WO1993005653A1 - Synergistic herbicidal compositions - Google Patents

Abstract

The invention relates to a new herbicidal composition with synergistic activity which comprises, as active components, a mixture of N-(2-allyloxy-6-nitrophenyl)-1-(4-chloro-6-methoxypyrimidin-2-yl)-1H-1,2,4-triazole-3-sulphonamide and at least one herbicide selected from the group of phenmedipham, desmedipham, metamitron, ethofumesate, diethatyl-ethyl and chloridazon. The composition is useful in the selective control of monocotyledenous and dicotyledenous weeds in crops, especially beets.

Description

SYNERGISTIC HERBICIDAL COMPOSITIONS

This invention relates to a new herbicidal composition having synergistic activity comprising a mixture of

N-(2-allyloxy-6-nitrophenyl)-1-(4-chloro-6-methoxy- pyrimidin-2-yl)-1H-1,2,4-triazole-3-sulphonamide (I) and at least one other herbicide. The herbicidal activity of N-(2-allyloxy-6-nitro- phenyl)-1-(4-chloro-6-methoxypyrimidin-2-yl)- 1H-1,2,4-triazole-3-sulphonamide is already known

(EP 338 465). Other known compounds with herbicidal activity are phenmedipham, desmedipham, metamitron, ethofumesate, diethatyl-ethyl and chloridazon. These known substances however are not always satisfactory in their activity in all areas of use.

It has now been found that a herbicidal composition which comprises, as active components, a mixture of I and at least one herbicide selected from the group of

phenmedipham, desmedipham, metamitron, ethofumesate, diethatyl-ethyl and chloridazon shows especially high activity without losing the selectivity properties in agricultural crops, especially beets.

Phenmedipham is the common name for 3-methoxycarbonyl- aminophenyl 3'-methylcarbanilate;

desmedipham is the common name for 3-ethoxycarbonyl- aminophenyl phenylcarbamate;

metamitron is the common name for 4-amino-4,5-dihydro-3- methyl-6-phenyl-1,2,4-triazin-5-one;

ethofumesate is the common name for 2-ethoxy-2,3-dihydro-

3,3-dimethyl-5-benzofuranyl methanesulfonate; diethatyl-ethyl is the common name for ethyl N-chloro- acetyl-N-(2,6-diethylphenyl)glycinate; and

chloridazon is the common name for 5-amino-4-chloro- 2-phenylpyridazin-3 (2H) -one.

All these herbicides are described in the "Pesticide Manual", ninth edition, 1991, published by the British Crop Protection Council, London. Surprisingly the herbicidal activity of the combination of the active ingredients of the invention is essentially higher than the individual components and also of the sum of the individual components. A synergistic effect is also seen.

The combination of active ingredients of the invention can used for example against the following plant species:

Dicotyledonous weeds of the species Sinapis, Lepidium, Galium, Stellaria, Matricaria, Anthemis, Galinsoga,

Chenopodium, Brassica, Urtica, Senecio, Amaranthus,

Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum, Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Solanum, Rorippa, Lamium, Veronica, Abutilon, Datura, Viola,

Galeopsis, Papaver, Centaurea and Chrysanthemum.

Monocotyledonous weeds of the species Avena, Alopecurus, Echinochloa, Setaria, Panicum, Digitaria, Poa, Eleusine, Brachiaria, Lolium, Bromus, Cyperus, Agropyron,

Sagittaria, Monocharia, Fimbristylis, Eleocharis,

Ischaemum and Apera.

The combinations can be applied pre or post-emergently, but generally pre-emergently. Selectivity is seen in range of crops such as maize, cereals and sunflowers. The rate of use lies between 0.001 and 5 kg/ha of the mixture, depending on the use. By using the mixtures for control of weeds the amount of herbicide needed can be generally reduced.

The weight ratio of the mixing components is generally between 50:1 and 1:10.

The mixtures of the invention can also be used in

admixture with other active agents for example other plant-protection agents or pesticides.

An improvement in the intensity and speed of action can be obtained, for example, by addition of suitable adjuvants, such as organic solvents, wetting agents and oils. Such additives may allow a decrease in the dose.

The designated active ingredients or their mixtures can suitably be used, for example, as powders, dusts,

granules, solutions, emulsions or suspensions, with the addition of liguid and/or solid carriers and/or diluents and, optionally, binding, wetting, emulsifying and/or dispersing adjuvants. Suitable liquid carriers are, for example aliphatic and aromatic hydrocarbons, such as benzene, toluene, xylene, cyclohexanone, isophorone, dimethyl sulfoxide,

dimethylformamide and other mineral-oil fractions and plant oils.

Suitable solid carriers include mineral earths, e.g.

bentonite, silica gel, talc, kaolin, attapulgite,

limestone, silicic acid and plant products, e.g. flours. As surface-active agents there can be used for example calcium lignosulfonate, polyoxyethylenealkylphenyl ethers, naphthalenesulfonic acids and their salts, phenolsulfonic acids and their salts, formaldehyde condensates, fatty alcohol sulfates, as well as substituted benzenesulfonic acids and their salts.

The percentage of the active ingredient(s) in the various preparations can vary within wide limits. For example, the compositions can contain about 10 to 90 percent by weight active ingredients, and about 90 to 10 percent by weight liguid or solid carriers, as well as, optionally up to 20 percent by weight of surfactant.

The agents can be applied in customary fashion, for

example with water as the carrier in spray mixture volumes of approximately 100 to 1,000 1/ha. The agents can be applied using low-volume or ultra-low-volume techniques or in the form of so-called microgranules. The preparation of these formulations can be carried out in known manner, for example by milling or mixing

processes. Optionally, individual components can be mixed just before use for example by the so-called commonly used tank-mixing method.

The following Examples illustrate the use of compositions of the invention.

The calculation of synergistic effect is carried out according to S R Colby "Calculating Synergistic and

Antagonistic Response to Herbicide Combinations" , Weeds, 15/1, 1967 pages 20 to 22. In this the following formula was used: XY

E = X + Y - -------

100

in which X = the herbicidal activity (%) of substance A at a rate of p g/ha.

Y = the herbicidal activity (%) of substance B at a rate of q g/ha., and

E = the expected additive activity of the

herbicide (%) of the substances A + B at a rate of p + q g/ha.

If the observed value is greater than the value of E calculated according to Colby, the combination shows synergistic activity.

Experiments In a greenhouse the plant species shown in the tables were treated pre-emergently with the components at the stated rates. The compositions were diluted with 500 litres of water and sprayed over the soil. Two weeks after treatment the herbicidal effect was evaluated. In the examples component I is N-(2-allyloxy-6-nitro-phenyl)-1-(4-chloro- 6-methoxypyrimidin-2-yl)-1H-1,2,4-triazole-3-sulphonamide

Table A

Mixtures of I with phenmedipham (II)

Component Rate Herbicidal E (according

(g/ha) activity (%) to Colby)

Table G

Mixtures with I with phenmedipham (II) and desmedipham

(III) (II + III = 1: 1)

Component Rate Herbicidal E (according

(g/ha) activity (%) to Colby)

Claims

Claims

1. A herbicidal composition which comprises, as active components, a mixture of N-(2-allyloxy-6-nitro- phenyl)-1-(4-chloro-6-methoxypyrimidin-2-yl)- 1H-1, 2 ,4-triazole-3-sulphonamide and at least one

herbicide selected from the group of phenmedipham, desmedipham, metamitron, ethofumesate, diethatyl-ethyl and chloridazon.

2. A composition according to claim 1 in which the weight ratio of the mixture components is between 50:1 and 1:10.

3. A method of combating weeds which comprises applying post-emergently a composition as claimed in claim 1 or 2.