6% a.e. by weight of glyphosate potassium salt in
aqueous solution together with approximately 10% surfactant. The
surfactant was a blend of alkoxylated coco and tallow amines. The
potassium salt of glyphosate was made from a technical grade
glyphosate having <100 ppm PMIDA (dry weight basis) resulting in
non-detectable levels of PMIDA level in the composition. [0266]
Composition C: which contains approximately 37.2% a.e. by weight of
glyphosate IPA salt in aqueous solution together with approximately
12% surfactant. The surfactant was a blend of an alkoxylated
alkylamine and an alkoxylated phosphate ester. The composition
contained 280 ppm PMIDA, equivalent to approximately 720 ppm PMIDA
(dry weight basis) in the technical grade glyphosate from which the
composition was prepared. [0267] Composition D: sold by Monsanto
Company as ROUNDUP WEATHERMAX and containing approximately 39.9%
a.e. by weight of glyphosate potassium salt in aqueous solution.
The PMIDA concentration was determined to be 1890 ppm, equivalent
to approximately 4760 ppm PMIDA (dry weight basis) in the technical
grade glyphosate from which the composition was prepared. [0268]
Composition E: which contains approximately 37.2% a.e. by weight of
glyphosate IPA salt in aqueous solution together with approximately
11.7% surfactant. The surfactant was a blend of an alkoxylated
alkylamine and an alkoxylated phosphate ester. The IPA salt of
glyphosate was made from a technical grade glyphosate having 1880
ppm PMIDA (dry weight basis) resulting a PMIDA level in the
composition of 730 ppm. [0269] Composition F: sold by Monsanto
Company as ROUNDUP WEATHERMAX and containing approximately 39.4%
a.e. by weight of glyphosate potassium salt in aqueous solution.
The PMIDA concentration was determined to be 550 ppm, equivalent to
approximately 1340 ppm PMIDA (dry weight basis) in the technical
grade glyphosate from which the composition was prepared. [0270]
Composition G: was prepared by blending two samples of commercial
ROUNDUP WEATHERMAX sold by Monsanto Company containing glyphosate
potassium salt in aqueous solution. The blend comprised
approximately 56.4% of a sample containing 0.085% PMIDA and 43.6%
of another sample containing 0.174% PMIDA. The resulting blend
contained 0.1238% PMIDA, equivalent to approximately 0.300% PMIDA
(dry weight basis) in the technical grade glyphosate from which the
samples were prepared. [0271] Composition H: sold by Monsanto
Company as ROUNDUP WEATHERMAX and containing approximately 39.5%
a.e. by weight of glyphosate potassium salt in aqueous solution and
0.205% PMIDA, equivalent to approximately 0.498% PMIDA (dry weight
basis) in the technical grade glyphosate from which the composition
was prepared. [0272] Composition I: sold by Monsanto Company as
ROUNDUP WEATHERMAX and containing approximately 39.8% a.e. by
weight of glyphosate potassium salt in aqueous solution. The PMIDA
concentration was determined to be 1740 ppm, equivalent to
approximately 4190 ppm PMIDA (dry weight basis) in the technical
grade glyphosate from which the composition was prepared.
[0273] For greenhouse testing of the glyphosate concentrates, 30 mL
spray solutions were prepared as follows:
1. A stock solution was prepared for each concentrate sprayed by
adding 14.502 g of concentrate to 15.50 g de-ionized (DI) water. 2.
From the stock solution, the following dilutions were made to
prepare the actual spray solution (total volume of 30 mL).
TABLE-US-00006 Stock Solution Rate Desired (mL) DI Water (mL) 1X
(1260 g/ha) 2.11 27.89 2X (2520 g/ha) 4.22 25.78 4X (5040 g/ha)
8.43 21.57
Greenhouse Testing
[0274] The following greenhouse testing procedure provides a highly
reproducible assay for showing PMIDA-induced necrosis in ROUNDUP
READY FLEX cotton and was used for evaluating compositions of the
Examples to determine their effectiveness in reducing the necrosis.
[0275] 1. Two seeds of a ROUNDUP READY FLEX cotton variety were
planted in six inch round plastic pots containing a commercially
available potting mix (Redi-Earth), supplemented with fertilizer
(Osmocote 14-14-14 slow release, 100 g/ft.sup.3). [0276] 2. Pots
were then placed in a greenhouse with the following conditions:
33.degree. C. day/21.degree. C. night, variable relative humidity,
and 14-hour day-length. Water was provided as needed through
sub-irrigation. [0277] 3. Upon emergence plants were thinned to one
per pot. [0278] 4. Plants were grown for 21-25 days in order to
achieve a minimum growth stage of four true leaves (five-six leaves
was preferred). [0279] 5. Plants were then transferred to a growth
chamber with the following conditions: [0280] 27.degree. C./60%
relative humidity day, 15.degree. C./80% relative humidity night,
and 14-hour day-length. Plants were maintained in these conditions
for forty-eight hours. [0281] 6. Plants were removed from the
growth chamber for an application of glyphosate with a known level
of PMIDA. Applications were made utilizing a standard research
track sprayer with a single spray nozzle (flat fan even spray tip).
The sprayer was calibrated to deliver ninety-four liters of spray
solution per hectare at a spray pressure of 165 kPa. Glyphosate
application rates varied depending upon the objectives of the test,
but typically were 1260, 2520 and 5040 g/ha which are,
respectively, 1.times., 2.times. and [0282] 4.times. of the highest
proposed field use rates on ROUNDUP READY FLEX cotton. When
applications were complete the plants were returned to the growth
chamber for another forty-eight hour incubation under the
conditions listed in number 5 above. [0283] 8. Plants were
evaluated at this point, two days after treatment (2 DAT), with a
visual assessment of percent necrosis (tissue death) relative to an
untreated check plant. Maximum injury was evident at this time
point. [0284] 9. Resulting assessment data was statistically
evaluated by least significant difference (LSD). The LSD is a valid
statistical test procedure for evaluating multiple comparisons. The
magnitude of the LSD value is related to the variability across
replicates for each comparison. The greater the variability among
replicates the higher the LSD value. Comparisons are thus made
between mean values generated across replicates. The LSD, typically
provided as a 95% confidence limit (LSD 0.05), specifies the
minimum degree of difference between mean comparisons that would be
considered statistically significant. In other words one is 95%
sure that this minimum difference is statistically valid. For
example, where Treatment A mean value is 10, Treatment B mean value
is 15, and Treatment C mean value is 20. Calculated LSD (0.05) is
7.2. The difference between Treatment A and Treatment C would be
considered statistically significant, whereas Treatment B would not
be considered statistically different from either Treatment A or
Treatment C.
Example 1
[0285] Aqueous concentrate compositions were prepared containing
PMIDA at known concentrations. For composition A-1, 0.05 g of dry
PMIDA (99% assay) were added to 100 g of composition A and stirred
until the PMIDA was dissolved. PMIDA concentrations reported in
these Examples were determined or confirmed by high-pressure liquid
chromatography (HPLC) analysis in accordance with the procedure in
Example 3 below. Compositions A-2 and A-3 were prepared in like
manner using 0.15 g and 0.20 g PMIDA, respectively.
TABLE-US-00007 TABLE 1a PMIDA g/ha % necrosis (2 DAT) Composition
(1X, 2X, 4X rates) 1260 g/ha 2520 g/ha 5040 g/ha A nd, nd, nd* 0 0
4 C 0.95, 1.90, 3.79 0 0 15 A-1 1.69, 3.39, 6.77 0 6 65 E 2.47,
4.95, 9.89 0 25 66 A-2 5.08, 10.16, 20.3 4 40 83 D 5.97, 11.9, 23.9
9 51 79 A-3 6.77, 13.6, 27.1 9 61 83 LSD (0.05) 4.4 9.2 8.8 *nd =
not detected
[0286] Results show a clear titration effect as increasing levels
of PMIDA cause a proportionate rise in necrosis. Maximum necrosis
appears to reach a plateau at the 80-85% range as noted with the
highest application rate and higher levels of PMIDA.
Example M1
[0287] Spray solutions for glyphosate application rates of 2520 and
5040 g/ha were prepared using composition D. All metal salts were
tank-mixed at a glyphosate:metal salt weight ratio of 10:1. For
each spray solution, the amount of metal salt required to give the
10:1 ratio was dissolved in an equal amount of water. This 50% w/w
metal salt solution was then mixed with the requisite amount of
composition D and water to provide the desired volume of spray
solution. This resulted in Metal:PMIDA molar ratios as follows:
TABLE-US-00008 Metal:PMIDA Metal Salt CAS Number Molar Ratio Ferric
chloride 7705-08-0 29.6:1 Nickel sulfate hexahydrate 10101-97-0
18.2:1 Aluminum chloride 7784-13-6 19.9:1 hexahydrate Cupric
Nitrate (2.1) hydrate 19004-19-4 20.6:1 Zinc sulfate heptahydrate
7446-20-0 16.7:1 Magnesium sulfate 10034-99-8 19.5:1 heptahydrate
Calcium chloride (anhydrous) 10043-52-4 43.2:1
TABLE-US-00009 TABLE M1a Necrosis Reduction Relative % necrosis (2
DAT) to Control Glyphosate (g/ha) 2520 5040 2520 5040 PMIDA (g/ha)
Tank-mix Additive 11.9 23.9 11.9 23.9 None 38 78 na* na Ferric
chloride 0 2 100% 97% Nickel sulfate 4 28 89% 64% Aluminum chloride
2 23 95% 71% Cupric Nitrate 3 25 92% 68% Zinc sulfate 10 54 74% 31%
Magnesium sulfate 46 73 0% 6% Calcium chloride 26 73 32% 6% LSD
(0.05) 6.2 8 *na = not applicable
[0288] Several of the metal salts significantly reduce necrosis at
both application rates. These included nickel, zinc, aluminum,
copper, and iron. Calcium and magnesium, known glyphosate
antagonists, had relatively little impact on the degree of
necrosis.
Example M2
[0289] An aqueous concentrate composition containing Iron(III)
Citrate at known Iron:PMIDA molar ratios was prepared from
composition F as follows:
TABLE-US-00010 Iron:PMIDA Molar Ratio Composition F (g) Iron(III)
Citrate (g) 1.5:1 99.882 0.118 2.5:1 99.804 0.196 3.5:1 99.725
0.275
[0290] Composition D containing 1890 ppm PMIDA and no iron was used
as a control.
TABLE-US-00011 TABLE M2a % necrosis Necrosis Reduction (2 DAT)
Relative to Control Glyphosate (g/ha) 1260 2520 5040 1260 2520 5040
Iron:PMIDA PMIDA (g/ha) (molar ratio) 1.76 3.52 7.04 1.76 3.52 7.04
No Iron 9 34 71 na na na 1.5:1 0 2 16 100% 94% 77% 2.5:1 0 0 11
100% 100% 85% 3.5:1 0 1 9 100% 97% 87% LSD (0.05) 1.6 3.4 7.5
[0291] Previous studies have shown that a formulation with PMIDA at
549 ppm will produce necrosis of 60-65% at the high application
rate.
[0292] An aqueous concentrate composition containing Iron(III)
Citrate at known Iron:PMIDA molar ratios was prepared from
composition G as follows:
TABLE-US-00012 Iron:PMIDA Molar Ratio Composition G (g) Iron(III)
Citrate (g) 1.5:1 99.735 0.265 2.5:1 99.559 0.441 3.5:1 99.484
0.616
[0293] Composition D containing 1890 ppm PMIDA and no iron was used
as a control.
TABLE-US-00013 TABLE M2b % necrosis Necrosis Reduction (2 DAT)
Relative to Control Glyphosate (g/ha) 1260 2520 5040 1260 2520 5040
Iron PMIDA (g/ha) citrate:PMIDA 3.95 7.90 15.8 3.95 7.90 15.8 No
Iron 9 34 71 na na na 1.5:1 0 3 30 100% 91% 58% 2.5:1 0 1 18 100%
97% 75% 3.5:1 0 1 11 100% 97% 85% LSD (0.05) 1.6 3.4 7.5
[0294] Previous studies have shown that a formulation with PMIDA at
1238 ppm will produce necrosis at slightly lower levels than that
of composition D at all three application rates.
[0295] An aqueous concentrate composition containing Iron(III)
Citrate at known Iron:PMIDA molar ratios was prepared from
composition H as follows:
TABLE-US-00014 Iron:PMIDA Molar Ratio Composition H (g) Iron(III)
Citrate (g) 1.5:1 99.562 0.438 2.5:1 99.272 0.728 3.5:1 98.984
1.016
[0296] Composition D containing 1890 ppm PMIDA and no iron was used
as a control.
TABLE-US-00015 TABLE M2c % necrosis Necrosis Reduction (2 DAT)
Relative to Control Glyphosate (g/ha) 1260 2520 5040 1260 2520 5040
Iron PMIDA (g/ha) citrate:PMIDA 6.54 13.08 26.16 6.54 13.08 26.16
No Iron 9 34 71 na na na 1.5:1 0 18 43 100% 47% 39% 2.5:1 0 2 31
100% 94% 56% 3.5:1 0 0 30 100% 100% 58% LSD (0.05) 1.6 3.4 7.5
[0297] Previous experience has shown that the composition with 2050
PMIDA will cause slightly more necrosis than composition D with
1890 ppm PMIDA.
Example M3
[0298] An aqueous concentrate composition containing iron(III)
citrate in a 2.5:1 molar ratio with PMIDA was prepared by mixing
together 99.559 g of composition G and 0.441 g iron(III)
citrate.
[0299] An aqueous concentrate composition containing iron(III)
sulfate plus citric acid having an iron:PMIDA molar ratio of 2.5:1
was prepared by first dissolving 15.638 g iron(III) sulfate
pentahydrate (CAS Number 15244-10-7) into 46.48 g of a 50% aqueous
solution of citric acid to make an "iron sulfate+citric acid"
premix. Then 1.381 g of the premix was added drop-wise to 98.619 g
composition G while stirring continuously.
[0300] An aqueous concentrate composition containing iron(III)
ethylenediaminetetraacetic acid having an iron:PMIDA molar ratio of
2.5:1 was prepared by mixing together 99.434 g of composition G and
0.566 g iron(III) EDTA sodium salt hydrate (CAS Number
15708-41-5).
TABLE-US-00016 TABLE M3a % necrosis Necrosis Reduction (2 DAT)
Relative to Control Glyphosate (g/ha) 1260 2520 5040 1260 2520 5040
PMIDA (g/ha) Iron Addition 3.95 7.90 15.8 3.95 7.90 15.8 None 9 34
71 na na na Iron citrate 0 1 18 100% 97% 75% Iron sulfate + citric
acid 0 2 20 100% 94% 72% Iron + EDTA 0 11 39 100% 68% 45% LSD
(0.05) 1.6 3.4 7.5
[0301] There was no significant difference between iron citrate and
iron sulfate plus citric acid relative to the reduction in necrosis
at any application rate. Iron plus EDTA was significantly less
effective.
Example M4
[0302] The metal salt compositions in this Example were prepared as
in Example M3 except that the metal salts were added to composition
I which has 1740 ppm PMIDA. Mixtures were prepared containing
1.5:1, 2.5:1 or 3.5:1 Metal:PMIDA molar ratios.
TABLE-US-00017 TABLE M4a % necrosis Necrosis Reduction (2DAT)
Relative to Control Glyphosate (g/ha) 1260 2520 5040 1260 2520 5040
PMIDA (g/ha) Metal Addition metal:PMIDA 5.51 11.0 22.0 5.51 11.0
22.0 None 6 43 63 na na Na zinc sulfate + citric acid 1.5:1 2 40 67
67% 7% 0% zinc sulfate + citric acid 2.5:1 1 28 67 83% 35% 0% zinc
sulfate + citric acid 3.5:1 4 23 60 33% 47% 5% zinc oxide + citric
acid 1.5:1 9 47 63 0% 0% 0 zinc oxide + citric acid 2.5:1 3 43 72
50% 0% 0% zinc oxide + citric acid 3.5:1 1 38 57 83% 12% 10% Ferric
sulfate + citric acid 1.5:1 0 20 57 100% 53% 10% ferric sulfate +
citric acid 1.5:1 blended with zinc oxide + citric acid 2.5:1 0 8
60 100% 81% 5% LSD (0.05) 3.1 9.2 10.4
[0303] Ferric sulfate plus citric acid was significantly more
effective in reducing necrosis than either zinc sulfate plus citric
acid or zinc oxide plus citric acid. Ferric sulfate plus citric
acid and zinc sulfate plus citric acid combined in the same
formulation showed a significantly greater degree of necrosis
reduction at the 2520 g/ha glyphosate application rate than ferric
sulfate plus citric acid alone.
Example AO1
[0304] Spray solutions for glyphosate application rates of 2520 and
5040 g/ha were prepared using composition D. All antioxidants were
tank-mixed at a glyphosate:antioxidant weight ratio of 10:1. This
resulted in an antioxidant:PMIDA weight ratio of 22:1. The sodium
sulfite and L-ascorbic acid were added to the spray solutions as
solids. Butylated hydroxy anisole and butylated hydroxyl toluene
were added as 33% solutions in 2-ethyl-1-hexanol. The hydroquinone
was added as a 33% solution in ethanol and the resorcinol was added
as a 50% aqueous solution.
TABLE-US-00018 TABLE AO1a Necrosis Reduction % necrosis (2 DAT)
Relative to Control Glyphosate (g/ha) 2520 5040 2520 5040 PMIDA
(g/ha) Tank-mix Additive 11.9 23.9 11.9 23.9 None 49 78 na na
butylated hydroxy anisole 10 55 80% 29% butylated hydroxy toluene
10 60 80% 23% Hydroquinone 15 74 69% 5% Resorcinol 14 61 71% 22%
L-ascorbic acid 33 78 33% 0% Sodium sulfite 30 83 39% 0% LSD (0.05)
6.1 7.8
[0305] All antioxidants significantly reduced necrosis at the 2520
g a.e./ha application rate. Butylated hydroxy anisole, butylated
hydroxy toluene, and resorcinol also significantly reduced necrosis
at the higher application rate.
Example H1
[0306] Spray solutions for glyphosate application rates of 2520 and
5040 g/ha were prepared using composition D. Additionally, urea
(50% w/w solution) or glycerin were added to the spray solution on
a % volume/volume (v/v) basis.
TABLE-US-00019 TABLE H1a Necrosis Reduction Relative % Necrosis (2
DAT) to Control Glyphosate (g/ha) 2520 5040 2520 5040 PMIDA (g/ha)
Tank-mix Additive 11.9 23.9 11.9 23.9 Study 1 None 33 76 na na
glycerin 2% v/v 29 65 12% 14% glycerin 4% v/v 18 45 45% 41% LSD
(0.05) 6.4 9.5 Study 2 None 28 86 na na glycerin 4% v/v 5 70 82%
19% urea 8% v/v 18 75 36% 13% LSD (0.05) 7 7.8
[0307] Glycerin (4% v/v) and urea (8% v/v) significantly reduced
necrosis in ROUNDUP READY FLEX cotton.
Example H2
[0308] Various proprietary additives were used in the compositions
of this Example. They may be identified as follows:
TABLE-US-00020 Trade Name Chemical Description Surfynol 104A
tetramethyl-6-decyne-4,7-diol Surfonic ADA-170 ethylenediamine
ethoxylate Tetronic 304 ethylenediamine ethoxylate/propoxylate
Pluronic L64 EO/PO block copolymer Agrimul PG 2069 decyl
polyglucose
[0309] Spray solutions for glyphosate application rates of 2520 and
5040 g/ha were prepared using composition D. All tank-mix additives
were tested at a glyphosate:additive weight ratio of 10:1. Tank-mix
additives were added to the spray solution in neat form except for
the following:
TABLE-US-00021 Tank-mix Additive Form Added to Spray Solution
Polyethylene glycol 900 50% aqueous solution Surfynol 104A 50%
solution in ethyl hexyl alcohol Agrimul PG 2069 50% aqueous
solution Corn syrup (light) 50% aqueous solution
trimethylol-propane 50% aqueous solution
TABLE-US-00022 TABLE H2a % Necrosis Necrosis Reduction (2 DAT)
Relative to Control Glyphosate (g/ha) 2520 5040 2520 5040 PMIDA
(g/ha) Tank-mix Additive 11.9 23.9 11.9 23.9 None 46 79 na na
propylene glycol 49 81 0% 0% dipropylene glycol 45 80 2% 0%
Ethylene glycol 40 78 13% 1% Diethylene glycol 28 73 39% 8%
triethylene glycol 40 75 13% 5% polyethylene glycol 200 35 71 24%
10% polyethylene glycol 900 31 75 33% 5% 2-methyl-2,4-pentanediol
34 73 26% 8% 1,4-butanediol 28 73 39% 8% 3-hexyne-2,5-diol 33 80
28% 0% Surfynol 104A 23 73 50% 8% Surfonic ADA-170 33 73 28% 8%
Tetronic 304 45 80 2% 0% Triethanolamine 34 76 26% 4%
Triisopropanolamine 49 84 0% 0% Pluronic L64 50 76 0% 4% Agrimul PG
2069 36 80 22% 0% Glycerol propoxylate, 38 78 17% 1% mw 260
(1PO/OH) Corn syrup (light) 55 86 0% 0% trimethylol-propane 53 84
0% 0% LSD (0.05) 8.8 6.6
[0310] Several of these additives significantly decreased necrosis
at the 2520 g/ha application rate. These included diethylene
glycol, polyethylene glycol 200, polyethylene glycol 900,
2-methyl-2,4-pentanediol, 1,4-butanediol, 3-hexyne-2,5-diol,
Surfynol 104A, Surfonic ADA-170, triethanolamine, and Agrimul PG
2069.
Example D1
[0311] Spray solutions for glyphosate application rates of 2520 and
5040 g/ha were prepared using composition D. Dyes were tested at a
glyphosate: dye weight ratio of 10:1, 100:1 or 1000:1. The dyes
were added to the spray solution as aqueous solutions with the
following concentrations: FD&C Yellow #5 and FD&C Blue #1
were at 15% while the remaining dyes were at 10%.
TABLE-US-00023 TABLE D1a % necrosis Necrosis Reduction (2 DAT)
Relative to Control Glyphosate (g/ha) 2520 5040 2520 5040 PMIDA
(g/ha) Tank-mix Additive glyphosate:dye 11.9 23.9 11.9 23.9 Study 1
None 49 78 na na FD&C Yellow #5 10:1 2 35 96% 55% LSD (0.05)
6.1 7.8 Study 2 None 38 78 na na FD&C Yellow #5 10:1 6 38 84%
51% FD&C Yellow #5 100:1 31 55 18% 29% FD&C Yellow #5
1000:1 28 69 26% 12% FD&C Blue #1 10:1 13 46 66% 41% LSD (0.05)
6.2 8 Study 3 None 54 73 na na FD&C Red #40 100:1 48 75 11% 0%
FD&C Red #33 100:1 51 75 6% 0% FD&C Violet #1 100:1 34 75
37% 0% Fast Green FCF 100:1 53 78 2% 0% Methylene Blue 100:1 28 54
48% 26% LSD (0.05) 11.6 13.2
[0312] Results indicate that dyes in the spray solution that absorb
light in the visible light spectrum can decrease necrosis induced
by PMIDA.
Example M5
[0313] A potassium glyphosate formulation containing iron (III)
citrate to mitigate the adverse effects of PMIDA is prepared by
simply mixing the following ingredients in a 250 ml beaker. The
mixture becomes homogeneous in a few minutes at 23.degree. C.
TABLE-US-00024 Weight Added Ingredient (grams) Description
Potassium Glyphosate 84.2 58% K salt of glyphosate Salt Concentrate
acid in water, containing 47.387% a.e. glyphosate, 0.1974% PMIDA
Blend of alkoxylated 10.0 Proprietary Blend coco and tallow amines
Agnique DFM 111S 0.0075 A silicone defoamer from Cognis
Corporation, Cincinnati, Ohio Iron (III) Citrate 0.713 (CAS Number
3522-50-7, containing 17.2% iron) from Sigma-Aldrich, St. Louis,
Missouri De-ionized Water 5.078 Total weight 100.00
[0314] The finished formulation contains 39.9% a.e. glyphosate,
0.1663% PMIDA, and 0.1226% iron, which is a 3 to 1 mole ratio of
iron to PMIDA.
[0315] These values are calculated from the amounts and assays of
the ingredients.
0.842*47.387% a.e.=39.9% a.e. glyphosate in formulation
0.842*0.1974% PMIDA=0.1663% PMIDA in formulation
(0.713 g iron citrate/100 g)*(17.2% iron in iron citrate)=0.1226%
iron in formulation
0.1663 g/(226.97 g/mole of PMIDA)=0.7327.times.10.sup.-3 moles
PMIDA
0.1226 g/(55.847 g/mole of iron)=2.195.times.10.sup.-3 moles
iron
The mole ratio of Iron to PMIDA=(2.195/0.7327)=3.0.
Example M6
[0316] A potassium glyphosate formulation that uses a mixture of
iron sulfate pentahydrate, zinc oxide, and citric acid to mitigate
the effects of PMIDA is prepared by mixing the ingredients given in
the following table in a 250 ml beaker. Before proceeding, the
salts are premixed with citric acid. A 50% citric acid solution is
made by mixing 100 g of citric acid (CAS Number 77-92-9, anhydrous)
with 100 g of de-ionized water. Adding 25.17 g of iron (III)
sulfate pentahydrate (CAS Number 15244-10-7, containing 21.6% iron)
to 74.83 g of the 50% citric acid solution yields the iron
sulfate+citric acid premix. Adding 10.046 g zinc oxide (CAS Number
1314-13-2, containing 80.35% zinc) to 89.954 g of the 50% citric
acid solution, and stirring until the oxide dissolves, produces the
zinc premix. The components can now be mixed in a 250 ml beaker
with stirring.
TABLE-US-00025 Weight Added Ingredient (grams) Description
Potassium Glyphosate 84.2 58% K salt of glyphosate Salt Concentrate
acid in water, containing 47.387% a.e. glyphosate, 0.1974% PMIDA
Etheramine surfactant 7.48 Proprietary Surfactant Agnique DFM 111S
0.01 A silicone defoamer from Cognis Corporation, Cincinnati, Ohio
Sethness P212 0.01 Caramel dye from Sethness- Roquette Company,
Chicago IL Premix of 1.128 Amounts by component: Iron (III) Sulfate
Added 0.284 g iron sulfate hydrate Citric Acid drop-wise 0.422 g
citric acid Water 0.422 g water Premix of 1.431 Amounts by
component: Zinc Oxide Added 0.149 g zinc oxide Citric acid
drop-wise 0.641 citric acid Water 0.641 water De-ionized Water
5.741 Total weight 100.00
[0317] The preparation used the same potassium glyphosate salt
concentrate as Example M5, so the finished formulation contains
39.9% a.e. glyphosate and 0.1663% PMIDA. The iron content is
0.06134%, and the zinc content is 0.1197%.
[0318] These values are obtained from the salt amount and metal
assays of same.
0.284 g iron sulfate/100 g*21.6% iron in salt=0.06134% iron
0.149 g zinc oxide/100 g*80.35% zinc in oxide=0.1197% zinc
Moles of iron/100 g=0.06134 g/(55.847 g/mole)=1.098.times.10.sup.-3
moles
Moles of zinc/100 g=0.1197 g/(65.38 g/mole)=1.831.times.10.sup.-3
moles
The moles of PMIDA is the same as in Example M5,
0.7327.times.10.sup.-3 moles PMIDA.
The mole ratio of iron to PMIDA (1.098/0.7327) is 1.5.
The mole ratio of zinc to PMIDA (1.831/0.7327) is 2.5.
Example M7
[0319] The metal salts to be tested were first dissolved in water
at a high concentration. This facilitates the handling and dilution
required to make the spray solutions.
[0320] For example 15.0 grams of aluminum chloride hexahydrate (CAS
Number 7784-13-6, containing 11.17% Al) was first dissolved in 15
grams water to give a 50% solution in salt. To prepare the
application mixture for the 2520 g (glyphosate acid)/ha, wherein
the metal salt is to be applied 10 parts glyphosate acid to 1 part
metal salt, one needs to use 252.0 g/ha aluminum chloride
hexahydrate. The spray volume of water is usually 94 liters/ha. A
simple ratio is used to scale the batch size to the amount needed
for a small greenhouse application of 0.03 liters. Using
composition 270 as the source of glyphosate, containing 0.1890%
PMIDA and 39.7% a.e. glyphosate, for the selected rate, (2520 g
a.e./ha)/(94 l/ha)="g needed"/0.03 l) is solved for "g needed", and
one obtains 0.80425 g of glyphosate acid. Dividing by the
glyphosate assay of composition 270, 0.80425 g a.e./(0.397 g a.e./g
of composition=) one determines that 2.026 g of composition 270
must be added to 0.03 liters. The "grams needed" calculation is
repeated for the 252.0 g/ha rate for the metal salt, and after
dividing by the 50% assay of the premix, one determines that 0.1609
g of the 50% aqueous aluminum chloride hexahydrate premix must be
added to the 0.03 liters. This completes the preparation of the
spray solution, and the other materials are handled similarly.
Example M8
[0321] An isopropyl amine (IPA) glyphosate formulation with a metal
salt added to mitigate the effects of PMIDA is prepared by mixing
the following ingredients in a 250 ml beaker equipped with a
stirrer. Before proceeding, in a separate beaker, 100 grams of an
"aluminum and citric acid" premix is made; 16.338 g of citric acid
(CAS Number 77-92-9) is dissolved in 49.172 g of de-ionized water,
then, while stirring, 34.44 g of aluminum (III) sulfate
octadecahydrate (CAS Number 7784-31-8, containing 8.1% aluminum) is
added. Continue stirring until the aluminum salt dissolves
completely. Once completed, the formulation can be prepared by
adding the following.
TABLE-US-00026 Weight Added Ingredient (grams) Description
Isopropyl amine 66.13 62% IPA salt of glyphosate Glyphosate Salt
acid in water, containing Concentrate 45.93% a.e. glyphosate,
0.09569% PMIDA Ethoxylated tallow 8.0 Proprietary Surfactant amine
Premix of 0.810 Amounts by component: Al Sulfate 18Hydrate Added
0.279 g Al sulfate 18hydrate Citric Acid drop-wise 0.133 g Citric
acid Water 0.398 g Water De-ionized Water 25.06 Total weight
100.00
[0322] The finished formulation contains 41% IPA salt of
glyphosate, 30.37% a.e. glyphosate, 0.06346% PMIDA, 0.02260%
aluminum, and an aluminum to PMIDA mole ratio of 3.
[0323] These values were calculated from the amounts and assays of
the ingredients.
66.13 g/100 g*62% IPA salt=41.00% IPA salt of glyphosate in
formulation
66.13 g/100 g*45.93% a.e. glyphosate=30.37% a.e. glyphosate in
formulation
66.13 g/100 g*0.09596% PMIDA=0.06346% PMIDA in formulation
0.279 g/100 g*8.1% Al in salt=0.02260% aluminum in formulation
Moles of PMIDA in formulation (0.06346 g/226.97 g/mole) are
0.2796.times.10.sup.-3 moles.
Moles of aluminum in formulation (0.02260 g/26.98 g/mole) are
0.8377.times.10.sup.-3 moles.
Example M9
[0324] Two spray solution sets (A and B) for glyphosate application
to ROUNDUP READY FLEX COTTON were prepared from ROUNDUP WEATHERMAX
(Monsanto Company), an aqueous glyphosate potassium salt
concentrate. The concentrate used to prepare spray solution set A
contained 0.2% PMIDA and the concentrate used to prepare a spray
solution set B contained 0.4% PMIDA. For each spray set, six spray
solutions were prepared that varied with respect to the amount of
added ferric sulfate content. Solution 1 of each spray set was
prepared with no ferric sulfate addition and solutions 2 through 6
of each set were prepared with ferric sulfate additions at a molar
ratio of metal ion to PMIDA of 0.2:1, 0.4:1, 0.6:1, 0.8:1 and 1:1,
respectively. Using the greenhouse testing protocol described above
and an application volume of 94 L/hectare, spray solution set A was
applied to ROUNDUP READY FLEX cotton at application rates of 1260,
2520 and 5040 grams acid equivalent per hectare and spray solution
set B was applied at application rates of 2520 and 5040 grams acid
equivalent per hectare.
[0325] The results for the evaluation of the two spray solution
sets are presented in the following two tables.
TABLE-US-00027 % Necrosis 2 DAT for ROUNDUP WEATHERMAX containing
0.2% by weight PMIDA and ferric sulfate % necrosis (2 DAT) Spray
Iron:PMIDA 1260 g 2520 g 5040 g Solution Molar Ratio a.e./ha
a.e./ha a.e./ha 1A 0 2 9 44 2A 0.2:1 0 4 34 3A 0.4:1 0 4 38 4A
0.6:1 0 2 19 5A 0.8:1 0 0 19 6A 1.0:1 0 1 24 LSD 0.4 7.2 10.8
TABLE-US-00028 % Necrosis 2 DAT for ROUNDUP WEATHERMAX containing
0.4% by weight PMIDA and ferric sulfate % necrosis (2 DAT)
Iron:PMIDA 2520 g 5040 g Spray Solution Molar Ratio a.e./ha a.e./ha
1B 0 28 66 2B 0.2:1 14 47 3B 0.4:1 11 49 4B 0.6:1 11 45 5B 0.8:1 3
38 6B 1.0:1 3 31 LSD 7.2 10.8
[0326] Iron to PMIDA ratios of 0.6:1 and higher significantly
reduced necrosis at the two highest application rates with ROUNDUP
WEATHERMAX containing 0.2% PMIDA. When the PMIDA level was raised
to 0.4%, all iron to PMIDA ratios, including the lowest at 0.2:1,
significantly reduced necrosis at both 2520 and 5040 g glyphosate
a.e./ha application rates. This may be due to the greater magnitude
of necrosis with 0.4% PMIDA allowing for a more clearly discernable
decrease in necrosis with iron addition. It should be noted with
the higher PMIDA levels that 0.8:1 and 1:1 ratios were the only
ones to reduce necrosis below the commercially acceptable level of
about 5% at the 2.times. normal application rate (2520 g/ha). The
1:1 ratio also reduced necrosis to a significantly greater degree
than ratios of 0.2:1, 0.4:1, and 0.6:1 at the highest application
rate. This would suggest that as PMIDA levels increase and necrosis
potential increases, the iron to PMIDA ratio may need to increase
to mitigate cotton necrosis, and certainly within the context of
ratios of 1:1 and lower.
Example M10
[0327] A comparison was made between the standard greenhouse
incubation conditions of 27.degree. C./60% relative humidity day,
15.degree. C./80% relative humidity night, 14 hour day, 48 hours
before and after glyphosate application (as described in the
greenhouse testing protocol and termed "low temp" conditions)
versus higher temperature/higher humidity incubation conditions of
35.degree. C./80% relative humidity day, 27.degree. C./80% relative
humidity night, 14 hour day, 48 hours before and after glyphosate
application (termed "high temp" conditions).
[0328] Two spray solutions for glyphosate application to ROUNDUP
READY FLEX COTTON were prepared from ROUNDUP WEATHERMAX (Monsanto
Company) containing either 0.2% PMIDA or 0.4% PMIDA and without
ferric sulfate addition. Using an application volume of 94
L/hectare, each spray solution was applied to ROUNDUP READY FLEX
cotton at application rates of 1260, 2520 and 5040 grams acid
equivalent per hectare. The greenhouse testing protocol described
above was utilized with either the "low temp" incubation conditions
or the "high temp" incubation conditions. The results are reported
in the table below.
TABLE-US-00029 % Necrosis 2 DAT for ROUNDUP WEATHERMAX containing
0.2% and 0.4% by weight PMIDA % necrosis (2 DAT) 1260 g 2520 g 5040
g a.e./ha a.e./ha a.e./ha 0.2% PMIDA - low temp 1 9 44 0.2% PMIDA -
high temp 0 1 8 0.4% PMIDA - low temp 0 28 65 0.4% PMIDA - high
temp 0 0 8 LSD 0.4 7.2 10.8
[0329] The data show that high temperature, high humidity
incubation conditions result in less PMIDA-induced necrosis than do
comparable treatments evaluated under "low temp" incubation
conditions.
Example 2 (Field Trials)
[0330] Field trials were conducted at Fredricksburg, Tex., Leland,
Miss., and Loxley, Ala., USA. Glyphosate formulations were applied
to ROUNDUP READY FLEX cotton at the 5-6 leaf node stage of
development or later and was dependent upon environmental
conditions to maximize necrosis expression. Application rates were
1250, 1680, and 2520 g glyphosate a.e./ha, representing 1.times.,
1.5.times., and 2.times. use rates. All treatments were replicated
four times in each study. Cotton necrosis was evaluated 2 DAT.
Eight trials were conducted for each example.
[0331] Commercial glyphosate formulations containing known amounts
of PMIDA were fortified as necessary with PMIDA and iron to give
the compositions listed below for use in the field trials. The iron
was added as a solution of ferric sulfate including citric acid as
a solubilizing ligand.
TABLE-US-00030 PMIDA Fe:PMIDA Ratio Composition Formulation (wt %)
(wt:wt) 539 ROUNDUP WEATHERMAX 0.06 No Fe Added 640 ROUNDUP
WEATHERMAX 0.1 No Fe Added 922 ROUNDUP WEATHERMAX 0.2 No Fe Added
740 ROUNDUP WEATHERMAX 0.3 No Fe Added 825 ROUNDUP WEATHERMAX 0.4
No Fe Added 739 ROUNDUP WEATHERMAX 0.1 4:1 734 ROUNDUP WEATHERMAX
0.2 1.5:1.sup. 770 ROUNDUP WEATHERMAX 0.2 2:1 735 ROUNDUP
WEATHERMAX 0.2 2.5:1.sup. 741 ROUNDUP WEATHERMAX 0.3 1.3:1.sup. 742
ROUNDUP WEATHERMAX 0.4 1:1 736 ROUNDUP WEATHERMAX 0.4 1.5:1.sup.
737 ROUNDUP WEATHERMAX 0.4 2:1 738 ROUNDUP WEATHERMAX 0.4
2.5:1.sup. 772 ROUNDUP ORIGINALMAX 0.1 No Fe Added 807 ROUNDUP
ORIGINALMAX 0.2 No Fe Added 775 ROUNDUP ORIGINALMAX 0.3 No Fe Added
902 ROUNDUP ORIGINALMAX 0.4 No Fe Added 773 ROUNDUP ORIGINALMAX 0.1
6:1 743 ROUNDUP ORIGINALMAX 0.2 1.5:1.sup. 831 ROUNDUP ORIGINALMAX
0.2 2:1 744 ROUNDUP ORIGINALMAX 0.2 2.5:1.sup. 774 ROUNDUP
ORIGINALMAX 0.2 3:1 776 ROUNDUP ORIGINALMAX 0.3 2:1 745 ROUNDUP
ORIGINALMAX 0.4 1.5:1.sup. 746 ROUNDUP ORIGINALMAX 0.4 2:1 747
ROUNDUP ORIGINALMAX 0.4 2.5:1.sup. 817 ROUNDUP ORIGINAL 0.4 2:1
[0332] A number of trials were applied relatively early in the
season when the cotton was at the 5-6 leaf node stage and
environmental conditions were cool and dry. There was no necrosis
evident in any of these early trials. Later trials sprayed over
8-12 leaf node stage cotton with hot temperatures, high relative
humidity, and abundant soil moisture showed high levels of necrosis
with compositions containing no iron. The analyses that follow
include only trials where necrosis was observed. T-test analyses
combine data across trials and application rates.
Example 2A
[0333] This example investigated ROUNDUP WEATHERMAX-type
compositions with set levels of PMIDA (0.2% or 0.4%) and varying
ratios of iron to PMIDA. Necrosis was evident in one trial and only
at the higher level of PMIDA (composition 825, 0.4% PMIDA). All
iron containing compositions with 0.4% PMIDA showed significantly
less necrosis than the standard (Table 2A). Necrosis reduction was
similar for all iron containing compositions regardless of the iron
to PMIDA ratio (1.5:1, 2:1, or 2.5:1). An example of the degree of
necrosis reduction is shown in FIG. 5.
TABLE-US-00031 TABLE 2A T-Test Pairwise Mean Comparisons For 1
Experiment Compositions compared to 825 as a Standard - Overall and
by Species % Difference Standard Composition In Necrosis
Significance n 825 736 6.1 .dagger-dbl. 12 825 737 6.1 .dagger-dbl.
12 825 738 6.1 .dagger-dbl. 12 .dagger-dbl. Composition shows
significantly less necrosis than Standard (p < 0.05)
Example 2B
[0334] This example investigated ROUNDUP WEATHERMAX-type
compositions with constant levels of iron and varying levels of
PMIDA. Necrosis was evident in two of the eight trials. Due to the
low levels of necrosis with compositions containing 0.1% and 0.2%
PMIDA, differences between compositions with and without iron were
not evident. When the level of PMIDA was 0.3% or 0.4%, compositions
containing iron showed significantly less necrosis than
compositions with no iron (Table 2B). FIG. 6 graphically represents
the data.
TABLE-US-00032 TABLE 2B T-Test Pairwise Mean Comparisons For 2
Experiments Compositions compared to 640, 922, 740, or 825 as a
Standard % Difference Standard Composition In Necrosis Significance
N 640 739 1.3 - 24 922 770 1.9 - 24 740 741 6.0 .dagger-dbl. 24 825
742 11.1 + 24 - Composition can not be distinguished from Standard
(p .gtoreq. 0.05) .dagger-dbl. Composition shows significantly less
necrosis than Standard (p < 0.05) + Composition shows
significantly less necrosis than Standard (p < 0.01)
Example 2C
[0335] This example investigated the ability of iron to mitigate
necrosis in ROUNDUP ORIGINALMAX-type compositions with set levels
of PMIDA (0.2 or 0.4%) and varying ratios of iron to PMIDA (1.5:1,
2:1, or 2.5:1). Necrosis was evident in three of the eight trials.
All compositions containing iron showed significantly less necrosis
than the relevant standards, composition 807 (0.2% PMIDA) and
composition 902 (0.4% PMIDA) (Table 2C). The decrease in necrosis
was similar for all ratios of iron to PMIDA (1.5:1, 2:1 or 2.5:1)
and necrosis was essentially eliminated (FIG. 7).
TABLE-US-00033 TABLE 2C T-Test Pairwise Mean Comparisons For 3
Experiments Compositions compared to 807 or 902 as a Standard %
Difference Standard Composition In Necrosis Significance n 807 831
2.1 .dagger-dbl. 35 807 744 2.3 + 36 807 743 2.4 + 36 902 745 10.1
+ 36 902 746 10.4 + 36 902 747 10.4 + 36 .dagger-dbl. Composition
shows significantly less necrosis than Standard (p < 0.05) +
Composition shows significantly less necrosis than Standard (p <
0.01)
Example 2D
[0336] This example investigated ROUNDUP ORIGINALMAX-type
compositions with constant levels of iron and varying levels of
PMIDA. Necrosis was evident in three of the eight trials. The lack
of necrosis with composition 772 (0.1% PMIDA) resulted in no
significant differences with composition 773 (Table 2D). The iron
containing compositions with higher levels of PMIDA all showed
significantly less necrosis than their corresponding compositions
without iron. FIG. 8 graphically represents the data
TABLE-US-00034 TABLE 2D T-Test Pairwise Mean Comparisons For 3
Experiments Compositions compared to 772, 807, 775, or 902 as a
Standard % Difference Standard Composition In Necrosis Significance
n 772 773 0.2 - 36 807 774 4.7 .dagger. 36 775 776 10.3 .dagger. 36
902 745 17.9 .dagger. 36 - Composition can not be distinguished
from Standard (p .gtoreq. 0.05) .dagger. Composition is
significantly less efficacious than Standard (p < 0.01)
Example 2E
[0337] All compositions contained 0.4% PMIDA, except composition
539 (0.06% PMIDA), and varying levels of iron. Those compositions
containing iron showed significantly less necrosis than composition
902 (ROUNDUP ORIGINALMAX, 0.4% PMIDA) and composition 825 (ROUNDUP
WEATHERMAX, 0.4% PMIDA) (Table 2E). Composition 539, the 0.06%
PMIDA and no iron composition, also was effective in minimizing
necrosis. A graphical representation of the data is shown in FIG.
9.
TABLE-US-00035 TABLE 2E T-Test Pairwise Mean Comparisons For 5
Experiments Compositions compared to 902 as a Standard % Difference
Standard Composition In Necrosis Significance n 902 825 -1.4
.dagger-dbl. 60 902 742 11.4 + 60 902 817 12.0 + 60 902 737 12.4 +
60 902 745 13.4 + 60 902 539 13.9 + 60 902 747 14.2 + 60
.dagger-dbl. Composition shows significantly more necrosis than
Standard (p < 0.01) + Composition shows significantly less
necrosis than Standard (p < 0.01)
Example 3 (Analytical Procedure)
[0338] N-(phosphonomethyl)iminodiacetic acid (PMIDA) levels were
determined using a high-pressure liquid chromatography (HPLC)
procedure. Separation was performed on a precolumn (5 .mu.m, Zorbax
SB-C18 Analytical Guard Column, 4.6.times.12.5 mm) and analytical
column (5 .mu.m, Zorbax SAX-300, 150 mm.times.4.6 mm ID) with an
isocratic solvent system of 100 mM KH.sub.2PO.sub.4 with the pH
adjusted to 2.0 with concentrated phosphoric acid or an alternative
isocratic solvent system of 54.4 g KH.sub.2PO.sub.4, 4 g
concentrated sulfuric acid and 22 mL concentrated phosphoric acid
diluted to 4 L with HPLC grade water. Flow rate was 0.70 mL/min.
Post-column reagent (3.2 mM CuSO.sub.4, 0.70 mL/min) was added to
the column eluate just prior to an in-line reaction coil [PTFE
tubing, 8 ft..times. 1/32 in. ID ( 1/16 in. OD)] installed before
the UV detector which produced a copper-PMIDA chromophore that was
quantified at 250 nm.
[0339] A stock solution of 0.2000 wt. % PMIDA was prepared in HPLC
grade water. The working solutions of 0.0020, 0.0050, 0.0080, and
0.0100 wt. % PMIDA were prepared by appropriate dilution of the
stock solution in HPLC grade water, were stored at 4.degree. C. and
replaced with fresh working solutions every 2 months. A calibration
curve was constructed from the working solutions for each set of
samples analyzed. Samples were prepared by weighing to four
significant figures and diluted with HPLC grade water to give a
sample solution containing between 0.0020 to 0.0100 wt. % PMIDA.
For both the working solutions and the sample solutions, 50 .mu.L
was injected in the chromatographic system.
[0340] First Isocratic Solvent System: The chromatogram for an
iron-containing glyphosate formulation concentrate sample diluted
20 fold with deionized water is shown in FIG. 10. The concentration
of PMIDA in the analyzed sample solution was 0.0021 wt. % PMIDA,
which corresponded to a concentration of 0.0437 wt. % PMIDA in the
glyphosate formulation concentrate.
[0341] Alternative Isocratic Solvent System: The chromatogram for
an iron-containing formulation concentrate sample diluted 20 fold
with HPLC grade water is shown in FIG. 11. The concentration of
PMIDA in the analyzed sample solution was 0.0025 wt. % PMIDA, which
corresponded to a concentration of 0.0519 wt. % PMIDA in the
glyphosate formulation concentrate.
[0342] The analytical method set forth in this Example is
particularly advantageous in that it can accurately assess PMIDA
content of materials containing appreciable quantities of one or
more metal ions such as iron used as a safening agent in accordance
with the present invention.
[0343] In view of the above, it will be seen that the several
objects of the invention are achieved and other advantageous
results attained.
[0344] As various changes could be made in the above methods
without departing from the scope of the invention, it is intended
that all matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
[0345] When introducing elements of the present invention or the
preferred embodiments thereof, the articles "a", "an", "the", and
"said" are intended to mean that there are one or more of the
elements. The terms "comprising", "including," and "having" are
intended to be inclusive and mean that there may be additional
elements other than the listed elements.
Sequence CWU 1
1
4120DNAArtificial SequenceChimeric DNA of cotton genomic DNA and
transgene insert DNA 1attcaatgta gtcaaacact 20220DNAArtificial
SequenceChimeric DNA of cotton genomic DNA and transgene insert DNA
2ttgaatatat attacaaagc 2032880DNAArtificial sequenceChimeric DNA of
cotton genomic DNA and transgene insert DNA 3gcttggtacc gagctcggat
ccactagtaa cggccgccag tgtgctggaa ttcgcccttt 60tttactacga tgttaagtcc
tattttacac agtttcttta agacagattt gaccgctcct 120acgatacttg
gagaaacgtt ggtcgaatgt ctcttagaat acaacaacac gatgatcaaa
180gcagtagcac ctctgtagtg attaacgaac aagcgttgtc tttttctatc
accaaaacat 240tggaaaacat ggagaggaaa agagtagaat tttggaaaga
aaataatctt ggtatgagag 300agtgagattg agcaaaaaat tttgaagagg
tcttagcctt ttatatgcgt tcaaagtgga 360ggaattttgg aaatatccat
gtataatgag acaaaatctg catttaaaat ggcatttcgc 420gtcgcctgcg
tcgtgcgagt gcgccccaac cctgacgggt ttggacttac accctcatac
480acgcgaggca ggattccaag tttagtcatt caatcactct taaagtgagc
ttcaagctta 540gacattacaa attaaattaa ataatataag ataattgcgc
taaataaaca aacatttttt 600ttgtgatcct gaacgtaatc aacgagggta
tgatggttat gattcacgga aagagcgaga 660gaagagaacc gtcgctcgaa
gaggatgatg attcatccta ttcatgcacg actgtccaac 720tccccaccca
atcaaattcc aaattatgac atgagaagaa catcatccca cgtggtctgt
780gcttcacgcc accatgtccc acgtgggctc cattttggtg gggcccttcc
ccaccgccca 840agctgatccc gggttggcca tccctacttt taattatcag
agccacctcc ccaatctgca 900aaacgacgga aatggaaaac tataattttc
ttttttttca acgtacttat aaaatatttt 960tcaaaaaagt atgaataaaa
ttgtgatatt gcttggccta agaggccaat cttttgcaaa 1020tctcgaagtc
gggaggcaca ataaaaactt ggaaagtttt ttcaagtgtc tgctttataa
1080aattattgaa atgcatgtat tcgtacttgc cttatttatc gacaatttaa
acattattat 1140ttcatgaaaa tgtccttcca ccgatttcaa tgacaaaacc
aataattact actttttatt 1200ttcaattatg tcacggttca catgtttatt
agggtttagg ttgaggttaa aactttcgac 1260tctctattcg taacgcttaa
agatgtaggg tttaggttga ggttaaaaca atcatgtaat 1320gtaaggatac
ctgaaaagct gtcattagtg taagtgttta ttactagggt tgtttaaatt
1380catgttgatg tcaagcttgg ataacccatt ttactaaaaa aataaatgaa
gtcccaaagg 1440gcattgggca tcctatcaaa gatgggaaat tttttcaaaa
ttttaaccta aaaaagaggt 1500ggaaagtctt agtccaaata atcagccaca
tcagaatttg attcgtttct ttcaagcaaa 1560ttatacctat tggctgcaat
atctttaagt ggaatggtcg gccaaacttt tccatatcag 1620cttgattcat
ctctaaactt gattattctt ttttattaat attaaattcc acaacttgaa
1680ctttaatttt tttaattaat taaaaaaatt gtcacctttt caagctgaaa
aagaaaaaga 1740aaccttaatt attatcacta gtattaaatt tcaaaacttg
atttgtccta aatttgaaaa 1800ggggtctcct tcaattcata tatgtagtca
tgaagattat aacttagctg aaaatggcct 1860ccattatttg gcttattcaa
tcaaaagttt acaaaactag tgcaaattta atatgataat 1920gtctacaaga
accaaatacg aattgagtaa atttttttgg ctaaaataaa ttacgaattg
1980atgaattatc attttaaaaa gttcttttta accatttctt ttactgaatt
aaaaaaaggt 2040tttattaatc atatatatta caaattaccc attaagtagc
caaattacaa attttaattc 2100aatgtagtca aacactgata gtttaaacat
gactctctta aggtagccaa agcccgggct 2160taattaaggc gcgccggcca
agtcggccgc ggccgcgtta tcaagcttct gcaggtcctg 2220ctcgagtgga
agctaattct cagtccaaag cctcaacaag gtcagggtac agagtctcca
2280aaccattagc caaaagctac aggagatcaa tgaagaatct tcaatcaaag
taaactactg 2340ttccagcaca tgcatcatgg tcagtaagtt tcagaaaaag
acatccaccg aagacttaaa 2400gttagtgggc atctttgaaa gtaatcttgt
caacatcgag cagctggctt gtggggacca 2460gacaaaaaag gaatggtgca
gaattgttag gcgcacctac caaaagcatc tttgccttta 2520ttgcaaagat
aaagcagatt cctctagtac aagtggggaa caaaataacg tggaaaagag
2580ctgtcctgac agcccactca ctaatgcgta tgacgaacgc agtgacgacc
acaaaagaat 2640tagcttgagc tcaggattta gcagcattcc agattgggtt
caatcaacaa ggtacgagcc 2700atatcacttt attcaaattg gtatcgccaa
aaccaagaag gaactcccat cctcaaaggt 2760ttgtaaggaa gaattcgata
tcaagcttga tatcggaagt ttctctcttg agggaggttg 2820ctcgtggaat
gggacacata tggttgttat aataaaccat ttccattgtc atgagatttt
288041675DNAArtificial sequenceChimeric DNA of cotton genomic DNA
and transgene insert DNA 4tgaccgaagt taatatgagg agtaaaacac
ttgtagttgt accattatgc ttattcacta 60ggcaacaaat atattttcag acctagaaaa
gctgcaaatg ttactgaata caagtatgtc 120ctcttgtgtt ttagacattt
atgaactttc ctttatgtaa ttttccagaa tccttgtcag 180attctaatca
ttgctttata attatagtta tactcatgga tttgtagttg agtatgaaaa
240tattttttaa tgcattttat gacttgccaa ttgattgaca acatgcatca
atcgacctgc 300agccactcga gtggaggcct catctaagcc cccatttgga
cgtgaatgta gacacgtcga 360aataaagatt tccgaattag aataatttgt
ttattgcttt cgcctataaa tacgacggat 420cgtaatttgt cgttttatca
aaatgtactt tcattttata ataacgctgc ggacatctac 480atttttgaat
tgaaaaaaaa ttggtaatta ctctttcttt ttctccatat tgaccatcat
540actcattgct gatccatgta gatttcccgg acatgaagcc atttacaatt
gaatatatat 600tacaaagcta tttgcttata acatatgcga aaaattttgt
actataatca ggggtaaatt 660taggaggggg cttgtaggtc tcgcttctct
taaaatgaaa aattttctat ttagttattt 720aaaattttaa aagtaaaata
taaaaatttc atttaatcct ttaaaaatta taaagatata 780gactattaaa
atgatgaaat tacaatttta ttatcataaa aattataatt taatttcgac
840ccctaacaaa attttctgat tttgccccta actgtaatat ttgtataaaa
acattttctt 900tttgcattta atgatttctt taattcagtc caagaaagaa
atttattaat tgcatatgcg 960aaagttagtc cttgcctagt gatattaaag
gaaagaaaca taaaatcaat aaattaattt 1020ttaaagcaaa tagtaaaaat
aaggaaaaac tttctacgat agtctataat tcaaaaaaag 1080aaataataat
ctttaaccat tgaattttaa aataacatca gaataatcta tttatttaat
1140ttaataaata ataataacat atatattaat attaaaattt ttattgagct
tagtgtcaca 1200aatcaataaa aaatttctta caaaataaat tatattattt
tgagggtgtt ttattatttt 1260atatatttta tacagacata tagaaatata
aatacacata ataaaatttg aatccaaatt 1320tttaattttt aacatttata
atttactatt caaccaaaat tttatttatt atttatatca 1380aatttttata
aatatattta tcagataatg cgattttttt tacctatata tagatgacat
1440aatctacttt aaattaagtc ctaaaaataa tatatcatac caaaaaaatt
cttaaaatga 1500atctgataat acttaacccc ttttataaaa caatcttaac
cccttatata ttttaatatt 1560aatatcatta taaatataaa tctattgagc
atatgtttta aaccaagtaa tgttgagtgc 1620ggtagtaaaa ctcattacac
attttaagta gaacgtagtt cgaaccttgg agaag 1675
* * * * *