Abstract:
Controlled release compositions releasing an effective amount of biologically active material such as pesticide into the environment over an extended period of time are disclosed. The compositions comprise an intimate admixture of an organic polymer and a component incorporating a biologically active material wherein the biologically active material is released by molecular diffusion through the matrix of the polymer at the surfaces exposed to the environment. The component including the biologically active material is incorporated in the polymer in amounts sufficient that diffusion of the component at the surfaces exposed to the environment results in loss of structural integrity and/or fraction of the polymer to thereby expose new surfaces to decomposition for further release of the biologically active material resulting in a rate of release over an extended period of time in proportion to that necessary to offer protection.

Description:
This is a continuation of application Ser. No. 434,083 filed Jan. 17, 1975, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Prior Art Relating to the Disclosure 
     A great deal of work has been carried out to increase the protection period of biologically active material such as pesticides which have relatively short lives while, at the same time, diminishing the residual waste of such pesticides which are the major cause of serious pollution problems and damage to wildlife. Systems have been developed which utilize the concept of &#34;controlled release&#34; to release the pesticide at a controlled rate effective to control the pest while minimizing the undesired contamination of water sources with subsequent damage to aquatic and wildlife. One method of accomplishing controlled release is by providing solid solutions of pesticides in polymers. U.S. Pat. No. 3,076,744 discloses a urea-formaldehyde resin incorporating up to 10 percent of an organic insecticide and an edible material attractive to insects. U.S. Pat. No. 3,269,900 discloses an intimate admixture of a polyurethane foam with a nonvolatile organic pesticide, the polyurethane foam forming a protective cover around the pesticide with release of the pesticide occurring gradually. U.S. Pat. No. 3,343,941 discloses physically admixing herbicidally active alkyd resins with other herbicides for slow release both by hydrolysis of the chemically incorporated herbicide as well as by physical release of the admixed herbicide. Canadian Pat. No. 846,785 discloses the incorporation of a pesticide in a thermoplastic polymer having desired permeability to the pesticide with release of the pesticide by diffusion of the pesticide through the polymer lattice. 
     The rate of release and length of protection afforded by the pesticide compositions disclosed in the above patents has not been commercially advantageous in many instances. The pesticide compositions disclosed in Canadian Pat. No. 846,785 release the pesticide rapidly at first and then too slowly to be effective for the purposes desired. Up to as much as 80 percent of the pesticide remains in the polymer after a reasonable period of time. Thereafter, the pesticide is released at too slow a rate to be effective. The rate of release of compositions disclosed in Canadian Pat. No. 846,785 is determined by the difference in pesticide concentration in the soil adjacent the polymer and that in the polymer surfaces exposed to the environment. Pesticide concentration sharply falls over a period of time, slowing the rate of release of the pesticide. 
     It has remained a problem to devise controlled release biologically active material compositions providing a release of a biologically active material over extended periods of time at effective rates for control. This application is directed to means providing release of the biologically active materials over an extended period of time and preventing the reduction of the release rate of the biologically active material from a biologically active material-polymer admixture below that necessary to be effective by continually exposing fresh surfaces of the polymer-biologically active material mixture to the environment. 
     SUMMARY OF THE INVENTION 
     The compositions described herein comprise an intimate mixture of an organic polymer and a component incorporating a biologically active mixture with or without a carrier material wherein the biologically active material is released to the environment by molecular diffusion through the lattice of the polymer at the surfaces exposed to the environment. A sufficient amount of the component is incorporated in the polymer so that diffusion of the component including the biologically active material at the surfaces exposed to the environment results in loss of structural integrity of the polymer and/or fracture thereof to thereby expose new surfaces of the biologically active material-polymer to the environment for further release of the component. 
     The objects of this invention are to provide controlled release compositions: (1) which have release rates effective for purposes desired over an extended period of time; (2) where loss of biologically active material in the composition at the surfaces of the composition exposed to the environment results in fracture and/or disintegration of the polymer at those surfaces to expose new surfaces to the environment for further diffusion of the biologically active material; (3) which in the case of pesticides, require much less pesticide for the same period of activity, are easier to handle, less toxic, provide lower risk of damage to plants, reduce toxicity to other organisms such as wildlife, reduce costs due to less frequent application and have minimal pollution hazard. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a graph of release rate vs. time of a composition made in accordance with this invention, and one prepared as described in Canadian Pat. No. 846,785; 
     FIG. 2 is a graph of release rate vs. time for compositions, prepared as described in Canadian Pat. No. 846,785, compared with those of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following are definitions of terms as used herein in the specification: 
     Polymer--Natural or synthetic compounds having a multiple of their molecular weight which are water insoluble, inert with respect to the biologically active material incorporated therewith and permeable to the biologically active material incorporated therewith, i.e. the biologically active material is diffusible through the polymer lattice. The polymer may be a partial solvent for the biologically active material or the biologically active material a solvent for the polymer. 
     Biologically active material--Those compounds used to inhibit, repel, exterminate or alter the activities of insects, moles, fungi, bacteria, protozoa, viruses, plants, invertebrates, worms and the like and including medicinals, herbicides, insecticides, miticides, rodenticides, fungicides and the like which are non-reactive with the polymer used in conjunction therewith but soluble or dispersible therein; not thermally degraded at the temperatures used in formulating the admixture, and which may be water-soluble or insoluble. 
     Carrier--A material which enhances fracture of the composition by dissolution, degradation, etc. which may be monomeric or polymeric and which is compatible with the biologically active material and polymer used, inert with respect thereto, and preferably water soluble. 
     Pesticide Component--The pesticide alone or in admixture with a carrier. 
     Polymers used in preparation of the controlled release compositions of this invention may include: (1) synthetic polymers such as polyethylene, polypropylene, polystryrene, polyacrylates, polymethacrylates, polyamides, polyureas, ethylene-vinylacetate copolymers, ethylene-acrylic acid copolymers, polyvinylchloride, polyvinylidene chloride, polyesters, polyvinyl alcohols, cellulose acetate, cellulose triacetate, polyanhydrides, polyacetals, polyepoxides, polyethers, acrylonitrile-butadiene copolymers and styrenemaleic anhydride copolymers; (2) natural thermoplastic polymers such as natural gums and &#34;Vinsol&#34;-type resins (high melting, thermoplastic polymers derived from southern pine stump wood); (3) bitumens such as asphalt, asphaltites, asphaltic pyrobitumens and uintaite (Gilsonite); (4) rosins such as wood rosins, hydrogenated rosin, heat treated rosin, polymerized rosins and esterified rosins; and lignin or lignin derivatives. Preferred polymers include polyvinylacetate, Gilsonite and kraft lignin. The polymer should be of such type as to disintegrate after the active and/or inactive component leaves the composition. 
     Where the biologically active material is a pesticide selected for use in the controlled release compositions may be from those commercial pesticides now available including the following: 
     
         ______________________________________N--sec-Butyl-4-tert-butyl-                A-8202,6-dinitroaniline2-Chloro-4-ethylamino-6-                AAtrexisopropylamino-s-triazine0,0,0&#39;,0&#39;-Tetramethyl 0,                Abate0&#39;-thiodi-p-phenylenephosphorothioateIsopropyl 4, 4&#39;-dichloro                AcaralatebenzilateIsopropyl 4, 4&#39;-dibromo-                Acarolbenzilate2-Diethylamino-6-methyl-                Actellicpyrimidin-4-yl dimethylphosphorothionate2-(0,0-Diethyl thionophos-                Afuganphoryl)-5-methyl-6-car-bethoxypyrazolo-(1,5a)pyrimidine2-[2-chloro-1-(2,5-dichloro-                Aktonphenyl)-vinyl]0,0-diethylphosphorothioaten-Octanol 28% plus n-Decanol 38%                Alcohol C.sub.8, C.sub.10n-Decanol            Alcohol C.sub.101, 2, 3, 4, 10, 10-Hexachloro-                Aldrin1, 4, 4a, 5, 8, 8a-hexahydro-1, 4 endo-exo-5, 8-dimethano-naphthaleneDL-2-Allyl-4-Hydroxy-3-methyl-                Allethrin2-cyclopenten-1-one esterifiedwith a mixture of cis and transDL-chrysanthemum monocarboxylicacid2-Propene-1-ol       Allyl alcohol3-Amino-2,5-dichlorobenzoic                Amibenacid3-Amino-1,2,4-triazole                Amitrole2-Propenal           Aqualin3-(4-Chlorophenyl)-1-methoxy-                Aresin1-methylurea4,6-Dinitro-2-sec-butylphenyl                Aretitacetate0,0,0,0-Tetrapropyl dithio-                AsponpyrophosphateMethy-4-aminobenzene sulfonyl-                AsuloxcarbamateS--2,3-Dichloroallyl diisopro-                AvadexpylthiocarbamateS--2,3,3-Trichloroallyl-diiso-                Avadex BWpropyl thiocarbamate2,6-di-tert-Butyl-ρ-tolylmethyl-                AzakcarbamateDimethyl phosphate of 3-hydroxy-                AzodrinN--methyl-cis-crotonamideBenzoyl chloride (2,4,6-tri-                Banamitechlorophenyl) hydrazone3,6-Dichloro-o-anisic acid                Banvel4-Chloro-2-butynyl-m-chloro-                Barbancarbanitate2-Isopropoxyphenyl N--methyl-                Baygoncarbamate2&#39;,5-Dichloro-4&#39;-nitro-                Bayluscidesalicylanilide ethanolamineN--Butyl-N--ethyl-α,α,α-trifluoro-                Benefin2,6-dinitro-ρ-toluidineMethyl-1-(butylcarbamoyl)-2                Benomylbenzimidazole carbamateEthyl 0-benzoyl-3-chloro-2,                Benzomate6-dimethoxybenzohydroximateMethyl m-hydroxycarbanilate                Betanalm-methylcarbanilateS--(0,0-Diisopropyl phosphoro-                Betasandithioate) ester of N--(2-mer-captoethyl)benzene-sulfonamideDimethyl phosphate of 3-hydroxy-                BidrinN,N--dimethyl-cis-crotonamide2-sec-Butyl-4,6-dinitrophenyl-                Binapacryl3-methyl-2-butenoate2-(4-Chloro-6-ethylamino-s-                Bladextriazin -2-ylamino)-2-methyl-propionitrileS--(4-Chlorobenzyl)-N,N--                Bolerodiethylthiol carbamateTriphenyltinacetate  Brestan5-Bromo-3-sec-butyl-6-                Bromacilmethyluracil3,5-Dibromo-4-hydroxybenzo-                Bromoxynilnitrile3,5-Dibromo-4-octanoyloxy-                Bromoxynilbenzonitrile         octanoatem-(1-Methylbutyl)phenyl methyl-                Bux Tencarbamate + m-(1-ethylpro-pyl)phenyl methylcarbamateDimethyl arsinic acid                Cacodylic acid1-(p-tert-Butylphenoxy)-2-                Calamitebutyl 1-(2-butynyl)sulfiteN--Tridecyl-2,6-dimethyl                Calixinmorpholinecis-N--((trichloromethyl)thio)-                Captan4-cyclohexene-1,2-dicarboximide1-Naphthyl methylcarbamate                Carbaryl2,3-Dihydro-2,2-dimethyl-7-                Carbofuranbenzofuranyl methylcarbamatem[[(Dimethylamino)methylene]-                Carzolamino]phenyl methylcarbamatehydrochlorideN--n-propyl-N--cyclopropylmethyl-                CGA-108324-trifluoromethyl-2,6-dinitroaniline0-(Methyl-2-propinylamino)                CGA-13608phenyl N--methylcarbamateIsopropyl N--phenylcarbamate                Chem Hoe3-(4-Bromo-3-chlorophenyl)-1-                Chlorbromuronmethoxy-1-methylureaMixture of 60% octachloro-4,7-                Chlordanemethanotetrahydroindane and40% related compoundsN&#39;--(4-Chloro-o-tolyl)-N,N--                ChlordimeformdimethylformamidineEthyl 4,4&#39;-dichlorobenzilate                Chlorobenzilate1,4-Dichloro-2,5-dimethoxy                ChloronebbenzeneTrichloronitromethane                Chloropicrin3-[ρ-(ρ-chlorophenoxy)phenyl]-                Chloroxuron1,1-dimethylureaIsopropyl m,-chlorocarbanilate                ChlorprophamDimethyl phosphate of α-methyl-                Ciodrinbenzyl 3-hydroxy-cis-crotonateN.sup.3, N.sup.3 --Diethyl-2,4-dinitro-6-                Cobextrifluoromethyl-m-phenylene-diamine0,0-Diethyl 0-3-chloro-4-                Co-Ralmethyl-2-oxo-2H--1-benzopyran-7-yl-phosphorothioate0-p-Cyanophenyl      Cyanox0,0-dimethyl phosphorothioate3-[2-(3,5-Dimethyl-2-oxocyclo-                Cycloheximidehexyl)-2-hydroxyethyl]-glutar-imide2-(Diethoxyphosphinylimino)-                Cyolane1,3-dithiolaneDodecylguanidine acetate                Cyprex2-(Diethoxyphosphinylimino)                Cytrolane4-methyl-1,3-dithiolane2,4-Dichlorophenoxyacetic acid:                2,4-Dalso used as amine salts and esters2,4,5,6-Tetrachloroisophthalo-                Daconil 2787nitrileDimethyl-2,3,5,6-tetrachloro-                Dacthalterephthalate2,2 Dichloropropionic acid                Dalapon0,0-Diethyl 0-[p-(methylsulfinyl)-                Dasanitphenyl]phosphorothioate4-(2,4-Dichlorophenoxy)butyric acid:                2,4-DBalso salt, amine salt and esterformulations1,2-Dibromo-3-chloropropane                DBCP2,6-Dichloro-4-nitroaniline                DCNA1,1,1-Trichloro-2,2-bis(p-chloro-                DDTphenyl) ethaneS,S,S--Tributyl phosphoro-                Deftrithioate0,0-Diethyl 0-(2-isopropyl-6-methyl-                Diazinon4-pyrimidinyl)phosphorothioate2,6-Dichlorobenzonitrile                Dichlobenil2,3-Dichloro-1, 4-naphthoquinone                Dichlone2-(2,4-Dichlorophenoxy)-                Dichlorproppropionic acid2,2-Dichlorovinyl dimethyl phosphate                Dichlorvos1,1-bis(p-Chlorophenyl)-2,2,2-                Dicofoltrichloroethanol1,2,3,4,10,10a, or a1,2,3,4,10,                Dieldrin10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo-exo-5,8-dimethanonaphthalenecis-N--[(1,1,2,2-Tetrachloroethyl)-                Difolatanthio]-4-cyclohexene-1,2-dicarboximide0,0-Dimethyl S--(N--methylcarbamoyl-                Dimethoatemethyl) phosphorodithioate2,4-Dimethylbenzyl 2,2-dimethyl-3-(2-                Dimethrinmethylpropenyl)cyclopropane-carboxylate2-Dimethylcarbamyl-3-methyl-5-                Dimetilanpyrazolyl dimethylcarbamate2-(sec-Butyl)-4,6-dinitrophenol                Dinoseb2,3-p-Dioxanedithiol-S, S--bis                Dioxathion(0,0-diethyl phosphorodithioate)2-Methoxy-4H--1,3,2-benzodioxa-                Salithionphosphorin-2-sulfide2-Diphenylacetyl-1,3-indandione                DiphacinN,N--Dimethyl-2,2-diphenyl-                DiphenamidacetamideDiphenylamine        Diphenylamine0,0-Diethyl-S--[2-(ethylthio)-                Disulfotonethyl]phosphorodithioate3-(3,4-Dichlorophenyl)-1,1-                Diurondimethylurea2-Methyl-4,6-dinitrophenol                DNOCsodium saltDL-2-Allyl-4-hydroxy-3-methyl-                D-trans Allethrin2-cyclopenten-1-one esterifiedwith D-trans chrysanthemummonocarboxylic acid0,0-Diethyl 0-(3,5,6-trichloro-                Dursban2-pyridyl) phosphorothioateTriphenyltin hydroxide                Du-Ter0-Ethyl-S--phenyl-ethylphos-                Dyfonatephonodithioate0,0-Dimethyl (2,2,2-trichloro-                Dylox1-hydroxyethyl)phosphonate2,4-Dichloro-6-(o-chloroaniline)-                Dyrenes-triazine6,7,8,9,10,10-Hexachloro-1,5,5a,                Endosulfan6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide7-Oxabicyclo(2.2.1)heptane-2,3-                Endothalldicarboxylic acid1,2,3,4,10,10-Hexachloro-6,7-                Endrinepoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo-endo-5,8-dimethanonaphthaleneEthyl 3,7,11-trimethyl-                Entocon ZR-512dodeca-2,4-dienoateIsopropyl 11-methoxy-3,7,11-                Entocon ZR-515trimethyldodeca-2,4-dienoate0-Ethyl-0-p-nitrophenyl                EPNphenylphosphonothioateS--Ethyl dipropylthiocarbamate                Eptam2-(2,4,5-Trichlorophenoxy) ethyl                Erbon2,2-dichloropropionate0,0,0&#39;,0&#39;-Tetraethyl S,S&#39;--methyl-                Ethionene bisphosphorodithioate(2-Chloroethyl) phosphonic acid                Ethrel2-Ethyl-1,3-hexanediol                Ethyl hexanediol2-(Ethylamino)-4-(isopropylamino) =                EVIK6-(methylthio)-s-triazine2,3,6-Trichlorophenylacetic acid                Fenacor sodium salt0,0-Dimethyl-0-[4-(methylthio)-m-                Fenthiontolyl]-phosphorothioate1,1-Dimethyl-3-(α,α,α-trifluoro-                Fluometuronm-tolyl)ureap-Nitriphenyl α,α,α,-trifluoro-                Fluorodifen2-nitro-p-tolyl etherS,S,S--Tributyl phosphoro-                FolextrithioiteN--(Trichloromethylthio)-                FolpetphthalimideIsomers of Benzene-  Fortified Benzenehexachloride containing 40%                Hexachloride(by weight) of gamma isomerContains 7.9% 2-(m-chlorophenoxy)-                Fruitone CPApropionamide and 0.4% free acid-3-(α-Acetonyl furfuryl)-4-                Fumarinhydroxycoumarin2-Chloro-1-(2,4,5-trichlorophenyl)                Gardonavinyl dimethyl phosphate2,4a,7-Trihydroxy-1-methyl-8-                Gibberellic acidmethylenegibb-3-ene-1,10-carboxylic acid-1 → 4 lactoneEthyleneglycol bis (trichloro-                Glytacacetate)0,0-bis (p-Chlorophenyl) aceti-                Gophacidemidoylphosphoramidothioate0,0-Diethyl-s-[4-oxo-1,2,3-                Guthionbenzotriazin-3(4H)--ylmethyl]-phosphorodithioate74% 1,4,5,6,7,8,8a-Heptachloro-                Heptachlor3a,4,7a-tetrahydro-4,7-methano-indene3-(Hexahydro-4,7-methanoinden-                Herban5-yl)-1,1-dimethylureaIndole-3-butyric acid                Hormodin1-Phenyl-3-(0,0-diethylthio-                Hostathionnophosphoryl)-1,2,4-triazolN--(Mercaptomethyl)phthalimide                ImidanS--(0,0-dimethyl phosphoro-dithioate)Butyl 3,4-dihydro-2,2-dimethyl-                Indalone4-oxo-1-2H--pyran-6-carboxylate2,6-Dinitro-N,N--dipropyl-                Isopropalincumidine2-(1-Methylheptyl)-4,6-dinitro-                Karathanephenyl crotonate3,5-Dichloro-N--(1,1-dimethyl-2-                Kerb 50Wpropynyl) benzamide3-Trifluoromethyl-4-nitrophenol,                Lamprecidsodium saltMixture of about 20% 2,3,5-Tri-                Landrinmethylphenyl methylcarbamate; and80% 3,4,5-trimethylphenyl-methylcarbamate2-Chloro-2&#39;,6&#39;-diethyl-N--                Lasso(methoxymethyl)acetanilide3-Cyclohexyl-6,7-dihydro-1H--                Lenacilcyclopentapyrimidine-2,4(3H,5H)--dioneβ-Butoxy-β&#39;-thiocyanodiethyl                Lethane 384ether1,2,3,4,5,6-Hexachlorocyclo-                Lindanehexane containing at least99% gamma isomer3-(3,4-Dichlorophenyl)-1-methoxy-                Linuron1-methylureaPhenyl 5,6-dichloro-2-trifluoro                Lovozalmethylbenzimidazole-1-carboxylate2-Chloro-2&#39;,6&#39;-diethyl-N--                Machete(butoxymethyl)-acetanilide0,0-Dimethyl phosphorodithioate of                Malathiondiethyl mercaptosuccinate1,2-Dihydro-3, 6-pyridazinedione                Maleic hydrazide4-(Dimethylamino)-m-tolyl meth-                Matacilylcarbamate2-Methyl-4-chlorophenoxyacetic                MCPAacid4-(2-Methyl-4-chlorophenoxy)                MCPBbutyric acid2-(2-Methyl-4-chlorophenoxy)                MCPPpropionic acidS--(4,6-Diamino-s-triazin-2-yl-                Menazonmethyl) 0,0-dimethyl3,4-Dimethylphenyl-N--methyl                Meobalcarbamate2-(4-Thiazolyl)benzimidazole                Mertect4-(Methylthio)-3, 5-xylylmethyl-                Mesurolcarbamate3-Methylphenyl-N--methyl carbamate                MetacrateS--[2-(Ethylsulfinyl)ethyl]                Meta-Systox R0,0-dimethyl phosphorothioateS--Methyl N--[(methylcarbamoyl)-                Methomyloxy]thioacetimidate2,2-bis (p-Methoxyphenyl)-1,1,                Methoxychlor1-trichloroethaneMethyl nonyl ketone  Methyl nonyl ketone0,0-Dimethyl 0-p-nitrophenyl                Methyl parathionphosphorothioate3-(p-Bromophenyl)-1-methoxy-1-                Metrobromuronmethylurea2-Carbomethoxy-1-methylvinyl                Mevinphosdimethyl phosphate, αisomerN--(2-Ethylhexyl) bicyclo[2.2.1]-                MGK 2645-heptene-2, 3-dicarboximide2,3,4,5-bis (2-Butenylene)tetra-                MGK Repellent 11hydrofurfuralDipropyl isochinchomeronate                MGK Repellent 3262-Hydroxyethyl-n-octyl sulfide                MGK Repellent 874Scilliroside glycoside                MGK Rodenticide5-Butyl-2-dimethylamino-4-hydroxy-                Milcurb6-methylpyrimidine5-Butyl-2-ethylamino-4-hydroxy-                Milstem6-methylpyrimidineDodecachlorooctahydro-1,3,4-                Mirexmetheno-1H--cyclobuta[cd]-pentalene4-Benzothienyl-N--methylcarbamate                Mobam0-Ethyl S, S--dipropyl phosphoro-                Mocapdithioate0,S--Dimethyl phosphoroamidothioate                Monitor3-(p-Chlorophenyl)-1,1-dimethylurea                Monuron3-(4-Chlorophenyl)-1, 1-dimeth-                Monuron TCAylurea trichloroacetate6-Methyl-2,3-quinoxalinedithiol                Morestancyclic-S, S--dithiocarbonate1,2-Dibromo-2,2-dichloroethyl                Naleddimethyl phosphate1-Naphthalene acetamide                Naphthalene acetamide1-Naphthaleneacetic acid                Naphthalene acetic acid1-n-Butyl-3(3,4-dichlorophenyl)-                Neburon1-methylureaO--Phenyl,N,N&#39;-dimethylphosphoro-                NellitediamidateEthyl 4-(methylthio)-m-tolyl                Nemacurisopropylphosphoramidate2,2-Dimethyl-3-(2-methylpropenyl)                Neo-Pynamincyclopropanecarboxylic acidester of N--(hydroxymethyl)-1-cyclohexane-1,2-dicarboximideEthyl hydrogen 1-propyl phosphonate                Nia 106371-Propylphosphonic acid                Nia 106566-tert-Butyl-3-isopropylisothia-                Nia 19873zolo-(3,4-d)pyrimidin-4(5H)--one6-tert-Butyl-3-isopropylisoxazo-                Nia 21844lo-(5,4-d)pyrimidin-4(5H)--one6-tert-Butyl-3-propylisoxazolo-                Nia 21861(5,4-d)pyrimidin-4(5H)--one6-tert-Butyl-3-isopropylisoxazolo-                Nia 23486(3,4-d)pyrimidin-4(5H)--one3-(1-Methyl-2-pyrrolidyl)pyridine                Nicotine2,4-Dichlorophenyl p-Nitrophenyl                Nitrofenether2,-Chloro-6-(trichloromethyl)                N-ServepyridineN--(3,5-Dichlorophenyl)succimide                Ohric2-(p-tert-Butylphenoxy) cyclohexyl                Omite2-propynyl sulfiteS--Ethyl hexahydro-1H--azepine-1-                OrdramcarbothioateO,S--Dimethyl acetylphosphorami-                Orthenedothioate2-sec Butyl phenyl-N--methyl car-                Osbacbamate2-Chloro-4-(cyclopropylamino)-                Outfox6-(isopropylamino)-s-triazine0,0-Diethyl 0-p-nitrophenyl phos-                Parathionphorothioateα,α-bis(p-Chlorophenyl)-3-pyri-                Parinoldine methanolPentachloronitrobenzene                PCNBPentachlorophenol    PCPDecachlorobis(2,4-cyclopentadiene-                Pentac1-yl)1,1-Dichloro-2,2-bis(p-ethylphenyl)                Perthaneethane (88%) plus related com-pounds, 12%Dibenzo 1,4-thiazine Phenothiazine0,0-Dimethyl S--(α-ethoxycarbon-                Phenthoateylbenzyl)-phosphorodithioate0,0-Diethyl S--(ethylthio)-methyl                PhoratephosphorodithioateTributyl 2,4-dichlorobenzylphos-                Phosfonphonium chloride2-Chloro-N,N--diethyl-3-(dimethox-                Phosphamidonyphosphinyloxy)crotonamide0-(4-Bromo-2,5-dichlorophenyl)                Phosvel0-methyl phenylphosphonothioate4-Amino-3,5,6-trichloropicolinic                Picloramacid3-(2-Methylpiperidino)propyl                Piperalin3,4-dichlorobenzoate2-Dimethylamino-5, 6-dimethylpy-                Pirimorrimidin-4-yl dimethylcarbamate4-(Methylsulfonyl)-2, 6-dinitro-                PlanavinN,N--dipropylaniline5,6-Dihydro-2-methyl-1,4-oxathiin-                Plantvax3-carboxanilide-4,4-dioxideTricyclohexyltin hydroxide                Plictran2-Diethylamino-6-methylpyrimidin-                Primicid4-yl diethyl phosphorothioate2-Chloro-4,6-bis (ethylamino)-                Princeps-triazine2-(3,4-Dichlorophenyl)-4-methyl-                Probe1,2,4-oxadiazolidine-3,5-dione2,4-bis(Isopropylamino)-6-meth-                Prometoneoxy-s-triazine2,4-bis(Isopropylamino)-6-                Prometryne(methylthio)-s-triazine3,4-Dichloropropionanilide                Propanil2-Chloro-4,6-bis(isopropylamino)-                Propazines-triazineDi-n-propyl 6,7-methylenedioxy-                Propyl isome3-methyl-1,2,3,4-tetrahydrona-phthalene-1,2-dicarboxylate1,8-Naphthalic anhydride                Protect5-Amino-4-chloro-2-phenyl-3(2H)--                Pyraminpyridazinone2-Chloro-N--isopropylacetanilide                RamrodN,N--Diallyl-2-chloroacetamide                Randox(5-Benzyl-3-furyl)methyl-2,2-di-                Resmethrinmethyl-3-(2-methyl-propenyl)cyclopropanecarboxylateS--Ethyl N--ethyl-N--cyclohexylthio-                Ro-Neetcarbamate0,0-Dimethyl-0-(2,4,5-trichloro-                Ronnelphenyl) phosphorothioate2-tert-Butyl-4-(2,4-dichloro-5-                Ronstarisopropyloxyphenyl)-5-oxo-1,3,4-oxadiazolineRotenone             Rotenone2,5 Dimethyl-1-pyrrolidinecarbo-                Rowtatexanilide4-tert-Butyl-2-chlorophenyl                Ruelene0-methyl methylphosphoroamidateSuccinic acid 2,2-dimethylhydra-                SADHzide2-Methoxy-4H--1,3,2-benzo-                Salithiondioxaphosphorin-2-sulfide2-Ethylthio-4,6-bis-isopropyla                Sancapmino-s-triazine4-Amino-6-t-butyl-3-(methylthio)-                Sencor1,2,4-triazin-5(4H)--one2-Methyl-5,6-dihydro-4-H--pyran-                Sicarol3-carboxylic acid anilide1-(2-Methylcyclohexyl)-3-pheny-                Siduronlurea2-(2,4,5-Trichlorophenoxy)-pro-                Silvexpionic acid6-Ethoxy-1,2-dihydro-2,2,4-                Stop Scaldtrimethylquinoline2,4-Diguanidino-3,5,6-trihydroxy-                Streptomycincyclohexyl 5-deoxy-2-0-(2-deoxy-2-methyl-amino-α-glucophyranosyl)-3-formyl pentanofuranoside1-Methyl-2-(3,4-methylenedioxy-                Sulfoxidephenyl) ethyl octyl sulfoxide0,0-Dimethyl 0-(4-nitro-m-tolyl)-                Sumithionphosphorothioate2-sec-Butylamino-4-ethylamino-                Sumitol6-methoxy-s-triazine0,0-Dimethyl S--(2-methoxy-1,3,4-                Supracidethiadiazol-5(4H) onyl-4-methylphosphorodithioate0-p-Cyanophenyl 0-ethylphenyl-                SurecidephosphonothioateS-13 Ethyl diisobutylthiocarbamate                SutanA 2:1 mixture of 0,0-diethyl-                Systox0-[2-(ethylthio)ethyl]phospho-rothioate (thiono isomer) I and0,0-diethyl-S--[2-(ethylthio)ethyl]phosphorothioate (thiolisomer) II2,4,5-Trichlorophenoxyacetic acid                2,4,5-Tm-(3,3-Dimethylureido)phenyl                Tandextert-butylcarbamateDimethylamine salt of 2,3,6-tri-                2,3,6-TBAchlorobenzoic acid and othertrichlorinated benzoic acidsTrichloroacetic acid, sodium salt                TCATrichlorobenzylchloride                TCBCTetrachlorothiophene TCTP2-Methyl-2-(methylthio)propio-                Temiknaldehyde 0-(methylcarbamoyl)-oximeTetraethyl purophosphate                TEPP3-tert-Butyl-5-chloro-6-methyl-                Terbaciluracil2-tert-Butylamino-4-ethylamino-                Terbutryn6-methylthio-s-triazine5-Ethoxy-3-trichloromethyl-                Terrazole1,2,4-thiadiazole4&#39;-Chlorophenyl2,4,5-trichloro-                Tetradifonphenyl sulfoneIsobornyl thiocycanoacetate                Thanite(82%) and related compoundsDiethyl 4,4&#39;-o-phenylene-bis                Thiophanate E(3-thioallophanate)Dimethyl 4,4&#39;-o-phenylene-bis                Thiophanate M(3-thioallophanate)bis(Dimethylthiocarbamoyl)disul-                Thiramfide1,4-Dithiaanthra-    Thynonquinone-2,3-di-carbonitrile2,3,5-Triiodobenzoic acid                TibaS--Propyl butylethylthiocarbamate                TillamS--(2-Chloro-1-phthalimido-ethyl)-                Torak0 0-diethyl phosohorodithioateN,N--bis(2-chloroethyl)-2,6-                Torpedodinitro-p-toluidineChlorinated camphene with 67-                Toxaphene69% chlorineα,α,α-Trifluoro-2,6-dinitro-                TrifluralinN,N--dipropyl-p-toluidineS--[[(p-Chlorophenyl)thio]methyl]                Trithion0,0-diethyl phosphorodithioatePiperonal bis [2-(2&#39;-n-butoxy-                Tropitalethoxy)ethyl]acetal3-Phenyl-1, 1-dimethylurea                Urabtrichloroacetate0-2, 4-Dichlorophenyl 0, 0-di-                VC-13ethyl phosphorothioate2-Chloroallyl diethyldithio-                VegadexcarbamateS--Propyl dipropylthiocarbamate                Vernam5,6-Dihydro-2-methyl-1,4-oxa-                Vitavaxthiin-3-carboxanilide4-Dimethylamino 3,5-xylyl methyl-                Zectrancarbamate0,0-Diethyl-2-(2-pyrazinyl)                Zinophosphosphorothioate0,0-Diethyl S[(6-chloro-2-oxo-                Zolonebenzoxazolin-3-yl)methyl]phosphorodithioate______________________________________ 
    
     Preferred are pesticides which act through the root system of the plant, such as organophosphorus, carbamate and phenoxyacid pesticides and particularly the following pesticides: 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate (Carbofuran). 
     The polymer and pesticide or pesticide and carrier are physically admixed generally by heating the solid polymer to the liquid state and then thoroughly admixing, at that temperature, the desired pesticide or pesticide and carrier until a uniform distribution is obtained. The choice of a particular polymer with a particular pesticide is determined by a number of factors. One of the most important is the ability of the pesticide to diffuse through the polymer lattice. In general, the pesticide and polymer must be mutually compatible. The amount of pesticide or pesticide and carrier incorporated in the polymer, in the case of a substantially non-biodegradable polymer must be sufficient to induce stresses within the structure of the composition of diffusion of the pesticide from the polymer at those surfaces exposed to the environment so that the polymer-pesticide or polymer-pesticide-carrier combination will lose its structural integrity at those surfaces exposed to the environment to expose fresh surfaces to the soil environment. If the pesticide component is used alone, it must generally be incorporated within the polymer in amounts greater than 50 percent by weight so that the pesticide forms the matrix of the composition although lower percentages can be used with kraft lignin because of the low cohesivity of this polymer. As the pesticide diffuses into the environment at the exposed surfaces of the composition, the polymer left behind loses its structural integrity and fractures or disintegrates exposing new surfaces of the composition to the environment for further diffusion thereof. When the pesticide is admixed with a carrier and incorporated into the polymer, the amount of pesticide-carrier should usually be greater than 50 percent by weight. 
     The carrier may be a water-soluble monomeric or polymeric material which is compatible with the polymer and the pesticide, nontoxic for the desired use and diffusable through the polymer lattice. The carrier may also be a polymeric material which is biodegradable in the environment in which the composition is to be used, such as cellulosic fibers, urea-formaldehyde polymers, etc. Examples of water soluble carriers which may be used include polyethylene glycols having molecular weights ranging from 600 to 6000, biodegradable monomeric materials such as maleic anhydride, tartaric acid, etc. 
     In the case of a biodegradable polymer such as kraft lignin the amount of pesticide or pesticide-carrier incorporated in the polymer should be at least the amount, when released, to effectively control the pest. The amount may range from 15 wt. % to 50 wt. % or greater. The biodegradable polymer-pesticide composition peels away at the soil-composition interface after release of the pesticide incorporated therewith to expose new surfaces of polymer-pesticide to the environment. 
     The relative amounts of carrier and pesticide used in the controlled release composition may range from 0 to 80 percent carrier to 100 to 20 percent pesticide. 
     The controlled release compositions may be and are generally cast in pellet form of any desired shape for ease of use and transportation. The pellets, when incorporating a pesticide, are either incorporated in the soil around the area desired to be treated or spread on the surface of the soil with release of the pesticide occurring over an extended period of time by diffusion from the composition into the soil environment surrounding the pellets. 
     The following examples are illustrative of the invention but are not intended to be limiting in any manner. 
     EXAMPLE 1 
     Pesticide-polymer prepared according to Canadian Pat. No. 846,785. 
     One part of 2,4-dichlorophenoxyacetic acid was blended with one part of molten polyvinyl acetate and cast into a block having a surface area of 20 square centimeters. The block was immersed in 500 ml. of water and the release rate of the pesticide into the water determined over a period of time. The results illustrated by FIG. 1 (Curve A) clearly show that the rate of release of the pesticide is initially rapid and then diminishes with time. 
     EXAMPLE 2 
     A mixture of one part 2,4-dichlorophenoxyacetic acid was admixed with one part of a 1:1 mixture of molten polyvinyl acetate and a water soluble polyoxyethylene glycol polymer having a molecular weight of about 6000. The molten composition was cast into a block having a surface area of 20 square centimeters and immersed in 500 ml. of water. The release rate of the pesticide was measured at various time intervals. Curve B in FIG. 1 clearly shows that the amount of pesticide released does not diminish with passage of time but is substantially constant. 
     EXAMPLE 3 
     Molten Gilsonite was mixed with varying amounts of Carbofuran to prepare pesticide-polymer compositions containing 10%, 20%, 30% and 50% by wt., respectively, of Carbofuran. Each of the homogeneous compositions was cast into plate form. The release rate of each of the compositions was determined by dipping the plates of the respective compositions in water (25 ml.) and withdrawing the plates from the water at varying time intervals for analysis by total UV determination. The release rates of the compositions containing 10% to 40% by wt. of Carbofuran were insignificant while the compositions containing 50% by wt. of Carbofuran showed significant release rates. The release rates of the 50% by wt. Carbofuran composition remained substantially constant over an extended period of time. 
     EXAMPLE 4 
     Kraft lignin (10 gm.) was dissolved in dry dioxane (500 ml.) after which dioxane (350 ml.) was evaporated off. Carbofuran (5 gm.) in dioxane (50 ml.) was then added and most of the solvent removed under reduced pressure. The viscous mixture was poured into a Waring blender containing hexane (500 ml.). The mixture was filtered, air-dried and pelletized. The pellets contained about 25 wt. percent of Carbofuran. 
     EXAMPLE 5 
     Kraft-lignin-Carbofuran mixtures were prepared similar to that of Example 4 with varying concentrations of Carbofuran. The mixtures were pressed into wafers or cast into cylinders and used in field tests by placing them in the soil around young trees (Sweitenia macrophylla) in Costa Rica. A randomized block approach was employed with 15 blocks of 16 trees each for a total of 240 trees. Within each block of trees was one replicate each of three formulations in three levels each. In seven blocks three additional formulations in one level each were included. The formulations and treatment levels were as follows: 
     
         ______________________________________                  Treatment                  Level     Desig-Formulation            (per tree)                            nation______________________________________A.    Kraft-lignin-Carbofuran wafers                      2 pellets L1 59.3% Carbofuran     3 pellets L2 9.8 cm.sup.2 /pellet (avg. area)                      4 pellets L3 1.28 g/pelletB.    Kraft-lignin-Carbofuran cylinders                      3 pellets C1 57.6 Carbofuran      4 pellets C2 4.35 cm.sup.2 /pellet (avg. area)                      6 pellets C3 0.73 g/pelletC.    Kraft-lignin-Carbofuran cylinders 79.9% Carbofuran 4.86cm.sup.2 /pellet (avg. area)                      4 pellets C4 0.439 g/pelletD.    Kraft-lignin-Carbofuran cylinders 89.2% Carbofuran 2.92 cm.sup.2 pellet (avg. area)                      4 pellets C5 0.42 g/pellet______________________________________ 
    
     A block of trees was selected at random after each two week period, infested with 20 eggs/tree of the Hypsipyla grandella shootborer pest and observed for survival of larvae and damage. Additionally, samples of fresh leaves from the trees were selected and bioassayed in the laboratory with first instar Hypsipyla larvae. To be considered &#34;toxic&#34;, as indicated in Table I, a tree had to both withstand the field infestation with an intact terminal and complete larvae mortality and also kill the larvae in the laboratory bioassay. Trees which exhibited poor growth or died were eliminated from the results. As Table I indicates, about 27% of the trees on the alloted site were eliminated due to the poor conditions of the site. The blocks were only able to be monitored for six months in the manner set out before drought conditions set in and prematurely aborted the experiment. 
     In Table I those marked with zeros are those tree eliminated from the results due to poor growth or death. The &#34;control&#34; (an average of 60 untreated trees) had a &#34;percentage effectiveness&#34; of 11.9% compared with the most successful test (C3) of 80%. Tests L1, L2 and L3, releasing, on the average, about 40% of the available Carbofuran in six months were not too effective in controlling the pest, probably because of inadequate-active released Carbofuran to cover the root system of the trees. 
     Tests C1 to C3 released, on the average, about 50% of their available Carbofuran in six months. Test C3 (6 pellets/tree) was about 80% effective in controlling the pest. 
     Tests C4 and C5, employing more concentrated mixtures of Carbofuran released, on the average, about 49% of the available Carbofuran in six months. The low percentage effectiveness was apparently due to inadequate active Carbofuran in the soil over an area sufficient to cover the root system of the tree. 
     
                                           TABLE I__________________________________________________________________________                                 Amount of                                 Active IngredientElapsed Time (days)     30       43         61           76             91               107                  125                     138                        153                           169                              183                                 Applied                                      Released                                            PercentageBlock No.  8       14          5           12              3                4  2  10                         6  13                               9 (g)  in 6 months                                            Effectiveness__________________________________________________________________________TreatmentsL1        + + + - + -  +  -  -  -  +  1.3  0.56   54%L2        - - 0 + - +  +  -  -  -  -  2.2  0.85  30L3        - - + - - -  -  -  -  +  +  3.1  1.13  27C1        - 0 - - - -  -  -  -  -  -  1.2  0.63   0C2        + 0 - 0 + -  -  -  -  -  +  1.7  0.84  33C3        + + + + - -  +  0  +  +  +  2.7  1.26  80C4        0 0 - 0 + -  0  -  -  0  0  1.7  0.88  20C5        0 0 - 0 - -  0  -  -  0  0  1.5  0.72   0Control*                              0.0  0.0     11.9__________________________________________________________________________ *Average of 60 trees. + = toxic - = not toxic 0 = not treated, tree dead or unhealthy