Note: Descriptions are shown in the official language in which they were submitted.
10~
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This invention relates to a herbicidal composition
comprising a mixture of esters of N-benzoyl-N-(3-chloro-4-
fluorophenyl)-2-aminopropionic acid which composition
exhibits a synergistic level of herbicidal activity
for the control of wild oat and to a method for controlling
wild oat in cereal crops using said composition.
Wild oat (Avena fatua) is a major world-wide weed
problem and is a wide-spread and abundant competitor in
cereal grain crops. As a result the annual economic
losses resulting from wild oat infestations are
considerable.
The methyl and isopropyl esters of N-benzoyl-N-
t3-chloro-4-fluorophenyl)-2-aminopropionic acid are both
establishing themselves as major selective wild oat
herbicides in cereal crops, the methyl ester being
particularly useful for wild oat infested wheat crops
and the isopropyl ester being useful for barley crops.
The methyl ester, though very effective in wheat crops
has hitherto been found insufficiently selective for
general use in barley crops.
The Applicant has found that a mixture of the methyl
and isopropyl esters gives rise to a synergistic response
to the eradication of wild oats in barley crops and~
moreover, the mixture can be applied without significant
damage to the barley crop.
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Accordingly the present invention provides a herbicidal
composition for tlle control of wild oat comprising: (a) methyl N-benzoyl~
N-(3~chloro-4-fluorophenyl)-2-aminopropionate; (b) isopropyl N-benzoyl-N-
(3-chloro-4-fluorophenyl)-2-aminopropionate; and (c) a carrier or a surface-
active agent, or both a carrier and a surface-active agent, wherein the
weight ratio of the methyl ester to the isopropyl ester is in the range
1:0.5 to 1:100.
~esting at a number of dosage levels indicates that such
a composition exhibits a synergistic level of herbicidal activity with
respect to wild oats. Even more surprising is the fact that, while the
herbicidal activity of the combination is increased with respect to wild
oat, there is no corresponding increase in the effect of the combination
upon barley so that the combination can be used safely in fields planted
with barley crops.
This invention makes it possible to control wild oat over
a wide range of its development by post~emergent foliar applications.
Wild oat can be controlled in barley crops by application of from 0.25
to 2.0 kg/ha of the composition according to the invention wherein the
weight ratio of the methyl ester to the isopropyl ester is in the range
1:0.5 to l:100, preferably in the range 1:2 to 1:30.
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In addition to the useful effect achieved on barley
crops the composition according to the invention has also
been found to be very effective in treating wild oat
infested wheat crops and thus the composition may be
regarded as an all-round wild oat herbicide.
The herbicidal composition according to the invention
employs a carrier, a surface-active agent or both a carrier
and a surface-active agent to facilitate application of the
composition to wild oat infested land at the desired dosage
rates. The term "carrier" as used herein means a solid or
fluid material, which may be inorganic or organic and of
synthetic or natural origin.
Typical solid carriers include natural and synthetic
clays and silicates, for example, natural silicas such as
diatomaceous earths and aluminium silicates, for example,
kaolinites, montmorillonites, and micas. Typical fluid
carriers are ketones, for example, methylcyclohexanone,
aromatic hydrocarbons, for example, methylnaphthalenes,
petroleum fractions, such as, for example, petroleum
xylenes and light mineral oils, and chlorinated hydrocarbons,
for example, carbon tetrachloride. Mixtures of liquids are
often suitable.
One or more surface-active agents and/or stickers can be
included in the formulation. The surface-active agent may
be an emulsifying agent or a dispersing agent or a wetting
agent; it may be non-ionic or ionic.
Any of the surface-active agents usually applied in
10~33()
~ormulating herbicides or insecticides may be used. Examples
of suitable surface-active agents are the sodium 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,
condensates of these with ethylene oxide and/or propylene
oxide; condensation products of fatty alcohols or alkyl
phenols,for example p-octyl phenol or p-octyl cresol, with
ethylene oxide and/or propylene oxide; sulpnates 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 castor oil, and sodium alkylaryl sulphonates
such as sodium dodecylbenzene sulphonate; and polymers of
ethylene oxide and copolymers of ethylene oxide and
propylene oxide.
Aqueous 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.
10f~9330
The invention also includes a mcthod of selectively con-
trolling wild oat in cereal crops which comprises applying the composition
according to the invention to a tract of land which is bearing cereal
crops and infested with Wild oat.
The compositions of this invention can be applied to the
wild oat plants in a conventional manner. The dust and liquid compositions
may be conveniently applied by the use of power-duster, boom and hand
sprayers, and spray-duster. The compositions can also be applied from
aeroplanes as a dust or spray because of the effec~iveness of the composi-
tions at low dosages.
If desired the composition according to the invention may
also be mixed with other wild oat herbicides, for example 4-chloro-2-
butynyl-m-chlorocarbanilate ~common name: Barban; trade mark: "Carbyne"),
or methyl 2-chloro-3-(4-chlorophenyl)propionate (common name: chlorphen-
prop methyl; trade mark: "Bidisin") or 1,2-dimethyl-3,5-diphenylpyrazoliwn
methyl sulphate (trade mark: "Avenge"~.
The invention is further illustrated by the following
Examples:
E~AMPLE 1
7 cm pots of John Innes No. 1 compost were sown with 25-30
seeds of barley or oat. When the plants had reached the 1-1-1/2 leaf
stage, a solution of the mixture under test was sprayed, using a logarith-
mic dilution sprayer, at five
7 1(~ 3330
different doses for each species. Five mixtures of
different proportions o~ the compounds were also sprayed
at five doses each.
Assessments were made 10-15 days after spraying.
The barley plants were cut at soil level and the plant
weight expressed as a percentage of untreated barley
weight. The percentage depression in growth of the oat
plants was assessed visually. These figures were
analyzed by computor to calculate the growth inhibition
dosages in kilogrammes per hectare (kg/ha) to give a 10%
reduction for barley and a 50% reduction for oat
abbreviated to GID50 oat respectively.
Mixtures of the methyl and isopropyl esters were
tested using the technique described above. The compounds
or mixtures of the two were applied at doses ranging from
7.0 to 0.5 kg/ha on barley and 4.0 to 0.2 kg/ha on oats.
The range of mixtures used and results obtained are shown
~n Table 1.
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TABL.E 1
Results of mixt re te~t~ with the
methyl and isopropyl esters
MIXTURE
PROPORTIONS BY WEIGHT GID1o barleY GID50 Oat
Methyl ester : Isopropyl ester (kg/ha) tkg/ha)
_
1 : 0 ~.62 0.25
1 : 2 0.76 0.47
1 : 3 0.97 0.55
1 : 4 0.92 0.59
1: 6 o.g8 0.63
1 : 14 1.14 0.75
_ 1.33 1.24
From these results it will be seen that the isopropyl
ester, which is the established barley wild oat herbicide,
requires 1.24 kg/ha to give 50% reduction in oat growth when
used alone, but when used in admixture with the methyl ester
considerably less than that amount is required to give the
same growth reduction, for example when a methyl to isopropyl
ester ratio of 1 : 4 is used,only 0.59 kg/ha of the mixture
is required to give the same effect. In this example
0.59 kg/ha of the mixture corresponds to 0.12 kg~ha of the
methyl ester and 0.47 kg/ha of the isopropyl ester and it
will be seen that a more than additive effect has been
achieved by the mixture.
9 ~0~;~ 330
It will also be noted that althou~h the use of the
methyl ester by itself gives very good control of wild
oat, the dosage to ~ive a 10% barley reduction is not
sufficiently high to give a satisfactory safety margin
~or a commercial wild oat herbicide thus making it un-
suitable for use in barley crops. However, in the case
of the mixtures, the GID1o figures for barley are much
higher than the figure for the methyl ester alone and
are sufficiently high to give the required safety margin
for a barley wild oat herbicide.
EXAMPLE 2
A second series of tests were carried out employing
the same methods as described in Example 1 but with a
different set of ester-mixture proportions. The results
are as follows:
TABLE 2
Results of mixture tests with the
methyl and isopropyl esters
MIXTURE
PROPORTIONS BY WEIGHT GID1o barleY GID50 oat
Methyl ester : Isopropyl ester (kg/ha) (kg/ha)
1 : 0 0.53 0.18
1 : 6 0.91 0.49
1 : 1~ 1.19 0.57
1 : 30 1.19 o.69 .
1 : 75 1.11 0.73
1 : 100 1.29 o . ~6
0 : 1 1.22 0.90
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From these results it will be seen that the isopropyl
ester, which is the estaklished barley wild oat herbicide,
requires 0.90 kg/ha to give 50% reduction in oat growth
when used alone, but when used in admixture with the methyl
ester considerably less than that amount is required to
give the same growth reduction, for example when a methyl
to isopropyl ester ratio of 1 : 30 is used only 0.69 kg/ha
of the mixture is required to give the same effect. In
this example 0.69 kg/ha of the mixture corresponds to
0.02 kg/ha of the methyl ester and o.67 kg/ha of the iso-
propyl ester and it will be seen that a more than additive
effect has been achieved by the mixture.
It will also be noted that although the use of the
methyl ester by itself gives very good control of wild oat,
the dosage to give a 10% barley reduction is not sufficiently
high to give a satisfactory safety margin for a commercial
wild oat herbicide thus making it unsuitable for use in
barley crops. However, in the case of the mixtures, the
GID1o figures Por barley are much higher than the figure for
the methyl ester alone and are sufficiently high to give
the required safety margin for a barley wild oat herbicide.
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