WO1982000400A1

WO1982000400A1 - Method for selectively controlling grassy weeds in rice

Info

Publication number: WO1982000400A1
Application number: PCT/US1980/000956
Authority: WO
Inventors: Chem Co Dow
Original assignee: Smith L; Egli E
Priority date: 1980-07-30
Filing date: 1980-07-30
Publication date: 1982-02-18
Also published as: BR8009097A; IT8123183A0; JPS57501028A; IT1138113B; AU7155881A; GB2091103A

Abstract

Selectively controlling grassy weeds in the presence of rice by applying to the weeds or their habitats a herbicidally effective amount of certain compounds such as 2-(4-((3-chl-5-(trifluoromethyl)2-pyridinyl)oxy)ph-N-(3,5-dimethylphenyl)propanamide.

Description

METHOD FOR SELECTIVELY CONTROLLING GRASSY WEEDS IN RICE

Background of the Invention

Belgian Patent 868,875 to Ishihara Sangyo Kaisha Ltd. discloses and claims a number of 4-(5- trifluoromethyl-2-pyridyloxy)phenoxy alkanoic acids and their derivatives as well as their use as herbicides in broad-leaved crops.

British Patent 1,550,574 to Ciba Geigy Ag discloses and claims a number of pyridyloxyphenoxy propionic acid compounds and their herbicidal use. This reference teaches the use of such compounds as plant growth regulators, as for controlling tobacco sucker growth.

Other pyridyloxyphenoxy propionic acid products and methods are disclosed in copending application S.N. 817,943 filed July 22, 1977, corresponding to European Patent Application 483.

U.S. Patent 3,816,092, issued June 11, 1974, teaches the selective control of weeds in a variety of crops, including rice. This reference teaches, Col. 1, lines 42-45, that herbicidally active agents cannot be predicted from the prior knowledge of compounds that have herbicidal activity.

The principal weed of rice is an annual grass, Echinochloa crusgalli. This grass and its close relatives are troublesome weeds in many countries of the world. Although a number of chemicals and techniques have been developed to attack this problem, there has not yet been a completely acceptable method for controlling such species in the presence of desirable crops such as rice.

Summary of the Invention

This invention provides a method for selectively controlling grassy weeds in the presence of rice which comprises applying to the weeds or their habitats at least a herbicidally effective amount, but less than an amount which is phytotoxic to the rice, of at least one compound having the formula:

wherein T is O or S, Y is H, Br or Cl, and 2 is 2-pyridinylamino, SAr, OAr, or NRAr where R is H or alkyl of 1 to 3 carbon atoms and Ar is a naphthyl group which may be substituted with one or two halogens or a benzyl or phenyl group which may be independently substituted at 1 to 3 ring positions with halogen, C₁_₄ straight or branched chain alkyl groups, C₁_₃ thioalkyl, C₁_₃ alkoxy, hydroxy, C₁_₂ mono or dialkylamino, amino, trifluoro methyl, cyano, thioamide or nitro groups.

Detailed Description of the Invention

The compounds employed in the method of the present invention are known compounds and may be prepared using the requisite starting materials by the methods disclosed in the above-identified references, particularly copending application S.N. 817,943 filed July 22, 1977, the teachings of which are incorporated herein by reference.

The compounds employed in accordance with this invention exist with an optically active center,

Enantiomorphs often show the same biological effect but to a very different degree. A general discussion of this phenomenon may be found in A. Albert, Selective Toxicity, 4th Ed. Met Luen & Co., Ltd., London, 1968, pp. 387-390 and more particular discussions in A. Fredga and B. Åberg, "Stereoisomerism in plant growth regulators of the auxin type", Ann. Rev. Plant Physiology 16:53-72, 1965 and in E. J. Lien, J. F. R. DeMiranda and E. J. Ariens "Quantitative structure-activity correlation of optical isomers". Molecular Pharmacology 12:598-604, 1976. The finding that the D-enantiomers of substituted phenoxypropionates were twice as active as grass control herbicides as the L-form (DT 2623558) suggests that the D-enantiomers of the present case should also be the more active of the enantiomorphs. The compounds utilized in the method of the present invention provide control of a wide variety of annual and perennial grassy weeds and advantageously provide selective control of grassy weeds in rice (Oryza sativa), and give particular and advantageous selective postemergent control of Echinochloa crusgalli (commonly known as barnyardgrass or watergrass) in the presence of rice.

For such uses, unmodified active ingredients of the present invention can be employed. However, the present invention embraces the use of the compounds in composition form with an inert material known in the art as an adjuvant or carrier in solid or liquid form. Thus, for example, an active ingredient can be dispersed on a finely-divided solid and employed therein as a dust or granule. Also, the active ingredients, as liquid concentrates or solid compositions comprising one or more of the active ingredients can be dispersed in water, typically with aid of a wetting agent, and the resulting aqueous dispersion employed as a spray. In other procedures, the active ingredients can be employed as a constituent of organic liquid compositions, oil-in-water and water-in-oil emulsions or water dispersions, with or without the addition of wetting, dispersing, or emulsifying agents. Suitable adjuvants of the foregoing type are well known to those skilled in the art.

The concentration of the active ingredients in solid or liquid compositions generally is from about 0.0003 to about 95 percent by weight or more. Concentrations from about 0.05 to about 50 percent by weight are often employed. In compositions to be employed as concentrates, the active ingredient can be present in a concentration from about 5 to about 98 weight percent. The active ingredient compositions can also contain other compatible additaments, for example, phytotoxicants, plant growth regulants, fungicides, insecticides, and other biologically active compounds used in agriculture.

The exact rate to be applied is dependent not only on a specific active ingredient being applied, but also on a particular action desired, the plant species to be modified and the stage of growth thereof as well as the part of the plant to be contacted with the toxic active ingredient. Thus, all of the active ingredients of the present invention and compositions containing the same may not be equally effective at similar concentrations or against the same plant species.

In selective postemergent operations a dosage of about 0.01 to about 20 pounds/acre (0.011-22.4 kg/-hectare) is generally applicable, although not all compounds are equally effective and some weeds are more difficult to control. Thus, a dosage rate in the range of about 0.05 to about 2.0 pounds/acre (0.056-2.24 kg/hectare) is preferred in postemergent control of grassy weeds.

The following examples illustrate effects of the compounds of this invention. Example 1

In representative operations, each compound to be utilized in a series of tests was dissolved in acetone to one-half of the final volume (twice the final concentration) to be used and the acetone solution in each case was admixed with an equal volume of water containing 0.1 percent by weight of surface active material. The compositions, generally in the nature of an emulsion, were employed to spray separate respective plant species which had been grown to a height of 2-6 inches in soil of good nutrient content in a greenhouse. Sufficient amounts were employed to provide various application rates as listed below in the table. The various beds were positioned side by side and exposed to substantially identical conditions of temperature and light. Each bed was maintained so as to prevent any interaction with test compounds in different seed beds. Other plants were left untreated to serve as controls. After treat ment, the plants were maintained for two weeks under greenhouse conditions conducive for good plant growth and watered as necessary. The specific plant specie, test compound and dosage and the percent postemergent control obtained are set forth in the table below. Control refers to the reduction in growth compared to the observed results of the same untreated specie.

Plant species in these tests were the following:

Common Name Scientific Name

Rice Oryza sativa Watergrass (Barnyardgrass) Echinochloa crusgalli

Crabgrass Digitaria sanguinalis

Yellow foxtail Setaria lutescens

Johnson grass Sorghum halepense

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The above data indicate the excellent control of the grasses in the presence of rice, with little or no adverse effects on the rice plants.

Example 2 Further tests were conducted comparing the effects of the indicated compounds on barnyardgrass and one or two different strains of rice which had been grown in a vermiculite based potting mixture of good nutrient content to a height of 2-6 inches and then carefully treated with aqueous spray solutions containing the indicated amount of compound to be tested. The procedures were as indicated for Example 1 with care being taken to apply the spray to the aboveground portions of the plants. Control refers to the reduction in growth compared to the observed results for the same untreated specie.

In accordance with this invention, other derivatives wherein T is O or S and Z is a heterocyclic or polycyclic radical such as, for example, substituted or unsubstituted pyridines, pyrimidines, pyrazines, pyridazines, quinolines, isoquinolines, quinazolines, symtriazines, asymtriazines, naphthalenes, cycloalkanes of 3 to 6 carbon atoms, benzothiazoles, benzoxazoles, benzimidazoles, benzothiophenes, thiazoles, thiophenes, oxazoles, isoxazoles, thiadiazoles, benzofurans and indoles may also be employed, if desired, for the selective control of grassy weeds in rice. However, such compounds are generally more difficult to manufacture and are not more efficacious than the described compounds.

Where an additional spectrum of weed control is desired, particularly where it is desirable to control broadleaf and/or sedge weeds, compounds of the present invention may be advantageously mixed at appropriate rates with suitable formulations of at least one or more of the following herbicides or their derivatives: 2,4-dichlorophenoxyacetic acid (2,4-D); 2-methyl-4-chlorophenoxyacetic acid (MCPA); ((3,5, 6-trichloro-2-pyridinyl)oxy)acetic acid (tri-chlopyr) ; 3 ' ,4' -dichloropropionanilide (propanil); 3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one-2,2- dioxide (bentazon).

Claims

WHAT IS CLAIMED IS:

1. A method for selectively controlling grassy weeds in the presence of rice which comprises applying to the weeds or their habitats at least a herbicidally effective amount, but less than an amount which is phytotoxic to the rice, of at least one compound having the formula:

wherein T is O or S, Y is H, Br or Cl, and Z is 2-pyridinylamino, SAr, OAr, or NRAr where R is H or alkyl of 1 to 3 carbon atoms and Ar is a naphthyl group which may be substituted with one or two halogens or a benzyl or phenyl group which may be independently substituted at 1 to 3 ring positions with halogen, C₁_₄ straight or branched chain alkyl groups, C₁_₃ thioalkyl, C₁_₃ alkoxy, hydroxy, C₁_₂ mono or dialkylamino, amino, trifluoro- methyl, cyano, thioamide or nitro groups.

2. Method of Claim 1 wherein Y is chlorine.

3. Method of Claim 2 wherein Z is -NRAr.

4. Method of Claim 3 wherein R is H

5. Method of Claim 4 wherein Ar is 4-chloro substituted phenyl.

6. Method of Claim 4 wherein Ar is 4-bromo substituted phenyl.

7. Method of Claim 4 wherein Ar is 4-fluoro substituted phenyl.

8. Method of Claim 4 wherein Ar is 3,5- dimethyl substituted phenyl.

9. Method of Claim 3 wherein R is CH₃ and Ar is phenyl.

10. Method of Claim 3 wherein R is C₂H₅ and Ar is phenyl.

11. Method of Claim: 2 wherein Z is -OAr.

12. Method of Claim 11 wherein Ar is 4-t- butyl phenyl.

13. Method of Claim 2 wherein Z is -SAr.

14. Method of Claim 13 wherein Ar is phenyl.

15. Method of Claim 13 wherein Ar is p-chlorophenyl.

16. Method of Claim 13 wherein Ar is o-chlorophenyl.

17. Method of Claim 13 wherein Ar is p-methoxyphenyl.

18. Method of Claim 13 wherein Ar is m-methylphenyl.

19. Method of Claim 1 wherein the active ingredient is applied in postemergent operations at a rate of 0.01 to 20 pounds/acre.

20. Method of Claim 19 wherein the active ingredient is applied at a rate of 0.05 to 2.0 pounds/-acre for the control of grassy weeds.

21. Method of Claim 20 wherein the active ingredient is employed to control barnyardgrass in rice.