Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~Z9665
METHOD OF COMBATING WEEDS IN CEREAL CROPS
AND HERBICIDAL FORMULATIONS THEREFOR
The invention relates to a method of combating weeds in cereal crops and
to herbicidal formulations for use in such method.
Heretofore, the broadleaf weed species Matricaria spp has proved
particularly resistant to conventional herbicides, causing much damage to winterand spring cereal crops such as wheat, barley, oats and rye. We have now found
that by using a combination of particular known herbicides this weed species is
controlled to a surprisingly high level, synergism, in accordance with the
well-known "Colby Equation" tW~, 15, 20-22, 1967), being observed.
Additionally, control of other problematic weed species has been found to be
very satisfactory when using the combination, synergism again being observed in
several cases.
Thus, according to the present invention a method of combating weeds in
a cereal crQp locus comprises applying to said locus, post emergence the crop, acompound of formula 1,
., ID
CH3D- C:l
02N __~3 0 ~ Cl
and one or more compounds of formula 11,
' .~
~CH3 (II)
Cl ~ ~0- X- COOH
/
6~5
wherein X is -~H2- or -(CH2)3-, said compound of ormula II be mg optionally
~n a salt or ester form which is non-phytotoxic to cereal c.rops; where a
compound of formLla II, m which X is -C~ -, is employed, t~ compound of
formLla I being applied at a rate of 0.7 to 2.0 kg/ha and the compound of
formula II being applied at a rate of 0.7 to 3.0 kg/ha, and where a co~pound
of formNla II, in which X is -(CH2)3-, is employed, the co~pound of
formula I being applied at a rate of 0.25 t~ 3.0 k~/ha and the compound of
formula II being applied at a rate of 0.1 to 3.5 kg/ha.
In general, the compound of formula I is applied at a rate of from û.7 to
2.0 kg/ha and the compound(s) of formuta 11 at a rate of from 0.7 to 3.0 kg/ha.
The compound of formula I is known as bifenox, the preparation thereof
being described in United Kingdom Patent Specification No. 11232,368 and its use
as a herbicide being described in Proc. N E.~. 1973~ 27, 31.
The compound of formula 11, where X is -CH2_, is known as M.C.P.A.
The compound of formula 11, wherein X is -tCH2)3_, is known qs M.C.P.B.
M.C.P.A., M.C.P.B., their salts and esters, their manufacture and their
herbicidal properties are well documented in the literature.
The compounds of formula 11 may be employed in free acid form or in a
salt or ester form which is non-phytotoxia to cereals. As examples of sqlt forms
may be giv~ the alkali-metal, e.g. sodium and potassium salt forms and the
ammonium, alkylammonium and aikanolammonium salt forms, e.g. the
ethanolammonium salt form. As examples of ester forms may be given the
lower, e.g. C~ 8' alkyl ester forms, e.g. the methyi and octyl ester forms. The
use ~f such salts and ester forrns is embraced by the present invention.
In the method of the present invention, the compound of formula I
(bifenox) is preferably employed at an applicGtion rate of from 0.7 to 1.5 kg/ha
and more preferably at a rate of about 0.75 to 1.0 kg/ha.
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The compound of formula 11, wherein X is -(CH2)3_, i.e. A~.C.P.B., is preferablyemployed at an application rate of from 1.0 to 2.0 kg/ha. The compound of
formula 11, wherein X is -CH2_, i.e. M.C.P.A., is preferably employed at an
application rate of from 0.7 to 1.5 kg/ha and more preferably at a rate of about0.75 to l.Okg/ha.
The weight ratio of the compound of formula I to the compound(s) of
formula 11 is generally in the range of from 1:4 to 3:1. Where the bifenox is
employed together with All.C.P.B., the weight ratio of the former to the latter is
preferably in the range of from i:3 to 1.5:1, more preferqbly about 1:2. Where
the bifenox is employed together with l~A.C.P.A., the weight rqtio of the formerto the latter is preferqbly in the r~nge of from 1:2 to 2:1, more preferably about
1:1.
In the case of the cornpounds of formula 11, the above weights and ratios
are based on the acid equivalent thereof if a sqlt or ester is employed.
The method of the present invention is preferably carried out when the
3 crop is between the one leaf stage and appearance of the second node .
The preferred crops for treatment by the method of the present invention
are winter wheat, spring barley and winter bqrley.
The compound of formulq I and the compound(s~ of formulq 11 may be
applied together or separately. If the latter, the time period between
applications is preferably short, sqy one day or less. It is by far preferred,
however, for the compounds to be applied simultaneously as a single
formulation. In order to simplify mqnufacture, storage and transport, herbicidalformulations will normally be produced in concentrate form intended for dilutionin w~ter to the degree necessqry to enable the above qpplicqtion rates to be
Gchieved. Such concentrate formulations may contain from I to 9û%, preferably
15 to 85%, by weight of qctive ingredients qssociated with one or more inert, non
phytotoxic, carriers therefor. Such formulations will usually be in the form of a
wettable powder, an emulsifiable concentrate or ~n aqueous suspension or
so~uti on.
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Herbicidal formulations form a further aspect of the present invention.
Thus, there is provided a herbicidal formulation to be used in the method of theinvention, after dilution if appropriate, and comprising a compound of formula Iand one or more compounds of formula 11, or a salt or ester thereof, in a weightratio range of from 1:4 to 3:1 (based on the acid equivalent of the compound(s) of
formula 11) together with a non-phytotoxic diluent or carrier. The preferred
weight ratio ranges are as given above.
As a further separate aspect of the present invention, there is provided a
herbicidal formulation comprising a compound of formula l,stated above,
together with a compound of formula- Il, in which X is -(CH2)3_, or a salt or ester
thereof, in a weight ratio range of from 1:4 to 3:1 (based on the acid equivalent
of the compound of formula 11), together with q non-phytotoxic diluent or
carrier. Again, the preferred weight ratio ranges are as given above.
The herbicidal formulations of the present invention are intended to
embrace not only the so-called concentrate formulation forms, but also
ready-to-use dilute formulations such as tank mixes and application spray
liquors. Such dilute formulations are generally produced by dilution down to theappropriate degree of concentrate formulations but, if desired, may be produced
by the sepclrate <Iddition of appropriate amounts of the individual components to
an appropriate diluent or carrler.
Turning, however, to the concentrate formulations, wettable powders
comprise an intimote mixture of the active ingredients, one or more inert
carriers and one or more appropriate surfactants. The inert carrier may be
chosen from the attapulgite clays, the montmorillonite clays, the diatomaceous
earths, kaolins, micas, talcs and purified silicates. Effective surfactants may be
found among the sulphonated lignins, the naphthalene sulphonates and condensed
naphthalene sulphonates, the alkyl succinates, the alkylbenzene sulphonates,
~2~3t665
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the alkyl sulphates and non-ionic surfactants such as ethylene oxide adducts of
phenol. Illustrative wettable powders are those having the following composition
WETTABLE POWDERS
% by weight.
Compound of f ormu la I I to 73
Compound of formula 11* I to 79
Surf actant(s) I to I û
DispersingAgent Oto 10
Anticaking Agent û to lû
Inert carrier(s) to lûû
* based on acid equivalent
Emulsifiable concentrates comprise the active ingredients dissolved in one
or more suitable solvents, together with a surfactant. As examples of solvents
may be given qlkyl substituted benzenes, o-chlorotoluene, heavy aromatic
naphthalenes, glycol ethers and cyclic ketones. Illustrative emulsifiable
concentrates are those having the following composition:
.
EMULSIFIA13LE CONCENTRATES
% weight/volume
Compound of formula II to 55
Compound of formula 11* I to 60
SurfactGnt(s) 2 to 10
Co-solvent 0 to 40
Solvent to 100
* Based on acid equivalent
Aqueous suspensions and solutions comprise the active ingredients
suspended or dissolved in water together with any desired surfactants, thickening
agents, cntifreezing agents or p~eservcltivesO
~.
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Suitable surfactants may be chosen from those mentioned above in connection
with wettable powders. Thickening agents, if used, are normally chosen from
appropriate cellulose materials and natural gums whilst glycols will generally be
used when an antifreezing agent is required. Preservatives may be chosen from a
wide range of materials such as the various paraben antibacteriqls, phenol,
o-chlorocresol, phenyl mercuric nitrate Qnd formaldehyde. Illustrqtive aqueous
suspensions are those having the following composition:
AQUEOUS SUSPENSIONS
% weight/volume
l o Compound of formula 4 to 59
Compound of formula 11* 5 to 65
Wetting Agent 0 to 10
Dispersing Agent 0 to 6
Thickening/Suspending Agent 0 to 5
Antifree2e Agent 0 to 15
Preservative 0 to ;~
Water to lû0
* Based on acid eauivalent
The aqueous suspension and wettable powder formulations are preferred
o for use in the method of the present invention, giving significantly lower
phytotoxicity to the cereal crop than the emulsifiable concentrate formulations.The followîng Examples further illustrate the invention '. In qll Examples,
the amount of M.C.P.A and M.C.P.B used is based on the acid equivalent.
EXAMPLES I AND 2
The following wettable powders were prepared, in each case having the
ingredients shown:
6~5
-8-
% by weight
(!\ R~jfenox ?!~
M.C.P.B. (sodium salt) 45
Sodium lauryl sulphate
Sodium lignin sulphonate 3
Precipitated silica 5
Montmorillonite to lû0
Y by weight
~2) Bifenox 30
1 h~.C.P.A. (sodium salt) 30
Sodium lauryl sulphate 2
Sodium lignin sulphonate 3
Precipitated siliw 5
Montmori!lonite to 100
In each ~xample, the active ingredients were carefully blended with
the specified excipients in conventional mixing equipment. The blend was
then further milled in a fluid energy mill to a size range of from I to 10
microns .
EXAMPLES 3 AND 4
;~o The following emulsifiable concentrqtes were prepared having the
constituents shown below:
by volume
(3) Bifenox 20
M.C.P.B. (rnixed butyl esters) 3û
Calcium dodecylbenzene sulphonate 3
Alkyl phenoxypolyoxyethylene
ethanols 4
Isophorone 30
Orthochlorotoluene to 100
, ,, ,':
~ .. : ~ . ~ . !
-' ' ' ' ~"'';~ .
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% by weight/
by volume
(4) Bifenox 20
Nl.C.P.A 20
Calcium dodecylbenzene sulphonate 3
Alkylphenoxypolyoxyethylene
ethanols 4
Isophorone 30
: Orthochlorotoluene to 10û
The cctive ingredients were added to the appropriate solvent(s) with
stirring and optional heating to facilitate dissolution of the active materials.The surfactants were then added. The solutions were then filtered to remove
E~ insoluble impurities.
EXAMPLES 5 AND 6
The following aqueous suspensions were prepared hcving the constituents
shown below:
(5) ,~o by weight
Bifenox 30
M.C.P.A (amine salt~ 3û
; (Ethyl)hydroxyethyl cellulose û.2
Lignin sulphonate 3
Propylene glycol 2
Water to 100
.
.. . :
:, . . . .. . :
: . ~ . . .
.:
,. ~
6 Ei~
-10-
/~ by weight
t~ Bifenox ~n
M.C.P.B (amine salt) 35
Hydroxyethyl cellulose û.2
Amine ethoxylate 3
Wqter to lOû
The following Examples serve to illustrqte the synergistic effect
demonstrated by the method of the invention
EXAMPLE 7
Several field trials were carried out on winter wheat and one on spring
barley on sandy and clay loam soils. Applications was made as tank mixtures
with a knapsack sprayer at a volume of 3ûû-8ûO l/ha. The crop stage at
application varied from the start of tillerir1g to the stage at which the secondnode was visible. Visual assessments of herbicidal activity were made from 2 to
15 weeks after application using the 8arratt and Horsfall (1945) rating system.
In the following table is set out the average of the results obtained in
terms of percent control of the weed species Matricariq spp for the individual
herbicides Bifenox, and M.C.P.A and for the tank mix combination of Bifenox +
M.C.P.A., there also being given the control value estimated by the Colby
formula for additive effect..The concentrates from which the aqueous spray
liquors were formed were Bifenox 8û% wettable power, and M.C.P.A 40~0
aqueous solution.
~: . ; , :
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TABLE
Yn fontro!
Dosage Rate
Kg/ha Observed Colby formula
Bifenox 1.0 16.1 N/A
Bifenox 1.5 25.5 N/A
Bifenox 2.0 4û.3 N/A
hl.C.P.A (amine salt) 0.8 38.5 N/A
M.C.l'.A.(amine salt) 1.6 64.8 N/A
E~ifenox + M.C.P.A.
(amine salt) 1.0 + 0.8 85.1 4804
" 1.5+0.8 93.4 54.2
" 2.0+ 1.6 95.3 79.û
Thus, from the above it can be seen that a genuine synergistic effect is
observed when employing the method of the present invention.
Slight scorching of the crop was noted, which was subsequently out-grown.
As well as excellent control of the Matricaria spp, the following weed
species were well controlled (greater than û0%) employing? in separate tests, the
above combined tank mixes: Anethum ~raveolens9 Capsella bursa-pas~
Centaurea cyanus, Fumaria officinQlis, Lamium amplexicaule, Papaver rhoeas,
Silene spp and Stellaria media.
Anagallis arven~, C od , Polygonum aviculare Ranunculus
arvensis, Ranuncules repens, Raphanus r~phanistrum, Rumex crispus, Sinapis
arvensis, Sonchus arvensis cnd Veronica hederifolia .
EXANIPLE 8
-
The following greenhouse test was carried out to aSsess the efficac~, of
bifenox combined with M.C.P.E~.
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NIETHOD Seeds: Galium aparine
~ atricaria recutita
Veronica persica
Planting 0.5cm depth.(A/~atricaria
sp light covering)
Temperature/li,a,hting: Greenhouse (cool)
Watering: when required
Fertilisation- none
Experiment design: randomised block (4
repl icates)
Plot size treated 10 x 10cm pots
Soi I texture: loam
Application equipment: single nozzle
microsprayer, 50cm band width,
volume rate per area 50 ml per sq
metre.
Weed Stage at Application: 3-5 true leaves
In the following table is set out the average of the results obtained
in terms of per cent control of the weed species together with the control
~ value estimated by the Colby formula. For the Veronica persica a visual
control rating was made. For the other two species fresh weight of shoots
was obtained. The bifenox from which the spray li~uorwas formed was an
80% wettable powder. the M.C.P.B. was a 48Y~ aqueous solution, the
combination being a tank mix.
25~6~i5
WEED SPECIES % CONTROL
P~ate ~atricariaSp Galium Veronica
kg/ha aparine persica
Observed Colby Observed Colby Observed Colby
Bifenox 0.75 56.5 N/A 62.5 N/A 77.0 N/A
M.C.P.B 1.0 7.5 N/A 0.0 N/A 73.0 N/A
M.C.P.B 1.5 2.4 N/A 0.0 N/A 78.0 N/A
Bifenox
+ MCPB 0.75+1.0 73.0 60.0 72.1 62.5 100.0 94.0
" 0.75+ I.S 82.0 57.5 78.3 62.5 100.0 96.0
Thus, from the above, it can be seen that a genuine synergistic
effect is observed when employing the method of the present invention.
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