Novel process and composition for controlling weeds

Abstract: The combination of a first ingredient which is a C₇₋₂₀ monocarboxylic acid or a salt thereof, and a second ingredient which is a chemical herbicide, is useful for weed control.

Description: Weeds cost farmers billions of dollars annually in crop losses and in the expense of keeping weeds under control. Much of the cost of intertillage of row crops, maintenance of fallow, seedbed preparation, and seed cleaning is chargeable to weed control. Suppression of weeds along highways and railroad right-of-ways, and in irrigation ditches, navigation channels, yards, parks, grounds, and home gardens also is expensive. Ragweed pollen is the source of annual periodic distress to several million hayfever sufferers. Poison ivy, poison oak, poison sumac, nettles, thistles, sandburs, and puncturevine also bring pain to millions. Weeds also serve as hosts for other crop diseases as well as for insect pests. The losses caused by weeds in agricultural production environments include decrease in crop yield, reduced crop quality, increased irrigation costs, increased harvesting costs, decreased land value, injury to livestock, and crop damage from insects and diseases harbored by the weeds. Chemical herbicides have provided an effective method of weed control; however, the public has become concerned about the amount of residual chemicals which might be found in food, ground water, and the environment. Stringent new restrictions on the use of herbicides and the elimination of some effective herbicides from the market place could limit economical and effective options for controlling costly weeds. Additionally, the visually apparent phytotoxic effects of some systemic herbicides appear very slowly on the target weeds, so pesticide users often seek methods by which the apparent speed of action of the herbicide is increased. There is a great need for novel weed control methods which reduce the amount of chemical herbicide necessary to obtain acceptable levels of weed control. Researchers have experimented with various combinations of chemicals as one approach to identify compositions which have desirable herbicidal characteristics. In the rare instance, unexpected activity of the combination of chemicals is obtained. For example, selective control of annual weeds with a composition of fatty acids mixed with ethylmaleimide, colchicine, 2,4-dinitrohalobenzene, or 2,4-dinitrophenol has been described in the Japanese patent abstract JP61106501. It should be noted that the compounds which were mixed with the fatty acids are not known for their agricultural use and, in fact, may be inappropriate for many herbicidal applications. Other abstracts disclosing a variety of fatty acid derivatives with various chemical compounds include JP59199608 (halogen or cyano derivatives of fatty acids with 2-amino 1,2,4-triazole), JP59199609 (halogen or cyano derivative of fatty acid with 3-amino 1,2,4-triazole), and JP59193804 (acetylenic derivative). Unlike the abstracts mentioned above, the current invention pertains to certain combinations of fatty acids and chemical herbicides which can provide broad range or selective herbicidal activity. EP-A-0115622 discloses a combination of a triazine-derived herbicide with lecithin or linoleic acid, i.e. a C 18 fatty acid. Centr. Pat. Index, Absr. no. C94-309683/50 discloses a herbicidal composition comprising a triazine herbicide and an unsaturated carboxylic derivative having 4 to 18 carbon atoms in its main chain. US-A-4134754 discloses a composition comprising barban and linoleic or linolenic acid, both of which are unsaturated and contain 18 carbon atoms. US-A-2622975 discloses a herbicidal composition comprising undecylenic acid, or a derivative thereof, and chloroacetic acid. Centr. Pat. Index, Absr. no. 86-173305/27 discloses a herbicidal composition comprising a monocarboxylic acid having a 6 to 12 carbon linear chain, and one or more compounds selected from ethyl maleimide, colchicine, 2,4-dinitrohalobenzene and 2,4-dinitrophenol. Brief Summary of the Invention This invention concerns novel compositions and methods for selective or non-selective control of plants. We have discovered that application to weeds of a combination of certain chemical herbicides and one or more substituted (or unsubstituted) saturated (or unsaturated) fatty acids (or their salts) as defined in claim 1 results in the effective control of a broad range of plants. The fatty acids of the subject invention are selected from C7 to C20 fatty acids and can be, for example, in the epoxide, cyclopropane, methylated, or hydroxylated forms. The fatty acids of the subject invention can be represented by the following formula: R 1 Y 1 Y 2 COOR 2 wherein R 1 = C6 to C19 saturated or unsaturated hydrocarbon, or an epoxide, or cyclopropane thereof Y 1 = H, C1-C5 hydrocarbon, or hydroxyl at any position along R 1 Y 2 = H, C1-C5 hydrocarbon, or hydroxyl at any position along R 1 R 2 = H, or salt. Preferred are saturated fatty acids of length C7 to C11 in combination with chemical herbicides. The use of the compositions described here, when used in the proportions and application rates set forth more fully hereinafter, results in an unexpected, enhanced herbicidal effect. The composition of the present invention comprises a mixture of components wherein said mixture is sufficiently active so that application of the composition enables utilization of reduced amounts of each of the active ingredients while still providing effective weed control. Additionally, application of the prescribed combination of fatty acids and a systemic chemical herbicide often reduces the time required for systemic phytotoxic symptoms to appear on the target weed. Since the level of weed control obtained following application of the prescribed mixture is generally much superior to that obtained following application of either active component alone, the practice of the present invention provides a desirable economic advantage to the user. Furthermore, the reduction in the amount of chemicals introduced into the environment is an additional advantageous element of the subject invention. Advantageously, the compositions of the subject invention can provide broad range non-selective herbicidal activity. The compositions of the subject invention may also be used to obtain selective Detailed Description of the Invention The fatty acids used according to the subject invention can be unsubstituted, or substituted, saturated, or unsaturated fatty acids (or their salts), of C7 to C20. Preferred are fatty acids of length C7 to C11, as typified by, but not limited to, decanoic acid or nonanoic acid. The fatty acid component of the subject invention may be a single fatty acid or a mixture of two or more fatty acids. A variety of different chemical herbicides can be used alone or in combination according to the subject invention. The specific herbicides which should be used for a given application can be readily ascertained by a person skilled in the art. Following is a list of herbicides which may be used according to the subject invention. CHEMICAL HERBICIDE FAMILIES AND EXAMPLES HERBICIDE EXAMPLE 1. Aryloxy phenoxypropionate (acids, esters, salts) Fluazifop, Dichlofop 2. Sulfonyl ureas (acids, esters) Chlorimuron, Bensulfuron 3. Imidazilinones Imazethapyr Another chemical herbicide that may be used is bentazon. The compositions of the subject invention may advantageously comprise a herbicide from one of the following families: phenoxy acids, aryloxy phenoxypropionates, sulfonyl ureas, and imidazilinones. Of these families, imidazilinones and sulfonyl ureas are particularly advantageous. One specific example of a chemical herbicide which can be used together with the fatty acid in the composition of the subject invention is imazapyr ([±],-2-[4,5-dihydro-4-methyl-4-[1-methylethyl]-5-oxo-1H-imidazol-2-yl]-3-pyridine carboxylic acid), used alone or optionally with agricultural adjuvants with which the herbicides is normally admixed. One embodiment of the present invention consists of the application of a tankmix of a fatty acid and chemical herbicide. A further embodiment contemplates sequential application of a fatty acid and a chemical herbicide.

Claims: A product comprising a first ingredient which is a C 7-20 monocarboxylic acid or a salt thereof, and a second ingredient which is a chemical herbicide, for simultaneous, separate or sequential use in weed control, the chemical herbicide being selected from aryloxy phenoxypropionate acids, esters and salts; sulfonylurea acids and esters; and imidazilinones; and bentazon. A product according to claim 1, wherein the acid is a C 7-11 monocarboxylic acid. A product according to claim 1 or claim 2, wherein the acid is saturated. A product according to any of claims 1 to 3, wherein the acid is unsubstituted. A product according to claim 4, wherein the acid is decanoic or nonanoic acid. A product according to claim 4, wherein the acid is nonanoic acid. A product according to any preceding claim, wherein the herbicide is a foliar herbicide. A product according to any preceding claim, wherein the herbicide is an aryloxy phenoxypropionate, a sulfonylurea or an imidazilinone. A product according to claim 8, wherein the herbicide is a sulfonylurea or imidazilinone. A product according to claim 9, wherein the herbicide is imazethapyr or imazapyr. A product according to claim 10, wherein the herbicide is imazethapyr and the acid is nonanoic acid. A product according to claim 9, wherein the herbicide is chlorimuron or bensulfuron. A product which comprises a mixture of the first and second ingredients defined in any preceding claim. Use of the first and second ingredients as defined in any of claims 1 to 12, by administration to the weeds or the locus thereof. Use of the first and second ingredients as defined in any of claims 1 to 12, by sequential administration to the weeds or the locus thereof.

Inventors: CAULDER JERRY, CROWLEY R HUGH, EVANS STEVEN L, ZORNER PAUL S, CAULDER, JERRY, CROWLEY, R. HUGH, EVANS, STEVEN L., ZORNER, PAUL S.
Applicants: MYCOGEN CORP, MYCOGEN CORPORATION
Application year: 1992
Main classification: A01N37
IPC codes: A01N37, A01N39, A01N43, A01N31, A01N47