CA1069330A - Composition and method for controlling wild oat - Google Patents

Abstract

A B S T R A C T

A herbicidal composition for the control of wild oat comprising:
(a) methyl N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate;
(b) isopropyl N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate; and (c) a carrier or a surface-active agent or both a carrier and a surface-active agent.

Description

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This invention relates to a herbicidal composition comprising a mixture of esters of N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionic acid which composition exhibits a synergistic level of herbicidal activity for the control of wild oat and to a method for controlling wild oat in cereal crops using said composition.
Wild oat (Avena fatua) is a major world-wide weed problem and is a wide-spread and abundant competitor in cereal grain crops. As a result the annual economic losses resulting from wild oat infestations are considerable.
The methyl and isopropyl esters of N-benzoyl-N-t3-chloro-4-fluorophenyl)-2-aminopropionic acid are both establishing themselves as major selective wild oat herbicides in cereal crops, the methyl ester being particularly useful for wild oat infested wheat crops and the isopropyl ester being useful for barley crops.
The methyl ester, though very effective in wheat crops has hitherto been found insufficiently selective for general use in barley crops.
The Applicant has found that a mixture of the methyl and isopropyl esters gives rise to a synergistic response to the eradication of wild oats in barley crops and~
moreover, the mixture can be applied without significant damage to the barley crop.

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Accordingly the present invention provides a herbicidal composition for tlle control of wild oat comprising: (a) methyl N-benzoyl~
N-(3~chloro-4-fluorophenyl)-2-aminopropionate; (b) isopropyl N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate; and (c) a carrier or a surface-active agent, or both a carrier and a surface-active agent, wherein the weight ratio of the methyl ester to the isopropyl ester is in the range 1:0.5 to 1:100.
~esting at a number of dosage levels indicates that such a composition exhibits a synergistic level of herbicidal activity with respect to wild oats. Even more surprising is the fact that, while the herbicidal activity of the combination is increased with respect to wild oat, there is no corresponding increase in the effect of the combination upon barley so that the combination can be used safely in fields planted with barley crops.
This invention makes it possible to control wild oat over a wide range of its development by post~emergent foliar applications.
Wild oat can be controlled in barley crops by application of from 0.25 to 2.0 kg/ha of the composition according to the invention wherein the weight ratio of the methyl ester to the isopropyl ester is in the range 1:0.5 to l:100, preferably in the range 1:2 to 1:30.

9~30 In addition to the useful effect achieved on barley crops the composition according to the invention has also been found to be very effective in treating wild oat infested wheat crops and thus the composition may be regarded as an all-round wild oat herbicide.
The herbicidal composition according to the invention employs a carrier, a surface-active agent or both a carrier and a surface-active agent to facilitate application of the composition to wild oat infested land at the desired dosage rates. The term "carrier" as used herein means a solid or fluid material, which may be inorganic or organic and of synthetic or natural origin.
Typical solid carriers include natural and synthetic clays and silicates, for example, natural silicas such as diatomaceous earths and aluminium silicates, for example, kaolinites, montmorillonites, and micas. Typical fluid carriers are ketones, for example, methylcyclohexanone, aromatic hydrocarbons, for example, methylnaphthalenes, petroleum fractions, such as, for example, petroleum xylenes and light mineral oils, and chlorinated hydrocarbons, for example, carbon tetrachloride. Mixtures of liquids are often suitable.
One or more surface-active agents and/or stickers can be included in the formulation. The surface-active agent may be an emulsifying agent or a dispersing agent or a wetting agent; it may be non-ionic or ionic.
Any of the surface-active agents usually applied in 10~33() ~ormulating herbicides or insecticides may be used. Examples of suitable surface-active agents are the sodium calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol, condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohols or alkyl phenols,for example p-octyl phenol or p-octyl cresol, with ethylene oxide and/or propylene oxide; sulpnates or sulphonates of these condensation products, alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic acid esters containing at least 10 carbon atoms in the molecule, for example, sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as sodium dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.
Aqueous dispersions and emulsions, for example, compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick "mayonnaise"-like consistency.

10f~9330 The invention also includes a mcthod of selectively con-trolling wild oat in cereal crops which comprises applying the composition according to the invention to a tract of land which is bearing cereal crops and infested with Wild oat.
The compositions of this invention can be applied to the wild oat plants in a conventional manner. The dust and liquid compositions may be conveniently applied by the use of power-duster, boom and hand sprayers, and spray-duster. The compositions can also be applied from aeroplanes as a dust or spray because of the effec~iveness of the composi-tions at low dosages.
If desired the composition according to the invention may also be mixed with other wild oat herbicides, for example 4-chloro-2-butynyl-m-chlorocarbanilate ~common name: Barban; trade mark: "Carbyne"), or methyl 2-chloro-3-(4-chlorophenyl)propionate (common name: chlorphen-prop methyl; trade mark: "Bidisin") or 1,2-dimethyl-3,5-diphenylpyrazoliwn methyl sulphate (trade mark: "Avenge"~.
The invention is further illustrated by the following Examples:
E~AMPLE 1 7 cm pots of John Innes No. 1 compost were sown with 25-30 seeds of barley or oat. When the plants had reached the 1-1-1/2 leaf stage, a solution of the mixture under test was sprayed, using a logarith-mic dilution sprayer, at five 7 1(~ 3330 different doses for each species. Five mixtures of different proportions o~ the compounds were also sprayed at five doses each.
Assessments were made 10-15 days after spraying.
The barley plants were cut at soil level and the plant weight expressed as a percentage of untreated barley weight. The percentage depression in growth of the oat plants was assessed visually. These figures were analyzed by computor to calculate the growth inhibition dosages in kilogrammes per hectare (kg/ha) to give a 10%
reduction for barley and a 50% reduction for oat abbreviated to GID50 oat respectively.
Mixtures of the methyl and isopropyl esters were tested using the technique described above. The compounds or mixtures of the two were applied at doses ranging from 7.0 to 0.5 kg/ha on barley and 4.0 to 0.2 kg/ha on oats.
The range of mixtures used and results obtained are shown ~n Table 1.

- 8 1(~f~9330 TABL.E 1 Results of mixt re te~t~ with the methyl and isopropyl esters MIXTURE
PROPORTIONS BY WEIGHT GID1o barleY GID50 Oat Methyl ester : Isopropyl ester (kg/ha) tkg/ha) _ 1 : 0 ~.62 0.25 1 : 2 0.76 0.47 1 : 3 0.97 0.55 1 : 4 0.92 0.59 1: 6 o.g8 0.63 1 : 14 1.14 0.75 _ 1.33 1.24 From these results it will be seen that the isopropyl ester, which is the established barley wild oat herbicide, requires 1.24 kg/ha to give 50% reduction in oat growth when used alone, but when used in admixture with the methyl ester considerably less than that amount is required to give the same growth reduction, for example when a methyl to isopropyl ester ratio of 1 : 4 is used,only 0.59 kg/ha of the mixture is required to give the same effect. In this example 0.59 kg/ha of the mixture corresponds to 0.12 kg~ha of the methyl ester and 0.47 kg/ha of the isopropyl ester and it will be seen that a more than additive effect has been achieved by the mixture.

9 ~0~;~ 330 It will also be noted that althou~h the use of the methyl ester by itself gives very good control of wild oat, the dosage to ~ive a 10% barley reduction is not sufficiently high to give a satisfactory safety margin ~or a commercial wild oat herbicide thus making it un-suitable for use in barley crops. However, in the case of the mixtures, the GID1o figures for barley are much higher than the figure for the methyl ester alone and are sufficiently high to give the required safety margin for a barley wild oat herbicide.

A second series of tests were carried out employing the same methods as described in Example 1 but with a different set of ester-mixture proportions. The results are as follows:

Results of mixture tests with the methyl and isopropyl esters MIXTURE

PROPORTIONS BY WEIGHT GID1o barleY GID50 oat Methyl ester : Isopropyl ester (kg/ha) (kg/ha) 1 : 0 0.53 0.18 1 : 6 0.91 0.49 1 : 1~ 1.19 0.57 1 : 30 1.19 o.69 .
1 : 75 1.11 0.73 1 : 100 1.29 o . ~6 0 : 1 1.22 0.90 -- ~.o -- , From these results it will be seen that the isopropyl ester, which is the estaklished barley wild oat herbicide, requires 0.90 kg/ha to give 50% reduction in oat growth when used alone, but when used in admixture with the methyl ester considerably less than that amount is required to give the same growth reduction, for example when a methyl to isopropyl ester ratio of 1 : 30 is used only 0.69 kg/ha of the mixture is required to give the same effect. In this example 0.69 kg/ha of the mixture corresponds to 0.02 kg/ha of the methyl ester and o.67 kg/ha of the iso-propyl ester and it will be seen that a more than additive effect has been achieved by the mixture.
It will also be noted that although the use of the methyl ester by itself gives very good control of wild oat, the dosage to give a 10% barley reduction is not sufficiently high to give a satisfactory safety margin for a commercial wild oat herbicide thus making it unsuitable for use in barley crops. However, in the case of the mixtures, the GID1o figures Por barley are much higher than the figure for the methyl ester alone and are sufficiently high to give the required safety margin for a barley wild oat herbicide.

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Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A herbicidal composition for the control of wild oat comprising (a) methyl N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate; (b) isopropyl N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate; and (c) a carrier or a surface_active agent or both a carrier and a surface-active agent, wherein the weight ratio of the methyl ester to the isopropyl ester is in the range 1:0.5 to 1:100.

2. A composition according to claim 1 wherein the weight ratio is in the range 1:2 to 1:30.

3. A method of selectively controlling wild oats in cereal crops which comprises applying from 0.25 to 2.0 kg/ha of a composition according to claim 1 to a tract of land which is bearing cereal crops and infested with wild oat.

4. A method according to claim 3 which comprises applying the com-position when the cereal crops have reached the 1 - 1 1/2 leaf stage in their growth.