CA1192054A - Herbicidal composition and method of combating undesired plant growth - Google Patents

Abstract

Abstract "HERBICIDAL COMPOSITION AND METHOD OF COMBATING UNDESIRED
PLANT GROWTH"
A herbicidal composition which comprises 3-(3-methyl-4-isopropylphenyl)-1,1-dimethylurea together with at least one compound selected from:
(i) a compound which has the general formula (I) or is a salt or an ester thereof, in which each of X1 and X2 independently represents an iodine, bromine or chlorine atom;
(ii) 2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline, and (iii) a compound which has the general formula:

Description

'HERBICIDAL COMPOSITION AND METHOD OF COMBATING ~NDESIRED
PLANT GROWTH"

This invention relates to herbicidal compositions and method of combating undesired plant growth.
U.K. Patent Application No. 2064537 discloses that the compound 3-(3-methyl-4-isopropylphenyl)-l,l-dimethylurea is effective in the control of weeds. It has now been found tha-t this compound can also act as a synergist when mixed with certain other herbicidal compounds, and thus -that mixtures of certain herbicides with 3-(3-methyl-4-isopropylphenyl)-l,l-dimethylurea exhibit an unexpected synergistic effect.
The invention therefore provides a herbicidal composition which comprises 3-(3-methyl-4-isopropylphenyl)~ dimethylurea (hereinafter referred to as compound A), together with at leas-t one compound selected from:
(i) a compound which has the generaL formula C~

xl ~x2 or is a salt or an ester thereof, in which each of X and X
independently represents an iodine, bromine or chlorine atom;

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~i~

~ 3~

(ii) 2,6-dinitro-N,N-dipropyl-4-trifluoromethylarliline;
and (iii) a compound which has -the general formula:
R
02N ~ / \ ~ OH (II) ~ NO
or is a salt or an ester thereof, in which R is a C(1-4) alkyl group.
The composi-tions according to the invention may con-tain two or more compounds within one of the groups (i) and (iii), and/or two or more compounds from different groups (i), (ii) and (iii). Preferably however the compositions con-tain components selected from one only of groups (i), (ii) and (iii).
The invention further provides a method of combating un-desired plant growth at a locus, which comprises applying to the locus compound A and at least one compound selected from (i) to (iii) above.
In the formula I, each of Xl and X preferably independently represents an iodine or bromine atom, and preferably Xl and X are the same.
A compound (i) may be the free phenol of formul I, or it may be a salt or an ester thereof. Suitable salts include alkali metal salts, especially the sodium or potassium sa~t, and a~nine salts. Suitable amine salts include for example those of amines having up to three organic groups attached to the nitrogen, the organic groups being, for example, aIkyl groups having up to 10 carbon atoms and being optionally substituted by, for example, hydro~y groups or halogen atoms. Suitable esters are for example alkyl esters, having for example up to 20, especially 6 to 12, carbon atoms in -the aIkyl moiety. Preferably, a compound (i) is the free phenol or its octanoate ester.
An alkyl group Rl in the formula II is preferably a butyl group. Most preferably R is a secondary or tertiary butyl group.
~ ypical compounds of group (iii) include 2-tert-butyl-4,6-dinitrophenol, 2-sec-butyl-4,6-dinitrophenol and salts and esters thereof.

A compound of group (iii) may be the free alcohol of formula II or it may be a salt or an ester thereof. Suitable salts include alkali metal salts, especially the sodium or potassium salt, alkaline earth metal salts, for example the magnesium salt, the ammonium salt and amine salts.
Suitable esters are derived from substituted or unsubstituted carboxylic acids, especially alkanoic acids.
Preferably a compound of group (iii) is the free alcohol or the ace-tate thereof.
The weight ratio of compound A to the compound selected from (i) to (iii) may vary widely depending on the intended application.
Preferably said ratio is 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 co~pound applied is in the range of from 0.05 to 5 kg/ha.
Especially preferred dosages of certain binary mixtures are for example, from 0.3 to 3 kg/ha of compound A together with 0.05 to 2.5 kg/ha of a compound of group (i); 0.25 to 3 kg/ha of compound A together with 0.25 -to 3 kg/ha of compound (ii); and 0.25 to 3 kg/ha of compound A together with 0.25 to 3 kg/ha of a compound of group (iii).
The composition and method of the invention may be used for the control of weeds in a wide variety of crops, depending of course on the nature of the compound (i) to (iii). Typical crops include, for example, cotton, soyabean, plantation crops such as sugar cane or vines, and, especially, cereals such as wheat, barley, maize and sorghum. Mixtures containing a compound of group (iii) may also be especially useful in leguminous crops such as peas and beans. A wide range of broad leaved and grassy weeds are controlled. Application may be pre-emergence or, preferably, post-emergence. For certain applications, especially ~hen resistant weeds are present, it may be desirable also -to apply a further herbicide. For example, if severe infestations of wild oat are present in cereal crops, it may be advan-tageous to apply along with compound A and one or more compounds (i) to ~iii), one of the 5~

N,N-disubstituted alanine derivatives which are specialised narrow spectrum herbicides and described in U.I~. Patent No.
1,16~,160, for example the e-thyl ester of N-benzoyl-N-(3,4-dichloro-phenyl)-2-aminopropionic acid, or the racemic mixture or laevo-rotatory isomer of the methyl or isopropyl ester of N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionic acid or a broad-spectrum herbicide such as a triazine, for example cyanazine, atra~ine or simazine. Fur-ther suitable compounds which may be present as a third component include metolachlor, chlortoluron, isoproturon and dichlofopmethyl.
A composition according to the invention preferably also comprises one or more carriers. A carrier is 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 liquid, 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 3 for example attapulgites and vermiculites; alumin-ium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; synthetic 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 beeswax, paraffin wax, and chlorinated mineral waxes; 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 ben~ene, -toluene and xylene;
petroleum fractions, for example kerosine and light mineral oils;

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chlorina-ted hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloroethane. Mixtures of different liquids are of-ten suitable.
Agricultural compositions are often formula-ted and transported in a concentrated form which is subse~uently diluted by the user before application. The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution.
A surface-ac-tive agent may be an emulsifying agent, a dis-persing agent or a wetting agent; it may be nonionic or ionic.
Examples 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; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensa-tes of -these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for example p-octylphenol or p-oetylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation produc-ts;
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 castor oil, and sodium alkylaryl sulphonates such as sodium dodecyl-benæene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.
The compositions of the invention may for example be formu-lated as wettable powders, dusts, granules, solutions, emulsifi-able concentrates, emulsions, suspension concentrates and aero-sols. Wettable po~ders usually contain 25, 50 and 75% w of 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 o-ther additives such as penetrants or stickers. Dusts are usually formulated as a dus-t concentrate .L~

having a similar compositions to -that of a we-ttable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 2-10% 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-factured by agglomera-tion 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. Emulsifiable concentra-tes usually contain, in addition to a solvent and, when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other addi-tives such as stabilisers, penetrants and corrosion inhibitors.
Suspension concentrates are usually compounded so as to obtain a stable, 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-tropi~ 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 formulation to assist in preventing sedimentation or as anti-freeze agents for water.
~ queous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, 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 may have a thick 'mayonnaise'-like consistency.
The compositions of the invention may also contain other ingredients, for example~ compounds possessing insecticidal or fungicidal properties.
The following Examples illustrate the invention.
General Procedure The tests conducted were foliar spray tests, in which seed-ling plants were sprayed with a formulation containing the test compound. Various test plant species were used, including black-grass9 speedwell, black nightshade and wild oats.
The soil used in the tests was a prepared horticultural loam.
Speedwell and wild oat seedlings had O or 1 true leaves, and blackgrass and black nightshade seedlings had 2 or 3 true leaves.
The formulations used in -the tests were prepared by diluting wi-th water, solutions of -the test compound or mix-ture in acetone containing 0.4% by weight of an alkylphenol/ethylene oxide conden-sate available under the trade name TRITON X-155. The acetone solutions were diluted with an equal volume of water and the resulting formulations applied at 4 different dosage levels designed to produce a range of responses. Three replicate pots were used for each treatment. Untreated seedlings plants were used as controls.
As specifie~ number of days after treatment, phytotoxicity compared with the untreated control, was assessed visually on a O
to 9 scale, O 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, required 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:

GID of B in mix-ture = a 5 c~ ~ a (i) b GID50 f A in mixture = (GID50 f B in mixture)xG~ (ii) where a = GID50 of A used alone b = GID50 f B used alone = weigh-t ratio of compound A to compound B in mixture.
If the measured GID50 values are in fact less than the calculated values, the mixture is synergistic.

The results of the tes-ts are given in the following Tables.
The GID50 values are actual~ measured values in kg/ha, and calculated values are given in brackets after -the measured values.
Example 1 This Example was carried out using the following compounds:

A: 3-(3-methyl-4~isopropylphenyl)-1,l~dimethylurea.
B: 3,5-dibromo-4-hydroxybenzonitrile, the commercial herbicide "Bromoxynil".

It can be seen from the table of results (Table I) that this mixture was synergistic against all plant species tested - i.e., the measured dosages of the mixture required to kill 50% of the test plants were less than the calculated dosages.

3~'~

_ABLE I

_esults .
Blackgrass Speedwell (assessment after 2 days) (assessment after 2 days) Mixture GID50 Mixture GID50 ratio A B ratio A B
A:B A:B
. . . _ 1:0 .46(.46) o(o) 1:0 .27(.27) o(o) 1:1 .16(.21) .16(.21)16:1 .091(.15) .oo6(.oog) 1:2 .070(.14) .14(.28) 8:1 .051(.10) .006(.013) 1:4 .056(.082) .23(.33) 4:1 .051(.064) .013(.016) 1:8 .039(.045) .31(.3~) 2:1 .022(.036) .011(.018) 0:1 0(0) .40(.40) 0:1 o(o) .021(.021) .
Black Ni~htshade Wild Oats (assessment after 2 days) (assessment after 7 days) Mixture GID50 Mixture GID50 ratio A B ratio A B
A:B A:B
1:0 .28(.28) 0(0) 1:0 .092(.092) 0(0) 4:1 .11(.18) .025(.044) 1:2 .034(.071) .068(.14)

2:1 .052(.13) .026(.065) 1:4 .045(.057) .18(.23) 1:1 .o55(.084) .055(.084) 1:8 .035(.042) .28(.33) 1:2 .o40(.o49) .080(.099) 1:16 .022(.027) .36(.43) 0:1 0(0) .12(.12) 0:1 0(0) .61(,61) le 2 This Example was carried out using the following compounds:

A: 3-(3-methyl-4-isopropylphenyl)-1,1 dimethylurea B: 3,5-dibromo-4-hydro,Yybenzonitrile octanoate ester.

It can be seen from the table of results (Table II) that this mixture was synergistic in its action against black night-shade and wild oa-ts, and approximately additi~e in its effect against speedwell and blackgrass.

S'~

TABBE II

Example 2 - Resul-ts Blackgrass Speedwell (assessment after 2 days) (assessment after 2 days) Mixture GID50 Mixture GID50 ratio A B ratio A B
A:B A:B

1:0 .44(.44)0(0) 1:0 .49(.44) 3(0) 1:1 .13(.12).13(.12)32:1 .26(.34) .008(.010) 1:2 .054(.072) .11(.14) 16:1 .30(.27) .01~(.017) 1:4 .o46(.o39) .18(.16) 8:i .22(.1g) .028(.024) 1:8 .023(.021) .18(.17) 4:1 .11(.12) .027(.031) 0:1 0(0) .17(.17) 0:1 0(0) .044(.043) -Black Nightshade Wild Oats (assessment a~ter 2 days) (assessment a~ter 12 days) Mixture GID50 ~ixture GID~o ratio A B ratio A B
A:B A:B
_ . . .
1:0 .34(.34)0(0) 1:0 .14(.14) 0(0) l~:l .14(.25) .035(.063) 1:2 .057(.13) .11(.26) 2:1 .20(.20) .10(.10) 1:4 .10(.12) .41(.47) 1:1 .072(.14) .072(.14) 1:8 .058(.10) .46(.81) 1:2 .038(.089) .076(.18) 1:16 .034(.079) .54(1.27) 0:1 0(0) .24(.24) 0:1 0(0) 2.93(2.93) Example 3 In this Example, the following compouncls were used:

A: 3-(3-methyl-4-isopropylphenyl)-1,1-dimethylurea.
B: 2,6 Dinitro-N,N-dipropyl-4-trifluoromethlaniline the commercial herbicide trifluralin. The resul-ts, assessed after 13 days, are given in Table III, and show that the mixtures tested showed significant synergism.

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TABLE III

Speedwell Mix-ture 5 Ratio A:B A B

1:0 0.37(0.37) () 8:1 0.27(0.32) 0.033(0.039) l~ l 0.16(0.28) 0.039(0.069) 2:1 0.13(0.22) 0.066(0.011) 1:1 0.10(0.16) 0.10(0.16) 0:1 0(0) 0.27(0.27) Blackgrass GID
Mixture 5 Ratio A:B A B

1:0 0.~13(0.013) 0(0) 1:2 0.006(0.011) 0.011(0.021) 1:4 0.003(0.009) 0.014(0.035) 1:8 0.003(0.007) 0.023(0.053) 1:16 0.003(0.00l~) 0.048(0.072) 0:1 0(0) 0.11(0.11) Wild Oats GID
5o Mixture Ratio A:B A B
_ 1:0 o.96(o.96) o(o) 2:1 0.25(0.56) 0.13(0.28) 1:1 0.15(0.39) 0.15(0.39) 1:2 0.085(0.25) 0.17(0.49) 1:4 0.081(C.14) 0.32(0.56) 0/1 0(0) o.66(o.66) _ ple 4 In this Example, -the following compounds were used:

A: 3-(3-methyl-4-isopropylphenyl)-l,l-dimethylurea.
B: 2-tert-butyl-4,6-dinitrophenol the commercial herbicide Dinoterb.
The results, assessed af'ter 6 days, are gi~en in Table IV, and show that the mixtures tested showed significant synergism.

~ rp~

_ .
Speedwell GID,~o Mixture Ratio A:B A B

1:0 3-55(3-55) () 16:1 0.99(1.10) o.o62(o.069) 8:1 0.52(0.65) o.o65(0.082)

4:1 0.27(0.36) o.o66(Q.o90) 2:1 0.13(0.19) 0.067(0.095) 0:1 0(0) 0.10(0,10) _ _ .
Black ~ightshade GID O
Mixture 5 Ra-tio A:B A

1:0 0.0~7(0.047) () ~:l 0.012(0.027) 0.003(0.007) 2:1 0.008(0.019) 0.004(0.010) 1:1 0.00~(0.012) 0.004(0.012) 1:2 0.003(0.007) 0.005(0.014) 0:1 0(0) 0.016(0.016) Wild Oats Mixture Ratio A:B A B

1:0 3.36(3.36) 0(0) 2:1 1.24(2.18) 0.62(1.09) 1:1 1.~8(1.61) 1.48(1.61) 1:2 0.86(1.06) 1.73(2.12) 0.58(0.63) 2.31(2.51) 0:1 0(0) 3.09(3.09) _

Claims (13)

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

1. A herbicidal composition which comprises 3-(3-methyl-4-isopropylphenyl)-l,l-dimethylurea (hereinafter referred to as compound A), together with at least one compound selected from:
(i) a compound which has the general formula (I) or is a salt or an ester thereof, in which each of X1 and X2 independently represents an iodine, bromine or chlorine atom;
(ii) 2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline; and (iii) a compound which has the general formula:

(II) or is a salt or an ester thereof, in which R1 is a C(l-4) alkyl group, the weight ratio of between compound (A) and compound (i), (ii) or (iii) being from 1:50 to 50:1.

2. A composition as claimed in claim 1, in which X1 and X2 in formula I both represent iodine atoms or both represent bromine atoms.

3. A composition as claimed in claim 1 in which a compound of group (i) is the free phenol of formula I or is an alkali metal salt, amine salt, or alkyl ester thereof.

4. A composition as claimed in claim 3, in which a compound of group (i) is the free phenol of formula I or the octanoate ester thereof.

5. A composition as claimed in claim 1 in which R1 in the formula II is a butyl group.

6. A composition as claimed in claim 5 in which R1 in the formula II is a secondary or tertiary butyl group.

7. A composition as claimed in claim 1, in which a compound of group (iii) is the free alcohol of formula II or is an alkali metal salt, alkaline earth metal salt, ammonium salt, amine salt or an ester thereof.

8. A composition as claimed in claim 7 in which a compound of group (iii) is the free alcohol of formula II or the acetate thereof.

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

10. A method of combating undesired plant growth at a locus, which comprises applying to the locus an effective amount of compound A together with at least one compound selected from groups (i) to (iii) as defined in claim 1, the weight ratio of between compound (A) and compound (i), (ii) or (iii) being from 1:50 to 50:1

11. A method as claimed in claim 10, in which the compounds are applied in the form of a composition.

12. A method as claimed in either claim 10 or claim 11 in which the locus treated is a crop area bearing plants or seeds of cereals.

13. A method as claimed in claim 10 or 11 in which -the application rate for each of compound (A) and of at least one compound (i), (ii) or (iii) is from 0.05 to 5 kg/ha.