AU2013201552B2 - Synergistic herbicidal composition containing a substituted phenoxy alkanoic acid derivative and a glyphosate derivative - Google Patents

Abstract

A herbicidal composition containing (a) a herbicidal substituted phenoxy alkanoic acid derivative component and (b) a herbicidal glyphosate component provides synergistic control of selected weeds.

Description

P/00/01 1 Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Synergistic herbicidal composition containing a substituted phenoxy alkanoic acid derivative and a glyphosate derivative The following statement is a full description of this invention, including the best method of performing it known to us: SYNERGISTIC HERBICIDAL COMPOSITION CONTAINING A SUBSTITUTED PHENOXY ALKANOIC ACID DERIVATIVE AND A GLYPHOSATE DERIVATIVE This application claims the benefit of United States Provisional 5 Application Serial Number 60/937,788 filed on June 29, 2007. This invention concerns a synergistic herbicidal composition containing (a) a substituted phenoxy alkanoic acid derivative and (b) a glyphosate derivative. More particularly, the invention concerns a synergistic herbicidal composition containing (a) a 2,4 dichlorophenoxy acetic acid (2,4-D) or 2,4-dichlorophenoxy propionic acid 10 (dichlorprop) derivative and (b) a glyphosate salt. The protection of crops from weeds and other vegetation which inhibit crop growth is a constantly recurring problem in agriculture. To help combat this problem, researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control 15 of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use. In some cases, herbicidal active ingredients have been shown to be more effective in combination than when applied individually and this is referred to as "synergism." As described in the Herbicide Handbook of the Weed Science 20 Society of America, Seventh Edition, 1994, p. 318, "'synergism' [is] an interaction of two or more factors such that the effect when combined is greater than the predicted effect based on the response of each factor applied separately." The present invention is based on the discovery that substituted phenoxy alkanoic acid derivatives and glyphosate derivatives, already known individually for their 25 herbicidal efficacy, display a synergistic effect when applied in combination. - 0- The herbicidal compounds forming the synergistic composition of this invention are independently known in the art for their effects on plant growth. For example, 2,4-D, 2,4-dichlorophenoxy acetic acid, is a selective systemic herbicide used to control annual and perennial broad-leaved weeds in various crops as well as in non-crop 5 land, including areas adjacent to water. It is commercially available, for example, as an ester such as EsteronTM herbicide from Dow AgroSciences and as a salt such as DMA-4TM herbicide from Dow AgroSciences. Dichlorprop, 2,4-dichlorophenoxy propionic acid, is a selective systemic herbicide used to control annual and perennial broad-leaved weeds in various crops as well as in non-crop land. It is commercially available, for example, as a salt such as DicopurTM [0 DP herbicide or Duplosan T M DP herbicide from Nufarm. Glyphosate, N-(phophonomethyl)glycine, is a non-selective systemic herbicide used to control annual and perennial grasses and broad-leaved weeds, particularly in crops that have been genetically modified to be tolerant of glyphosate. It is commercially available, for example, as RoundupTM herbicide from Monsanto or Glyphomax PlusTM herbicide from Dow 15 AgroSciences. Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. 20 As used herein, except where the context requires otherwise the term 'comprise' and variations of the term, such as 'comprising', 'comprises' and 'comprised', are not intended to exclude other additives, components, integers or steps. The present invention concerns a synergistic herbicidal mixture comprising an herbicidally effective amount of (a) a substituted phenoxy alkanoic acid derivative of the formula O (CH) C0 2 H C1 X 25 wherein X represents Cl or CH 3

;

R independently represents H or CH 3 ; and n is an integer from 1-3; and (b) a glyphosate derivative. Preferred substituted phenoxy alkanoic acids are 2,4-D and dichlorprop. The compositions may also contain an agriculturally acceptable adjuvant or carrier. The present invention concerns a synergistic herbicidal mixture comprising (a) dichlorprop potassium salt, and (b) glyphosate isopropylamine salt as active ingredients, wherein the concentration of the active ingredients in the herbicidal mixture is 0.001 to 98% by weight. The present invention also concerns a method of controlling the growth of undesirable vegetation, particularly in crops that are tolerant, either naturally or through genetic ) modification, to the active herbicides of the synergistic mixture, and the use of this synergistic composition. The species spectrums of the compounds of the synergistic mixture, i.e., the weed species which the respective compounds control, are broad and highly complimentary. While glyphosate is a non-selective herbicide, resistance to glyphosate by several weed species, for example, 5 horseweed (Conyza canadensis, ERICA), has been well documented. The synergistic mixture of 2,4-D or dichlorprop and glyphosate is particularly effective at controlling these glyphosate resistant weeds. Other weeds which the mixture of 2,4-D or dichlorprop and glyphosate synergistically control include ivyleaf morningglory (Ipomoea hederacea; IPOHE), Canada thistle (Cirsium arvense; CIRAR), prickly sida (Sida spinosa; SIDSP), velvetleaf (Abutilon 0 theophrasti; ABUTH), common ragweed (Ambrosia artemesifolia; AMBEL), spiderwort (Commelina benghalensis; COMBE), hemp sesbania (Sesbania exaltata; SEBEX), field bindweed (Polygonum convolvulus; POLCO), and common waterhemp (Amaranthus rudis; AMATA). The term herbicide is used herein to mean an active ingredient that kills, controls or Z5 otherwise adversely modifies the growth of plants. An herbicidally effective or vegetation controlling amount is an amount of active ingredient which causes an adversely modifying effect and includes deviations from natural development, killing, regulation, desiccation, retardation, and the like. The terms plants and vegetation include germinating seeds, emerging seedlings and established vegetation. 5 Herbicidal activity is exhibited by the compounds of the synergistic mixture when they are applied directly to the plant or to the locus of the plant at any stage of growth or before planting or emergence. The effect observed depends upon the plant species to be controlled, the stage of growth of the plant, the application parameters of dilution and spray drop size, the particle size of solid 10 components, the environmental conditions at the time of use, the specific compound employed, the specific adjuvants and carriers employed, the soil type, and the like, as well as the amount of chemical applied. These and other factors can be adjusted as is known in the art to promote non-selective or selective herbicidal action. Generally, it is preferred to apply the composition of the 15 present invention postemergence to relatively immature undesirable vegetation to achieve the maximum control of weeds. The substituted phenoxy alkanoic acid derivatives in which R is CH 3 contain asymmetric carbon atoms and are capable of existing as a racemic mixture such as dichlorprop or as an individual enantiomer or an enriched enantiomeric 20 mixture such as dichlorprop-P By substituted phenoxy alkanoic acid derivatives and glyphosate derivatives is meant the acids themselves and their agriculturally acceptable esters and salts. Suitable salts include those derived from alkali or alkaline earth metals and 25 those derived from ammonia and amines. Preferred cations include sodium, potassium, magnesium, and aminium cations of the formula: -4-

R

1

R

2

R

3 NH+ wherein R 1 , R 2 , and R 3 each, independently represents hydrogen or C-C 12 alkyl,

C

3

-C

12 alkenyl or C 3

-C

12 alkynyl, each of which is optionally substituted by one or more hydroxy, C 1

-C

4 alkoxy, C 1

-C

4 alkylthio or phenyl groups, provided that R 1 , 5 R 2 , and R 3 are sterically compatible. Preferred amine salts are those derived from ammonia, methylamine, dimethylamine, trimethylamine, isopropylamine, monoethanolamine, diethanolamine, triethanolamine, triisopropanolamine, 2-methylthiopropylamine, bisallylamine, 2-butoxyethylamine, morpholine, cyclo dodecylamine, or benzylamine. Amine salts are often preferred because they are 10 water-soluble and lend themselves to the preparation of desirable aqueous based herbicidal compositions. Suitable esters include those derived from C 1

-C

12 alkyl, C 3

-C

12 alkenyl or

C

3 -C1 2 alkynyl alcohols, such as methanol, iso-propanol, butanol, 2-ethylhexanol, butoxyethanol, methoxypropanol, allyl alcohol, propargyl alcohol or 15 cyclohexanol. In the composition of this invention, the weight ratio on an acid equivalent basis of the substituted phenoxy alkanoic acid component to glyphosate component at which the herbicidal effect is synergistic lies within the range of between 5:1 and 1:48. Preferably the weight ratio of the substituted phenoxy 20 alkanoic acid component to the glyphosate component lies within the range of between 3:1 and 1:12 with a weight ratio of between 1:1 and 1:12 being especially preferred. The rate at which the synergistic composition is applied will depend upon the particular type of weed to be controlled, the degree of control required, and the 25 timing and method of application. In general, the composition of the invention can be applied at an application rate of between 100 grams of acid equivalents per -5hectare (g ae/ha) and 2000 g ae/ha based on the total amount of active ingredients in the composition. An application rate between 200 g ae/ha and 1000 g ae/ha is preferred. In an especially preferred embodiment of the invention, the 2,4-D component is applied at a rate between 35 g ae/ha and 560 g ae/ha, the 5 dichlorprop component is applied at a rate between 35 g ae/ha and 280 g ae/ha and the glyphosate component is applied at a rate between 100 g ae/ha and 750 g ae/ha. The components of the synergistic mixture of the present invention can be applied either separately or as part of a multipart herbicidal system. 10 The synergistic mixture of the present invention can be applied in conjunction with one or more other herbicides to control a wider variety of undesirable vegetation. When used in conjunction with other herbicides, the composition can be formulated with the other herbicide or herbicides, tank mixed with the other herbicide or herbicides or applied sequentially with the other 15 herbicide or herbicides. Some of the herbicides that can be employed in conjunction with the synergistic composition of the present invention include: amide herbicides such as allidochlor, beflubutamid, benzadox, benzipram, bromobutide, cafenstrole, CDEA, chlorthiamid, cyprazole, dimethenamid, dimethenamid-P, diphenamid, epronaz, etnipromid, fentrazamide, flupoxam, 20 fomesafen, halosafen, isocarbamid, isoxaben, napropamide, naptalam, pethoxamid, propyzamide, quinonamid and tebutam; anilide herbicides such as chloranocryl, cisanilide, clomeprop, cypromid, diflufenican, etobenzanid, fenasulam, flufenacet, flufenican, mefenacet, mefluidide, metamifop, monalide, naproanilide, pentanochlor, picolinafen and propanil; arylalanine herbicides such 25 as benzoylprop, flamprop and flamprop-M; chloroacetanilide herbicides such as acetochlor, alachlor, butachlor, butenachlor, delachlor, diethatyl, dimethachlor, metazachlor, metolachlor, S-metolachlor, pretilachlor, propachlor, propisochlor, prynachlor, terbuchlor, thenylchlor and xylachlor; sulfonanilide herbicides such as -6benzofluor, perfluidone, pyrimisulfan and profluazol; sulfonamide herbicides such as asulam, carbasulam, fenasulam and oryzalin; antibiotic herbicides such as bilanafos; benzoic acid herbicides such as chloramben, dicamba, 2,3,6-TBA and tricamba; pyrimidinyloxybenzoic acid herbicides such as bispyribac and 5 pyriminobac; pyrimidinylthiobenzoic acid herbicides such as pyrithiobac; phthalic acid herbicides such as chlorthal; picolinic acid herbicides such as aminopyralid, clopyralid and picloram; quinolinecarboxylic acid herbicides such as quinclorac and quinmerac; arsenical herbicides such as cacodylic acid, CMA, DSMA, hexaflurate, MAA, MAMA, MSMA, potassium arsenite and sodium 10 arsenite; benzoylcyclohexanedione herbicides such as mesotrione, sulcotrione, tefuryltrione and tembotrione; benzofuranyl alkylsulfonate herbicides such as benfuresate and ethofumesate; carbamate herbicides such as asulam, carboxazole chlorprocarb, dichlormate, fenasulam, karbutilate and terbucarb; carbanilate herbicides such as barban, BCPC, carbasulam, carbetamide, CEPC, chlorbufam, 15 chlorpropham, CPPC, desmedipham, phenisopham, phenmedipham, phenmedipham-ethyl, propham and swep; cyclohexene oxime herbicides such as alloxydim, butroxydim, clethodim, cloproxydim, cycloxydim, profoxydim, sethoxydim, tepraloxydim and tralkoxydim; cyclopropylisoxazole herbicides such as isoxachlortole and isoxaflutole; dicarboximide herbicides such as 20 benzfendizone, cinidon-ethyl, flumezin, flumiclorac, flumioxazin and flumipropyn; dinitroaniline herbicides such as benfluralin, butralin, dinitramine, ethalfluralin, fluchloralin, isopropalin, methalpropalin, nitralin, oryzalin, pendimethalin, prodiamine, profluralin and trifluralin; dinitrophenol herbicides such as dinofenate, dinoprop, dinosam, dinoseb, dinoterb, DNOC, etinofen and 25 medinoterb; diphenyl ether herbicides such as ethoxyfen; nitrophenyl ether herbicides such as acifluorfen, aclonifen, bifenox, chlomethoxyfen, chlornitrofen, etnipromid, fluorodifen, fluoroglycofen, fluoronitrofen, fomesafen, furyloxyfen, halosafen, lactofen, nitrofen, nitrofluorfen and oxyfluorfen; dithiocarbamate herbicides such as dazomet and metam; halogenated aliphatic herbicides such as -7alorac, chloropon, dalapon, flupropanate, hexachloroacetone, iodomethane, methyl bromide, monochloroacetic acid, SMA and TCA; imidazolinone herbicides such as imazamethabenz, imazamox, imazapic, imazapyr, imazaquin and imazethapyr; inorganic herbicides such as ammonium sulfamate, borax, 5 calcium chlorate, copper sulfate, ferrous sulfate, potassium azide, potassium cyanate, sodium azide, sodium chlorate and sulfuric acid; nitrile herbicides such as bromobonil, bromoxynil, chloroxynil, dichlobenil, iodobonil, ioxynil and pyraclonil; organophosphorus herbicides such as amiprofos-methyl, anilofos, bensulide, bilanafos, butamifos, 2,4-DEP, DMPA, EBEP, fosamine, glufosinate 10 and piperophos; phenoxy herbicides such as bromofenoxim, clomeprop, 2,4-DEB, 2,4-DEP, difenopenten, disul, erbon, etnipromid, fenteracol and trifopsime; phenoxyacetic herbicides such as 4-CPA, 3,4-DA, MCPA-thioethyl and 2,4,5-T; phenoxybutyric herbicides such as 4-CPB, 3,4-DB, and 2,4,5-TB; phenoxypropionic herbicides such as cloprop, 4-CPP, 3,4-DP and fenoprop,; 15 aryloxyphenoxypropionic herbicides such as chlorazifop, clodinafop, clofop, cyhalofop, diclofop, fenoxaprop, fenoxaprop-P, fenthiaprop, fluazifop, fluazifop P, haloxyfop, haloxyfop-P, isoxapyrifop, metamifop, propaquizafop, quizalofop, quizalofop-P and trifop; phenylenediamine herbicides such as dinitramine and prodiamine; pyrazolyl herbicides such as benzofenap, pyrazolynate, pyrasulfotole, 20 pyrazoxyfen, pyroxasulfone and topramezone; pyrazolylphenyl herbicides such as fluazolate and pyraflufen; pyridazine herbicides such as credazine, pyridafol and pyridate; pyridazinone herbicides such as brompyrazon, chloridazon, dimidazon, flufenpyr, metflurazon, norflurazon, oxapyrazon and pydanon; pyridine herbicides such as cliodinate, dithiopyr, fluroxypyr, haloxydine, picolinafen, pyriclor, 25 thiazopyr and triclopyr; pyrimidinediamine herbicides such as iprymidam and tioclorim; quaternary ammonium herbicides such as cyperquat, diethamquat, difenzoquat, diquat, morfamquat and paraquat; thiocarbamate herbicides such as butylate, cycloate, di-allate, EPTC, esprocarb, ethiolate, isopolinate, methiobencarb, molinate, orbencarb, pebulate, prosulfocarb, pyributicarb, -8sulfallate, thiobencarb, tiocarbazil, tri-allate and vernolate; thiocarbonate herbicides such as dimexano, EXD and proxan; thiourea herbicides such as methiuron; triazine herbicides such as dipropetryn, triaziflam and trihydroxytriazine; chlorotriazine herbicides such as atrazine, chlorazine, 5 cyanazine, cyprazine, eglinazine, ipazine, mesoprazine, procyazine, proglinazine, propazine, sebuthylazine, simazine, terbuthylazine and trietazine; methoxytriazine herbicides such as atraton, methometon, prometon, secbumeton, simeton and terbumeton; methylthiotriazine herbicides such as ametryn, aziprotryne, cyanatryn, desmetryn, dimethametryn, methoprotryne, prometryn, simetryn and 10 terbutryn; triazinone herbicides such as ametridione, amibuzin, hexazinone, isomethiozin, metamitron and metribuzin; triazole herbicides such as amitrole, cafenstrole, epronaz and flupoxam; triazolone herbicides such as amicarbazone, bencarbazone, carfentrazone, flucarbazone, propoxycarbazone, sulfentrazone and thiencarbazone-methyl; triazolopyrimidine herbicides such as cloransulam, 15 diclosulam, florasulam, flumetsulam, metosulam, penoxsulam and pyroxsulam; uracil herbicides such as butafenacil, bromacil, flupropacil, isocil, lenacil and terbacil; 3-phenyluracils; urea herbicides such as benzthiazuron, cumyluron, cycluron, dichloralurea, diflufenzopyr, isonoruron, isouron, methabenzthiazuron, monisouron and noruron; phenylurea herbicides such as anisuron, buturon, 20 chlorbromuron, chloreturon, chlorotoluron, chloroxuron, daimuron, difenoxuron, dimefuron, diuron, fenuron, fluometuron, fluothiuron, isoproturon, linuron, methiuron, methyldymron, metobenzuron, metobromuron, metoxuron, monolinuron, monuron, neburon, parafluron, phenobenzuron, siduron, tetrafluron and thidiazuron; pyrimidinylsulfonylurea herbicides such as amidosulfuron, 25 azimsulfuron, bensulfuron, chlorimuron, cyclosulfamuron, ethoxysulfuron, flazasulfuron, flucetosulfuron, flupyrsulfuron, foransulfuron, halosulfuron, imazosulfuron, mesosulfuron, nicosulfuron, orthosulfamuron, oxasulfuron, primisulfuron, pyrazosulfuron, rimsulfuron, sulfometuron, sulfosulfuron and trifloxysulfuron; triazinylsulfonylurea herbicides such as chlorsulfuron, -9cinosulfuron, ethametsulfuron, iodosulfuron, metsulfuron, prosulfuron, thifensulfuron, triasulfuron, tribenuron, triflusulfuron and tritosulfuron; thiadiazolylurea herbicides such as buthiuron, ethidimuron, tebuthiuron, thiazafluron and thidiazuron; and unclassified herbicides such as acrolein, allyl 5 alcohol, aminocyclopyrachlor, azafenidin, benazolin, bentazone, benzobicyclon, buthidazole, calcium cyanamide, cambendichlor, chlorfenac, chlorfenprop, chlorflurazole, chlorflurenol, cinmethylin, clomazone, CPMF, cresol, ortho dichlorobenzene, dimepiperate, endothal, fluoromidine, fluridone, flurochloridone, flurtamone, fluthiacet, indanofan, methazole, methyl 10 isothiocyanate, nipyraclofen, OCH, oxadiargyl, oxadiazon, oxaziclomefone, pentachlorophenol, pentoxazone, phenylmercury acetate, pinoxaden, prosulfalin, pyribenzoxim, pyriftalid, quinoclamine, rhodethanil, sulglycapin, thidiazimin, tridiphane, trimeturon, tripropindan and tritac. The synergistic composition of the present invention is particularly useful 15 when used on glyphosate-tolerant, glufosinate-tolerant, 2,4-D-tolerant, dicamba tolerant or imiazolinone-tolerant crops. It is generally preferred to use the synergistic composition of the present invention in combination with herbicides that are selective for the crop being treated and which complement the spectrum of weeds controlled by these compounds at the application rate employed. It is 20 further generally preferred to apply the synergistic composition of the present invention and other complementary herbicides at the same time, either as a combination formulation or as a tank mix. The synergistic composition of the present invention can generally be employed in combination with known herbicide safeners, such as benoxacor, 25 benthiocarb, brassinolide, cloquintocet (mexyl), cyometrinil, daimuron, dichlormid, dicyclonon, dimepiperate, disulfoton, fenchlorazole-ethyl, fenclorim, flurazole, fluxofenim, furilazole, isoxadifen-ethyl, mefenpyr-diethyl, MG 191, -10- MON 4660, naphthalic anhydride (NA), oxabetrinil, R29148 and N-phenyl sulfonylbenzoic acid amides, to enhance their selectivity. In practice, it is preferable to use the synergistic composition of the present invention in mixtures containing an herbicidally effective amount of the herbicidal 5 components along with at least one agriculturally acceptable adjuvant or carrier. Suitable adjuvants or carriers should not be phytotoxic to valuable crops, particularly at the concentrations employed in applying the compositions for selective weed control in the presence of crops, and should not react chemically with herbicidal components or other composition ingredients. Such mixtures can 10 be designed for application directly to weeds or their locus or can be concentrates or formulations that are normally diluted with additional carriers and adjuvants before application. They can be solids, such as, for example, dusts, granules, water dispersible granules, or wettable powders, or liquids, such as, for example, emulsifiable concentrates, solutions, emulsions or suspensions. 15 Suitable agricultural adjuvants and carriers that are useful in preparing the herbicidal mixtures of the invention are well known to those skilled in the art. Liquid carriers that can be employed include water, toluene, xylene, petroleum naphtha, crop oil, acetone, methyl ethyl ketone, cyclohexanone, trichloroethylene, perchloroethylene, ethyl acetate, amyl acetate, butyl acetate, 20 propylene glycol monomethyl ether and diethylene glycol monomethyl ether, methanol, ethanol, isopropanol, amyl alcohol, ethylene glycol, propylene glycol, glycerine, N-methylpyrrolidinone, N-N-dimethylalkylamides, dimethyl sulfoxide and the like. Water is generally the carrier of choice for the dilution of concentrates. 25 Suitable solid carriers include talc, pyrophyllite clay, silica, attapulgus clay, kaolin clay, kieselguhr, chalk, diatomaceous earth, lime, calcium carbonate, -11bentonite clay, Fuller's earth, cotton seed hulls, wheat flour, soybean flour, pumice, wood flour, walnut shell flour, lignin, and the like. It is usually desirable to incorporate one or more surface-active agents into the compositions of the present invention. Such surface-active agents are 5 advantageously employed in both solid and liquid compositions, especially those designed to be diluted with carrier before application. The surface-active agents can be anionic, cationic or nonionic in character and can be employed as emulsifying agents, wetting agents, suspending agents, or for other purposes. Typical surface-active agents include salts of alkyl sulfates, such as diethanol 10 ammonium lauryl sulfate; alkylarylsulfonate salts, such as calcium dodecyl benzenesulfonate; alkylphenol-alkylene oxide addition products, such as nonylphenol-Cis ethoxylate; alcohol-alkylene oxide addition products, such as tridecyl alcohol-C 1 6 ethoxylate; soaps, such as sodium stearate; alkylnaphthalene sulfonate salts, such as sodium dibutylnaphthalenesulfonate; dialkyl esters of 15 sulfosuccinate salts, such as sodium di(2-ethylhexyl) sulfosuccinate; sorbitol esters, such as sorbitol oleate; quaternary amines, such as lauryl trimethyl ammonium chloride; polyethylene glycol esters of fatty acids, such as poly ethylene glycol stearate; block copolymers of ethylene oxide and propylene oxide; and salts of mono and dialkyl phosphate esters. 20 Other adjuvants commonly used in agricultural compositions include compatibilizing agents, antifoam agents, sequestering agents, neutralizing agents and buffers, corrosion inhibitors, dyes, odorants, spreading agents, penetration aids, sticking agents, dispersing agents, thickening agents, freezing point depressants, antimicrobial agents, and the like. The compositions may also 25 contain other compatible components, for example, other herbicides, plant growth regulants, fungicides, insecticides, and the like and can be formulated with liquid fertilizers or solid, particulate fertilizer carriers such as ammonium nitrate, urea and the like. -12- The concentration of the active ingredients in the synergistic composition of the present invention is generally from 0.001 to 98 percent by weight. Concentrations from 0.01 to 90 percent by weight are often employed. In compositions designed to be employed as concentrates, the active ingredients are 5 generally present in a concentration from 5 to 98 weight percent, preferably 10 to 90 weight percent. Such compositions are typically diluted with an inert carrier, such as water, before application. The diluted compositions usually applied to weeds or the locus of weeds generally contain 0.0001 to 1 weight percent active ingredient and preferably contain 0.001 to 0.05 weight percent. 10 The present compositions can be applied to weeds or their locus by the use of conventional ground or aerial dusters, sprayers, and granule applicators, by addition to irrigation water, and by other conventional means known to those skilled in the art. The following examples illustrate the present invention. -13- Examples 2,4-D (dimethylamine salt), dichlorprop (potassium salt) and Glyphomax XRT@ herbicide (isopropylamine salt) alone and in combinations were applied to the foliage of rapidly growing plant material utilizing a track sprayer calibrated to 5 deliver an application volume of 187 L/ha. Treated plant material was maintained in a greenhouse that provided a 16-hr photoperiod, supplemented with metal halide-generated light, set to provide a minimum of 500 pmolm 2 s 1 . The greenhouse was maintained at a temperature of 26 to 28 *C and a relative humidity of 50 to 70%. Assessment of herbicidal activity was performed visually 14 to 21 10 days after application. The expected growth reduction of plant species from the combination of herbicides was calculated utilizing the Colby equation: Expected growth reduction (E) = X+Y - (X*Y/100) where X is % of growth reduction of a weed at a given concentration of a 15 herbicide (or herbicide formulation) and Y is the % growth reduction of the same species and size weed at a given concentration of an independent herbicide (or herbicide formulation). Tables I, II, III and IV contain the data for expected and actual herbicidal growth reduction caused by relevant individual herbicides and combinations of 20 these herbicides on agronomically important weeds. -14- TABLE I: Herbicidal effects of Glyphomax XRT*, 2,4-D and combinations of the two herbicides on select broadleaf weeds. Glyphomax Expected Actual Species XRT Rate 2,4-D Rate Injury* Injury (% growth (% growth (g ae/ha) (g ae/ha) reduction) reduction) IPOHE 210 0 - 43 0 70 -- 17 210 70 53 93 CIRAR 210 0 -- 25 0 280 -- 38 210 280 54 95 SIDSP 420 0 -- 33 0 140 -- 17 420 140 44 72 ABUTH 210 0 -- 17 0 280 -- 28 210 280 40 60 AMBEL 105 0 -- 12 0 140 -- 61 105 140 66 96 COMBE 560 0 -- 38 0 140 -- 48 560 140 68 95 SEBEX 210 0 -- 13 0 280 -- 37 210 280 45 93 POLCO 420 0 -- 18 0 280 -- 32 420 280 44 83 AMATA 210 0 - 8 0 280 -- 53 210 280 57 99 *Expected injury values were calculated using Colby's equation. 5 -15- Table II: Herbicidal effects of Glyphomax XRT*, 2,4-D and combinations of the two herbicides on glyphosate-susceptible and glyphosate-resistant Conyza canadensis (ERICA). Glyphomax Expected Species XRT Rate 2,4-D Rate Injury* Actual Injury (% growth (% growth (g ae/ha) (g ae/ha) reduction) reduction) ERICA 420 0 -- 50 Glyphosate 0 35 -- 47 Susceptible 420 35 74 86 ERICA 420 0 -- 12 Glyphosate 0 70 -- 38 Resistant 420 70 45 99 5 *Expected injury values were calculated using Colby's equation. Table III: Herbicidal effects of Glyphomax XRT*, dichlorprop and combinations of the two herbicides on glyphosate-susceptible and glyphosate-resistant Conyza 10 canadensis (ERICA). Glyphomax Dichlorprop Expected Species XRT Rate Rate Injury* Actual Injury (% growth (% growth (g ae/ha) (g ae/ha) reduction) reduction) ERICA 420 0 - 50 Glyphosate 0 210 -- 43 Susceptible 420 210 72 92 ERICA 420 0 -- 12 Glyphosate 0 210 -- 43 Resistant 420 210 50 93 *Expected injury values were calculated using Colby's equation. -16- Table IV: Herbicidal effects of Glyphomax XRT*, dichlorprop and combinations of the two herbicides on select broadleaf weeds. Glyphomax Dichlorprop Expected Species XRT Rate Rate Injury* Actual Injury (% growth (% growth (g ae/ha) (g ae/ha) reduction) reduction) IPOHE 105 0 -- 12 0 70 -- 68 105 70 72 92 CIRAR 210 0 -- 25 0 70 -- 48 210 70 61 85 ABUTH 210 0 -- 17 0 70 -- 33 210 70 44 58 AMBEL 105 0 -- 12 0 280 -- 58 105 280 63 82 COMBE 560 0 -- 38 0 70 -- 80 560 70 88 96 SEBEX 210 0 -- 13 0 140 -- 38 210 140 46 75 POLCO 420 0 -- 18 0 140 -- 38 420 140 49 87 AMATA 210 0 -- 8 0 280 -- 48 210 280 52 98 5 *Expected injury values were calculated using Colby's equation. -17- A field study was conducted at Church Hill, MD where glyphosate resistant horseweed (ERICA, Conyza canadensis) had been observed for 2-3 years prior to the start of this study. The study design was a split-plot with 4 replications per treatment and each plot was 3.048 M wide and 9.144 M long. The 5 environmental conditions at the time of application were as follows: air temperature, 22 'C; wind speed, 6 kph; wind direction, south; releative humidity, 85%; cloud cover, 80%; target foliage moisture, none; soil moisture, moist; soil temperature at 5 cm depth, 21 0 C. The treatments were applied using a backpack

CO

2 sprayer, with six XR8003 flat fan nozzles spaced 46 cm apart (boom length: 10 2.76 M) and held 40 cm above the plant canopy. The sprayer was operated at 103 kPa and 4,8 kilometers per hour to deliver 187 L of water per hectare. At the time of applications the glyphosate-resistant horseweed were 30 - 38 cm tall and there were betweenlO and 20 plants per square meter (M 2 ). The percent visual control of glyphosate-resistant horseweed was rated over the entire plot (27.87 M 2 ) 29 15 days after application.. In each plot between 278 and 557 glyphosate-resistant horseweed plants were rated, collectively, for percent visual control. The results are tabulated in Table V. -18- Table V: Herbicidal effects of Glyphomax Plus*, 2,4-D and combinations of the two herbicides on glyphosate-resistant Conyza canadensis (ERICA) Glyphomax Plus Rate 2,4-D Rate Expected Injury* Actual Injury (% growth (% growth (g ae/ha) (g ae/ha) reduction) reduction) 280 0 - 2.5 0 _ 280 -- 12.5 280 280 14.7 35.0 280 - 2.5 0 560 23.0 280 560 24.9 43.8 0 1120 - 36.3 280 1120 37.9 57.5 560 0 - 8.8 0 280 -- 12.5 560 280 20.2 61.3 560 0 - 8.8 0 560 : 23.0 560 560 29.8 68.8 560 0 - 8.8 0 1120 . .. 36.3 560 1120 41.9 86.8 840 0 -- 13.8 0 280 -- 12.5 840 280 24.6 60.0 840 0 13.8 0 560 - 23.0 840 560 33.6 87.5 840 0 13.8 0 1120 - 36.3 840 1120 45.1 74.5 *Expected injury values were calculated using Colby's equation. -19- Although the invention has been described with reference to preferred embodiments and examples thereof, the scope of the present invention is not limited only to those described embodiments. As will be apparent to persons skilled in the art, modifications and adaptations to the above-described invention 5 can be made without departing from the spirit and scope of the invention, which is defined and circumscribed by the appended claims. -20-

Claims (7)

1. An herbicidal mixture comprising (a) dichlorprop potassium salt, and (b) glyphosate isopropylamine salt as active ingredients, wherein the concentration of the active ingredients in the herbicidal mixture is 0.001 to 98% by weight. i

2. The mixture of claim 1, wherein the weight ratio on an acid equivalent basis of the dichlorprop potassium salt to the glyphosate isopropylamine salt is between 5:1 and 1:48.

3. The mixture of claim 1 or 2, wherein the weight ratio on an acid equivalent basis of the dichlorprop potassium salt to the glyphosate isopropylamine salt is between 3:1 and 1: 12.

4. An herbicidal composition comprising the herbicidal mixture of any one of claims 1 to 3 ) and an agriculturally acceptable adjuvant or carrier.

5. A method of controlling undesirable vegetation which comprises contacting the vegetation or the locus thereof with or applying to the soil to prevent the emergence of vegetation the herbicidal mixture of claims 1 to 3.

6. The method of claim 5, wherein the undesirable vegetation is glyphosate-resistant 5 horseweed.

7. The mixture of claim 1, substantially as herein described.