AQUEOUS CONCENTRATED HERBICIDAL COMPOSITIONS CONTAINING GLYPHOSATE SALTS AND DICAMBA SALTS
Herbicidal concentrate compositions containing a combination of glyphosate salt and dicamba salt are provided. For example, a low volatility aqueous herbicidal concentrate composition including a glyphosate salt, dicamba salt, and a surfactant is described, wherein (i) the composition contain a total active herbicide loading of glyphosate salt and dicamba salt of at least about 450 grams acid equivalent per liter; (ii) the pH of the concentrate composition is less than about 5.7; and (iii) the acid equivalent weight ratio of glyphosate salt to dicamba salt is from about 1:1 to about 3:1.
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This application is a continuation of U.S. application Ser. No. 14/405,036, filed Dec. 2, 2014, which is the 371 National Stage of International PCT Application No. PCT/US2013/043995, filed Jun. 4, 2013, which claims the benefit of U.S. Provisional Application Nos. 61/655,018, filed Jun. 4, 2012, the contents of which are incorporated herein in their entirety.
FIELD OF THE INVENTIONThe present invention generally relates to herbicidal concentrate compositions containing a combination of herbicides. In particular, the present invention relates to aqueous herbicidal concentrate compositions containing glyphosate salt and dicamba salt herbicides.
BACKGROUND OF THE INVENTIONThe present invention relates generally to herbicidal concentrate compositions, processes for preparing these concentrates, and methods of using such compositions to kill or control the growth and proliferation of unwanted plants. In particular, the present invention relates to herbicidal concentrate compositions which comprise a salt of N-(phosphonomethyl)glycine (glyphosate) and a salt of 3,6-dichloro-2-methoxy benzoic acid (also known as 3,6-dichloro-o-anisic acid and commonly referred to as dicamba).
Glyphosate is well known in the art as an effective post-emergent foliar-applied herbicide. In its acid form, glyphosate has the following structure:
Glyphosate acid is relatively insoluble in water (1.16 wt. % at 25° C.). For this reason it is typically formulated as a water-soluble salt. For example, herbicidal concentrate compositions and application formulations containing the sodium, potassium, ammonium, isopropylamine, or monoethanolamine salts of glyphosate are well known in the art.
Herbicidal compositions and formulations comprising glyphosate or salts thereof are useful for suppressing the growth of, or killing, unwanted plants such as grasses, weeds and the like. Glyphosate is typically applied to the foliage of the target plant. After application, glyphosate is absorbed by the foliar tissue of the plant and translocated throughout the plant. Glyphosate noncompetitively blocks an important biochemical pathway which is common to virtually all plants, but which is absent in animals. Although glyphosate is very effective in killing or controlling the growth of unwanted plants, the uptake (i.e., absorption) of glyphosate by the plant foliar tissue and translocation of glyphosate throughout the plant is relatively slow. Visual symptoms that a plant has been treated with glyphosate may not appear until one week or more after treatment.
Dicamba has proven to be a particularly effective auxin herbicide. In its acid form, dicamba has the following structure:
Like glyphosate, dicamba is typically formulated as a salt, such as a sodium, potassium, diethanolamine, isopropylamine, diglycolamine, or dimethylamine salt.
Generally, auxin herbicides such as dicamba mimic or act like natural auxin plant growth regulators. Auxin-like herbicides appear to affect cell wall plasticity and nucleic acid metabolism, which can lead to uncontrolled cell division and growth. The injury symptoms caused by auxin-like herbicides include epinastic bending and twisting of stems and petioles, leaf cupping and curling, and abnormal leaf shape and venation.
Off-site movement is commonly associated with dicamba and other auxin herbicides. Under certain conditions of application, dicamba can migrate from the application site to adjacent crop plants, such as soybeans and cotton, where contact damage to sensitive plants can occur. Various strategies have been suggested to reduce off-site movement of dicamba including formulating dicamba in the form of certain mineral or amine salts, encapsulating dicamba with a polymeric coating, and complexing with a polybasic polymer.
With the development of transgenic plants including stacked glyphosate-tolerant and dicamba-tolerant traits, herbicidal compositions containing a combination of glyphosate and dicamba are particularly beneficial and convenient for control of unwanted plants. There is a need for highly concentrated herbicidal compositions containing glyphosate and dicamba that can be economically produced while having sufficient stability and that can be diluted to provide effective spray formulation solutions for application to unwanted plants.
As will be clear from the disclosure that follows, these and other benefits are provided by the present invention.
SUMMARY OF THE INVENTIONIn general, the present invention is directed to herbicidal concentrate compositions containing a combination of glyphosate salt and dicamba salt. In various embodiments, the concentrate compositions are low volatility aqueous herbicidal concentrate compositions including a glyphosate component comprising a glyphosate salt (e.g., monoethanolamine salt of glyphosate), a dicamba component comprising a dicamba salt (e.g., diglycolamine salt of dicamba), and a surfactant. In these embodiments, (i) the compositions contain a total active herbicide loading of glyphosate salt and dicamba salt of at least about 450 grams acid equivalent per liter; (ii) the pH of the concentrate composition is less than about 5.7; and (iii) the acid equivalent weight ratio of glyphosate salt to dicamba salt is from about 1:1 to about 3:1.
Other objects and features will be in part apparent and in part pointed out hereinafter.
DESCRIPTION OF THE PREFERRED EMBODIMENTSThe present invention is directed to aqueous herbicidal concentrate compositions comprising glyphosate salt and dicamba salt herbicides.
One aspect of the present invention is to provide a highly concentrated herbicidal composition containing glyphosate salt and dicamba salt that can be diluted to provide an effective spray formulation solution. A highly concentrated composition reduces the volume of the liquid and associated packaging that would otherwise be required for more dilute compositions. The smaller volume reduces space required to store and transport the concentrate composition prior to sale or use. Further, a highly concentrated herbicidal composition containing both glyphosate salt and dicamba salt is convenient for agricultural workers that formulate spray solutions and avoids the risk of tank mixing errors.
Another aspect of the present invention is to provide a stable and compatible highly concentrated herbicidal composition containing both glyphosate salt and dicamba salt that is relatively clear and does not appreciably separate into phases or form precipitates upon standing or storage. A stable and compatible highly concentrated herbicidal composition beneficially provides a uniform spray formulation solution upon dilution without the need for excessive agitation.
Another aspect of the present invention is to provide a highly concentrated herbicidal composition containing glyphosate salt, dicamba salt, and at least one surfactant. Incorporation of at least one surfactant beneficially increases the effectiveness of the glyphosate and dicamba active ingredients upon application to the foliar tissues of undesired plants.
Yet another aspect of the present invention is to provide a highly concentrated herbicidal composition containing glyphosate salt and dicamba salt that is economical to produce.
In accordance with the present invention, the aqueous herbicidal concentrate composition comprises a glyphosate component comprising one or more water-soluble salts of glyphosate. Glyphosate salts known in the art include mono, di- or tribasic and include ammonium (e.g., mono-, di- or triammonium), alkali metal (e.g., potassium or sodium), sulfonium (e.g., mono-, di- or trimethylsulfonium) and organic ammonium salts of N-(phosphonomethyl)glycine. The organic ammonium salts, commonly referred to as amine salts, can comprise aliphatic or aromatic amine salts and can include primary, secondary, tertiary or quaternary amine salts. Representative examples of such organic amine salts include isopropylamine, n-propylamine, ethylamine, dimethylamine, monoethanolamine, ethylenediamine and hexamethylenediamine salts of N-(phosphonomethyl)glycine. The monoethanolamine salt and potassium salt of glyphosate have been found to be particularly suitable for achieving high herbicidal loadings in the concentrate compositions of the present invention that further include a dicamba salt. Therefore, in various embodiments, the glyphosate component of the aqueous herbicidal concentrate composition of the present invention comprises a glyphosate salt selected from the group consisting of the monoethanolamine salt, potassium salt, and mixtures thereof. In certain embodiments, the aqueous herbicidal concentrate contains glyphosate in the form of the monoethanolamine salt. In other embodiments, the aqueous herbicidal concentrate composition contains glyphosate in the form of the potassium salt. In some embodiments, the aqueous herbicidal concentrate composition contains glyphosate in the form of the isopropylamine salt.
In accordance with the present invention, the aqueous herbicidal concentrate composition further comprises a dicamba component comprising one or more salts of dicamba. Dicamba salts known in the art include, for example, the sodium, potassium, monoethanolamine, diethanolamine, isopropylamine, diglycolamine and dimethylamine salts. Accordingly, in various embodiments, the dicamba component of the aqueous herbicidal concentrate composition comprises a dicamba salt selected from the group consisting of the sodium, potassium, monoethanolamine, diethanolamine, isopropylamine, diglycolamine and dimethylamine salts. In these and other embodiments, the aqueous herbicidal concentrate composition comprises a dicamba salt selected from the group consisting of the monoethanolamine salt, diglycolamine salt, potassium salt, and mixtures thereof. In certain embodiments, the aqueous herbicidal concentrate composition contains the monoethanolamine salt of dicamba. In other embodiments, the aqueous herbicidal concentrate composition contains the diglycolamine salt of dicamba.
Other salts of dicamba for use in the practice of the present invention include polyamine salts such as those described in International Patent Application Publication WO 2011/039172, which is incorporated herein by reference for all relevant purposes. The salts described in WO 2011/03917 include an anionic pesticide, such as dicamba, and a cationic polyamine of formula (A)
wherein R1, R2, R4, R6 and R7 are independently H or C1-C6-alkyl, which is optionally substituted with OH, R3 and R5 are independently C2-C4-alkylene, X is OH or NR6R7, and n is from 1 to 20; or a cationic polyamine of formula (B)
wherein R10 and R11 are independently H or C1-C6-alkyl, R12 is C1-C12-alkylene, and R13 is an aliphatic C5-C8 ring system, which comprises either nitrogen in the ring or which is substituted with at least one unit NR10R11. Examples of these cationic polyamines include tetraethylenepentamine, triethylenetetramine, diethylenetriamine, pentamethyldiethylenetriamine, N,N,N′,N″,N″-pentamethyl-dipropylenetriamine, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, N′-(3-(dimethylamino)propyl)-N,N-dimethyl-1,3-propanediamine, N,N-bis(3-aminopropyl) methylamine, N-(3-dimethylaminopropyl)-N,N-diisopropanolamine, N,N,N′-trimethylaminoethyl-ethanolamine, aminopropylmonomethylethanolamine, and aminoethylethanolamine. Accordingly, in various embodiments, the aqueous herbicidal concentrate composition comprises a dicamba salt comprising a cationic polyamine of formula A or B above.
The aqueous herbicidal concentrate composition may contain various combinations of glyphosate and dicamba salts. However, in accordance with some embodiments, certain combinations of glyphosate and dicamba salts are selected in order to achieve highly concentrated and stable herbicidal compositions and provide other advantages as described herein. In various embodiments, the aqueous herbicidal concentrate composition comprises glyphosate in the form of the monoethanolamine salt and a dicamba salt selected from the group consisting of the diglycolamine salt, monoethanolamine salt, potassium salt and mixtures thereof. In these and other embodiments, the aqueous herbicidal concentrate composition comprises the monoethanolamine salt of glyphosate and the diglycolamine salt of dicamba. In still other embodiments, the aqueous herbicidal concentrate composition contains glyphosate in the form of the potassium salt and a dicamba salt selected from the group consisting of the diglycolamine salt, monoethanolamine salt, potassium salt and mixtures thereof. In certain embodiments, the counter-ion of the glyphosate salt component and the dicamba salt component of the herbicidal concentrate composition are the same. For example, the herbicidal concentrate composition can include glyphosate and dicamba both in the form of the monoethanolamine or potassium salt of the herbicidal active ingredients.
Generally, the aqueous herbicidal concentrate compositions of the present invention include glyphosate and dicamba in relatively equal proportions or an excess of glyphosate on an acid equivalent (a.e.) basis. As used herein, the term “acid equivalent” or “a.e.” refers to the amount of herbicide present without taking into account the weight of the counter-ion of the salt species present. In various embodiments, the acid equivalent weight ratio of glyphosate salt to dicamba salt ranges from about 1:1 to about 5:1, from about 1:1 to about 3:1, from about 1.5:1 to about 3:1, from about 1.5:1 to about 2.5:1, or from about 1.5:1 to about 2:1. In certain embodiments, the acid equivalent weight ratio of glyphosate salt to dicamba salt is about 1.5:1, about 2:1, or about 3:1. It has been discovered that the ability to incorporate a surfactant into a stable glyphosate and dicamba herbicidal concentrate (i.e., without precipitation or phase separation) is influenced by the ratio of glyphosate to dicamba present in the herbicidal concentrate composition. More particularly, surfactant compatibility in the herbicidal concentrate composition improves as the acid equivalent weight ratio of glyphosate salt to dicamba salt decreases.
Within these relative proportions of glyphosate and dicamba salts, the aqueous herbicidal concentrate compositions of the present invention provide a high total active herbicide loading of glyphosate salt and dicamba salt. Typically, the total active herbicide loading of glyphosate salt and dicamba salt is at least about 360 g/l, at least about 380 g/l, at least about 400 g/l, at least about 410 g/l, at least about 420 g/l, at least about 430 g/l, at least about 440 g/l, at least about 450 g/l, at least about 460 g/l, at least about 470 g/l, at least about 480 g/l, at least about 490 g/l, at least about 500 g/l, at least about 510 g/l, at least about 520 g/l, or at least about 530 g/l on an acid equivalent basis. In various embodiments, the total active herbicide loading of glyphosate salt and dicamba salt is from about 360 g/l to about 550 g/l, from about 380 g/l to about 540 g/l, from about 400 g/l to about 540 g/l, from about 410 g/l to about 540 g/l, from about 420 g/l to about 540 g/l, from about 430 g/l to about 540 g/l, from about from about 440 g/l to about 540 g/l, from about 450 g/l to about 540 g/l, from about 460 g/l to about 540 g/l, from about 470 g/l to about 540 g/l, from about 480 g/l to about 540 g/l, from about 480 g/l to about 530 g/l, or from about 480 g/l to about 520 g/l on an acid equivalent basis. In these and other embodiments, the aqueous herbicidal concentrate compositions contain a total active herbicide loading of glyphosate salt and dicamba salt of about 480 g/l, about 500 g/l, about 520 g/l, or about 530 g/l on an acid equivalent basis.
The pH of the aqueous herbicidal concentrate composition is an important aspect of the present invention. The pH of the herbicidal concentrate composition has an effect on the compatibility between glyphosate and dicamba herbicide salt components and the total herbicide loading that can be achieved, the ability to incorporate a surfactant into a stable concentrate composition as well as the volatility of the dicamba component of the composition. Increasing the pH of the concentrate composition often allows a higher concentration of surfactant to be incorporated and also generally reduces volatility of the dicamba herbicide component. However, increasing the pH requires greater expenditure of base used to neutralize the herbicidal active ingredients. Moreover, the effect of pH on compatibility between the glyphosate and dicamba salts and total herbicide loading is dependent upon the particular salt of glyphosate employed and is not always consistent over the entire pH range. For example, it has been discovered that the monoethanolamine salt of glyphosate exhibits a high degree of compatibility with dicamba salts. However, the compatibility of the isopropylamine salt of glyphosate with dicamba salts and the total herbicide loading that can be achieved tends to decrease as the pH increases, while the compatibility of the potassium salt of glyphosate with dicamba salts generally increases as the pH increases, at least over some interval of the pH range typically employed.
Despite these various and sometimes countervailing considerations with respect to pH, it has been discovered that a stable, compatible herbicidal concentrate of glyphosate and dicamba salts can be advantageously prepared at a relatively acidic pH thereby minimizing the cost associated with neutralization of the herbicidal active ingredients, while nevertheless maintaining dicamba volatility at acceptable levels and permitting the formulation of herbicidal concentrate compositions containing appreciable concentrations of useful surfactants.
Typically, the pH of the concentrate compositions is less than about 5.7, less than about 5.6, less than about 5.5, less than about 5.4, less than about 5.3, less than about 5.2, less than about 5.1, less than about 5, less than about 4.9, or less than about 4.8. In various embodiments, the pH of the concentrate compositions is from about 4.5 to about 5.7, from about 4.8 to about 5.7, from about 5 to about 5.7, from about 4.5 to about 5.6, from about 4.8 to about 5.6, from about 5 to 5.6, from about 4.5 to about 5.5, from about 4.8 to about 5.5, from about 5 to 5.5, from about 4.5 to about 5.4, from about 4.8 to about 5.4, or from about 5 to about 5.4. The pH of the herbicidal concentrate compositions is measured using conventional pH measuring equipment (e.g., by immersing the probe of a pH meter into the concentrate). A suitable pH measurement protocol is described in Example 6.
The aqueous herbicidal concentrate compositions of the present invention typically include a surfactant to enhance the herbicidal effectiveness of the glyphosate and dicamba salts in spray formulations prepared by dilution of the concentrate for application to unwanted plants. As noted above, it is believed the ratio of glyphosate to dicamba affects the degree to which one or more surfactants may be incorporated into the aqueous herbicidal concentrate composition. When dicamba salt is present in higher concentrations (e.g., from about 1:1 to about 3:1 glyphosate to dicamba acid equivalent weight ratio), it has been observed that a wider range of surfactants can be incorporated into the aqueous herbicidal concentrate composition without precipitation or phase separation as compared to compositions having a lower concentration of dicamba salt (e.g., 5:1 glyphosate to dicamba acid equivalent weight ratio). Accordingly, in certain embodiments, the acid equivalent weight ratio of glyphosate salt to dicamba salt is from about 1:1 to about 3:1, from about 1.5:1 to about 3:1, from about 1.5:1 to about 2.5:1, from about 1:1 to about 2:1, from about 1.5:1 to about 2:1, or from about 1.7:1 to about 2:1.
It has been discovered that some surfactants conventionally used in the art in combination with glyphosate and/or dicamba herbicides are difficult to successfully incorporate into a stable concentrate composition, even at lower acid equivalent weight ratios of glyphosate salt to dicamba salt. Nevertheless, applicants have identified several classes of surfactants and surfactant combinations that provide stable aqueous herbicidal concentrate compositions for use in conjunction with the present invention.
In one embodiment, the surfactant comprises a quaternary ammonium salt having the structure of formula (I):
wherein R11 is hydrocarbyl or substituted hydrocarbyl having from 1 to about 30 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently C2-C4 alkylene; R13 is hydrogen, or a linear or branched alkyl group having from 1 to about 4 carbon atoms; R14 is hydrocarbyl or substituted hydrocarbyl having from 1 to about 30 carbon atoms; x and y are independently an average number from 1 to about 40; and X− is an agriculturally acceptable anion. In this context, preferred R11 and R14 hydrocarbyl groups are linear or branched alkyl, linear or branched alkenyl, linear or branched alkynyl, aryl, or aralkyl groups. Preferably, R11 and R14 are independently a linear or branched alkyl or linear or branched alkenyl group having from 1 to about 25 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently C2-C4 alkylene; R13 is hydrogen, methyl or ethyl; and the sum of x and y is an average number from about 2 to about 30. More preferably, R11 and R14 are independently a linear or branched alkyl group having from 1 to about 22 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and the sum of x and y is an average number from about 2 to about 20. Even more preferably, R11 is a linear or branched alkyl group having from about 8 to about 22 carbon atoms; R14 is a linear or branched alkyl group having from 1 to about 22 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and x is an average number from about 2 to about 20. Most preferably, R11 is a linear or branched alkyl group having from about 8 to about 22 carbon atoms; R14 is a linear or branched alkyl group having from 1 to about 6 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and x is an average number from about 2 to about 15; or R11 and R14 are independently a linear or branched alkyl group having from about 8 to about 22 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and x is an average number from about 5 to about 15.
One example of a preferred dialkoxylated quaternary ammonium surfactants is ETHOQUAD C-12 (a cocoalkylmethylbis(2-hydroxyethyl) ammonium chloride surfactant available from Akzo Nobel). In various embodiments, the surfactant or surfactant system may include a solvent or other additives. For example, when ETHOQUAD C-12 is incorporated into the aqueous herbicidal concentrate composition, it may be added as a mixture containing diethylene glycol (DEG) or polyethylene glycol (PEG). Therefore, in certain embodiments, the surfactant comprises ETHOQUAD C-12 dissolved in diethylene glycol or polyethylene glycol (e.g., a mixture containing 75 wt. % ETHOQUAD C-12 and 25 wt. % diethylene glycol or polyethylene glycol). Other examples of preferred quaternary ammonium surfactants that can be used to form stable aqueous glyphosate and dicamba salt concentrate compositions are ARQUAD T27W and ARQUAD C33W, which are available from Akzo Nobel.
In another embodiment, the surfactant comprises an alkoxylated tertiary etheramine having the structure of formula (II):
wherein R1 is a hydrocarbyl or substituted hydrocarbyl having from about 4 to about 22 carbon atoms; R2 and R3 are each independently a hydrocarbylene having 2, 3, or 4 carbon atoms; each R4 is independently hydrogen or C1-6 alkyl, m is an average number from about 1 to about 10; and the sum of x and y is an average value ranging from about 2 to about 60. R1 is preferably an alkyl having an average value ranging from about 4 to about 22 carbon atoms, more preferably from about 8 to about 22 carbon atoms, and still more preferably from about 10 to about 20 carbons atoms, for example coco, tallow, oleyl, and stearyl. Sources of the R1 group include, for example, coco or tallow, or R1 may be derived from synthetic hydrocarbyls, such as decyl, dodedecyl, tridecyl, tetradecyl, hexadecyl, or octadecyl groups. The number m is preferably from about 1 to 5, such as 2 to 3. R2 and R3 are preferably independently ethylene, propylene, isopropylene, and are preferably ethylene. R4 is preferably hydrogen. The sum of x and y is preferably an average value ranging from about 2 to about 25.
One preferred example of an alkoxylated tertiary etheramine surfactant is SURFONIC AGM 550 available from Huntsman Petrochemical Corporation wherein R1 is C12-14, R2 is isopropyl, R3 is ethylene, R4 is hydrogen, m is 2 and the sum of x and y is 5. Other examples of preferred alkoxylated tertiary etheramine surfactants that can be used to form stable aqueous glyphosate and dicamba salt concentrate compositions are ETHOMEEN C-15, ETHOMEEN C-12, and AROMOX C12W, all available from Akzo Nobel.
In order to sufficiently compatibilize and increase the amount of an alkoxylated tertiary etheramine surfactant or quaternary ammonium salt surfactant incorporated into the aqueous herbicidal concentrate compositions of the present invention, it may be useful to utilize a surfactant system comprising the combination of an alkoxylated tertiary etheramine surfactant or quaternary ammonium salt surfactant as described above with a non-ionic alkylpolysaccharide (e.g., alkylpolyglucoside or APG) surfactant. Alkylpolysaccharide surfactants are generally reported to be less effective in enhancing herbicidal activity as compared to cationic or amphoteric surfactants when used as the sole surfactant component of solution concentrate formulations of a glyphosate salt. Advantageously, however, it has been discovered that the inclusion of an alkylpolysaccharide surfactant allows a higher concentration of an alkoxylated tertiary etheramine surfactant or quaternary ammonium salt surfactant to be incorporated into the aqueous herbicidal concentrate composition to take advantage of its improved efficacy in enhancing the herbicidal effectiveness of the glyphosate and dicamba salts.
Suitable alkylpolysaccharide surfactants have the structure of formula (III):
R5—O-(sug)u (III)
wherein R5 is a straight or branched chain substituted or unsubstituted hydrocarbyl selected from alkyl, alkenyl, alkylphenyl, alkenylphenyl having from about 4 to about 22 carbon atoms. The sug moiety is a saccharide residue, and may be an open or cyclic (i.e., pyranose) structure. The saccharide may be a monosaccharide having 5 or 6 carbon atoms, a disaccharide, an oligosaccharide or a polysaccharide. Examples of suitable saccharide moieties, including their corresponding pyranose form, include ribose, xylose, arabinose, glucose, galactose, mannose, telose, gulose, allose, altrose, idose, lyxose, ribulose, sorbose (sorbitan), fructose, and mixtures thereof. Examples of suitable disaccharides include maltose, lactose and sucrose. Disaccharides, oligosaccharides and polysaccharides can be a combination of two or more identical saccharides, for example maltose (two glucoses) or two or more different saccharides, for example sucrose (a combination of glucose and fructose). The degree of polymerization, u, is an average number from 1 to about 10, from 1 to about 8, from 1 to about 5, from 1 to about 3, and from 1 to about 2. As known to those skilled in the art, as depicted in formula (III), R5 is linked to an oxygen atom of the sug moiety. In various particular embodiments, the alkylpolysaccharide surfactant may be an alkylpolyglucoside (APG) surfactant of formula (III) wherein: R5 is a branched or straight chain alkyl group preferably having from 4 to 22 carbon atoms, more preferably from 8 to 18 carbon atoms, or a mixture of alkyl groups having an average value within the given range; sug is a glucose residue (e.g., a glucoside); and u is from 1 to about 5, and more preferably from 1 to about 3. In various embodiments, the surfactant comprises an APG of formula (III) wherein R5 is a branched or straight chain alkyl group having from 8 to 10 carbon atoms or a mixture of alkyl groups having an average value within the given range and u is from 1 to about 3.
Examples of surfactants of formula (III) are known in the art. For example, one preferred surfactant is AGNIQUE PG8107-G (AGRIMUL PG 2067) available from BASF.
Representative alkylpolysaccharide surfactants are presented in the table below wherein for each surfactant sug in formula (III) is a glucose residue.
In various embodiments, the aqueous herbicidal concentrate composition contains at least about 1 wt. %, at least about 2 wt. %, at least about 3 wt. %, at least about 4 wt. %, or at least about 5 wt. % of surfactant. In these and other embodiments, the aqueous herbicidal concentrate composition contains from about 1 wt. % to about 20 wt. %, from about 2.5 wt. % to about 20 wt. %, from about 5 wt. % to about 20 wt. %, from about 2.5 wt. % to about 15 wt. %, from about 2.5 wt. % to about 10 wt. %, from about 5 wt. % to about 15 wt. %, or from about 5 wt. % to about 15 wt. % of surfactant.
In some embodiments, the aqueous herbicidal concentrate composition contains at least about 5 wt. % of a quaternary ammonium salt surfactant of formula (I) as described above. In other embodiments, the aqueous herbicidal concentrate composition contains a surfactant system comprising from about 5 wt. % to about 7.5 wt. % of an alkylpolyglucoside surfactant of formula (III) and at least about 2.5 wt. % of an alkoxylated tertiary etheramine surfactant of formula (II) as described above.
The aqueous herbicidal concentrate composition of the present invention may be prepared by a process that includes adding a dicamba salt or solution thereof to an aqueous solution concentrate comprising the glyphosate salt.
In various embodiments, the glyphosate salt solution concentrate contains glyphosate that is neutralized using a molar excess of base to fully neutralize the acidic site of glyphosate having the lowest pKa, but less than two molar equivalents of base to glyphosate (e.g., prepared using 1.3 molar equivalents of base to neutralize 1.3 acidic sites of glyphosate). Accordingly, in various embodiments glyphosate salt solution concentrates may be prepared using molar equivalents of neutralizing base to glyphosate from about 1:1 to about 1.5:1, from about 1.1:1 to about 1.5:1, from about 1.2:1 to about 1.5:1, from about 1.25:1 to about 1.5:1, from about 1:1 to about 1.4:1, from about 1.2:1 to about 1.4:1, from about 1.25:1 to about 1.4:1, or from about 1.25:1 to about 1.35:1. The glyphosate salt concentrate can be prepared by adding additional neutralizing base corresponding to the relevant glyphosate salt to an existing aqueous glyphosate salt solution concentrate. Additional water may be added as necessary in order to maintain the glyphosate salt in solution. Alternatively, the glyphosate salt concentrates can be prepared by adding the neutralizing base directly to glyphosate acid wetcake and then dissolving the mixture of wetcake and base in water.
Off-site movement is a known problem of spray formulations containing salts of dicamba. Under certain conditions of application, dicamba can migrate from the application site to adjacent crop plants. As noted above, as pH increases, the volatility of dicamba generally decreases. In accordance with the present invention, it has been discovered that significant decreases in dicamba volatility are realized when the pH of the aqueous herbicidal glyphosate and dicamba salt concentrate composition is controlled as described above. Additional base can be added as necessary to the glyphosate salt solution concentrate and/or aqueous herbicidal glyphosate and dicamba salt concentrate composition as necessary to adjust the pH within the desired range as disclosed herein. Adjusting the pH within the disclosed ranges typically provides greater than about a 40%, 50%, 60% or even 75% reduction in volatility when compared to a conventional tank mixes of potassium or monoethanolamine glyphosate with diglycolamine salt of dicamba (e.g., a tank mix of CLARITY available from BASF and ROUNDUP WEATHERMAX available from Monsanto).
One or more surfactants or surfactants or surfactant systems as described above may be introduced at any step of the preparation process. In various embodiments, the surfactant is added once the dicamba and glyphosate salts have been combined in the concentrate solution. In other embodiments, the surfactant can be added to the dicamba salt solution before adding to the aqueous glyphosate salt solution concentrate.
The aqueous herbicidal concentrate compositions containing glyphosate salt and dicamba salt of the present invention are typically formulated to exhibit good storage stability at relatively low temperatures, relatively high temperatures, and/or over a wide temperatures range such that the compositions remain relatively clear without precipitation or phase separation after prolonged storage. In various embodiments, the concentrate compositions exhibit good storage stability at a temperature of less than about 0° C., less than about −10° C., less than about −20° C., or less than about −20° C. Additionally or alternatively, the concentrate compositions exhibit good storage stability at a temperature of at least about 25° C., at least about 40° C., at least about 55° C., or at least about 60° C. In various embodiments, the concentrate compositions exhibit good storage stability from about −30° C. to about 80° C., from about −30° C. to about 70° C., from about −30° C. to about 60° C., from about −10° C. to about 90° C., from about −10° C. to about 70° C., from about −10° C. to about 60° C., from about 0° C. to about 90° C., from about 0° C. to about 70° C., or from about 0° C. to about 60° C. In these embodiments, the concentrate compositions exhibit good storage stability over the period of at least about one week, at least about two weeks, at least about three weeks, or at least about four weeks.
The herbicidal concentrate compositions may further comprise other conventional adjuvants, excipients or additives known to those skilled in the art. These other additives or ingredients may be introduced into the compositions of the present invention to provide or improve certain desired properties or characteristics of the formulated product. Hence, the herbicidal concentrate composition may further comprise one or more additional ingredients selected from, without limitation, foam-moderating agents, preservatives or anti-microbials, antifreeze agents, solubility-enhancing agents, dyes, and thickening agents. For example, in various embodiments the aqueous herbicidal concentrate composition includes a foam-moderating agent such as SAG 1572 (a silicone antifoam emulsion available from Momentive). Typically the concentration of foam-moderating agent in the aqueous herbicidal concentrate composition is less than about 0.1 wt. % or less than about 0.05 wt. % (e.g., about 0.01 wt. %)
The aqueous herbicidal glyphosate and dicamba concentrate composition may be diluted with water and applied to the foliage of unwanted plants as a spray formulation solution by methods known in the art. In accordance with the methods of using a formulation of the present invention, an application mixture comprising a dilution of the aqueous herbicidal concentrate composition may be prepared, which typically comprises from about 0.1 to about 50 g a.e./L herbicide active. The application mixture is then applied to the foliage of a plant or plants at an application rate sufficient to give a commercially acceptable rate of weed control. Depending on plant species and growing conditions, the period of time required to achieve a commercially acceptable rate of weed control can be as short as a week or as long as three weeks, four weeks or 30 days. The application rate is usually expressed as amount of herbicide per unit area treated, e.g., grams acid equivalent per hectare (g a.e./ha) and can readily be determined by those skilled in the art.
The application mixture comprising a dilution of the aqueous herbicidal concentrate composition of the present invention can be applied pre-planting of the crop plant, such as from about 2 to about 3 weeks before planting glyphosate and dicamba-susceptible crop plants or crop plants not having a dicamba-resistant trait. Crop plants that are not susceptible to glyphosate and dicamba herbicides, such as corn, or plants having glyphosate-tolerant and dicamba-tolerant traits typically have no pre-planting restriction and the application mixture can be applied immediately before planting such crops.
The application mixture comprising a dilution of the aqueous herbicidal glyphosate and dicamba salt concentrate composition of the present invention can be applied at planting or post-emergence to crop plants having glyphosate-tolerant and dicamba-tolerant traits to control glyphosate and/or dicamba-susceptible weeds in a field of the crop plants and/or adjacent to a field of the crop plants.
EXAMPLESThe following non-limiting examples are provided to further illustrate the present invention.
Example 1Various aqueous herbicidal concentrate compositions containing glyphosate salt and dicamba salt were prepared by adding the desired base (e.g., monoethanolamine (MEA), isopropylamine (IPA) or potassium hydroxide) to stock glyphosate salt solutions. Salt solutions of dicamba (e.g., diglycolamine (DGA), MEA, and K salts) were added to the glyphosate salt solutions to the desired acid equivalent weight ratio (e.g., glyphosate to dicamba weight ratios of 3:1, 2:1, or 1.5:1).
The solutions which provided stable, compatible herbicidal concentrate compositions upon mixing are listed below in Table 1.
To evaluate whether surfactant(s) could be effectively incorporated into the aqueous herbicidal concentrate compositions of the present invention, several concentrate solutions containing MEA glyphosate and DGA dicamba and having a total herbicidal loading of approximately 480 g/l a.e. were prepared as described in Example 1, except various surfactants were combined the solution concentrates. The stability of the solutions was observed upon mixing and any precipitation or phase separation was noted. The stability of the solutions that appeared relatively homogeneous upon mixing was tested further by storing them at room temperature for 24 hours. Any precipitation or phase separate was noted after the 24 hour time period. Table 2 presents the results of these experiments.
The results show that stable, clear herbicidal concentrates containing surfactant Ethoquad C-12 or surfactant system APG and AGM 550 were successfully prepared. The other surfactants tested resulted in concentrates that were either hazy in appearance or separated into phases on standing.
Example 3To evaluate whether higher concentrations of surfactant(s) could be effectively incorporated into the aqueous herbicidal concentrate compositions of the present invention, concentrate solutions containing a 1.5:1 weight ratio of MEA glyphosate and DGA dicamba and having a total herbicidal loading of approximately 480 g/l a.e. were prepared in accordance with Example 1. Ethoquad C-12 dissolved in propylene glycol or diethylene glycol was then combined with the concentrates. The stability of the solutions was observed and any precipitation or phase separation was noted. Table 3 presents the results of these experiments.
The results show that stable, clear herbicidal concentrates containing surfactant 10 wt. % Ethoquad C-12 dissolved in diethylene glycol were successfully prepared. The concentrate containing 10 wt. % Ethoquad C-12 dissolved in propylene glycol separated on standing.
Other surfactants were also tested with this concentrate solutions containing a 1.5:1 weight ratio of MEA glyphosate and DGA dicamba and having a total herbicidal loading of 480 g/l a.e., including Armeen APA 810, Ammonyx 810-DO, Surfonics L12-8, L14-4 and L24-5, Tergitol 15-S-7 and Tomadol 1-3. However, concentrates containing these surfactants were either hazy in appearance or separated into phases on standing.
Example 4To test the storage stability of the concentrate compositions, samples of selected concentrate compositions containing approximately 480 g/l a.e. of MEA glyphosate salt and DGA dicamba salt prepared in accordance with Example 2 were subjected to prolonged storage for four weeks at various storage temperatures. Table 4 shows that the selected concentrate compositions exhibited good storage stability, remaining relatively clear without precipitation or phase separation, after four weeks at the temperatures indicated below.
This example describes experiments conducted to measure the dicamba concentration in the gas phase (air) volatilized from 2 wt. % a.e. dicamba spray solutions prepared from concentrates containing MEA glyphosate and DGA dicamba and having a total herbicidal loading of 480 g/l a.e. prepared in accordance with Example 1 and prior art tank mix spray solutions containing 2 wt. % a.e. DGA dicamba (CLARITY) plus 6 wt. % a.e. potassium glyphosate (WEATHERMAX) or MEA glyphosate.
10 mL samples of each solution were placed into a 50 mL plastic centrifuge tube with one hole approximately ⅛ in diameter drilled into the tube at the mark between 20 mL and 30 mL lines. A 22 mm×30 mm Polyurethane Foam (PUF), cut from a 76 mm length, available from SKC Inc., catalog #P22692, was placed into a glass tube of approximately 20 mm diameter with parafilm wrapped around the outside to obtain a snug fit into the top of the centrifuge tube. A hose was connected to the other end of the glass tube leading to a vacuum line. The air flow was regulated to approximately 2 L/min using a flow controller. Air was pulled through the tube at approximately 2 L/min for 24 hours. Note that the air conditions of flow rate, temperature, pressure and composition (e.g., relative humidity) are not narrowly critical as long as the various samples are analyzed under similar conditions. For instance, air at from about 5° C. to about 40° C., from about 0.5 to about 1.5 bar pressure, from about 0% to about 95% relative humidity, and at a flow rate of from about 0.1 to 10 L/min-mL sample could be suitably used for volatility analysis. The PUF was removed from the glass tube, extracted with 20 mL methanol and the resulting solution analyzed for dicamba concentration by LC-MS. The results are presented in Table 5.
As shown on Table 5, the spray solutions prepared from concentrates having a 2:1 or 1.5:1 weight ratio of glyphosate to dicamba exhibited lower dicamba volatility when compared to prior art spray solutions of CLARITY plus WEATHERMAX and CLARITY plus MEA glyphosate.
Example 6Five glyphosate/dicamba premix concentrate formulations were prepared using five different MEA glyphosate salt solution concentrates. The MEA glyphosate salt solution concentrates employed were prepared using different molar ratios of MEA:glyphosate. The molar ratios that were used were 1.2:1, 1.25:1, 1.3:1, 1.35:1, and 1.4:1 MEA:glyphosate. To form the glyphosate/dicamba premix concentrate formulations, MEA glyphosate salt concentrate, CLARITY (DGA dicamba salt concentrate) and water were combined in a beaker. AGNIQUE PG8107 (a C8-10 alkyl polyglycoside surfactant available from COGNIS) and AGM 550 (a C12-14 alkoxylated tertiary available from Huntsman) were added followed by ferric citrate and SAG 1572 (a silicone antifoam emulsion available from Momentive). The ingredients were stirred together for 30 minutes. The list of ingredients for the glyphosate/dicamba premix concentrate formulations is set forth below in Table 6.
The following observations/tests were performed on the glyphosate/dicamba premix concentrate formulations: appearance, specific gravity, cloud point, temperature stability at 55° C. and −20° C. and pH, and are reported below in Tables 7 and 8.
For the formulation prepared using the 1.2:1 MEA:glyphosate concentrate, when MEA glyphosate salt concentrate, CLARITY, and water were mixed, a clear green liquid formed. The salts themselves were compatible at that pH. Upon addition of the surfactants, the liquid turned hazy and 2 layers formed on standing. The formulation prepared using the 1.25 MEA:glyphosate concentrate was slightly hazy, but cleared on heating when the cloud point was measured. For the temperature stability study all of the formulation samples at −20° C. were viscous liquids. The formulation samples at 55° C. were all clear liquids. In the formulation sample prepared using the 1.25 MEA:glyphosate concentrate, there were slight wisps, probably surfactant, that were observed.
The pH of each premix concentrate formulation was measured. The pH measurements were made using a Mettler Toledo model SevenEasy pH meter with a Thermo Scientific ROSS Sure-flow pH probe. The pH meter was calibrated in accordance with the manufacturer's recommended protocol at pH 4 and pH 7 using standard buffer solutions (available from BDH). The pH measurements were obtained by immersing the probe of calibrated pH meter into each concentrate formulation and recording the digital reading.
Some samples of concentrate may exhibit sample matrix effects which have a negative interaction with pH electrodes. To determine if a sample causes an interaction, a calibration should be performed prior to sample analysis. During sample analysis, the response time to obtain a stable pH reading should be observed. Then, the response time and pH reading of the two buffers used for calibration should be rechecked. If the pH reading of the calibration buffers has a significant difference and the electrode response is slow (e.g., >20 seconds), a negative interaction of the pH electrode and sample is occurring. Different electrode should be tested until sample matrix effects are not observed.
To avoid clogging of the electrode junction, the electrode should be flushed with deionized water after each sample analysis.
Table 8 shows the pH measurements for each premix formulation tested.
Selected premix concentrate formulations prepared in accordance with Example 6 were tested for dicamba volatility using the humidome method as described below. The formulations were compared to BANVEL (dimethylamine dicamba salt solution)+ROUNDUP WEATHERMAX, CLARITY+ROUNDUP WEATHERMAX, and CLARITY alone.
Humidomes were obtained from Hummert International (Part Nos 14-3850-2 for humidomes and 11-3050-1 for 1020 flat tray) and modified by cutting a 2.2 cm diameter hole on one end approximately 5 cm from the top to allow for insertion of a glass air sampling tube (22 mm OD) containing a polyurethane foam (PUF) filter. The sampling tube was secured with a VITON o-ring on each side of the humidome wall. The air sampling tube external to the humidome was fitted with tubing that was connected to a vacuum manifold immediately prior to sampling.
The flat tray beneath the humidome was filled 1 liter of sifted dry or wet 50/50 soil (50% Redi-Earth and 50% US 10 Field Soil) to a depth of about 1 cm. The flat tray bottom containing the dicamba formulation on soil was covered with a humidome lid and the lid was secured with clamps. The assembled humidomes were placed in a temperature and humidity controlled environment and connected to a vacuum manifold through the air sampling line. Air was drawn through the humidome and PUF at a rate of 2 liters per minutes (LPM) for 24 hours at which point the air sampling was stopped. The humidomes were then removed from the controlled environment and the PUF filter was removed. The PUF filter was extracted with 20 mL of methanol and the solution was analyzed for dicamba concentration using LC-MS methods known in the art.
To measure the dicamba concentration in the gas phase (air) volatilized from the spray solutions, solutions were prepared to contain 1.2% a.e. dicamba which is equivalent to an application rate of 1.0 lb/A a.e. at 10 GPA. Where glyphosate was added or was part of the formulation, the solution was sprayed at 2.4% a.e. or 2.0 lb/A a.e. The growth chambers were set at 35° C. and 40% RH. For each formulation four separate humidome boxes were sprayed to have 4 replicates measurements for each formulation. Table 9 also provides the mean concentration of dicamba in air for each formulation.
The results show that the spray solutions prepared from premix concentrate formulations 8-2, 8-3, 8-4, and 8-5 exhibited significantly lower dicamba volatility when compared to prior art spray solutions of BANVEL plus WEATHERMAX and CLARITY plus WEATHERMAX.
When introducing elements of the present invention or the preferred embodiments(s) 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.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
As various changes could be made in the above compositions and processes without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.
Claims
1. An aqueous herbicidal concentrate composition comprising: wherein (i) the composition contains a total active herbicide loading of glyphosate monoethanolamine salt and dicamba diglycolamine salt of at least about 360 grams acid equivalent per liter; (ii) the pH of the concentrate composition is from 4.5 to 5.7; and (iii) the acid equivalent weight ratio of glyphosate monoethanolamine salt to dicamba diglycolamine salt is from about 1:1 to about 3:1.
- (a) a glyphosate component comprising the monoethanolamine salt of glyphosate;
- (b) a dicamba component comprising the diglycolamine salt of dicamba; and
- (c) a quaternary ammonium salt surfactant,
2. The composition of claim 1 wherein the quaternary ammonium salt surfactant comprises a dialkoxylated quaternary ammonium salt surfactant.
3. The composition of claim 1 wherein the quaternary ammonium salt surfactant has a structure of formula (I): wherein R11 is hydrocarbyl or substituted hydrocarbyl having from 1 to about 30 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently C2-C4 alkylene; R13 is hydrogen, or a linear or branched alkyl group having from 1 to about 4 carbon atoms; R14 is hydrocarbyl or substituted hydrocarbyl having from 1 to about 30 carbon atoms; x and y are from 1 to about 40; and X− is an agriculturally acceptable anion.
4. The composition of claim 3 wherein the R11 and R14 hydrocarbyl groups are independently selected from linear or branched alkyl having from 1 to about 25 carbon atoms, linear or branched alkenyl having from 1 to about 25 carbon atoms, linear or branched alkynyl having from 1 to about 25 carbon atoms, aryl, and aralkyl groups.
5. The composition of claim 3 wherein R13 is hydrogen, methyl or ethyl; and the sum of x and y is a number from about 2 to about 30.
6. The composition of claim 3 wherein R11 is a linear or branched alkyl group having from about 8 to about 22 carbon atoms; R14 is a linear or branched alkyl group having from 1 to about 22 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and x is a number from about 2 to about 20.
7. The composition of claim 3 wherein R11 is a linear or branched alkyl group having from about 8 to about 22 carbon atoms; R14 is a linear or branched alkyl group having from 1 to about 6 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and x is a number from about 2 to about 15.
8. The composition of claim 3 wherein R11 and R14 are independently a linear or branched alkyl group having from about 8 to about 22 carbon atoms; R12 in each of the (R12O)x and (R12O)y groups is independently ethylene or propylene; R13 is hydrogen or methyl; and x is a number from about 5 to about 15.
9. The composition of claim 1 wherein the quaternary ammonium salt surfactant comprises a cocoalkylmethylbis(2-hydroxyethyl) ammonium chloride salt.
10. The composition of claim 1 wherein the concentrate composition further comprises diethylene glycol or polyethylene glycol.
11. The composition of claim 1 wherein the composition further comprises an alkylpolysaccharide surfactant.
12. The composition of claim 11 wherein the alkylpolysaccharide surfactant has a structure of formula (III): wherein R5 is a straight or branched chain substituted or unsubstituted hydrocarbyl selected from alkyl, alkenyl, alkylphenyl, alkenylphenyl having from about 4 to about 22 carbon atoms; the sug moiety is a saccharide residue; and u is a number from 1 to about 10.
- R5—O-(sug)u (III)
13. The composition of claim 12 wherein the alkylpolysaccharide surfactant is an alkylpolyglucoside wherein R5 is a branched or straight chain alkyl group having from 4 to 22 carbon atoms or a mixture of alkyl groups having an average value within the given range; sug is a glucose residue; and u is from 1 to about 5.
14. The composition of claim 1 wherein the composition has a total surfactant concentration of from about 2.5 wt. % to about 15 wt. %.
15. The composition of claim 1 wherein the total active herbicide loading of glyphosate monoethanolamine salt and dicamba diglycolamine salt is at least about 450 grams acid equivalent per liter.
16. The composition of claim 1 wherein the total active herbicide loading of glyphosate monoethanolamine salt and dicamba diglycolamine salt is from about 360 g/l to about 550 g/l on an acid equivalent basis.
17. The composition of claim 1 wherein the total active herbicide loading of glyphosate monoethanolamine salt and dicamba diglycolamine salt is from about 480 g/l to about 540 g/l on an acid equivalent basis.
18. The composition of claim 1 wherein the total active herbicide loading of glyphosate monoethanolamine salt and dicamba diglycolamine salt is from about 480 g/l to about 520 g/l on an acid equivalent basis.
19. The composition of claim 1 wherein the composition does not include a polybasic polymer.
20. The composition of claim 1 wherein the pH of the concentrate composition is from about 4.7 to 5.5.
21. The composition of claim 1 wherein the pH of the concentrate composition is from about 5 to 5.5.
Type: Application
Filed: Jul 7, 2020
Publication Date: Nov 12, 2020
Applicant: Monsanto Technology LLC (St. Louis, MO)
Inventor: Alison MacInnes (St. Louis, MO)
Application Number: 16/922,121
