GB2167959A - Combination of pyridoxyphenoxypropionate and triazinone as selective weed killer - Google Patents

Abstract

A selective herbicidal composition for combating weeds, comprising a herbicidally effective amount of (a) (trimethylsilyl)-methyl 2-[4-(3,5-dichloro-pyridin-2-oxy)-phenoxy]-propionate of the formula <IMAGE> and (b) 4-amino-6-tert.-butyl-3-ethylthio-1,2,4-triazin-5(4H)-one of the formula <IMAGE> is especially useful for killing weeds in cereal grain cultivation.

Description

SPECIFICATION Agent for the selective combating of weeds The present invention relates to a new active compound combination which consists of a known pyridoxy-phenoxy-propionic acid derivative, on the one hand, and a known triazinone, on the other hand, and which is particularly suitable for the selective combating of weeds in crop plant cultures.

It has already been disclosed that (trimethylsilyl )-methyl 2-[4-(3,5-dichloropyridin-2-oxy)-phenoxy]- propionate possesses herbicidal activity (compare EP-OS (European Published Specification) 0,096,354).

Further, it is known that weeds can be selectively combated with the aid of 4-amino-6-tert.-butyl-3-ethylthio1 ,2,4-triazin-5(4H)-one (compare U.S. Patent Specification 3,671,523). The substances mentioned are distinguished by good selective herbicidal activity, but the toleration by crop plants leaves something to be desired in certain cases.

It has now been found that the new active compound combination of (a) (trimethylsilyl)-methyl 2-[4-(3,5-dichloro-pyridin-2-oxy)-phenoxy]-propionate of the formula

and (b) 4-amino-6-tert.-butyl-3-ethylthio-1,2,4-triazin-5(4H)-one of the formula

possesses particularly good selective herbicidal activity.

Surprisingly, the tolerance of the active compound combination according to the invention by crop plants is markedly higher than the sum of the tolerances of the individual active compounds. Accordingly, one is dealing with an unforeseeable antagonistic effect and not merely a complementary action.

The compound of the formula (I) contains an asymmetrically substituted carbon atom in the propionic acid unit and can therefore exist in two enantiomeric forms. The invention relates both to an active compound combination which contains the racemate of the compound of the formula (I) and an active compound combination which contains the R-enantiomer of the formula (I). (By the R-enantiomerthere is to be understood, in the present case, the particular optically active compound of the formula (I) which has the R-configuration at the asymmetrically substituted carbon atom of the propionic acid unit).

The active compounds contained in the active compound combination according to the invention are already known (compare EP-OS (European Published Specification) 0,096,354 and U.S. Patent Specification 3,671,523).

The antagonistic effect of the active compound combination according to the invention manifests itself above all if the active compounds of the formulae (I) and (II) are present in particular weight ratios.

However, the weight ratios in the active compound combination can be varied within relatively wide ranges. In general, 0.01 to 0.6 parts by weight, preferably 0.05 to 0.5 part by weight, of active compound of the formula (I) is present per part by weight of active compound of the formula (II).

The active compound combination according to the invention shows a very good action against broadleaved weeds and grass-like weeds in crop plant cultures, especially in cereals. By broad-ieaved weeds and grass-like weeds, in the broadest sense, there are to be understood all plants which grow in locations where they are undesired.

The active compound combination according to the invention can be used, for example, in connection with the following plants: Dicotyledon weeds of the genera: Sinapis, Lepidium, Galium, Stellaria, Matricaria, Anthemis, Galinsoga, Chenopodium, Urtica, Senecio, Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum, Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Solanum, Rorippa, Rotala, Lindernia, Lamium, Veronica, Abutilon, Emex, Datura, Viola, Galeopsis, Papaver and Centaurea.

Dicotyledon cultures of the genera: Gossypium, Glycine, Beta, Daucus, Phaseolus, Pisum, Solanum, Linum, Ipomoea, Vicia, Nicotiana, Lycopersicon, Arachis, Brassica, Lactuca, Cucumis and Cucurbita.

Monocotyledon weeds of the genera: Echinochloa, Setaria, Panicum, Digitaria, Phleum, Poa, Festuca, Eleusine, Brachiaria, Lolium, Bromus, Avena, Cyperus, Sorghum, Agropyron, Cynodon, Monochoria, Fimbristylis, Sagittaria, Eleocharis, Scirpus, Paspalum, Ischaemum, Sphenoclea, Dactyloctenium, Agrostis, Alopecurus and Apera.

Monocotyledon cultures of the genera: Oryza, Zea, Triticum, Hordeum, Avena, Secale, Sorghum, Panicum, Saccharum, Ananas, Asparagus and Allium.

The use of the active compounds according to the invention is however in no way restricted to these genera but extends in similar manner also to other plants.

The use of the active compound combination according to the invention for the selective combating of weeds is preferentially possible in cereal cultures, such as, for example, wheat and barley.

The active compound combination can be converted to the customary formulations, such as solutions, emulsions, wettable powders, suspensions, powders, dusting agents, pastes, soluble powders, granules, suspension-emulsion concentrates, natural and synthetic materials impregnated with active compound and very fine capsules in poiymeric substances.

These formulations are produced in known manner, for example by mixing the active compounds with extenders, that is, liquid solvents, liquefied gases under pressure and/or solid carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing agents and/or foam-forming agents. In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents.As liquid solvents, there are suitable in the main: aromatics, such as xylene, toluene or alkyl naphthalenes, chlorinated aromatics or chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, strongly polar solvents, such as dimethylformamide and dimethylsulphoxide, as well as water.

As solid carriers there are suitable: for example, ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth, and ground synthetic minerals, such as highly-disperse silicic acid, alumina and silicates; as solid carriers for granules there are suitable: for example, crushed and fractionated natural rocks such as calcite, marble, pumice, sepiolite and dolomite, as well as synthetic granules of inorganic and organic meals, and granules of organic materials such as sawdust, coconut shells, maize cobs and tobacco stalks; as emulsifying and/or foam-forming agents there are suitable: for example, non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylaryl polyglycol ethers, alkyl sulphonates, alkyl sulphates, aryl sulphonates as well as albumin hydrolysation products; as dispersing agents there are suitable, for example, ligninsulphite waste liquors and methylcellulose.

Further additives which may be used are surface-active substances. Preferentially usable are lecithins, phospholipids, isopropyl myristate and the substances known under the names Agridex, Azone, Surfactant WK and Emulgator OX.

Adhesives such as carboxymethyicellulose and natural and synthetic polymers in the form of powders, granules or latices, such as gum arabic, polyvinyl alcohol and polyvinyl acetate, can be used in the formulations.

It is possible to use colorants such as inorganic pigments, for example iron oxide, titanium oxide and Prussian Blue, and organic dyestuffs, such as alizarin, azo and metal phthalocyanine dyestuffs, and trace nutrients such as salts or iron, manganese, boron, copper, cobalt, molybdenum and zinc.

The formulations in general contain between 0.1 and 95% by weight of active compound, preferably between 0.5 and 90%.

The active compound combination according to the invention, as such or in the form of its formulations, can also be employed for weed combating as mixtures with known herbicides, finished formulations or tank mixing being possible. Mixtures with other known active compounds, such as fungicides, insecticides, acaricides, nematicides, bird repellants, growth factors, plant nutrients and agents which improve soil structure are also possible.

The active compound combination can be employed as such, in the form of its formulations or in the use forms prepared therefrom by further dilution, such as ready-to-use solutions, suspensions, emulsions, powders, pastes and granules. It is used in the customary manner, for example by watering, spraying, atomising or scattering.

The active compound combination according to the invention can be applied either before or after emergence of the plants. It can also be incorporated into the soii before sowing.

The amount of active compound employed can vary within substantial ranges. It depends essentially on the nature of the desired effect. In general the amounts employed are between 0.1 and 5 kg of active compound per ha, preferably between 0.5 and 2.5 kg/ha.

The good herbicidal action and excellent plant toleration of the active compound combination according to the invention can be seen from the example which follows. Whilst the individual active compounds have weaknesses in plant toleration, the combination exhibits a plant toleration which goes beyond a simpie additive action.

An antagonistic effect exits with herbicides whenever the plant toleration of the active compound combination is better than that of the individually applied active compounds, and at the same time the herbicidal potency is not impaired.

The action to be expected for a given combination of two herbicides can (compare Colby, S.R., "Calculating synergistic and antagonistic responses of herbicide combinations", Weeds 15, pages 20--22, 1967) be calculated asfollows: If X = % damage by herbicide A used in an amount of p kg/ha and Y = % damage by herbicide B used in an amount of q kg/ha and E = the expected damage by herbicides A and B used in amounts of p and q kg/ha then X.Y.

E=X+Y- 100 If the actual damage to the crop plants is less than calculated, the action of the combination is nonadditive, that is to say an antagonistic effect exists.

The example which follows shows that the damaging action of the active compound combination according to the invention in crop plants is less than the calculated action. Accordingly, a genuine antagonistic effect is present.

EXAMPLE A Post-emergence test in the open Solvent: 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether.

To produce a suitable preparation of active compound, 1 part by weight of active compound or mixture of active compounds is mixed with the stated amount of solvent, the stated amount of emulsifier is added and the concentrate is diluted with water to the desired concentration.

In the open, test plants which have a height of S10 cm are sprayed with the preparation of the active compound in such a way as to apply the particular amount of active compound desired per unit area. The concentration of the spray liquor is so chosen that the particular amount of active compound desired is applied in 2,000 1 of water/ha. Afterthree weeks, the degree of damage to the plants is rated in % damage in comparison to the development of the untreated control. The figures denote: 0% = no action (like untreated control) 100% = total destruction In this test, the active compound combination according to the invention exhibits a better plant toleration than that of the individual active compounds.

The active compounds, active compound concentrations and test results are shown in the table which follows.

TABLE A Post-emergence test in the open

Amount of active compound Alopecurus Barley Wheat Active compound applied kg/ha found*) calc.**) found*) calc.**) found*) calc.**) (II) 1.25 100 0 15 (I) 0.18 100 10 5 (R-enantiomer) (II) 1.25 + # + # 100 100 0 10 0 19.25 (I) 0.18 (R-enantiomer) *) found = damage found **) calc. = damage calculated from the Colby equation given above.

Claims (5)

1. Herbicidal agent for the selective combating of weeds, characterised in that it contains an active compound combination consisting of (a) (trimethylsilyl)-methyl 2-[4-(3,5-dichloro-pyridin-2-oxy)-phenoxy]-propionate of the formula

and (b) 4-amino-6-tert.-butyl-3-ethylthio-1 ,2,4-triazin-5(4H)-one of the formula

2. Agent according to Claim 1, characterized in that the active compound combination of the weight ratio of active compound of the formula (II) to active compound of the formula (I) is between 1:0.01 and 1:0.6.

3. Process for the selective combating of weeds in crop plant cultures, characterised in that an active compound combination of the active compounds of the formulae (I) and (II) is applied to the plants or to their habitat.

4. Use of an active compound combination of the active compounds of the formulae (I) and (II) for the selective combating of weeds in crop plant cultures.

5. Process for the preparation of herbicidal agents for the selective combating of weeds in crop plant cultures, characterised in that an active compound combination of the active compounds of the formulae and (II) is mixed with extenders and/or surface-active substances.