NO794206L - HERBICID PREPARATION. - Google Patents

Description

The present invention relates to herbicidal preparations, especially for regulating the growth of weeds in cereal crops.

In order to control the growth of a number of different types of weeds in crops, such as cereal crops, it is often necessary to use more than one herbicide. Despite the use of such mixtures, weeds are still resistant to herbicide treatment and cause damage to both winter and spring grain crops such as e.g. wheat, barley, oats and rye.

It has now been found that particular combinations of herbicides not only provide broad-spectrum control, but are also unexpectedly effective against weeds, especially broadleaf weeds, in cereal crops.

According to the present invention, there is thus provided a method for controlling weeds, especially broad-leaved weeds, in a cereal crop, whereby bifenox is applied to the appropriate location, post emergence of the crop, which is a compound with the formula:

and one or more active ingredients selected from (1) a benzoic acid herbicide which is dicamba or 2,3,6-TBA or a salt or ester thereof, (2) a phenoxy acid herbicide which is dichlorprop or 2,4-DB or a salt or ester thereof, (3) a dinitrophenol herbicide which is DNOC, dinoterb or dinoseb or a salt or ester thereof, (4) a benzonitrile herbicide which is ioxynil or bromoxynil or a salt or ester thereof, (5) benazoline or a salt or ester thereof, (6) bentazone and (7) 3,6-DCP or a salt or ester thereof.

It will be understood that more than one of the active ingredients :(.l) to (7) can be used and that further herbicidally active compounds can be used together with these ingredients (1) - (7). When the active ingredient is acidic or phenolic, derivatives such as salts and esters can be used provided that they are non-phytotoxic to the crop, i.e. not significantly more phytotoxic than the free acid or phenol. The type of such salts and esters is well known to those skilled in the art.

The preparation of bifenox, methyl 5-(2,4-dichloro-phenoxy)-2-nitrobenzoate, is described in British Patent No. 1,232,368 and its use as a herbicide in Proe. N.E.

Weed Sei. Conf. 1973, 27_, 31. The benzoic acid herbicide dicamba, which is 3,6-dichloro-2-methoxybenzoic acid is described in US Patent No. 3,013,054 and 2,3,6-TBA, which is 2,3,6-trichloro -benzoic acid is described in US patents no. 2,848,470 and 3,081,162. The phenoxy acid herbicides are a well-known group of compounds and have long been widely available. D±-chloroprop is a common name for 2-(2,4-dichlorophenoxy)propionic acid, otherwise known as 2,4-DP; 2,4-DB is the common name for 4-(2,4-dichlorophenoxy)butyric acid. The dinitrophenol herbicide (DNOC, chemical name 2-methyl-4,6-dinitrophenol) was introduced by British Patent No. 425,295; dinoseb is the common name for 2-sec-butyl-4,6-dinitrophenol and is described in US Patent No. 2,192,197; and dinoterb, 2-tert-butyl-4,6-dinitrophenol is e.g. described in British Patent No. 1,126,658. The benzonitrile herbicides ioxynil (4-hydroxy-3,5-di-iodobenzonitrile) and bromoxynil (3,5-dibromo-4-hydroxy-benzonitrile) are both described, e.g. in British Patent No. 977,755. Benazolin, 4-chloro-2-oxo-3-benzothiazolineacetic acid, is described in British Patent No. 862,226 and bentazone, which is the common name for 3-isopropyl-(1H)-benzo-2,1?3-thiadiazine -4-one-2,2-dioxide, is described in US patent no. 3,708,277. 3,6-DCP, which is 3,6-dichloropicolinic acid is described in US patent no. 3,317,549.

The grain crop can, for example, be wheat, barley, oats or rye, and the method has its greatest potential when treating wheat and barley, especially winter wheat and spring and winter barley. Crop sensitivity and also the spread of weeds determine the amount of active ingredients to be applied. Usually, however, bifenox is applied in an amount of 0.25-3.0 kg per hectare, preferably 0.5-1.5 kg per hectare and especially 0.5-0.75 kg per hectares.

Preferred application rates for

the additional active ingredients (1) - (7). When a component is derived from an acid or phenol, the amounts are based on the free acid or phenol equivalent.

Thus, when a benzoic acid herbicide, which is dicamba or 2,3,6-TBA, is used, this is preferably applied in an amount of 0.05-0.2 kg per hectare, the weight ratio between bifenox and the benzoic acid herbicide being suitably from 60:1 to 1:1, preferably 30:1 to 4:1. The benzoic acid herbicide can be used in the form of a salt thereof, especially an alkali metal salt such as a sodium or potassium salt, or in the form of an ester thereof, e.g. a C 1 -C 8 alkyl ester.

When a phenoxy acid herbicide, which is dichlorprop or 2,4-DB, is used, this is preferably applied in an amount of 0.1-3.5 kg per hectare, the weight ratio between bifenox and the phenoxy acid herbicide being suitably from 30:1 to 1:15, especially from 8:1 to 1:6. In a particularly preferred embodiment, bifenox is applied in an amount of 0.5-0.75 kg per hectare, and the phenoxy acid herbicide in a quantity of 1.5-3.0 kg per hectares. The phenoxy acid herbicide is suitably used in the form of a salt thereof, e.g. as an alkali metal salt, especially the sodium or potassium salt or as an amine or ammonium salt. Examples of ester forms of the phenoxy acid herbicide include those containing 1-8 carbon atoms in the ester group, e.g. the ethyl, isopropyl and butyl esters.

When a dinitrophenol herbicide that is DNOC, dinoterb or dinoseb is used, this is preferably applied in an amount of 0.5-5.0 kg per hectare, preferably and especially in the case of dinoterb or dinoseb, in an amount of 0.5-2.0 kg per hectare. The weight ratio between bifenox and dinitrophenol herbicide is preferably from 6:1 to 1:20, preferably from 3:1 to 1:6. As examples of suitable salt forms of the dinitrophenol herbicide can be mentioned those formed with both inorganic and organic bases, especially amine and the ammonium salts. Examples of esters are those formed with organic acids, e.g. carboxylic acids, e.g. dinoseb acetate.

When a benzonitrile herbicide, which is ioxynil or bromoxynil is used, this is preferably applied in an amount of from 0.05-0.5 kg per hectare, preferably in an amount of from 0.1-0.35 kg per hectares. The weight ratio of bifenox to the benzonitrile herbicide is preferably from 60:1 to 1:2, more preferably from 15:1 to 2:1. In a particular embodiment, both ioxynil and bromoxynil are used together with bifenox, and in this case the preferred application rates and weight ratios given above are based on the total weight of both ioxynil and bromoxynil. Preferred salt forms of ioxynil and bromoxynil are the alkali metal salts such as the sodium and potassium salts. Preferred esters include ioxynyl octanoate and bromoxynyl octanoate.

When benazolin is used, this is preferably applied

in a quantity of 0.05-0.25 kg per hectares. The weight ratio between bifenox and benazolin is preferably from 60:1 to 1:1, preferably from 15:1 to 5:2. Suitable salt forms of benazoline are the alkali metal salts, especially the sodium and potassium salts. The preferred esters are those containing 1-4 carbon atoms in the ester group, especially the ethyl ester.

When bentazon is used, this is preferably applied

in an amount of 0.1-1.5, more preferably 0.2-1.5 and preferably 0.5-1.5 kg per hectares. A preferred weight ratio between bifenox and bentazone is from 6:1 to 1:6, preferably from 3:1 to 1:2.

When 3,6-DCP is used, this is preferably applied

in a quantity of 0.025-0.15 kg per hectare, preferably in an amount of 0.05-0.1 kg per hectares. A preferred weight ratio of bifenox to 3,6-DCP is from 30:1 to 3:1, preferably from 15:1 to 5:1. Examples of salt forms of 3,6-DCP include the alkali metal salt, e.g. the sodium and potassium salt as well as the amine and ammonium salt, e.g. the monoethanolamine salt. Examples of esters include those containing 1-8 carbon atoms in the ester group.

The method according to the invention is preferably carried out when the grain crop is between the one-leaf stage and emergence

of the other knot or joint.

When bifenox is used together with the benzoic acid herbicide, particularly good control of the weed species Stellaria media, Polygonum spp, Spergula arvensis, Tripleuro-sperraum maritimum, Viola spp and Veronica spp is observed.

When bifenox is used together with the phenoxy acid herbicide, particularly good control of the weed species Galium aparine, Stellaria media and Veronica spp is observed.

When bifenox is used together with the dinitrophenol herbicide, particularly good control of the weed species Galeopsis tetrahit, Fumaria officinalis, Polygonum convolvulus and Galium aparine is observed.

When bifenox is used together with the benzonitrile herbicide, particularly good control of the weed species Matricaria spp, Polygonum spp and Galium aparine is observed.

When bifenox is used together with benazolin, particularly good control of the weed species Stellaria media, Galium aparine and Viola spp is observed.

When bifenox is used together with bentazon, particularly good control of the weed species Viola spp, Veronica spp and Matricaria spp is observed.

When bifenox is used together with 3,6-DCP, particularly good control of the weed species Veronica spp and Matricaria spp is observed.

As examples of additional herbicide-active compounds that can be used together with bifenox and component (1) - (7), mention can be made of MCPA, MCPB and mecoprop, all of which are well-known herbicides, which are well documented in the literature and indicated in the "Pesticide Manual" , 5th ed., published by the British Crop Protection Council.

Bifenox and the active ingredients (1) - (7), possibly together with a further herbicide-active compound, can be applied to the crop site either simultaneously or separately.

In the latter case, the time period between applications is preferably short, e.g. a day or less. However, it is far preferable that the compounds are applied at the same time as a single preparation. In order to simplify production, storage and transport, herbicidal preparations will normally be prepared in concentrate form intended for dilution with water to the extent necessary to achieve the application amounts specified above, and this dilution is usually such that the preparation to be applied at the crop site contains 0.05-

3.0% by weight of the active herbicidal ingredients.' The concentrate preparations usually contain 1-90%, preferably 15-85% active ingredients in connection with one or more non-phytotoxic carriers or diluents.

Concentrate preparations form part of the invention. A concentrated herbicidal preparation is thus provided which can be particularly, but not exclusively, used in the present method, and this preparation comprises bifenox, one or more additional active ingredients selected from (1) a benzoic acid herbicide which is dicamba or 2,3, 6-TBA or a salt or ester thereof, (2) a phenoxy acid herbicide which is dichlorprop or 2,4-DB or a salt or ester thereof, (3) a dinitrophenol herbicide which is DNOC, dinoterb or dinoseb or a salt or ester thereof, (4) a benzonitrile herbicide which is ioxynil or bromoxynil or a salt or ester thereof, (5) benazoline or a salt or ester thereof, (6) bentazon and (7) 3,6 -DCP or a salt or ester thereof, in conjunction with one or more non-phytotoxic carriers or diluents.

In such a preparation, the weight ratios between bifenox and each of the components (1) - % 1) are preferably as stated above in connection with the specified method.

The concentrate preparations according to the invention will usually be in the form of a wettable powder, an emulsifiable concentrate or an aqueous suspension. Preparations in the form of an aqueous suspension and a wettable powder are preferred for use in the present method, as these give significantly lower phytotoxicity to grain crops than the emulsifiable concentrate.

Wettable powders comprise an intimate mixture of the active ingredients, one or more inert carriers and suitable surfactants. The inert carrier can e.g. selected from the attapulgite clays, montmorillonite clays, diatomaceous earth, kaolins, mica, talc and purified silicates. Effective surfactants are found among the sulfonated lignins, the naphthalene sulfonates and the condensed naphthalene sulfonates, the alkyl succinates, the alkylbenzene sulfonates, the alkyl sulfates, and nonionic surfactants such as ethylene oxide adducts of phenol.

Emulsifiable concentrates comprise the active ingredients dissolved in a suitable solvent or suitable solvents, together with the surfactant. Suitable surfactants can e.g. are chosen from them

which is mentioned above in connection with wettable powders. Suitable solvents are alkyl substituted benzenes, o-chlorotoluene, heavy aromatic naphthalenes, glycol ethers and cyclic ketones.

Aqueous suspensions and solutions comprise the active ingredients suspended or dissolved in water or suitable solvents respectively together with any desired surfactants, thickeners, anti-freeze agents or preservatives. Suitable surfactants can be selected from those mentioned above in connection with wettable powders. Thickeners, if such are used, are normally selected from appropriate cellulose materials and natural rubbers, while glycols will usually be used when it is necessary to use an antifreeze. Preservatives can be chosen from a number of different materials such as the various paraben antibacterial substances, phenol, o-chlorocresol, phenylmercury nitrate and formaldehyde.

Herbicide preparations can alternatively be formed by mixing the two or more active ingredients with water in a spray tank just before use, the water thus acting as a non-phytotoxic carrier. Such preparations are termed "tank mixtures" and constitute a further part of the invention. In such tank mixtures, the weight ratios between r bifenox and the second component (1) - (7) are also as stated in connection with the above method.

The following examples illustrate concentrated herbal preparations according to the invention. Where a herbicidal ingredient is a derivative of an acid or phenol, the amount is based on the acid or phenol equivalent.

EXAMPLES 1-10

The following wettable powders were prepared in each case with the indicated ingredients.

In each example, the active ingredients were carefully mixed with the specified excipients in conventional mixing equipment. The mixture was then further ground in a fluid energy mill to a size range of 1-10 microns.

EXAMPLES 11 - 22

The following emulsifiable concentrates were prepared with the ingredients listed below:

The active ingredients were added to the appropriate solvent or agents with stirring and possibly heating to facilitate solubilization of the active substances. The surfactants were then added. After solubilization, the solution was filtered to remove insoluble impurities.

EXAMPLES 23-26

The following aqueous suspensions were prepared from the ingredients listed below:

The herbicide ingredients were mixed with surfactants and antifoam, then vigorously stirred in water to form a coarse aqueous suspension. This was then wet ground to reduce the particle size of the active ingredients to 0.5-20 microns. An aqueous suspension of the thickener or suspending agent (hydrated) was then added to this wet-ground preparation. -o The following example 27 represents the test method that was used to determine the effectiveness of the method and preparation according to the invention.

EXAMPLE 27, Test Method

The appropriate amount of formulated product (eg of one of the concentrate preparations in previous examples 1-26) is added to water in a micro-spray device which is then shaken to ensure dispersion. The spray device is set so that it can deliver a volume equivalent to 200 liters per hectares with a pressure of approx. 2.72 atmospheres. A standard nozzle (Allman No. 0) which produces a fan-shaped jet is mounted on the spray device.

Application is made post emergence on both crop and weeds, as the crop size for different applications varies from the 3-leaf stage to the beginning of stem extension. Weed size at application can also be variable, varying from the cytoledon stage to a small plant.

Claims (14)

1. Method for combating weeds in a cereal crop, characterized by applying bifenox, which is a compound with the formula, to the relevant location, post-emergence of the crop and one or more additional active ingredients selected from (1) a benzoic acid herbicide which is dicamba or 2,3,6-TBA or a salt or ester thereof, (2) a phenoxy acid herbicide which is dichlorprop or 2,4 -DB or a salt or ester thereof, (3) a dinithaiophenol herbicide which is DNOC, dinoterb or dinoseb or a salt or ester thereof, (4) a benzonitrile herbicide that is ioxynil or bromoxynil or a salt or ester thereof, (5) benazoline or a salt or ester thereof, (6) bentazone and (7) 3,6-DCP or a salt or an ester thereof. 2. Method according to claim 1, characterized in that bifenox is applied in an amount of 0.25-3.0 kg per hectares. 3. Method according to claim 2, characterized in that the quantity is 0.5-1.5 kg per hectares. 4. Method according to claim 3, characterized in that the quantity is 0.5-0.75 kg per hectares. 5. Method according to any one of the preceding claims, characterized in that the benzoic acid herbicide is applied in an amount of 0.05-0.2 kg per hectare, the phenoxy acid herbicide is applied in an amount of 0.1-3.5 kg per hectare, the dinitrophenol herbicide is applied in a quantity of 0.5-5.0 kg per hectare, the benzonitrile herbicide is applied in a quantity of 0.05-0.5 kg per hectare, benazolin is applied in a quantity of 0.05-0.25 kg per hectare, bentazon is applied in a quantity of 0.1-1.5 kg per hectare and 3,6-DCP is applied in a quantity of 0.025-0.15 kg per hectares. 6. Method according to any one of the preceding claims, characterized in that bifenox is applied in an amount of 0.5-0.75 kg per hectare and that the phenoxy acid herbicide is applied in a quantity of 1.5-3.0 kg per hectares. 7. Method according to any one of claims 1-5, characterized in that bifenox is applied together with both ioxynil and bromoxynil. 8. Method according to claim 1, essentially as described above. 9. Herbicidal preparation, characterized in that it is extracted from a concentrate or a tank mixture and comprises bifenox and one or more of the active ingredients (1) - (7), as stated in claim 1, in connection with one or more non -phytotoxic diluents or carriers. 10. Herbicide preparation according to claim 9, characterized in that the weight ratio between bifenox and the benzoic acid herbicide is from 60:1 to 1:1, the weight ratio between bifenox and the phenoxy acid herbicide is from 30:1 to 1:15, the weight ratio between bifenox and dinitrophenol -herbicide is from 6:1 to 1:20, the weight ratio of bifenox to benzonitrile herbicide is from 60:1 to 1:2, the weight ratio of bifenox to benazolin is from 60:1 to 1:1, the weight ratio of bifenox to bentazon is from 6:1 to 1:6, and the weight ratio of bifenox to 3,6-DCP is from 30:1 to 3:1. 11. Herbicidal preparation according to claim 9 or 10, characterized in that it consists of a concentrate preparation and contains 15-85% active ingredients. 12. Herbicidal preparation according to claim 11, characterized in that it consists of an emulsifiable concentrate, an aqueous suspension or a wettable powder preparation. 13. Herbicidal preparation according to claim 9, essentially as described above with reference to any of the preceding examples 1-26. 14. Herbicidal preparation according to any one of claims 9-13, for use in the method according to any one of claims 1-8.