CA1188534A - Herbicidal composition and method of combating undesired plant growth - Google Patents

Abstract

ABSTRACT

"HERBICIDAL COMPOSITIONS AND METHODS OF COMBATING UNDESIRED
PLANT GROWTH"

A herbicidal composition which comprises 1-benzothiazol-2-yl-1,3-dimethylurea (the herbicide methabenzathiazuron) together with 3-(3-methyl-4-isopropylphenyl)-1,1-dimethylurea.

Description

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"HERBICIDAL COMPOSITION ND METHOD OF COMBATI~G UNDESIRED
PLANT GROW~H'' This invention relates to herbicidal compositions and method of combating undesired plant growth.
l-Ben70thiazol-2-yl-1,3-dimethylurea is useful as a herbicide, and is sold under the common name Metha'oenzthiazuron.
U.K. Patent Application No. 2064537 discloses that the compound 3-(3-methyl-4-isopropylphenyl)-1~1-dimethylurea is effective in the control of weeds.
~he Applicants have now found that mixtures of methabenzthia-zuron with 3-(3-methyl-4~isopropylphenyl)-1,1-dimethylurea exhibit an unexpected synergistic effect against broad-leaved weeds .
The invention therefore provides a herbicidal composition which comprises the compound 1-benzothiazol-2-yl-1,3-dime-thylurea (hereinafter referred to as compound I) together with 3 (3-methyl-4-isopropylphenyl)--]~1-dimethylurea (hereinafter referred to as compound II).
The invention further pro~ides a method of combating un=
desired plant growth at a locus, which comprises applying to the locus compound I and compound II.
The weight ratio of compound I to compound II may vary widely depending on the intended application. Preferably said ratio i9 in the range of from 1:50 to 50:1, preferably 1:20 to 20:1, especially 5:1 to 1:5. Suitably the dosage of each com-5~

pound applied i5 in the range o~ from 0.05 to 5 kg/ha. For example, a dosage of O.3 to 4 kg/ha o~ compoun~ I may be applied to~ether with 0.3 to 3 kg/ha o~ compound II.
The composition and method o~ the in~ention may be used ~or the control o~ weeds in a wide variet~ o~ crops, for example, cotton, soyabean, plantation crops such as sugar cane or vines 9 and, especially, cereals such as wheat, barley, maize and sorghum.
A wide range o~ broad leaved and grassy weeds are controlled.
Application may be pre-emergence or, preferably, post-emergence.
For certain applications, especially when resistant weeds are present, it may be desirable also to apply a third herbicide.
For example, i~ severe infestations o~ wild oat are presen-t in cereal crops, it may be advantageous to apply along with compound I and compound II, one o~ the ~,N-disubstituted alanine derivatives which are specialised narrow spectrum herbicides and described in ~.K. Patent ~o. 1,164,160, for example the ethyl ester of N-benzoyl-N-(3,4-dichlorophenyl)-2~aminopropionic acid, or the racemic mixture or laevo rotato~ isomer o~ the methyl or isopropyl ester of N-benzoyl-N-(3-chloro-4-~luorophenyl)-2 aminopropionic acid or a broad-spectrum herbicide such as a triazinea ~or example cyana~ine, atra%ine or simazine. Further suitable compounds which may be present as a third component include metolachlor, chlortoluron, isoproturon and dichlofopmethyl, phenoxyalkanoic acids such as dichlorprop, mecoprop, 2,4--D, 2,L~-DB, MCPA and MCPB and their salts and es-ters, and compounds o~
the ~eneral ~ormula: C~

xl ~x2 OH
or salts or esters thereo~ in which each of Xl and x2 independ~
ently represents an iodine, bromine or chlorine atom. Examples o~ the latter include bromoxynil and iGxynil and their respective octanoa-tes.

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A composition according to the invention preferably also comprises one or more carriers. A carrier i8 any material with which the active ingredients are formulated to facilitate appli-cation to the locus to be treated, or to facilitate storage~
transport or handling. A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquidg and any of the carriers normally used in formulating herbicidal compositions may be used.
Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium alumin-ium silicates, for example attapulgites and vermiculites~ alumin-ium silicatesg for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate~ syn-thetic hydrated silicon oxides and synthetic calcium or aluminium silicates;
elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen;
waxes~ for example beeswa~9 paraffin wax, and chlorinated mineral wa~es; and solid fertlisers, for example superphosphates.
Suitable liquid carriers include water; alcohols, for example isopropanol and glycols, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene;
petroleum fractions, for example kerosine and li~ht mineral oils;
chlorinated hydrocarbons, for example carbon tetrachloride, perchl.oroethylene and trichloroethane. ~ix-tures of different li~uids are often suitable.
Agricultural compositions are often formulated and trans-ported in a concentrated form which is subsequently diluted bythe user before application. ~he presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution.
A surface-active agent may be an emulsifying agent, a dis-persin~ agent or a wetting agent; it may be nonionic or ionic~

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~amples of suitable surface-active agents include the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids;
the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; ~atty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for example ~-octylphenol or ~-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products, alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated cas-tor oil, and sodium alkylaryl sulphonates such as sodium dodecyl-benzene sulphonate; and polymers of ethylene oxide and copolymers o~ ethylene oxide and propylene oxide.
The compositions of the invention may for example be formu-lated as wettable powders, dusts, granules, solutions, em~sifi-able concentrates, emulsions, suspension concentrates and aero-sols. Wettable powders usually contain 25, 50 and 75% ~r o~
active ingredient and usually contain, in addition -to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0 10% w of stabiliser(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar compositions to that of a wettable powder but without a dispersant, and are diluted in the field with f~rther solid carrier to give a composition usually containing ~-10% w of active ingredient. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676 - 0.152 mm), and may be manu-~actured by agglomeration or impregnation techniques. Generally, granules will contain ~-25% w active ingredient and 0-10% w of additives such as stabilisers, slow release modifiers and binding agents. Emulsi~iable concentrates usually contain~ in addition to a solvent and, when necessary~ co~solvent, 10-50% w/v active 53~

ingredient, 2-20~ w/v emulæifieræ and 0-20~ w/v of other addi-tives such as stabilisers1 penetrants and corrosion inhibitors.
Suspension concentrates are usually compounded so as to ob-tain a stable9 non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixo-tropic agents, 0-10% w of other additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble, certain organic solids or inorganic salts may be present dissolved in the formulat;on to assist in preventing sedimentation or as anti-freeze agents for water.
Aqueous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with wa-ter, also lie within the scope of the present invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and ma~ have a thick 'mayonnaise'-like consistency.
The compositions of the in~ention may also contain other ingredients, for example, compounds poæsessing insecticidal or ~ungicidal properties.
The followine Example illustrates the invention.
Exam~~
~ 1e tests conducted were foliar spray tests, in which seed-ling plants o~ broadleaved weeds were sprayed with a formulation containing the test compound. The test plant species were speedwell and black nightshade.
The soil used in the tests was a prepared horticultural loam. The seedlings had 2 to 4 true leaves.
The formulations used in the tests were prepared by diluting with water, solutions of the test compound or mi~ture in acetone containing 0~4% b~ weight of an alkylphenol/ethylene oxide -condensate available under the trade name TRIT0~ X-155. The acetone solutions were diluted with an equal volume of wa-ter and the resulting formulations applied at 4 different dosage levels 3~
, designed to produce a range of responses. Three replicate pots were used for each treatment. Untreated seedlings plants were used as controls.
12 days after treatment, phytotoxicity compared with the untreated control, was assessed visually on a 0 to 9 scale, 0 indicating no effect and 9 indicating death.
The results were subjected to a standard probit analysis by computer to calculate the dosage of each compound or mixture~ in Kg/ha, re~uired to kill 50% of the test species. This dosage is referred to as the GID50 dosage. If a mixture of herbicides A
and B act together in an additive way, one would expect the GID50 values for A and B in the mixture to be given by the equations (i) and (ii) below:

GID50 ~ B in mixture = a o~ + a (i) b GID50 of A in mixture = (GID50 of B in mixture)x C~ (ii) where a = GID50 of A used alone b = GID50 f B used alone CX = ~Jeight ratio of compound A to compound B in mi~ture.

If the measured GID50 values are in fact less than the calculated values, the mixture is synergistic.
The results of the tests are given in the Pollo~ing Table.
~ The GID50 values are actual, measured values in kg/hag and ; calculated values are given in brackets after -the measured values~ In the Table, the follo~ing abreviations are used:

A: 3-(3-methyl-4-isopropylphenyl)-1,1-dime-thylurea.
B: l-Benzothiazol-2-yl-1,3-dimethylurea the commercial herbicide methabenzthiazuron.
.

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The results show that the mixtures tested showed signi*icant s~nergism against both speedwell and black nightshade.

TABLE OF RESULTS

_ _ _ __ _ ., _ __ ___ ~ _ _ r~ , Speedwell Mixture GID50 Ratio A:B A B
. ~ . ___._________ . ..... __ _ 1:00.62(0.62) 0(0) 32:10.34(0.42) 0.010(0.013) 16:10.25(0.32) 0.016(0.020) 8:10.18(0.22) 0.022(0.027) 4:10.084(0.13) 0.021(0.033) 0:1 _ ~ 0.042(0.042) Black Nightshade MixtureGID50 Ratio A:B A B

1:00.014(0.014) 0(0) 4:10.018(0.013) 0.004(0.003)

2:10.014(0.013) o.oo7(o.oo6) 1:10.005(00012) 0.005(0.012) 1:20.003(0.010) 0.006(0.019) 0:1 _ -- - _ _0.059(0.059)

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A herbicidal composition which comprises 1-benzothia-zol-2-yl-1,3-dimethylurea (compound I) together with 3-(3-methyl-4-isopropylphenyl)-1,1-dimethylurea (compound II).

2. A composition as claimed in claim 1, which also includes one or more carriers.

3. A composition as claimed in claim 1, wherein the weight ratio of compound I to compound II is from 1:50 to 50:1.

4. A method of combating undesired plant growth at a locus which comprises applying to the locus a herbicidally effective amount of 1-benzothiazol-2-yl-1,3-dimethylurea (compound I) together with 3-(3-methyl-4-isopropylphenyl)-1,1-dimethylurea (compound II).

5. A method as claimed in claim 4, in which compound I and compound II are applied in the form of a composition.

6. A method according to claims 4 or 5 wherein the weight ratio of compound I to compound II is from 50:1 to 1:50.

7. A method according to claim 5 wherein the composition also includes one or more carriers.

8. A method as claimed in claim 4, in which the locus treated is a crop area bearing plants or seeds of cereals.