REVERSIBLE AGRICULTURAL GEL AND PASTE FORMULATIONS

Abstract: A thixotropic pesticide formulation which is water-based and relies on electrolytic differences among formulation ingredients to maintain thixotropy, and to a method for using the formulation to control crop pests.

Description: TITLE REVERSIBLE AGRICULTURAL GEL AND PASTE FORMULATIONS BACKGROUND OF THE INVENTION Aqueous suspensions of pesticides are well known in the art. For example, see International Union of Pure and Applied Chemistry (Applied Chemistry Division) "Pesticide Chemistry: Human Welfare and the Environment" Proceedings of the 5th International Congress of Pesticide Chemistry, Kyoto, Japan, 29 August - 4 September, 1982. The use of inorganic salts to reduce the solubility of an otherwise soluble pesticide acid, base or salt causing precipitation of the pesticide acid, base or salt, a process known as "salting-out," is also known in the art and traditionally taught in university Chemistry and Engineering Thermodynamics courses. For example, see D. J. Shaw, "Introduction to Colloid and Surface Chemistry," London Butterworths, 1966. U.S.4,936,900 teaches the use of carboxylic or inorganic acid salts-to chemically stabilize sulfonylurea pesticides, or agriculturally suitable sulfonylurea salt dispersions. Not disclosed or suggested in the prior art and the subject of the present invention are compositions of pesticides which are aqueous based, physically reversible structured-fluids which flow on application of shear and which spontaneously rebuild structure on standing. SUMMARY OF THE INVENTION This invention concerns a thixotropic pesticidal formulation comprising a pesticidal component, a structuring agent, and the balance to 100% being an aqueous medium wherein: the pesticidal component is selected from the group: a) a soluble electrolyte, b) a soluble non-electrolyte, c) an insoluble electrolyte, and d) an insoluble non-electrolyte; and the structuring agent is at least one anionic or cationic member selected from the group: e) apolyelectrolyte, f) a surfactant, and g) a suspending agent; provided that: (i) when the pesticidal component is a), b) or d), then the structuring agent is g) and at least one of e) and f), such that e) and g) bear dissimilar charges, or when e) is not present, f) and g) bear dissimilar charges; (ii) when the pesticidal component is c), then the structuring agent is selected from at least one of e) and f), such that e) and c) bear dissimilar charges, or when e) is not present, f) and c) bear dissimilar charges; the ingredients being present in the following amounts based on total weight of the formulation: 1-60% pesticidal component; 0.1-20% of at least one of a polyelectrolyte and a surfactant; 0-20% suspending agent; the combination of pesticidal component, polyelectrolyte, surfactant, and suspending agent comprising at least 4%; and 35-96% aqueous medium, The term "pesticidal component" is meant to include any chemicahised for crop protection or mixture of said chemicals. More specifically, ingredients are selected from the class of herbicides, fungicides, bactericides, insecticides, insect antifeedants, acaricides, miticides, nematocides and plant growth regulants. Herbicides include sulfonylurea herbicides which are meant to include the entire class of herbicides containing the following and any closely related chemical functionalities: Pesticidal components which are classified as "electrolytes" dissociate (separate) into two or more ions in water. Conversely, "non-electrolytes" do not dissociate in water. Suitable "polyelectrolytes" of the invention can be either cationic or anionic, and include all water-swellable or water-soluble polymers which bear more than one ionic functional group per each macromolecule. "Surfactants" consist of molecules lower in molecular weight than poly¬ electrolytes which are surface active and which bear one or two charges per molecule. A "suspending agent" can be clay and oxide participates which are traditionally used to retard settling in both aqueous and non-aqueous based suspensions. "Dissimilar charge" is defined such that the electronic energy of the substances are of different signs. Electrolytes, polyelectrolytes, surfactants, and suspending agents which have cationic polymer or surface-active portions are positively charged [i.e., sign is (+)], those which have anionic polymer or surface- active portions are negatively charged [i.e., sign is (-)], and pesticides which are non-electrolytes are not charged (i.e., neutral). For example, a cationic poly- electrolyte has a dissimilar charge to an anionic suspending agent and to a non- electrolyte pesticide. Conversely, two cationics or two non-electrolytes would have similar charge. This invention also concerns a method for protecting crops comprising applying to the crops, to the environment of the crops, or to the pests, an effective amount of the formulation of this invention to control the particular pest of interest. Preferred compositions (Preferred 1) of those described above are thixotropic pesticidal formulations wherein the ingredients are present in the following amounts based on total weight of the formulation: 10-50% pesticidal component; 0.1-10% at least one of a polyelectrolyte and a surfactant; 0-15% suspending agent; and 35-96% aqueous medium. More preferred compositions (Preferred 2) are compositions of Preferred 1 wherein the pesticidal component is a sulfonylurea herbicide and die ingredients are present in the following amounts based on total weight of the formulation: 10-40% sulfonylurea; 0.1-5% at least one of a polyelectrolyte and a surfactant; 0-10% suspending agent; 5-25% agriculturally suitable stabilizing salt, such that the sulfonylurea and stabilizing salt are less than 85% by total formulation weight; and 35-96% aqueous medium. Even more preferred compositions (Preferred 3) are compositions of Preferred 1 wherein the pesticidal component comprises a sulfonylurea herbicide and a non-sulf onylurea pesticide in the following amounts based on total weight of the formulation: 10-40% sulfonylurea and non-sulfonylurea pesticide; 0.1-5% at least one of a polyelectrolyte and a surfactant; 5 0-10% suspending agent; 5-25% agriculturally suitable stabilizing salt, such that the sulfonylurea, non-sulfonylurea pesticide and stabilizing salt are less than 85% by total formulation weight; and 35-96% aqueous medium. 10 The "agriculturally suitable stabilizing salts" include organic or inorganic salts which can be used to salt-out otherwise water-soluble ionic pesticides thereby rendering diem insoluble. In the case of sulfonylurea herbicides, wherein chemical stabilization can be achieved by the addition of salts, agriculturally suitable salts refer to carboxylic or inorganic acid salts with a solubility in water 15 of greater than or equal to 3% at 5°C and pH 6-10, and further provided that a 0.1 molar solution of the carboxylic or inorganic acid salt is between pH 6 and 10. Even more preferred compositions (Preferred 4) are compositions of Preferred 2 wherein the polyelectrolytes or charged surfactants are selected from the group consisting of: quaternary polyelectrolytes or surfactants, and 20 quaternary ammonium salts which may be protonated, ethoxylated or alkylated; polyaαylamides, such as aminomethylated polyacrylamide polymer having pendant dialkylated ammonium salt groups; primary, secondary or tertiary polyamines, such as ethoxylated octadecylamine-octadecylguanidine complexes; and primary, secondary or tertiary amine surfactants with or without ethoxylation, 25 protons or alkyl groups. More preferred compositions (Preferred 5) are those of Preferred 4 wherein the polyelectrolytes are selected from the group consisting of: polymers having pendant acid functionality and the ability to form salts; anionic polyacrylamides and acrylamide copolymers, such as the sodium salt of 2-propenamide, 30 2-prσpenoic acid; polycarbonates, such as polyacrylic acid, polymethacrylic and styrene maleic anhydride acid polymers and copolymers; polysulfonates, such as lignosulfonates and sulfonated polystyrene; and polyphosphates. Also preferred (Preferred 6) are compositions of Preferred 1 wherein the pesticidal component is a herbicide. Also preferred (Preferred 7) are compositions of Preferred 3 wherein the mixture comprises a sulfonylurea herbicide and 3,5-dibromo-4-hydroxybenzo- nitrile (bromoxynil). Even more preferred (Preferred 8) are compositions of Preferred 5 wherein the sulfonylurea herbicide is a compound of Formula I wherein: J is M hi hi -fcZ M L9. till -HI -H2 J-13 W4 RisHorCH 3 ; R 1 is F, Cl, Br, ΝO 2 , C r C 4 alkyl, C r C haloalkyl, C 3 -C 4 cycloalkyl, C2-C4 haloalkenyl, C1-C4 alkoxy, C1-C4 haloalkoxy, C2-C4 alkoxyalkoxy, CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR15R16, S(O) n R 17 , C(O)R I8 ,CH 2 CNorL; R 2 is H, F, Cl, Br, CN, CH 3 , OCH 3 , SCH 3 , CF 3 or OCF 2 H; R 3 is α, NO 2 , CO 2 CH 3 , CO2CH2CH3, SO 2 N(CH 3 ) 2 , SO 2 CH 3 , SO 2 CH 2 CH 3 , OCH 3 , or OCH 2 CH 3; R 4 is C r C 3 alkyl, C r C 2 haloalkyl, C r C 2 alkoxy, C 2 -C haloalkenyl, F, α, Br, NO 2 , CO 2 R 12 , C(O)NR 1 R 14 , SO 2 NR 15 R 16 , S(O)„R 17 , C(O)R 18 orL; R5isH,F,α,BrorCH 3 ; K 6 is C r C 3 alkyl, C r C 2 alkoxy, C 2 -C 4 haloalkenyl, F, Cl, Br, CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR I5 R 16 , S(O)„R 17 , C(O)R 18 orL; R 7 isH,F,Cl,CH 3 orCF 3 ; R 8 is H,C r C 3 alkyl orpyridyl; R9 is C r C 3 alkyl, C r C 2 alkoxy, F, Cl, Br, NO 2 , CO 2 R 12 , SOiNR^R lβ , S(O)- j R 17 , OCF 2 H, C(O)R 18 , C 2 -C 4 haloalkenyl or L; R 10 is H, α, F, Br, C r C 3 alkyl or C r C 2 alkoxy; R 11 is H, C r C 3 alkyl, C r C 2 alkoxy, C 2 -C 4 haloalkenyl, F, Cl, Br, CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR 1 5R16 S(O)--R 17 , C(O)R 18 or L; R 12 is C 1 -C3 alkyl optionally substituted by halogen, C1-C2 alkoxy or CN, allyl orpropargyl; R 13 is H, C r C 3 alkyl or C r C 2 alkoxy; R 14 is C r C 2 alkyl; R 15 is H, C1-C3 alkyl, C1-C2 alkoxy, allyl or cyclopropyl; R^ is H or C^ alkyl; R 17 is Cj-C 3 alkyl, Cj-C 3 haloalkyl, allyl orpropargyl; R 18 is C1-C4 alkyl, C1-C4 haloalkyl or C 3 -C5 cycloalkyl optionally substituted by halogen; n is 0, 1 or 2; L is R j is H or -Cs alkyl; W is O or S; X is H, C r C 4 alkyl, C r C 4 alkoxy, C r .C 4 haloalkoxy, Cj-C 4 haloalkyl, C1-C 4 haloalkylthio, C 1 -C4 alkylthio, halogen, C2-C5 alkoxyalkyl, C2-C5 alkoxyalkoxy, amino, Cj-C 3 alkylamino or di(Cι-C 3 alkyl)- amino; Y is H, C!-C 4 alkyl, C r C 4 alkoxy, C r C4 haloalkoxy, C r C alkylthio, C1-C4 haloalkylthio, C2-C5 alkoxyalkyl, C2-C5 alkoxyalkoxy, amino, Cχ-C3 alkylamino, di(Cι-C3 alkyl)amino, C 3 -C4 alkenyloxy, C3-C 4 alkynyloxy, C2-C5 alkylthioalkyl, C2-C5 alkylsulfinylalkyl, C2-C5 alkylsulfonylalkyl, C r C4 haloalkyl, C2-C4 alkynyl, C 3 -C 5 cycloalkyl, azido or cyano; Z is CH or N; and their agriculturally suitable salts; provided that: (a) when X and/or Y is C j haloalkoxy, then Z is CH; (b) when X is halogen, then Z is CH and Y is OCH 3 , OCH 2 CH 3 , N(OCH 3 )CH 3 , NHCH3, N(CH 3 ) 2 or OCF 2 H. Even more preferred (Preferred 9) are compositions of Preferred 8 wherein the herbicide is selected from the group: 2-cMoro-N-[[(4-memoxy-6-memyl-l,3,5-triazin-2-yl)amino]- carbonyl]benzenesulfonamide (cMorsulfuron); methyl 2-[[[[(4,6-dimemyl-2-pyrimidinyl)amino]carbonyl]- amino]sulfonyl]benzoate (sulfometuron methyl); ethyl 2-[[[[(4-cMoro-6-memoxy-2-pyrimidinyl)amino]- carbonyl]amino]sulfonyl]benzoate (chlorimuron ethyl); methyl 2-[[[[(4-methoxy-6-methyl-l,3,5-triazin-2-yl)amino]- carbonyl]amino]sulfonyl]benzoate (metsulfuron methyl); memyl 2-[[[[(4,6-dimemoxy-2-pyrimidinyl)amino]carbonyl]- arrjmo]sulfonyl]-6-(trifluoromemyl)-3-pyridinecarboxylate (ethametsulfuron methyl); memyl 2-[[[[[4-ethoxy-6-(memylamino)-l,3,5-triazin-2-yl]- am o]carbonyl]amino]sulfonyl]benzoate; 2-(2-chloroethoxy)-Ν-[[(4-methoxy-6-methyl-l,3,5-triazin-2- yl)amino]carbonyl]benzenesulfonamide; ethyl 5-[[[[(4,6-dimemoxy-2-pyriπύdinyl)amino]carbonyl]- ammo]sulfonyl]-l-methyl-lH-pyrazole-4-carboxylate; N-[[(4,6-dimetho-^-2-pyrimidmylamino]carbonyl]-3-(ethyl- sulfonyl)-2-pyridinesulfonamide; methyl 3-[[[[(4-methoxy-6-methyl-l ,3,5-triazin-2-yl)amino]- carbonyl]ammo]sulfonyl]-2-thiophene-carboxylate (thifen- sulfuron methyl); methyl 2-[[[[N-(4-methoxy-6-methyl-l,3,5-triazin-2-yl)-Ν- me yIammo]carbonyl]amino]sulfonyl]benzoate (tribenuron methyl); memyl 2-[[[[[(4,6-dimemoxy-2-pyrimidinyl)amino]carbonyl]- anιino]sιιlfonyl]methyl]benzoate (bensulfuron methyl); 2-[[[[(4,6-dimemoxy-2-pyrimidmyl)a-ι iιιo]carbonyl]amino]- sulfonyl]-N-N-dimethyl-3-pyridinecarboxamide (nico- sulfuron); and memyl 2-[[[[[4,6-bis(difluoromemoxy)-2-pyrirnidmyl]amino]- carbonyl]amino]sulfonyl]benzoate. Also preferred (Preferred 10) are compositions of Preferred 7 wherein the mixture comprises a sulfonylurea herbicide selected from the group in Preferred 9. OFT ATT ED DESCRIPTION OF THE INVENTION One method of formulating a pesticide is to form a suspension of one or more active ingredients in an aqueous based medium and then use thickeners, such as macromolecules of the natural or synthetic type, and/or suspending agents, such as clays or oxides, to slow the rate at which the suspended particles setde. An overview of this approach is given in "Physical Stability of Suspension Concentrates", Th. F. Tadros, Advances in Colloid and Interface Science, 12 (1980). The present invention introduces a novel product form which incorporates at least one polyelectrolyte or ionic surfactant, in addition to or in place of suspending agents, to create an aqueous based, physically stable, reversible structured-fluid which will flow on application of shear and which will rebuild its structure on standing (i.e., are thixotropic). The aqueous, reversible structured-fluid compositions of this invention are obtained by combination of a pesticidal component with the inert ingredients of the aqueous medium. The pesticides which are deliverable in the reversible structured-fluids of this invention can be water-soluble or -insoluble, and can themselves be electrolytes or non-electrolytes of agricultural significance. Depending on additional criteria, such as die solubility of the pesticide or its chemical stability, agriculturally suitable organic or inorganic salts may also be incorporated without effecting the ability to achieve an aqueous, reversible structured-fluid pesticidal composition. Examples of suitable pesticides are listed below. Herbicides such as acetochlor, acifluorfen, acrolein, 2-propenal, alachlor, ametryn, amidosulfuron, ammonium sulfamate, amitrole, anilofos, asulam, atrazine, barban, benefin, bensulfuron methyl, bensulide, bentazon, benzofluor, benzoylprop, bifenox, bromacil, bromoxynil, bromoxynil heptanoate, bromoxynil octanoate, butachlor, buthidazole, butralin, butylate, cacodylic acid, 2-chloro- N,N-di-2-propenylacetamide, 2-chloroallyl diethyldidiiocarbamate, chloramben, chlorbromuron, chloridazon, chlorimuron ethyl, chlormethoxynil, chlomitrofen, chloroxuron, chlorpropham, cWorsiilfuron, chlortoluron, cinmethylin, cinosulfuron, clethodim, clomazone, cloproxydim, clopyralid, calcium salt of methylarsonic acid, cyanazine, cycloate, cycluron, cyperquat, cyprazine, cyprazole, cypromid, dalapon, dazomet, dimethyl 2,3,5,6-tetrachloro-l,4- benzenedicarboxylate, desmedipham, desmetryn, dicamba, dichlobenil, dichlorprop, diclofop, diethatyl, difenzoquat, diflufenican, dimepiperate, dinitramine, dinoseb, diphenamid, dipropetiyn, diquat, diuron, 2-methyl-4,6- dinitrophenol, disodium salt of methylarsonic acid, dymron, endothall, S-ethyl dipropylcarbamothioate, esprocarb, ethalfluralin, ethametsulfuron methyl, ethofumesate, fenac, fenoxaprop, fenuron, salt of fenuron and trichloroacetic acid, flamprop, fluazifop, fluazifop-P, fluchloralin, flumetsulam, fluometuron, fluoro- chloridone, fluorodifen, fluoroglycofen, flupoxam, fluridone, fluroxypyr, fluzasulfuron, fomesafen, fosamine, glyphosate, haloxyfop, hexaflurate, hexazinone, imazamethabenz, imazapyr, imazaquin, imazamethabenz methyl, imazethapyr, imazosulfuron, ioxynil, isopropalin, isoproturon, isouron, isoxaben, karbutilate, lactofen, lenacil, linuron, metsulfuron methyl, methylarsonic acid, monoammonium salt of methylarsonic acid, (4-chloro-2-methylphenoxy)acetic acid, S,S'-dimethyl-2-(difluoromethyI)-4-(2-methylpropyl)-6-(tr-iιuorαmethyl)- 3-5-pyridinedicarbothioate, mecoprop, mefenacet, mefluidide, methalpropalin, methabenzthiazuron, metham, methazole, methoxuron, metolachlor, metribuzin, l,2-dihydropyridazine-3,6-dione, molinate, monolinuron, monuron, monuron salt and trichloroacetic acid, monosodium salt of methylarsonic acid, napropamide, naptalam, neburon, nicosulfuron, nitralin, nitrofen, nitrofluorfen, norea, norflurazon, oryzalin, oxadiazon, oxyfluorfen, paraquat, pebulate, pendimethalin, perfluidone, phenmedipham, picloram, 5-[2-chloro-4-(trifluoromethyl)phenoxy]- 2-nitroacetophenone oxime-O-acetic acid methyl ester, pretilachlor, primisulfuron, procyazine, profluralin, prometon, prometryn, pronamide, propachlor, propanil, propazine, propham, prosulfalin. prynachlor, pyrazolate, pyrazon, pyrazosulfuron ethyl, quinchlorac, quizalofop ethyl, rimsulfuron, secbumeton, sethoxydim, siduron, simazine, l-(α,α-dimemylbenzyl)-3-(4- methylphenyl)urea, sulfometuron methyl, trichloroacetic acid, tebudiiuron, terbacil, terbuchlor, terbuthylazine, terbutol, terbutryn, thifensulfuron methyl, thiobencarb, triallate, trialkoxydim, triasulfuron, tribenuron methyl, triclopyr, tridiphane, trifluralin, trimeturon, (2,4-dichlorophenoxy)acetic acid, 4-(2,4- dichlorophenoxy)butanoic acid, vemolate, andxylachlor, insecticides such as monocrotophos, carbofuran, tetrachlorvinphos, malathion, parathionmethyl, methomyl, chlordimeform, diazinon, deltamethrin, oxamyl, fenvalerate, esfenvalerate, permethrin, profenofos, sulprofos, triflumuron, diflubenzuron, methoprene, buprofezin, thiodicarb, acephate, azinphosmethyl, chloipyrifos, dimethoate, fonophos, isofenphos, methidathion, methamidophos, phosmet, phosphamidon, phosalone, pirimicarb, phorate, terbufos, trichlorfon, methoxy- chlor, bifenthrin, biphenate, cyfluthrin, fenpropathrin, fluvalinate, flucythrinate, tralomethrin, metaldehyde and rotenone; fungicides such as carbendazim, thiuram, dodine, maneb, chloroneb, benomyl, cymoxanil, fenpropidine, fenpropimorph, triadimefon, captan, thiophanate-methyl, thiabendazole, phosethyl-Al, chlorothalonil, dichloran, metalaxyl, captafol, iprodione, oxadixyl, vinclozolin, kasugamycin, myclobutanil, tebuconazole, difenoconazole, diniconazole, fluquinconazole, penconazole, propiconazole, uniconzole, flutriafol, prochloraz, pyrifenpx, fenarimol, triadimenol, diclobutrazol, copper oxychloride, furalaxyl, folpet and flusilazol; nematocides such as aldoxycarb, fenamiphos and fosthietan; bactericides such as oxytetracyline, streptomycin and tribasic copper sulfate; and acaricides such as binapaciyl, oxythioquinox, chlorobenzilate, dicofol, dienochlor, cyhexatin, hexythiazox, amitraz, propargite and fenbutatin oxide. The "agriculturally suitable salts" include organic or inorganic salts which can be used to salt-out otherwise water-soluble ionic pesticides thereby rendering diem insoluble. In the case of sulfonylurea herbicides, wherein chemical stabilization can be achieved by the addition of salts, agriculturally suitable salts refer to carboxylic or inorganic acid salts, provided that the solubility in water of such carboxylic or inorganic acid salts is greater than or equal to 3% at 5°C and a pH between 6 and 10, and further provided tiiat a 0.1 molar solution of the carboxylic or inorganic acid salt has a pH between 6 and 10. The component "polyelectrolyte" includes all water-swellable or water- soluble polymers which bear more tiian one ionic functional group per each macromolecule. The molecular weight of the polyelectrolytes of this invention can range from thousands to over a million and and can bear multiple positive or negative charges on the macromolecular backbone or attached pendant groups. "Surfactants" consist of molecules lower in molecular weight than polyelectro¬ lytes which are surface active and which bear one or two charges per molecule. Suitable polyelectrolytes of the invention can be either cationic or anionic. Non-limiting examples of cationic polyelectrolytes or charged surfactants include: polyacrylamides, such as aminomethylated polyaciylamide polymer having pendant dialkylated ammonium salt groups; primary, secondary or tertiary poly- amines, such as ethoxylated octadecylamine-octadecylguanidine complexes; quaternary ammonium salts with or without ethoxylation, protons or alkyl groups; and primary, secondary or tertiary amine surfactants with or without ethoxylation, protons or alkyl groups. Non-limiting examples of anionic polyelectrolytes include polymers having pendant acid functional groups and die ability to form salts such as: anionic poly- aciylamides and aciylamide copolymers, such as the sodium salt of 2-propen- amide and 2-propenoic acid; polycarbonates, such as polyacrylic acid, poly¬ methacrylic and styrene maleic anhydride acid polymers and copolymers; poly- sulfonates, such as lignosulfonates and sulfonated polystyrene; and poly- phosphates. Product literature available from most vendors of polymeric materials and die following reference indicate which ones are polyelectrolytes and their tolerance for salt if present; Handbook of Water Soluble Gums and Resins, Robert L. Davidson, Ed. McGraw-Hill, 1980. A "suspending agent" can be clay and oxide particulates which are traditionally used to retard settling in both aqueous and non-aqueous based suspensions. These solids are typically used to modify me viscosity of suspensions, but in combination with polyelectrolyte or ionic surfactant they can effectively be used to produce a reversible structured-fluid matrix to be used as a medium for the delivery of water-soluble or non-electrolyte pesticide active ingredients. Both surfactants and polyelectrolytes can associate widi themselves or other species in solution and also with the surfaces of particulates (e.g., pesticide, suspending agent) in suspension. In this invention, the ionic nature of the polyelectrolyte and surfactant is believed to be related to die ability to form a reversible structured-fluid in the presence of charged particles of active or inert suspending agents. The term "aqueous medium" is defined as water plus the portion of water- soluble components which are in solution. The latter can, but does not necessarily, include, such components as agriculturally suitable salts, dispersants, wetting agents, antibacterials, crystal growth inhibitors, antifreezing agents and low levels of thickeners provided diat their presence does not interfere with the formation of the reversible structured-fluid. Li order for die formation of the reversible structured-fluid, die sum of the pesticidal component and agriculturally suitable salt must not exceed 85% of the total weight percent of the formulation. Reversible structured-fluids can be made in several ways depending on die nature of the pesticide active ingredient (electrolyte or non-electrolyte) andits water solubility. In almost all cases, some mechanical milling or intense mixing is required to form the suspension precursor to the reversible structured-fluid. In general, the insoluble active-ingredient is added to die medium as a micronized powder of less than 10 microns in size, on average, or as a coarser solid which is then reduced in size to below 10 microns, on average, by a wet milling process. In die former case, me ingredients can be mixed well by stirring to disperse die solids. J-f the micronized powder is present as aggregates wherein the primary particles are held together by forces strong enough to make stirring impractical, wet milling is required to break-up the aggregates and reduce die solids to die primary particle size. Addition of the polyelectrolyte at any step in the preparation of the composition is acceptable, provided that the polyelectrolyte does not degrade during die wet milling step(s) and such a step is required. For example, U.S.4,936,900 describes die need to wet mill sulfonylurea herbicides in die process of creating a suspension of chemically-stable particles in an aqueous high salt medium. If die stability to wet milling is not known, the effect of mechanical energy on the polyelectrolyte in question can be determined by comparing the properties of a formulation made by pre- and post-milling addition of die polymer. The purpose of die dispersion process is to allow the medium to "wet" the surface of the particles and to displace die air between die particles. The efficiency of the wetting process can be gready improved by adding wetting agent(s). A dispersant can also be added to serve the function of keeping the particles separated once they have been dispersed.in the suspension to be reversibly structured. Dispersants serve a similar function once die reversible, structured-fluid is dunned and added to water or a spray tank mixture. The use and selection of dispersants and wetting agents are well-known in die art. See T. C. Patton, "Paint Flow and Pigment Dispersion," Wiley (1979). The function of these materials and die mechanical processes for forming dispersions and suspensions are also known in die art. See, for example, G. D. Parfitt, "Dispersion of Powders in Liquids," Applied Science Pub. Ltd. (1973); and Th. F. Tadros, "Advances in Colloid and Interface Science," 12 (1980). 1) In one embodiment of die invention, die pesticide is an electrolyte present in a high-salt aqueous medium as insoluble panicles (e.g., a sulfonylurea active ingredient, or an agricuiturally-suitable salt thereof). In tiiese cases, an appropriate water-soluble or water-swellable polyelectrolyte or ionic surfactant, which is also compatible with the carboxylic or inorganic acid salts and which will not lead to chemical decomposition of die active ingredients, is added to die suspension such that a reversible structured-fluid results. For insoluble pesticide particles which are weak acids, bases or salts (e.g., maneb and mancozeb fungicides) a water-soluble or water-swellable poly¬ electrolyte or ionic surfactant is added to die suspension to form a reversible structured-fluid. The interaction between die ionic-insoluble structured-fluid particulates and die polyelectrolyte or ionic surfactant is believed to be responsible for the reversible structured-fluid characteristics. 2) The present invention also comprises compositions in which non- electrolyte, active ingredients (e.g., hexazinone herbicide and methomyl insecticide) are soluble in the aqueous medium. In these cases a suspending agent, such as hydrophilic silica, is used in combination with a polyelectrolyte or ionic surfactant to form a reversible structured-fluid matrix. While the pesticide is not actually part of the network or matrix, the overall system in which the pesticide resides is the reversible structured-fluid. 3) Another embodiment of the invention are compositions comprising electrolyte pesticides which are soluble in water (e.g., the alkali metal or amine salts of 2,4-D or 2,4-DB, the mono(isopropylamine) salt of glyphosate, and the potassium salt of picloram) wherein the use of a suspending agent along with polyelectrolytes or ionic surfactants is necessary. Alternatively, the pesticide can in some cases be "salted-out" by d e addition of organic or inorganic salts and rendered partially if not completely water-insoluble. For example, 2,4-D alkali metal or amine salts can be "salted-out" by die addition of inorganic salts rendering die pesticide insoluble. The insoluble salt can, in turn, be milled to form an aqueous suspension which is suitable for reversible structured-fluid formation by die addition of polyelectrolyte or ionic surfactant. In such cases, die addition of a suspending agent is not nessary . 4) For compositions of the present invention containing non-electrolyte, insoluble, particulate pesticides (e.g., cyanazine, carbendazim, captafol, carbaryl, etc.), suspending agents such as clays and oxides are required in combination witii a polyelectrolyte or ionic surfactant to form a reversible structured-fluid. In tiiese cases, the pesticide particulates are immobilized by die reversible structured-fluid matrix as it forms. In essence, all the compositions of die instant invention incorporate at least one polyelectrolyte or ionic surfactant which is water-soluble or water-swellable and which retains its function as a fluid structuring agent if inorganic salts are present. In the case of sulfonylurea herbicides and tiieir salts, where ammonium or alkali metal acid salts of a carboxylic or inorganic acid are required for chemical stability, the polyelectrolyte or ionic surfactant must retain its function as a fluid structuring agent in die presence of these salts and not destabilize d e active sulfonylurea herbicide. In die case when salts are used to "salt-out" soluble pesticide electrolytes, the polyelectrolytes or ionic surfactant must retain its functionality as a fluid structuring agent, without resolubilization of the pesticide active. In the case when salt is required to enhance die functionality of die suspending agent, die polyelectrolytes or ionic surfactant must retain tiieir functionality as a fluid structuring agent in die presence of these salts. The effectiveness of the polyelectrolyte or ionic surfactant, and in some cases the suspending agent, is determined by comparison to a reference sample which does not contain one or more of tiiese structuring agents. Physical Measurements The reversible structured-fluids are rigid at rest as reflected by their ability to retain a solid-like shape in an 8-ounce container at or near rest and show little or no sign of movement on tilting or on complete inversion of die container. The reversible structured-fluids of tiiis invention are appreciably thinned by shaking, unlike gel or gelled-paste compositions which require vigorous shaking or mechanical agitation to assist tiieir dispersion into water. The thinning behavior of the reversible structured-fluid increases the ease with which the fluid disperses into water. The compositions of tiiis invention are pourable once shaken, but will rebuild their structure on standing. On further dilution by water, die aqueous, reversible structured-fluid can be sprayed dirough conventional spray nozzles in which 50 mesh screens precede each nozzle to protect it from blockage. By adjusting die amount of polyelectrolyte or ionic surfactant, die degree of reversibility and consistency of a reversible structured-fluid can be modified, spanning die range from that of an unstmctured suspension to that of a gel or gelled-paste. However, die reversible structured-fluid is unique in its superior ability over than of a gel or gelled paste to disperse into water and its superior ability over that of a suspension to immobilize particulate matter. i practice, verification of a reversible structured-fluid can be accomplished by experimental measurement and visual observation. The latter is the best method for differentiating reversible structured-fluids from suspension and gelled-paste controls. Visual observation requires a minimum of one observation of the composition on inversion through 180°, one observation of the composition on shaking, and one assessment of the ease of dispersion into water. In die case of unstructured suspensions, flow is observed on inversion, die suspensions pour easily, and die suspensions disperse homogeneously into water witii stirring. At die other extreme, gels and gelled-pastes do not flow on inversion or after intense shaking, and do not disperse into water without intense mechanical agitation. The reversible structured-fluid pesticide compositions of this invention behave in a manner between these two extremes. They show no flow on 180° inversion, reduce to a liquid-like consistency witii mild shaking, flow out of the container after shaking and disperse into water with litde more than mild stirring, provided tiiat thickeners have not been added at a level which retards die dispersion process. In such cases, more vigorous stirring may be required to achieve an agriculturally acceptable dispersion. Viscosity and yield stress measurements are two additional measures used to quantify die extent of structure formation and pourability of a reversible structured-fluid. Botii the viscosity and yield stress were measured using a rotational viscometer. Standard instruments are available from companies such as Haake, Contraves, Carri-Med, Bohlin and Brookfield. Both the instrument and accompanying geometry (parallel plate, cone and plate, concentric cylinder sample compartments) can be used to accurately measure yield stress and viscosity by one of die following techniques. Either a fixed shear rate can be imposed on a sample and die resulting stress measured, or a controlled stress can be imposed on a sample and die resulting shear rate measured. A plot of the shear rate versus stress can be constructed and analyzed to extract the plastic viscosity and yield stress of the sample using die Bingham Equation. This is done by fitting die linear portion of the data to die equation. The slope of the plot gives the plastic viscosity of die sample and die intercept of the plot gives its yield stress. A more in-depdi review of the art can be found in many texts on viscometry, iheology or rheometry. The following references contain such information: 1) K. Walters, "Rheometry: Industrial Applications," Research Studies Press (1980), 2) P. Sherman, "Industrial Rheology," Academic Press (1970), 3) T. C. Patton, "Paint Flow and Pigment Dispersion," Wiley (1979). Geometric constants, equations and instrumentation to automate instrument operation and calculation are supplied with die instruments mentioned above. In general, the plastic viscosity and/or yield stress of a reversible structured fluid will be higher than those for an unstructured suspension and lower than those for a gel or gelled-paste. Thus, the measurement of yield stress and plastic viscosity can be used to evaluate die extent and degree of reversibility in structured-fluid compositions and to provide an additional tool witii which to differentiate between unstructured suspensions, reversible structured-fluids, gels and gelled-pastes. For assessing the effectiveness of the polyelectrolytes, ionic surfactants and suspending agent structuring systems, an aqueous unstructured control suspension wherein one or more of the structuring components were absent was used as a reference. On occasion, comparison was made to gelled-paste compositions to illustrate the difference between reversible, structured-fluids and a gelled-paste. In all cases, die following visual and theological assessments were made: • Semi-rigidity, reflected by retention of shape in a container and resistance to flow when the container is inverted tiirough 180°. • Fluidity, reflected by die ease witii which a sample flows when subjected to shaking. • Phase separation, reflected by an ability to resist phase separation over time. • Restructuring, reflected by an ability to reform a semi-rigid structure within 24 hours after shaking. One quantitative assessment of die effectiveness of the polyelectrolyte, ionic surfactant and, if present, suspending agent was die measurement plastic viscosity and yield stress. These rheological responses of the reversible structured-fluids were evaluated by die conventional rotational rheometry techniques previously described. A controlled stress rheometer equipped witii a standard, calibrated, cup and bob geometry was used. The measurement was taken by applying a range of stresses between 0.1 to 20 Pascals to a given sample in 20 logarithmic steps, from lowest to highest, with each stress allowed to act on die sample for 30 seconds before the next higher stress was applied. Using die shear stress - shear rate data collected, die Bingham Equation was applied and a yield stress and plastic viscosity were calculated by die metiiods described previously. The selection of polyelectrolyte, ionic surfactant and, if needed, suspending agent was determined by comparing the reversible, structured fluid to a reference sample wherein the polymer was substituted by water. The polyelectrolyte, ionic surfactant and, if needed, suspending agent polymer(s) system is selected such tiiat die beneficial effect is demonstrated: a) by an increase in rigidity, consistency, fluidity, resistance to flow, and reduced phase separation as determined by visual inspection, or b) by an increase in viscosity as determined by viscosity measurement, or c) by an increase in yield stress as determined by yield stress measurement. Comparisons to gels and gelled-paste compositions are also included for die purpose of illustrating the novel behavior of the reversible structured-fluid compositions. EXAMPLES The following examples are presented to illustrate, but in no way limit, the present invention. All percentages are given by weight. The preparation of reversible structured-fluid compositions can be separated into two separate steps; formation of die dispersion followed by die addition of die structuring agent(s). For sulfonylureas, a preferred technique for the preparation of stabilized dispersions has been described in U.S.4,936,900. The procedure requires tiiat the sulfonylurea be suspended in water and that a dispersant, thickener or suspending agent be added, followed by neutralization with a desired base such as ammonium or sodium hydroxide to a pH of 6.0-10.0, preferably 7.0-9.0, followed by addition of an insolubilizing salt, such as a carboxylic or inorganic acid salt(s), with agitation. This method of preparation is used in the instant invention with the following exception. Organic thickening agents are not required to demonstrate die reversible structured-fluid in its most basic form, since any additional antisetding agents would only complement the novel antisetding properties of die compositions of die instant invention. All salts were added incrementally to the neutralized conjugate acids in order to develop die precipitated sulfonylurea salt slowly and to avoid die formation of a tacky solid or gum, per U.S.4,936,900. The resulting suspension was tiien bead-milled to an average particle size of 1-20 microns, preferably 1-8 microns. Polyelectrolyte and/or ionic surfactant structuring agent(s) were added after the milling step was completed to avoid me risk of degradation of die polymer during die high shear milling step. Cases wherein a composition is not referred to as a control, die composition contains a polyelectrolyte and/or ionic surfactant structuring agent and is classified as a reversible structured-fluid. In all the examples which follow, the reversible structured-fluid can be visually described as being semi-rigid fluid which flows easily when subjected to shaking, and which restructures to a semi¬ rigid fluid witiiin 24 hours after cessation of shaking. Conversely, the control unstructured dispersion to which the reversible structure-fluid is compared is always free flowing, showing no rigidity or resistance to flow. The reversible structured-fluids are also compared to gelled-paste systems which exhibit anotiier extreme of flow behavior. These systems are also semi-rigid, like die reversible structured-fluid, however they do not spontaneously flow on shaking and tiieir structure is everfast, showing instantaneous presence upon cessation of shaking. The ingredients used in the following Examples, and tiieir function, are as follows: Reax® 81 A (sodium alkylnaphdialenesulfonate), an anionic wetting agent which can be used to insure proper wetting and milling of the active ingredient; 50% aqueous sodium hydroxide solution which can be used to adjust die pH of die slurry, as needed; and sodium acetate which can be used as the stabilizing organic salt for all aqueous sulfonylurea suspensions, per U.S.4,936,900. A number of structuring agents can be used such as: Armeen® OL = a primary alkylamine, cationic surfactant; Adogen® 425-50% = a 50% aqueous solution of a trimethyl soya quaternary ammonium chloride surfactant; Cat-Hoc ® L and Cat-Floe® TL = diallyl dimetiryl quaternary ammonium chloride polyelectrolytes, and Nalcolyte ® 603 = a quaternary polyamine polyelectrolyte. EXAMPLES 1-2 Composition fwt. %~> The sodium alkylnaphdialenesulfonate was dissolved in ~80-90% of die total water, at room temperature, with stirring. Thifensulfuron methyl was added incrementally, in three equal portions, and allowed to disperse well. The 50% aqueous sodium hydroxide solution was then added slowly over a 15 min. period witii stirring to form the salt of the thifensulfuron metiiyl. Anhydrous sodium acetate was added in tiiree steps, in a 1:1:2 ratio by weight. The additions were made at 30, 45 and 55 minutes during which time the slurry was continually stirred. The dispersion was tiien bead-milled for 30 min. Upon completion the structuring agent and/or water were added to achieve the above statement of composition. The final mixture was stirred until visually homogeneous. The yield stress and plastic viscosity of each composition were measured as previously described. The results are tabulated below. System Yield Stress (Pa) Plastic Viscosity (Pa-s Control (No Stmcturing Agent) 1.0 0.05 Ex. 1 Nalcolyte ® 603 35.1 0.55 Ex. 2 Nalcolyte® 603 38.2 0.20 The control sample was fluid at die time of preparation and did not form a semi-rigid structure over time. The control also formed 11% supernatant (bleed) over a 3 week period and remained freely moving, whereas the reversible structured-fluids (Ex. 1 and 2) showed no tendency to form bleed (less than 2-3%) and were semi-rigid (fiim) within 24 h of preparation. The reversible structured-fluids would not move on tilting and required shaking to fiuidize. The yield stress and plastic viscosity of the reversible structured-fluids were significandy greater than tiiat of the control. From the data and visual characteristics of die reversible structure-fluids of these examples the ability to form a reversible stmctured-fluid of a sulfonylurea dispersion witii a polyelectro¬ lyte which retains its functionality in high salt medium is demonstrated. To determine the effect of the polyelectrolyte on tiie chemical stability of the sulfonylurea, all samples were aged at45°C for 3 weeks. After aging, tiieir chemical properties were assessed and compared. The results indicated that the structuring agent(s) did not impact die stability of the sulfonylurea when compared to die control. The stability of the latter is demonstrated in U.S.4,936,900. The compositions were prepared as described in Examples 1-2 and die final mixtur was stirred until visually homogeneous. The yield stress and plastic viscosity of each composition were measured as previously described. The results are tabulate below. System Yield Stress (Pa) Plastic Viscosity (Pa-s) Control (No Stmcturing Agent) 1.0 0.05 Ex. 3 Armeen ® OL 28.9 0.44 Ex.4 Adogen® 415-50% 44.3 0.26 The control sample was fluid at die time of preparation and did not form a semi-rigid structure over time. The control also formed 11% supernatant (bleed) over a 3 week period and remained freely moving, whereas die reversible structured-fluids (Ex. 3 and 4) developed little more than a trace amount of bleed (less tiian 2-3%) and became semi-rigid (firm) within 24 h of preparation. The yield stress and plastic viscosity of the reversible structured-fluids were significandy greater than tiiat of die control. The reversible structured-fluids would not move on tilting and required shaking to fiuidize. From the data and visual characteristics of the reversible structure-fluids of these examples the ability to reversibly structure a sulfonylurea dispersion witi a cationic surfactant which retains its functionality in high salt medium is demonstrated. To determine the effect of the polyelectrolyte on die chemical stability of the sulfonylurea, all samples were aged at 45°C for 3 weeks. After aging, their chemical properties were assessed and compared. The results indicated tiiat the structuring agent(s) did not impact the stability of the sulfonylurea when compared to die control. The stability of the latter is demonstrated in U.S.4,936,900. The sodium alkylnaphdialenesulfonate was dissolved in ~80-90% of die total water, at room temperature, with stirring. Chlorsulfuron was added incrementally, in three equal portions, and allowed to disperse well. The 50% aqueous sodium hydroxide solution was then added slowly over a 15 min. period witii stirring to form the salt of the cMorsulfuron. Anhydrous sodium acetate was added in tiiree steps, in a 1:1:2 ratio by weight. The additions were made at 30, 45 and 55 min. during which time the slurry was continually stirred. The dispersion was then bead-milled for 30 min. Upon completion the pH was adjusted to 8.3 witii acetic acid, dien structuring agent and/or water were added to achieve the above statement of composition. The final mixture was stirred until visually homogeneous. The yield stress and plastic viscosity of each composition were measured as previously described. The results are tabulated below. System Yield Stress (Pa Plastic Viscosity (Pa-s÷ Control (No Structuring Agent) 1.0 0.02 Ex.5 Cat Hoc® TL 30.3 0.08 Ex.6 Cat Hoc® L 22.1 0.06 The control sample was fluid at die time of preparation and did not form a semi-rigid structure over time. The control also formed 15% supernatant (bleed) over a 3 week period and remained freely moving, whereas the reversible structured-fluids (Ex.5 and 6) showed litde or no tendency to form bleed (less tiian 2-3%) and were semi-rigid (firm) within 24 h of preparation. The reversible structured-fluids would not move on tilting and required shaking to fiuidize. The yield stress and plastic viscosity of the reversible structured-fluids were significantly greater tiian that of the control. From the data and visual characteristics of the reversible stracture-fluids of these examples the ability to form a reversible structured-fluid of a sulfonylurea dispersion witii a polyelectro¬ lyte which retains its functionality in high salt medium is demonstrated. To determine the effect of me polyelectrolyte on the chemical stability of the sulfonylurea, all samples were aged at 45°C for 3 weeks. After aging, their chemical properties were assessed and compared. The results indicated that the stracturing agent(s) did not impact die stability of the sulfonylurea when compared to die control. The stability of the latter is demonstrated in U.S.4,936,900. EXAMPLES 7-9 Composition (wt. %) The following process sequence represents a route to die formation of the reversible structured-fluids of Examples 7 to 9. The sodium alkylnaphthalene- sulfonate is dissolved in 80-90% of the total water, at room temperature, with stirring. The technical active ingredients are added incrementally and disperse with mechanical agitation or stirring. The 50% aqueous sodium hydroxide solution is added slowly over a 15 min. period witii stirring to form tiie active ingredient salts. Anhydrous sodium acetate is added stepwise to slowly salt-out a portion or all of die active ingredient. The additions are made over a 1 h period during which die slurry is continually stirred. The dispersion is tiien bead-milled for 30 min. Upon completion the structuring agent and/or water is added to achieve the above statement of composition. The final mixture is stirred until visually homogeneous. The reversible structured-fluids of Examples 7-9 have yield stress and plastic viscosities in excess of compositions wherein die stracturing agent is replaced by water, and have a maximum yield stress of 60 Pa and a maximum plastic viscosity of 5 Pa-s. The compositions are rigid at rest once die structure forms and do not flow on inversion through 180° when contained by an 8-ounce wide-moudi container which is at least 1/2 to 3/4 full. They are easily fluidized by minimal shaking and completely disperse in water in 1-3 min., with mild stirring. The reversible structured-fluids of Examples 7-9 regain their rigidity within 24 h when returned to die rest state. The following sequence represents a route to the formation of the reversible structured fluid of Example 10. The Carbendazim was added to die water as an air-milled powder of approximately 2 microns in mean average particle size followed by die addition of Alkanol® XC. The mixture was then stirred for 5 minutes using an overhead paddle stirrer. During this time, a uniform suspension was attained. The Aerosil® 200 was then added and stirring continued for an additional 5 minutes. At this point and for several hours thereafter die composition was extremely fluid like. The sample was men split into two equal portions. The balance of water to 100% was added to one portion witii stirring to create a control. Nalcolyte® 603 was added to die second portion with continued sitrring to create the reversible structured-fluid. The final mixtures were visually homogeneous. The yield stress and plastic viscosity of the control and reversible structured-fluid were measured as previously described. The results are tabulated below. System Yield Stress (Pa) Plastic Viscosity (Pa-s) Control 0.28 0.005 Ex. 10 Nalcolyte® 603 7.73 0.041 The control sample was fluid at die time of preparation and did not form a semi-rigid structure overtime. The control also formed -50% supernatant (bleed) over a 24 hour period and remained freely flowing, whereas the reversible structured-fluid of Example 10 showed only a trace of bleed (<2-3%) and was semi-rigid exhibiting no tendency to flow on tilting, but being rapidly tiiinned by shaking. The yield stress and plastic viscosity of the reversible structured-fluid were significandy greater than tiiose of the control. From the data and visual characteristics of the reversible structured-fluid of Example 10, die ability to form a reversible structured-fluid of a fungicide dispersion where the active ingredient is a non-electrolyte, insoluble material was demonstrated. EXAMPLES 11 AND 12 Composition (wt.%) Ingredients Control Ex. 11 x. 12 Mancozeb Technical 29.4 Aerosil ® 200 2.0 Water 68.6 Stracturing Agent Nalcolyte® 603 0.0 The following sequence represents a route to die formation of die reversible structured-fluids of Examples 11 and 12. Technical mancozeb powder of particle size less than 20 microns was added to die water and stirred for 20 minutes with an overhead paddle stirrer. During this time, the powder wetted and a uniform suspension was attained. The Aerosil® 200 was then added and stirring was continued for an additional 55 minutes. The composition at this point was extremely fluid like. The sample was then split into three equal portions. Water was added to one portion witii stirring to create a control. Nalcolyte® 603 was added to die second and third portions witii continued stirring to create the reversible structured-fluids. The final mixtures were visually homogeneous. The yield stress and plastic viscosity of the control and reversible structured-fluid were measured as previously described. The results are tabulated below. System Yield Stress (Pa) Plastic Viscosity (Pa-s) Control 0.91 0.099 Ex. 11 Nalcolyte® 603 at 2% 1.27 0.039 Ex. 12 Nalcolyte® 603 at 3% 1.50 0.003 The control sample was fluid at die time of preparation and did not form a semi-rigid structure over time. The control also formed ~8% supernatant (bleed) over a 24 hour period and remained freely flowing, whereas the reversible structured-fluid of Examples 11 and 12 showed only a trace of bleed (<2-3%) and were semi-rigid exhibiting no tendency to flow on tilting, but being rapidly dunned by shaking. The yield stress and plastic viscosity of die reversible stractured-fluids were significandy greater tiian those of the control. The data and visual characteristics of the reversible stractured-fluids of Examples 11 and 12 demonstrate die ability to form a reversible structured-fluid of a fungicide dispersion where the active ingredient is an insoluble electrolyte. EXAMPLE 13 Composition (wt.%) Ingredients Control Ex. 13 Glyphosate 19.8 19.8 Aerosil® 200 4.0 4.0 Water 75.2 74.2 Structuring Agent Nalcolyte® 603 0.0 1.0 The following sequence represents a route to the formation of the reversible structured-fluid of Example 13. Technical glyphosate air-milled powder, approximately 2 micron in mean average particle size, was added to die water and stirred for -60 minutes using an overhead paddle stirrer. During tiiis time the powder dissolved into die water forming a clear solution. The Aerosil® 200 was then added and stirring was continued for an additional 30 minutes. The composition at tiiat time was fluid-like and lacked color. The sample was then split into two equal portions. Water was added to one portion witii stirring to create the control. Nalcolyte® 603 was added to die second portion witii continued stirring to create the reversible structured-fluid. The final mixtures were visually homogeneous. The yield stress and plastic viscosity of the control and reversible structured-fluid were measured as previously described. The results are tabulated below. System Yield Stress (Pa) Plastic Viscosity (Pa-s) Control 0.63 0.85 Ex. 13 Nalcolyte® 603 2.18 0.54 The control sample was fluid at die time of preparation and did not form a semi-rigid structure over time. The control remained freely flowing, whereas the reversible stractured-fluid of Example 13 was semi-rigid exhibiting no tendency to flow on tilting, but being rapidly dunned by shaking. The yield stress and plastic viscosity of the reversible structured-fluid were significandy greater than those of the control. Example 13 demonstrates die ability to form a reversible structured-fluid of a herbicide where the active ingredient is a soluble non- electrolyte. The sodium alkylnaphdialenesulfonate was dissolved in ~80-90% of die total water, at room temperature, with stirring. The Chlorsulfuron herbicide was added incrementally, in tiiree equal portions, with stirring, and allowed to disperse well. The 50% aqueous sodium nydroxide solution was then added slowly over a 30 min. period witii stirring to form the salt of the Clorosulfuron, raising the pH of the mixture to ~8.0. Anhydrous sodium acetate was then added in three portions, in a 1:1:2 ratio by weight. The additions were made at 30, 60, and 80 min. from the time of the final 50% aqueous sodium hydroxide addition. Stirring was continued for another 15 minutes after which the pH was adjusted to 8.0 by using a minute amount of an aqueous 50% sodium hydroxide solution. Witii continued stirring, the Aerosil ® 200 was added and mixed for 15 minutes. The resulting slurry was visually homogeneous. The dispersion was dien bead- milled for 30 minutes. Upon completion, Adogen® 415 and/or water were added to achieve die above statements of composition. The final mixture was stirred until visually homogeneous. The yield stress and plastic viscosity of each composition were not measured. The samples were however exposed to a series of aging tests to assess their stability via and alternative and reasonably standard test in the industry. The control sample was fluid at die time of preparation and formed 12%, 21%, and 16% supernatant (bleed) on storage for three weeks at 45°C, room temperature and -6°C, respectively. Conversely, the reversible structured-fluid of Example 14 showed almost no signs of bleed when stored under die same conditions. The reversible stractured-fluid of Example 14 was fluid at die time of preparation, but formed a semi-rigid stracture within 24 hours which exhibited no tendency to flow on tilting and which rapidly tiiinned on shaking. The yield stress and plastic viscosity of the reversible structured fluid were significandy greater than those of the control. The data and visual characteristics of the reversible stractured-fluid of Example 14 demonstrate die ability to form a reversible stractured-fluid of a sulfonylurea herbicide at relatively low rates of active ingredient witii a high resistance to the formation of bleed over long periods of time and at extremes in temperature. EXAMPLES 15-17 The sodium all- toaphthdenesulfonate was dissolved in ~80-90% of die total water, with stirring. The nicosulfuron herbicide was added incrementally, in tiiree equal portions, with stirring, and allowed to disperse well. The 50% aqueous sodium hydroxide solution was tiien added slowly over a 20 minute period witii stirring to form the salt of the nicosulfuron, raising thepH of the mixture to ~9.1. Anhydrous sodium acetate was then added in tiiree steps, in a 1:1:2 ratio, by weight. The additions were made at 30, 53, and 73 minutes from die time the final 50% aqueous sodium hydroxide was added. Stirring was continued for another 15 minutes after which the pH was measured at 8.9. With continued stirring, the bromoxynil was added and mixed for 20 minutes. At tiiis time more 50% aqueous sodium hydroxide solution was added to bring die pH to between 8.5-9.0. The resulting slurry was visually homogeneous. The dispersion was then bead-milled for 30 minutes. Upon completion Nalcolyte® 603 and/or Adogen® 415 and/or water were added to achieve die above statements of composition. The final mixture was stirred until visually homogeneous. The yield stress and plastic viscosity of the control and reversible stractured-fluid were measured as previously described. The results are tabulated below. The control sample was fluid at die time of preparation and formed some structure over time, but not a semi-rigid stracture per Examples 15-17. When the control sample was tilted 90° die sample structure resisted for an instant tiien turned fluid compared to the reversible structured-fluid of Examples 15-17 that were semi-rigid exhibiting no tendency to flow on tilting 180°,but being rapidly tiiinned (fluidizing) by shaking. The control also formed ~3% supematant (bleed) over a 15 hour period, whereas the reversible structured-fluid of Examples 15-17 only showed minute bleed (<0.25%). The yield stress and plastic viscosity of the reversible stractured-fluids were significandy greater than that of the control. The data and visual characteristics of the reversible stractured-fluids of Examples 15-17 demonstrate the ability to form a reversible structured-fluid using a mixture of widely diverse crop protection chemicals.

Claims: What is claimed is: 1. A thixotropic pesticidal formulation comprising a pesticidal component, a structuring agent, and die balance to 100% being an aqueous medium wherein: the pesticidal component is selected from the group: a) a soluble electrolyte, b) a soluble non-electrolyte, c) an insoluble electrolyte, and d) an insoluble non-electrolyte; and and die structuring agent is at least one anionic or cationic member selected from die group: e) a polyelectrolyte, f) a surfactant, and „ g) a suspending agent; provided tiiat: (i) when the pesticidal component is a), b) or d), tiien the structuring agent is g) and at least one of e) and f), such tiiat e) and g) bear dissimilar charges, or when e) is not present, f) and g) bear dissimilar charges; (ii) when die pesticidal component is c), men me stracturing agent is selected from at least one of e) and f), such tiiat e) and c) bear dissimilar charges, or when e) is not present, f) and c) bear dissimilar charges; the ingredients being present in the following amounts based on total weight of die formulation: 1-60% pesticidal component; 0.1-20% of at least one of a polyelectrolyte and a surfactant; 0-20% suspending agent; die combination of pesticide, polyelectrolyte, surfactant, and suspending agent at least 4%; and 35-96% aqueous medium. 2. A formulation according to Claim 1 wherein the pesticidal component is a herbicide and the ingredients are present in die following amounts based on total weight of the formulation: 10-50% herbicide; 0.1-10% at least one of a polyelectrolyte and a surfactant; 0-15% suspending agent; and — 35-96% aqueous medium. 3. A formulation according to Claim 2 wherein the pesticidal component is a sulfonylurea herbicide and die ingredients are present in the following amounts based on total weight of die formulation: 10-40% sulfonylurea; 0.1-5% of at least one of a polyelectrolyte and a surfactant; 0-10% suspending agent; 5-25% agriculturally suitable stabilizing salt, and 35-96% aqueous medium. 4. A formulation according to Claim 3 wherein the sulfonylurea is a sulfonylurea of Formula I wherein: J is hi hH h Mfi i M2 i l RisHorCH 3 ; R 1 is F, Cl, Br, NO 2 , C r C 4 alkyl, C r C 4 haloalkyl, C 3 -C 4 cycloalkyl, C2-C4 haloalkenyl, C J-C4 alkoxy, C1-C4 haloalkoxy, C2-C4 alkoxyalkoxy, CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR 15 R 1( , S(O) n R 17 , C(O)R 18 ,CH 2 CNorL; R 2 is H, F, Cl, Br, CN, CH 3 , OCH 3 , SCH 3 , CF 3 or OCF 2 H; R3 is Cl, NO 2 , CO 2 CH 3 , CO 2 CH 2 CH 3 , SO 2 N(CH 3 ) 2 , SO 2 CH 3 , SO 2 CH 2 CH 3 , OCH3, or OCH 2 CH 3 ; R 4 is C r C 3 alkyl, C r C 2 haloalkyl, C r C 2 alkoxy, C 2 -C 4 haloalkenyl, F, α, Br, NO 2 , CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR15R16 5 S^yt 17 , C(O)R 18 orL; R 5 isH,F,Cl,BrorCH 3 ; " R 6 is C r C 3 alkyl, C r C 2 alkoxy, C 2 -C 4 haloalkenyl, F, Cl, Br, CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR i5 R 16 , S(O)--R 17 , C(O)R 18 or L; R 7 is H, F, Cl, CH 3 or CF 3 ; R 8 s H, C r C 3 alkyl orpyridyl; R9 is C C 3 alkyl, C r C 2 alkoxy, F, Cl, Br, NO 2 , CO 2 R 12 , SO 2 NR 15 R 16 , S(O) n R 17 , OCF 2 H, C(O)R 18 , C 2 -C 4 haloalkenyl or L; R 10 is H, α, F, Br, C r C 3 alkyl or C r C 2 alkoxy; R 11 is H, C r C 3 alkyl, C r C 2 alkoxy, C 2 -C 4 haloalkenyl, F, Cl, Br, CO 2 R 12 , C(O)NR 13 R 14 , SO 2 NR 1 5Rl6 ? S(O) n R 17 , C(O)R 18 or L; R 12 is C ] !-C 3 alkyl optionally substituted by halogen, C j -C 2 alkoxy or CN, allyl or propargyl; R 13 is H, C r C 3 alkyl or C r C 2 alkoxy; R 14 is C r C 2 alkyl; R 15 is H, C1-C3 alkyl, Cι-C 2 alkoxy, allyl or cyclopropyl; Riδ is H or C j ^ alkyl; R 17 is C j -C3 alkyl, C j -C^ haloalkyl, allyl orpropargyl; R 18 is C1-C4 alkyl, C1-C4 haloalkyl or C3-C5 cycloalkyl optionally substituted by halogen; n is 0, 1 or 2; L is Rj is H or C r C 3 alkyl; W is O or S; X is H, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 haloalkoxy, C1-C4 haloalkyl, C1-C4 haloalkylthio, C1-C4 alkylthio, halogen, C 2 -C 5 alkoxyalkyl, C -C5 alkoxyalkoxy, amino, C1-C3 alkylamino or di(Cι-C 3 alkyl)amino; Y is H, C r C 4 alkyl, C r C 4 alkoxy, C r C 4 haloalkoxy, C r C 4 alkylthio, C j -C4 haloalkylthio, C 2 -C 5 alkoxyalkyl, C 2 -C5 alkoxyalkoxy, amino, C1-C3 alkylamino, di(C!-C3 alkyl)amino, C3-C4 alkenyloxy, C3-C4 alkynyloxy, C 2 -C 5 alkylthioalkyl, C 2 -C 5 alltylsulfinylalkyl, C 2 -C 5 alkylsulfonylalkyl, C!-C 4 haloalkyl, C 2 -C 4 alk nyl, C3-C5 cycloalkyl, azido or cyano; Z is CH or N; and tiieir agriculturally suitable salts; provided tiiat: (a) when X and or Y is C j haloalkoxy, then Z is CH; (b) when X is halogen, then Z is CH and Y is OCH 3 , OCH 2 CH 3 , N(OCH 3 )CH 3 , NHCH 3 , N(CH 3 ) 2 or OCF 2 H. 5. A formulation according to Claim 4 wherein the sulfonylurea is selected from die group: 2-cWoro-N-[[(4-methoxy-6-metiιyl-l,3,5-triazin-2-yl)amino]- carbonyljbenzenesulfonamide (c orsulfuron); methyl 2-[[[[(4,6-dimemyl-2-pyriιnidinyl)amino]carbonyl]- aminojsulfonyllbenzoate (sulfometuron methyl); ethyl 2-[[[[(4-cMoro-6-methoxy-2-pyriιnidmyl)amino]- carbonyl]amino]sulfonyl]benzoate (chlorimuron ethyl); methyl 2-[[[[(4-methoxy-6-methyl-l,3,5-triazin-2-yl)amino]- carbonyl]amino]sulfonyl]benzoate (metsulfiiron methyl); methyl 2-[[[[(4,6-dimemoxy-2-pyriιnidinyl)amino]carbonyl]- ammo]sulfonyl]-6-(trifluoromethyl)-3-pyridinecarboxylate (ethametsulfuron methyl); methyl 2-[[[[[4-ethoxy-6-(metiιylamino)-l,3,5-triazin-2-yl]- — ammo]carbonyl]amino]sulfonyl]benzoate; 2-(2-chloroetiιoxy)-Ν-[[(4-methoxy-6-methyl-l,3,5-triazin-2- yl)am o]carbonyl]benzenesulfonamide; ethyl 5-[[[[(4,6-dimemoxy-2-pyrimid yl)amino]carbonyl]- ammo]sulfonyl]-l-methyl-lH-pyrazole-4-carboxylate; N-[[(4,6-dimemoxy-2-pyriιnidmylamino]carbonyl]-3-(ethyl- sιιlfonyl)-2-pyriά^esulfonarnide; memyl 3-[[[[(4-memoxy-6-me yl-l,3-5-triazin-2-yl)arnino]- carbonyl]ammo3sulfonyl]-2-dιiophene-carboxylate (thifensulfuron methyl); methyl 2-[[[[N-(4-methoxy-6-methyl-l,3,5-triazin-2-yl)-Ν- memylan-dno]carbonyl]amino]sulfonyl] benzoate (tribenuron methyl); methyl 2-[[[[[(4,6-dimemoxy-2-pvrimidinyl)amino]carbonyl]- amino]sulfonyl]methyl]benzoate (bensulfuron methyl); 2-[[[[(4,6-dimemoxy-2-pyrimidinyl)am o]carbonyl]amino]- su1fonyl]-N^-dimethyl-3-pyridinecarboxamide (nicosulfuron); and metiιyl 2-[[[[[4,6-bis(difluoromemoxy)-2-pyrimidmyl]aιnino]- carbonyl]amino]sulfonyl]benzoate. 6. A formulation of Claim 1 wherein the pesticide is an insecticide. 7. A formulation of Claim 1 wherein die pesticide is a fungicide. 8. A metiiod for protecting crops comprising applying to the crop to be protected an effective amount of a formulation according to Claim 1. 9. A foimulation of Claim 2 wherein die pesticidal component comprises a sulfonylurea herbicide and a non-sulfonylurea pesticide in die following amounts based on total weight of die formula: 10-40% sulfonylurea and non-sulfonylurea pesticide; 0.1-5% at least one of a polyelectrolyte and a surfactant; 0-10% suspending agent; 5-25% agriculturally suitable stabilizing salt, such that the sulfonylurea and stabilizing salt are less than 85% by total formulation weight; and 35-96% aqueous medium. 10. A formulation of Claim 9 wherein the pesticidal component comprises a sulfonylurea herbicide and 3,5-dibromo-4-hydroxybenzonitrile.

Inventors: HERMANSKY CLARENCE GAETANO, HERMANSKY, CLARENCE, GAETANO
Applicants: DU PONT, HERMANSKY CLARENCE GAETANO, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1993
Main classification: A01N25
IPC codes: A01N25, A01N47, A01N57