GB1572398A

GB1572398A - Herbicides

Info

Publication number: GB1572398A
Application number: GB3239876A
Authority: GB
Original assignee: Fisons Ltd
Current assignee: Fisons Ltd
Priority date: 1976-08-04
Filing date: 1976-08-04
Publication date: 1980-07-30
Also published as: IT1115381B; DE2735209A1; FR2360252A1

Description

(54) HERBICIDES (71) We, FISONS LIMITED, a British Company of Fison House, 9 Grosvenor Street, London W1X OAH, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a method of combating weeds, herbicidal compositions and their preparation.

The invention provides a method of combating weeds at a locus infested or liable to be infested with them, which method comprises applying to the locus (a) ethofumesate, i.e. 2-ethoxy-2 ,3-dihydro-3 ,3-dimethylbenzo4urnn-5-yl methanesulphonate; and (b) a compound selected from: metolachlor, i.e. N-(2-methoxy-1-methylethyl)-2'-ethyl 6'-methyl-2-chloracetanilide; methazole, i.e. 2-(3 ,4-dichlorophenyl)-4-methyl-1 ,2,4- oxadiazolidine-3 5-dione; benzadox, i.e. 2-(benzamidoxy)-acetic acid; methyl 2-[4-(2,4 dichlorophenoxy)phenoxyjpropionate; chlorthal dimethyl, i.e. dimethyl 2,3,5 ,6-tetrachloro- terephthalate; and napropamide, i.e. N,N-diethyl-2-(1-naphthyloxy)-propionamide.

In addition, the invention provides a herbicidal composition comprising (a) and (b). The invention also provides a two-container pack in which (a) and (b) are provided in separate containers, especially in relative proportions as described hereinafter. Desirably, the twocontainer pack bears or contains directions, either separate or in conjunction with one of the containers, for mixing the contents of the containers or for separately applying the contents thereof.

It has been found that (a) and (b) seem to render weeds more susceptible to the action of the other, so that the present method and composition are unexpectedly advantageous, especially when used in the control of weeds in crops. Mixtures of (a) and (b) are synergistic, being surprisingly effective against weeds. The method and composition can be used to combat a wide range of weed species than when either (a) or (b) is used alone. Components (a) and (b) are also effective at lower dosage rates than those at which (a) or (b) alone is effective. In addition they are safe to crops.

The 2 essential components should preferably be employed in a ratio to each other of from 1:100 to 100:1. Parts, proportions and percentages in this specification are by weight unless otherwise indicated. preferably the proportions of (a) to (b) are from 1:10 to 10:1, especially from 1:4to4:1.

Ethofumesate and methazole is of especial use for combating weeds in onions.

Ethofumesate and napropamide is of especial use for combating weeds in sunflowers and beet species, e.g. sugar beet, and particularly in tobacco. Ethofumesate and metolachlor, benzadox or methyl 2-[4-(2,4-dichlorophenoxy)phenoxy]propionate, is of especial use for combating weeds in beet species, particularly sugar beet. Ethofumesate and chlorthal dimethyl is of use for combating weeds in a wide variety of crop species especially onions.

The essential herbicides (a) and (b) can be applied together in a composition comprising (a) and (b). The compositions can be prepared by admixing the ingredients. Usually the compositions are initially produced in the form of concentrates, e.g. containing 0.5-85% in toto of the essential components, and these are diluted with water or a hydrocarbon, usually water, for application, generally such that the concentration in toto of the essential components is 0.05-4%, though it may be up to 50% or more when sprayed from aircraft.

Thus, the present compositions usually contain 0.05-85% in toto of the essential components.

The compositions normally contain a surface active agent and/or a carrier.

The carrier may be a liquid, e.g. water (e.g. water used to dilute a concentrate for application). A concentrate containing water as carrier may advantageously also contain a surface active agent. In one embodiment, (a) and (b) are ground with water, a wetting agent and a suspending agent, usually in an agitated ball mill containing grinding media e.g. steatite balls to a particle size for both (a) and (b) of preferably less than 5 microns, to form a flowable susPension concentrate.

The carrier may be a liquid other than water, for example an organic solvent, usually a water-immiscible solvent, e.g. a hydrocarbon which boils within the range 130-270"C, in which the essential components are dissolved or suspended. A concentrate containing an organic solvent suitably also contains a surface active agent so that the concentrate acts as a selfemulsifiable oil on admixture with water. In a particular method, an emulsifiable concentrate is produced by stirring together, preferably with warming to aid dissolution, components (a) and (b), one or more emulsifiers and a water-immiscible solvent to form a solution, and usually filtering or centrifuging to remove insoluble impurities.

The carrier may be a solid, which may be finely divided. Examples of suitable solids are clays, sand, mica, chalk, attapulgite, diatomite, perlite and sepiolite, synthetic solid carriers, e.g. silicas, silicates and lignosulphonates, and solid fertilizers.

Wettable powders rapidly dispersible in water can be formed by admixing (a) and (b) in particulate form with a carrier or spraying molten (a) and (b) on to the carrier, admixing a wetting agent and a dispersing agent therewith, and fluid energy milling or pulverising the whole powder mixture to a particle size sufficiently small that the wettable powder in use can form the desired suspension.

The term 'surface active agent' is used in the broad sense to include materials variously called emulsifying agents, dispersing agents and wetting agents. Such agents are well known in the herbicide art.

The surface active agents used may comprise anionic surface active agents, for example mono- or di-esters of phosphoric acid with fatty alcohol ethoxylates or salts of such esters, fatty alcohol sulphates such as sodium dodecyl sulphate, ethoxylated fatty alcohol sulphonates, ethoxylated alkylphenol sulphates, lignin sulphonates, petroleum sulphonates, alkylaryl sulphonates such as alkyl-benzene sulphonates or lower alkyl-naphthalene sulphonates, salts of sulphonated naphthalene-formaldehyde condensates, salts of sulphonated phenolformaldehyde condensates, or more complex sulphonates such as the amide sulphonates, e.g.

the sulphonated condensation product of oleic acid and N-methyl taurine or the dialkyl sulphosuccinates, e.g. the sodium sulphonate of dioctyl succinate.

The surface active agents may also comprise non-ionic agents, for example condensation products of fatty acid esters, fatty alcohols, fatty acid amides or alkyl-substituted phenols with ethylene oxide, fatty esters of polyhydric alcohol ethers e.g. sorbitan fatty acid esters, condensation products of such esters with ethylene oxide e.g. polyoxyethylene sorbitan fatty acid esters, block copolymers of ethylene oxide and propylene oxide, acetylenic glycols such as 2,4,7,9-tetramethyl-5-decyn-4,7-diol, or ethoxylated acetylenic glycols.

The surface active agents may also comprise cationic agents, for example alkyl- and/or aryl-substituted quarternary ammonium compounds such as cetyl trimethylammonium bromide, or ethoxylated tertiary fatty amines.

Preferred surface active agents include ethoxylated fatty alcohol sulphates, lignin sulphonates, alkyl-aryl sulphonates, salts of sulphonated naphthalene-formaldehyde condensates, salts of sulphonated phenol-formaldehyde condensates, sodium oleoyl N-methyltauride, dialkyl sulphosuccinates, alkyl phenol ethoxylates, and fatty alkyl ethoxylates.

(a) and (b) may be mised immediately before use. Desirably, hoever, they would already have been mixed.

For the control of weeds in a crop, dependant on the nature of (b), the composition may be applied before sowing the crop (with or without incorporation of the composition into the soil), pre-emergence of the crop or post-emergence of the crop.

Instead of applying (a) and (b) together in a composition such as is discussed above, they can be applied separately in analogous compositions containing just (a) or (b), particularly as a chemical weed control programme or part of a chemical weed control programme in a crop season. When sequential application of (a) and (b) is employed, (a) is preferably applied before (b).

A further herbicide can be used in the present method besides (a) and (b). Thus, (a) and (b) can be applied separately and a further herbicide applied with (a). Alternatively, a composition comprising a mixture of (a), (b) and the further herbicide can be applied. Usually the proportions of (a) to the further herbicide are from 1:10 to 10:1 by weight, preferably from 1:3 to 3:1 by weight. Examples of such further herbicides include phenoxyaliphatic acids (e.g.

2,4-D, MCPA, 2,4,5-T, 2,4-DB, MCPB, and CMPP) including functional derivatives thereof, substituted ureas (e.g. monuron, diuron, neburon, monolinuron, fenuron and benzthiazuron), triazines (e.g. simazine, atrazine, trietazine, prometryne and metamitron), DNOC, PCP, bromoxynil, dichlobenil, diquat, paraquat, 2,3,6-tri-chlorobenzoic acid, endothal, dalapon, dicamba, TCA, chloropropham, barban, EPTC, butylate, diallate, allidochlor, propachlor, bromacil, lenacil, maleic hydrazide, salts of methanearsonic acid, cacodylic acid, aminotriazole, picloram, S,S,S-tributyl phosphorotrithioate, 3-(1-[ethoxyamino]propyli- dene)-6-ethyl-2H-pyran-2,4(3H)-dione, phenmedipham, azolamid, triallate, cycloate, propamide, carbetamide, diphenamid, pebulate, benfluralin, metobromuron, pyrazon, N (chloroacetyl)-N-(2,6-diethylphenyl) glycine ethyl ester or N-(phosphonomethyl)glycine, especially phenmedipham, lenacil, pyrazon, daapon, TCA or cycloate. Preferred such further herbicides are those which themselves selectively combat weeds in crops of beet, tobacco or onions. Preferred compositions comprise (a) and (b) optionally with phenmedipham, lenacil or pyrazon.

Fertilizers or pesticides other than herbicides can also be employed with the present essential herbicides.

Plants, the soil, land or aquatic areas can be treated by the present method. The method and composition are preferably used for selectively combating weeds, especially at a locus at which a crop, e.g. beetroot (otherwise known as red beet, Beta vulgaris) and especially sugar beet (Beta vulgaris), tobacco or onions, is growing or, less preferably, is to grow.

In the present method, usually 0.2-8 kg, preferably 0.5-4 kg, especially 1-4 kg, in toto of (a) and (b) are applied per hectare. Usually 0.1-5.3 kg, preferably 0.3-2.7 kg, especially 0.7-2.7 kg, of (a) are applied per hectare. Usually 0.1-2.7kg, preferably 0.2-1.3 kg, especially 0.3-1.3 kg, of (b) are applied per hectare. When (b) is chlorthal dimethyl, however, higher rates may be used; in that case, usually 2-16 kg, preferably 5-12 kg, in toto of (a) and (b) are applied per hectare, and usually 1-15 kg, preferably 4-11 kg, of (b) are applied per hectare.

The benzadox may be employed in its conventional herbicidal forms. It may be employed as a salt e.g. an alkali metal (for example sodium), ammonium, amine or ethanolamine salt.

The invention is illustrated by the following Examples.

Examples I and2 Tank mixes of ethofumesate and metolachlor were sprayed pre-emergence onto plots of sugar beet at rates of (1) 1.5 kg of ethofumesate and 2.0 kg of metolachlor per hectare, and (2) 1.5 kg of ethofumesate and 1.0 kg of metolachlor per hectare. In both cases, good weed control was obtained, particularly of mayweed.

Example 3 A tank mix of ethofumesate and napropamide was sprayed pre-emergence onto plots of sugar beet at a rate of 1.5 kg of ethofumesate and 0.75 kg of napropamide per hectare. Good weed control was obtained.

Example 4 A tank mix of ethofumesate and napropamide was sprayed onto plots of sugar beet at the 2-4 leaf stage at a rate of 1.0 kg of ethofumesate and 2.0 kg of napropamide per hectare. Good weed control was obtained.

Example 5 A tank mix of ethofumesate and methyl 2-[4(2,4-dichlorophenoxy)phenoxy]propionate was sprayed pre-emergence onto plots of sugar beet at a rate of 1.5 kg of ethofumesate and 2.0 kg of the propionate per hectare. Moderate weed control was obtained with a high level of safety to the crop.

Examples 6 and 7 Tank mixes of ethofumesate and methyl 2-[4-(2,4-dichlorophenoxy)phenoxy]propionate were sprayed at rates of 1.0 kg of ethofumesate and 1.5 kg of the propionate per hectare, and (2) 1.0 kg of ethofumesate and 0.75 kg of the propionate per hectare, onto plots of sugar beet at the 2-4 leaf stage. In both cases, good weed control was obtained, particularly of grasses e.g. blackgrass and wild oats, with a high level of safety to the crop.

Example 8 A tank mix of ethofumesate and benzadox (as ammonium salt) was sprayed post-emergence on to plots of sugar beet at a rate of 1.0 kg of ethofumesate and 1.0 kg of benzadox (calculated as acid) per hectare. Good weed control was obtained with a high level of safety to the crop.

Examples 9 and 10 A tank mix of ethofumesate and napropamide was sprayed onto plots just prior to transplanting tobacco plants into them, at a rate of 0.5 kg of ethofumesate and 2.5 kg of napropamide per hectare. The herbicides were lightly incorporated into the soil. Comparative plots were sprayed just with ethofumesate at a rate of 1.0 kg per hectare. The percentage weed control was assessed 6 weeks after treatment, and was found to be as follows: Treatment, kg/ha Percentage Control of Weeds Ethofu- Naprop- Amaranthus Cenopodium Solanum Anag- Digitaria Other mesate amide retroflexus album nigrum arvensis sanguinalisweeds 0.5 2.5 100 10 98 100 100 100 1.0 62 50 53 53 67 30 Examples 11-13 Tank mixes of ethofumesate andchlorthal dimethylwere sprayedpre-emergence onto plots of onions, and compared to plots treated with just chlorthal dimethyl. The rates at which the herbicides were employed, the percentage weed control they gave, and the crop stand (measured on a 0-100 scale where 0 = total crop kill and 100 = no crop damage were as ollows: Example Treatment, kg/ha Crop Stand Overall weed Ethofumesate Chlorthal Control, % Dimethyl 11 1.0 5.0 100 72 12 1.0 10.0 100 67 13 -- 10.0 98 55 Examples 14 & 15 Examples 14 & 15 At 7 different sites, under a wide variety of soil and climatic conditions, two chemical weed control programmes were carried out on plots of onions, (a) propachlor sprayed preemergence at a rate of 4 kg per hectare, followed by a tank mix of ethofumesate and methazole sprayed post-emergence at a rate of 1.0 kg of ethofumesate and 1.0 kg of methazole per hectare, and (b) a tank mix of ethofumesate and propachor sprayed preemergence at a rate of 1.0 kg of ethofumesate and 2.0 kg of propachlor per hectare, followed by a tank mix of ethofumesate and methazole sprayed post-emergence at a rate of 1.0 kg of ethofumesate and 1.0 kg of methazole. The percentage overall weed control obtained is shown in the following table.

Percentage Overall Weed Control Example Treatment Sites 1 2 3 4 5 6 7 14 (a) 86 51 86 49 100 100 88 15 (b) 79 82 90 60 100 Not 99 tested Examples 16-18 Tank mixes of ethofumesate and methazole were sprayed onto plots of onions at two sites of differing soil and climatic conditions, and compared with a spray of just methazole. The rates of application, the stage of growth of the onions at which treatment occurred, and the overall weed control obtained, were as shown in the following table.

Example Treatment, kg/ha Growth Percentage Overall Weed Control Ethofumesate Methazole Stage Site 1 Site 2 16 1 1 1 leaf 57 95 17 1 1 2leaf 38 84 18 - 2 2 leaf 34 76 WHAT WE CLAIM IS: 1. A method of combating weeds at a locus infested or liable to be infested with them, which method comprises applying to the locus (a) ethofumesate, i.e. 2-ethoxy-2,3-dihydro-3 ,3-dimethylbenzofuran-5-yl methanesulphonate, and (b) a compound selected from: metalachlor, i.e. N-(2-methoxy-1-methylethyl)-2'-ethyl- 6- -methyl-2-chloroacetanilide ; methazole i.e. 2-(3 ,4-dichlorophenvl)-4-methyl-1 ,2 ,4- oxadiazolidine-3 5-dione; benzadox, i.e. 2-(benzamidooxy)-acetic acid; methyl 2-[4-(2,4dichlorophenoxy) phenoxy]propionate; chlorthal dimethyl, i.e. dimethyl 2,3,5 ,6-tetrachloro- terephthalate; and napropamide, i.e. N,N-diethyl-2-(1-naphthyloxy)-propionamide.

2. A method according to claim 1 wherein (a) and (b) are applied together.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Percentage Control of Weeds Ethofu- Naprop- Amaranthus Cenopodium Solanum Anag- Digitaria Other mesate amide retroflexus album nigrum arvensis sanguinalisweeds 0.5 2.5 100 10 98 100 100 100 1.0 62 50 53 53 67 30 Examples 11-13 Tank mixes of ethofumesate andchlorthal dimethylwere sprayedpre-emergence onto plots of onions, and compared to plots treated with just chlorthal dimethyl. The rates at which the herbicides were employed, the percentage weed control they gave, and the crop stand (measured on a 0-100 scale where 0 = total crop kill and 100 = no crop damage were as ollows: Example Treatment, kg/ha Crop Stand Overall weed Ethofumesate Chlorthal Control, % Dimethyl 11 1.0 5.0 100 72 12 1.0 10.0 100 67 13 -- 10.0 98 55 Examples 14 & 15 Examples 14 & 15 At 7 different sites, under a wide variety of soil and climatic conditions, two chemical weed control programmes were carried out on plots of onions, (a) propachlor sprayed preemergence at a rate of 4 kg per hectare, followed by a tank mix of ethofumesate and methazole sprayed post-emergence at a rate of 1.0 kg of ethofumesate and 1.0 kg of methazole per hectare, and (b) a tank mix of ethofumesate and propachor sprayed preemergence at a rate of 1.0 kg of ethofumesate and 2.0 kg of propachlor per hectare, followed by a tank mix of ethofumesate and methazole sprayed post-emergence at a rate of 1.0 kg of ethofumesate and 1.0 kg of methazole. The percentage overall weed control obtained is shown in the following table. Percentage Overall Weed Control Example Treatment Sites

1 2 3 4 5 6 7 14 (a) 86 51 86 49 100 100 88 15 (b) 79 82 90 60 100 Not 99 tested Examples 16-18 Tank mixes of ethofumesate and methazole were sprayed onto plots of onions at two sites of differing soil and climatic conditions, and compared with a spray of just methazole. The rates of application, the stage of growth of the onions at which treatment occurred, and the overall weed control obtained, were as shown in the following table.

2. A method according to claim 1 wherein (a) and (b) are applied together.

3. A method according to claim 1 wherein (a) and (b) are applied in sequence.

4. A method according to any one of the preceding claims wherein the proportions of (a) to (b) are from 1:10 to 10:1 by weight.

5. A method according to any one of the preceding claims wherein 0.2-8 kg in toto of (a) and (b) are applied per hectare.

6. A method according to any one of the preceding claims wherein (b) is metolachlor.

7. A method according to any one of claims 1-5 wherein (b) is benzadox.

8. A method according to any one of claims 1-5 wherein (b) is methyl 2-[4-(2,4-dichloro phenoxy)phenoxy]propionate

9. A method according to any one of claims 1-5 where (b) is napropamide.

10. A method according to any one of claims 1-5 wherein (b) is methazole.

11. A method according to any one of claims 1-5 wherein (b) is chlorthal dimethyl.

12. A method according to any one of claims 6-8 wherein weeds are selectively combated in a sugar beet crop.

13. A method according to claim 9 wherein weeds are selectively combated in a crop of sugar beet or tobacco.

14. A method according to claim 10 or 11 wherein weeds are selectively combated in a crop of onions.

15. A method according to claim 1 performed substantially as hereinbefore described.

16. A method according to claim 1 performed substantially as hereinbefore described in any one of the Examples.

17. A herbicidal composition comprising (a) ethofumesate, i.e. 2-ethoxy-2,3-dihydro-3 ,3-dimethylbenzofuran-5-yl methanesulphonate; and (b) a compound selected from: metachor, i.e. N-(2-methoxy-1-methylethyl)-2'-ethyl-6'methyl-2-chloroacetanilide; methazole, i.e. 2-(3,4-dichlorophenyl)-4-methyl-1 ,2 ,4-oxadiaz- olidine-3,5-dione; benzadox, i.e. 2-(benzamidooxy)-acetic acid; methyl 2-[4-(2,4-dichlorophenoxy) phenoxy]propionate; chlorthal dimethyl, i.e. dimethyl 2,3,5,6-tetrachloroterephthalate; and napropamide, i.e. N,N-diethyl-2-(1-naphthyloxy)-propionamide.

18. A composition according to claim 17 wherein the proportions of (a) to (b) are from 1:10 to 10:1 by weight.

19. A herbicidal composition comprising ethofumesate and metolachlor.

20. A herbicidal composition comprising ethofumesate and benzadox.

21. A herbicidal composition comprising ethofumesate and methyl 2-[4-(2,4-dichloro phenoxy)phenoxyjpropionate.

22. A herbicidal composition comprising ethofumesate and napropamide.

23. A herbicidal composition comprising ethofumesate and methazole.

24. A herbicidal composition comprising ethofumesate and chlorthal dimethyl.

25. A composition according to claim 17 substantially as hereinbefore described.

26. A composition according to claim 17 substantially as hereinbefore described in any one of the Examples.

27. A two component pack for forming a composition claimed in any one of claims 17-26, which pack contains a first container containing (a) and a second container containing (b).