Note: Descriptions are shown in the official language in which they were submitted.
53~
K 1850 CAN
"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.
i3~
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~
i3~
~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.
.
s~
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)
