This invention relates to a method and composition for affecting plant physiology.

The invention provides a method of combating weeds or regulating the growth of a plant at a locus, which method comprises applying to the locus a weed-combating or plant growth regulant amount of

(a) thiobencarb; and

(b) one or more, usually one, of trietazine, prometryne, terbutryne, triallate, metoxuron, neburon, nitrofen and chlomethoxynil.

In addition, the invention provides a plant physio¬ logically active composition comprising (a) and (b) .

Each of the present compounds is known separately as a herbicide, but it has been found that (a) and (b) seem to render plants more susceptible to the action of the other, so that the present method and composition are unexpect¬ edly advantageous, especially when used, in the control of weeds in ryegrass (Loliu spp) or cereal crops. Components (a) and (b) are synergistic, being surprisingly effective, e.g. against weeds such as mayweed (Matricaria inodora) , and surprisingly safe to crops, e.g. wheat (Triticum vulqare) or barley (Hordeum vulqare) . In addition, the method and composition can be used to combat a wider range of weed species than when either (a) or (b)

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is .used alone .

Thiobencarb is S-4-chlorobenzyl diethylthiocarbamate. Triallate is S-2,3,3-trichloroallyl di-isopropylthio- carbamate. Prometryne is 2,4-di (isopropylamino)-β- ethyl- thio-l,3,5-triazine. Terbutryne is 2-tert-butyl ^" amino-4- ethylamino-6-methylthio-l,3,5-triazine. Trietazine is 2-chloro-4-diethylamino-6-ethylamino-l,3,5-triazine. Metoxuron is 3-(3-chloro-4-methoxyphenyl)-1,1-dimethyl- urea. Neburon is l-butyl-3-(3,4-dichlorophenyl)-1-methyl- urea. Nitrofen is 2,4-dichlorophenyl 4-nitrophenyl ether. Chlomethoxynil is 2,4-dichlorophenyl 3-methoxy-4- nitrophenyl ether.

In a particularly preferred embodiment (b) is triet¬ azine. usually the proportions respectively of (a) to (b) are from 200:1 to 1:100, e.g. 25:1 to 1:6. Parts, proportions and percentages in this specification are by weight unless otherwise indicated. Generally there is a greater weight of (a) than of (b) . In preferred embodiments, the propor- tions respectively of (a) to triallate are from 16:1 to 1:3; to prometryne are from 8:1 to 1:3; to terbutryne are from 8:1 to 1:3; to trietazine are from 25:1 to 1:2; to metoxuron are from 16:1 to 1:4; to neburon are from 40:1 to 1:3; to nitrofen are from 8:1 to 1:5; or to chlo- methoxynil are from 16:1 to 1:1.

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The essential components (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 0.5-95% jin toto of the essential components, and these are diluted with water or a hydrocarbon, usually water, for application, gener¬ ally such that the concentration jji 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 composi¬ tions usually contain 0.05-95% jLn 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 concen¬ trate 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 sus- pending 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 dis¬ solved or suspended. Thus, the invention provides a liquid composition comprising the compounds and a liquid hydrocarbon which boils within the range 130-270oC. A concentrate containing an organic solvent suitably also contains a surface active agent so that the concentrate acts as a self-emulsifiable oil on admixture with water.

In a particular method, an e ulsifiable 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 desirably com¬ prising xylene or isophorone to form a solution, and usually filtering or centrif ging to remove insoluble impurities.

The carrier may be a solid, which may be finely divided. Thus, the invention provides. a solid composition comprising the compound and a solid carrier. Examples of suitable solids are clays, sand, mica, chalk, attapulgite, diatomite, perlite, sepiolite, synthetic solid carriers, e.g. silicas, silicates and lignosulphonates, and solid fertilizers. ettable powders rapidly dispersible in water may 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 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 with alkylphenol ethoxylates, salts of such esters, fatty alcohol sulphates such as sodium dodecyl sulphate, sodium octadecyl sulphate or sodium cetyl sulphate, ethoxylated fatty alcohol sulphates, ethoxylated alkylphenol sul¬ phates, lignin sulphonates, petroleum sulphonates, alkyl- aryl sulphonates such as alkyl-benzene sulphonates or lower alkylnaphthalene sulphonates, e.g. butyl-naphthalene sulphonate, salts of sulphonated naphthalene-formaldehyde ^' condensates, salts of sulphonated phenol-formaldehyde 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 sulpho- succinates, e.g. the sodium sulphonate of dioctyl succinate.

_ OMPI

The surface active agents may also comprise non-ionic agents, for example condensation products of fatty acid esters, fatty alcohols, fatty acid amides or fatty-, alkyl- or alkenyl-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-tetra- methyl-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 quater¬ nary 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 con¬ densates, dialkyl sulphosuccinates, alkyl phenol ethoxy- lates, and fatty alkyl ethoxylates.

Non-ionic surface active agents are preferred, (a) and (b) may be admixed with a non-phytotoxic oil, e.g. Actipron, Agri-Oil Plus, Sun Oil HE or Fyzol HE. (a) and (b) may be employed in association with a herbicidal antidote (a substance having the property of

improving the safety to crops of the compounds), e.g. N,N-diallyl-2,2-dichloroacetamide, 1,8-naphthalic anhydride, 4'-chloro-2-(hydroxyimino)acetanilide, o<-(cyanomethoximino)-benzeneacetonitrile or 2,2-di- methyl-3-dichloroacetyloxazolidine. Although the antidote may be applied in admixture with active compound, it is preferably applied separately, and especially as a treat¬ ment for crop seeds. The ratio by weight of herbicide to antidote is preferably from 1:4 to 4:1. (a) and (b) may be in admixture with fertilizers, (a) and (b) may be mixed immediately before use Desirably, however, they would already have been mixed.

The composition is particularly useful for combating weeds in a crop. The composition can be applied after, or preferably, before, emergence of the crop. The composi¬ tion can be applied before sowing ^• the crop, with or with¬ out incorporation of the composition in the soil.

Instead of applying (a) ^' and (b) together in a ^' composi¬ tion such as is discussed above, they can be applied separately in analogous compositions containing just (a) or (b) , (e.g. (b) such as triallate applied by pre plant incorporation and (a) applied pre-emergence) , particularly as a chemical weed control programme, or part of a chemical weed control programme, in a crop season. The invention provides a one pack presentation, in

which (a) and (b) are already mixed, and also a single package adapted to hold (a) and (b) in separate containers, for use, e.g. by mixing in a spray tank. A further pesticide, e.g. herbicide, insecticide or fungicide, or another plant growth regulant can be employed in sequence or admixture with the present combi¬ nation of (a) and (b) . Particular advantages are obtained with a further herbicide or plant growth regulant, partic¬ ularly a ^' further herbicide, e.g. the present combination applied before emergence of a crop and the further herbi¬ cide after emergence of the crop. The proportions of (a) to further pesticide or plant growth regulant, depend¬ ing on the particular further pesticide or plant growth regulant, are usually from 200:1 to 1:2. The further herbicide may be for example one or more of a phenoxyaliphatiσ acid, substituted urea, triazine, phenol, nitrile, bipyridylium compound, substituted benzoic acid, halogenated aliphatic acid, carbamate, thio- carbamate, chloroacetamide, diazine or arsenic herbicide. The phenoxyaliphatiσ acid generally comprises alkyl and/or halogen substituted phenoxyaliphatic acids, and their salts, for example alkali metal, amine and alkanol- amine salts, and functional derivatives, for example esters and amides These compounds may be of activity such that they are recognised as commercial herbicides, or may

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be of only slight herbicidal activity. Examples of the substituted phenoxyaliphatic acids which may be mentioned include 2,4-dichlorophenoxyacetic acid, 2-(2,4-dichloro- phenoxy)propionic acid, 2-methyl-4-chlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, gamma-2,4-di- chlorophenoxybutyric acid, gamma-2-methyl-4-chlorophehoxy- butyric acid, alpha-2-methyl-4-chlorophenoxypropionic acid, 2-(4-[2, ^' 4-dichlorophenoxy]phenoxy)propionic acid and 2-(4-[4-chloroρhenoxy]phenoxy)propionic acid. The substituted urea generally comprises a tri- or tetra-substituted urea such as N'-(3-chloro-4-methyl- phenyl)-N,N-dimethylurea, N'-parachlorophenyl-N,N-di- methylurea, N'-parachlorophen l-0,N,N-trimethylisourea, N'-p-chlorophenyl-N-methoxy-N-methylurea, N,N-dimethyl- N'-phenylurea, 3-(4-bromophenyl)-l-methoxy-l-methylurea, l-(2-benzothiazolyl)-3-me hylurea, N,N-dimethyl-N'-(4-[l- methylethyl3phenyl)urea, N'-(3,4-dichlorophenyl)-N- methoxy-N-methylurea or N,N-dimethyl-N'-[3-(trifluoro- methyl)phenyl]urea. The triazine herbicide generally comprises 2-chloro- 4-(1-cyano-l-methylamino)-6-ethylamino-l,3,5-triazine or 2-isopropylamino-4-(3-methoxypropylamino)-6-methylthio- 1,3,5-triazine or a compound of the formula:-

^C ^

N N

where X is a halogen atom, OY group or SY group-, where Y is an alkyl group, R and R are the same or different and are hydrogen or alkyl and R 2 and R4 are the same or different alkyl groups, such as 2-chloro-4,6-bisethyl- amino-l,3,5-triazine or 2-chloro-6-ethylamino-4-isopropyl- amino-l,3,5-triazine.

The phenol herbicide generally comprises 4,6-dinitro- o-cresol,4,6-dinitro-2-sec-butylphenol or pentachloro- phenol. The nitrile herbicide generally comprises 3,5-di- iodo-4-hydroxybenzonitrile, 3,5-dibromo-4-hydroxybenzo- nitrile or 2;6-dichlorobenzonitrile. The bipyridylium herbicide generally comprises 1,l'-dimethyl-4,4'-bi¬ pyridylium dichloride or l,l'-ethylene-2-2'-bipyridylium dibromide. The substituted benzoic acid herbicide generally comprises 2,3,6-trichlorobenzoic acid, 2-methoxy-3,6-dichlorobenzoic acid or N-(1,1-dimethyl- propynyl)-3,5-dichlorobenzamide. The halogenated ali¬ phatic acid herbicide generally comprises trichloracetic acid or 2,2-dichloropropionic acid. The carbamate herbi¬ cide generally comprises isopropyl N-(3-chlorophenyl)- carbamate, 4-chloro-2-butynyl N-(3-chlorophenyl)carbamate,

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methyl 3- (m-tolylcarbamoyloxy)phenylcarbamate or D-N- ethyl-2- (phenylcarbamoyloxy)propionamide. The thio- carbamate herbicide generally comprises S-ethyl N,N-di- propylthiocarba ate, S-ethyl N,N-diisobutylthiocarbamate, S- (2,3-dichloroallyl) N,N-diisopropylthiocarbamate, S-ethyl N-ethyl-N-cyclohexylthiocarbamate or S-propyl butylethylthiocarbamate. The chloroacetamide herbicide generally comprises N,N-diallyl-2-chloroacetamide or N-isopropyl-2-chloroacetanilide. The diazine herbicide generally comprises 5-bromo-6-me thyl-3-sec-bu tylur ac il , 3-cyclohex l-5 , 6-tr imethyleneuracil , 5-amino-4-chloro-2- phenyl-3-pyridazinone or l,2-dihydropyridazine-3,6-dione. The arsenic herbicide generally comprises a salt of methane ar sonic acid or cacodylic acid. Other herbicides which may be used as the further herbicide include 1,2-di- methyl-3,5-diphenylpyrazolium ion, ethyl N-benzoyl-N- (3,4-dichlorophenyl) alanine, N-isobutyl-2-oxo-l-imidazol- idine-carboxamide , aminotr iazole , 2 , 3-dichloro-l , 4 ⁱ -naphtho- quinone, 4-amino-3,5,6-trichloropicolinic acid, N,N-di- methyl-2,2-diphenylacetamide, 2,6-dinitro-N,N-dipropyl-4- trifluoromethylaniline, N-butyl-N-ethyl-2,6-dinitro-4-tri- fluoromethylaniline, S,S,S-tributyl phosphorotrithioate, 2-ethoxy-2 , 3-dihydro-3 , 3-dimethyl-5-benzof uranyl methyl- sulphonate, 4-chloro-2-oxobenzothiazolin-3-yl acetic acid, 3-isopropyl-2,l,3-benzothiadiazinon-(4)-2,2-dioxide, 3,5-

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dibromo-4-hydroxybenzaldehyde 2,4-dinitrophenyloxime, methyl 2-chloro-3-(4-chlorophenyl)propionate, 2-chloro- ethyltrimethylammonium chloride, 4-methylsulphonyloxy-2- butynyl m-chlorocarbanilate, isopropyl 2-(N-benzoyl-3- chloro-4-fluoroanilino)propionate, methyl 2-(N-benzoyl-3- chloro-4-fluoroanilino)propionate, 2-chloro-N-(1,3-di- oxolan-2-ylmethyl)-2' ,6'-dimethyl-acetanilide, 2-chloro- l-(3-ethoxy-4-nitrophenoxy)-4-trifluoromethylbenzene, methyl 2-(4-[2* ,4'-dichlorophenoxy]phenoxy)propionate or isobutyl 2-(4-[4'-chlorophenoxy]phenoxy)propionate.

In a preferred embodiment (b) is trietazine and neburon.

It is especially preferred that (b) is trietazine and that it is used in combination with (c) linuron. The combination of thiobencarb, trietazine and linuron is synergistic. Linuron is N-(3,4-dichlorophenyl)-N- methoxy-N-methylurea. Usually the proportions of (a) to (c) are from 200:1 to 1:2, preferably 20:1 to 3:11 Generally there is a greater weight of (a) than of (c) . Preferably (a) thiobencarb, (b) trietazine and (c) linuron are applied together in a composition such as is discussed above for (a) and (b) .

Instead of applying (a) thiobencarb, (b) trietazine and (c) linuron together in a composition such as is discussed above, they can be applied in separate

applications in analogous compositions containing one or two of the essential herbicides, particularly as a chemical weed control programme, or part of a chemical weed control programme, in a crop season. The invention includes a one pack presentation, in which (a) thiobencarb, (b) trietazine and (c) linuron are already mixed, and also a single package adapted to hold either each of (a), (b) and (c) in separate containers, or two of them in one container and the other in another container, for use, e.g. by mixing in a spray tank.

A yet further pesticide,, e.g. herbicide, insecticide or fungicide, or another plant growth regulant can be employed in sequence or admixture with the present combi¬ nation of (a) thiobencarb, (b) trietazine and (c) linuron. The yet further pesticide can be as discussed above for the further pesticide. .Particular advantages are obtained with a yet further herbicide or plant growth regulant, particularly a yet further herbicide, e.g. the present combination applied before emergence of a crop and the yet further herbicide after emergence of the crop.

The proportions of (a) to .yet further pesticide or plant growth regulant, depending on the yet further pesticide or plant growth regulant, are usually from 200:1 to 1:2.

The present combination of (a) and (b) affects plant physiology so that the combination can be used as a

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herbicide or plant growth regulant. 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 at a locus where a crop is growing or is to grow. The crop is preferably ryegrass ^' , maize or a small-grained crop such as a cereal crop (e.g. wheat, barley, oats or rye) or rice. The crop is especially wheat or barley.

The present combination of (a) and (b) is active against a wide variety of weeds. It is particularly useful against blackgrass - Alopecurus myosuroides wild oats - Avena spp. meadow grass - Poa spp. chickweed - Stellaria media and mayweed - Matricaria sp .

In the present method, usually 0.3-26 kg, preferably 1-14 kg, j i toto of (a) and (b) are applied per hectare. Usually 0.2-20 kg, preferably 1-8 kg, of (a) are applied per hectare. Preferably 0.5-3 kg of triallate, 1-3 kg of prometryne, 0.3-2 kg of terbutryne, 0.05-1.5 kg (e.g. 0.1-1 kg) of trietazine, 0.5-4 kg of metoxuron, 0.2-3 kg of neburon, 1-5 kg of nitrofen, or -4 kg of chlomethoxy¬ nil, are applied per hectare. When (b) is trietazine, and linuron is used in

combination with it, preferably 0.05-1.5, e.g. 0.1-1, kg of linuron is applied per hectare.

The invention is illustrated by the following Examples. Examples 1-8

Tank mixes of (a) thiobencarb and (b) the other active ingredient shown in the table below are sprayed in the field at the rates of active ingredient shown in 200 litres of water per hectare pre-emergence onto plots where wheat has been sown and onto plots where barley has been sown. In each case, good weed control is obtained.

Example 9

Tank mixes in water of (a) thiobencarb and (b) triet¬ azine were sprayed at the rate of 4 kg of thiobencarb per hectare and 0.6 kg of trietazine per hectare per-emergence

in the field onto plots in which barley had been sown. The herbicidal effect was assessed compared to controls on the barley and weeds on a scale on which 0 represents no effect and 100 total kill. The results are shown below.

Plant Species % Herbicidal Effect

Barley - Hordeum vulgare 11

Pale Persicaria

- Polygonum lapathifolium 58

Wild Oats - Avena spp. 46

Charlock - Sinapis arvensis 57

Chickweed - Stellaria media 78

Fathen - Chenopodium album 84

The good weed control with safety to the barley is apparent. Examples 10-15

To test .the results from combinations of herbicides against those from the individual herbicides, tank mixes of (a) thiobencarb and (b) trietazine were sprayed in the greenhouse at the rates of active ingredient specified in the table below pre-emergent onto pots of soil in which the specified crop and weed species had been sown. The herbicidal effect was assessed 4 weeks after application to the mayweed and chickweed and 6 weeks after application to the wheat and barley, on a scale on which 0 represents

no effect and 100 total kill. The table below shows the results obtained and also those expected for the combination from the Colby formula.

t t H

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Thiobencarb, + Trietazine, % Herbicidal Effect kg per ha kg per ha Wheat Barley Mayweed Chickweed

1 0 6 - 0 0

0 0.15 0 - ^• 45 68

1 0.15 3 - 50 75 Actual

. 6 - 45 68 Expected

2 0 18 5 - -

0 0.3 0 8 - -

2 0.3 5 8 - - Actual

18 12 - Expected

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It can be seen that the effect of the combination of herbicides on the crops is less than expected (i.e. the combination is unexpectedly safer to the crops) , and that the effect of the combination of herbicides on the weeds is greater than expected (i.e. the combination is unexpectedly more active against weeds) . The combination is synergistic. Examples 16-18

Tank mixes in water of (a) thiobencarb, (b) trietazine and (c) linuron were sprayed in the greenhouse at the rates of active ingredient specified in the table below pre-emergent onto pots of soil in which the specified crop and weed species had been sown. On assessment of the herbicidal effect, 4 weeks after application to the broad-leaved weeds and 6 weeks after application to the grass weeds and cereal crops, the following figures were obtained, on a scale on which 0 represents no effect and 100 total kill.

t to O Cπ o cπ

Blackgrass is Alopecurus myosuroides Cleaver is Galium aparine

The good weed control with safety to the wheat or barley is apparent, especially at the 2 higher rates. Examples 19-22

To test the results from combinations of herbicides against those from the individual herbicides, analogous tests to those of Examples 16-18 were carried out on wheat and mayweed at the rates of active ingredient shown in the table below. The table also shows the results obtained and those expected for the combination from the Colby formula.

(a) Thiobencar ^■ b + (b) Trietazine + (c) Linuron, kg per ha Wheat Mayweed

2 0 0 18 0

0 0.15 0 0 45

0 0 0.15 0 10

2 0.15 0.15 12 Actual 98 18 Expected 51

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It can be seen that the combination of herbicides is markedly safer to wheat than expected and markedly more effective against mayweed than expected. The combination is synergistic.

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