AU767610B2 - Herbicidal compositions - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Rhone-Poulenc Agro ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: Herbicidal compositions The following statement is a full description of this invention, including the best method of performing it known to me/us:- #11049~ la The present invention relates to new herbicidal compositions comprising a mixture of 2-(2-chlorobenzyl)-4,4-dimethyl- 1,2-oxazolidin-3-one, i.e. clomazone and N-(2,4-difluorophenyl)-2-[3- (trifluoromethyl)phenoxy]-3-pyridinecarboxamide, i.e. diflufenican. It also relates to the use of the mixture and to a method of controlling weeds.

Clomazone is a well known selective herbicide disclosed in U.S.

Patent No. 4,405,357 (and Australian Patent Publication No. 86/53632) and The Pesticide Manual page 256-257, 11th edition (British Crop Protection Council) recommended for the control of grass and broadleaved weed species in soya beans, peas, sugar cane, cassava, pumpkins and tobacco, applied pre-emergence or pre-plant incorporated.

Diflufenican is a well known selective herbicide disclosed in European Patent No. 53011 and Australian Patent No. 557053 and The Pesticide Manual page 397-398, 11th edition (British Crop Protection Council), recommended for the control of grass and broad-leaved weed 20 species in autumn sown wheat and barley, applied pre- or early postemergence.

However certain individual weed species constitute a serious problem and are insufficiently controlled by either clomazone or diflufenican alone. Thus more effective control of (for example) annual ryegrass (Lolium perenne) is required.

As a result of research and experimentation it has been found that the use of clomazone in combination with diflufenican extends the spectrum of herbicidal activity to include the control of Lolium perenne.

Therefore the said combination represents an important technological advance. The term "combination" as used in this specification refers to the "combination" of clomazone and diflufenican.

Surprisingly, it has been found that the combined herbicidal activity of clomazone with diflufenican, for the control of certain weed species is greater than expected, without an unacceptable increase in 35 crop phytotoxicity, when applied pre- emergence of the weed species, i.e. the herbicidal activity of clomazone with diflufenican showed an unexpected degree of synergism, as defined by Limpel, P.H. Schuldt and D.

Lamont, 1962, 1. Proc. NEWCC 16, 48-53, using the formula:

E=X+Y-X.Y

100 where E the expected percent inhibition of growth by a mixture of two herbicides A and B at defined doses; X the percent inhibition of growth by herbicide A at a defined dose; Y the percent inhibition of growth by herbicide B at a defined dose.

When the observed percentage of inhibition by the mixture is greater than the expected value E using the formula above the combination synergistic.

The unexpected synergism on Lolium perenne gives improved reliability in controlling serious competitive weeds of many crop species, leading to a considerable reduction in the amount of active ingredient required for weed control.

A high level of control of this weed is desirable to prevent:- 1) yield loss, through competition and/or difficulties with harvest, 2) crop contamination leading to storage and cleaning difficulties, 3) unacceptable weed seed return to the soil, and 20 4) resistance problems faced when other herbicides are used.

There is indeed a widespread problem of resistance of annual ryegrass to herbicides such as ALS inhibitors, and a number of other herbicides. The herbicidal combination of the present invention does not suffer from this disadvantage.

Accordingly, the present invention provides a herbicidal composition comprising a synergistic herbicidally effective amount of:clomazone; and diflufenican; in association with a herbicidally acceptable diluent or carrier and/or surface active agent.

•o These compositions may be used as herbicides in a broad range of dose rates depending on the crop to be treated, the weeds present and their population, the compositions used, the timing of the treatment, the climatic and edaphic conditions, and the dose ratio of (b) required to obtain a satisfactory level of weed control but not necessarily total control. When applied to a crop-growing area, the rate of application should be sufficient to control the growth of weeds without causing substantial permanent damage to the crop.

Generally a composition in which the ratio of is from about 13.7:1 to about 1.2:1 wt/wt is used, preferably from about 6.4:1 to about 2.4:1 wt/wt.

Unless otherwise stated, the percentages and ratios appearing in this specification are by weight.

Generally the active ingredients are homogeneously dispersed in other components cited hereinafter, such as a diluent or carrier and/or surface-active agents.

The term "herbicidal compositions" is used in a broad sense, to include not only compositions which are ready for use as herbicides but also concentrates which must be diluted before use. Preferably, the 20 compositions contain from 0.05 to 90% by weight of clomazone and diflufenican.

The herbicidal composition may contain solid and liquid carriers and surface-active agents wetters, dispersants or emulsifiers alone or in combination). Surface-active agents that may be present in the 25 herbicidal compositions of the present invention may be of the ionic or non-ionic types, for example sulphoricinoleates, quaternary ammonium derivatives, products based on condensates of ethylene oxide with nonyl- or octyl-phenols, or carboxylic acid esters of anhydrosorbitols which have been rendered soluble by etherification of the free hydroxy 30 groups by condensation with ethylene oxide, alkali and alkaline earth metal salts of sulphuric acid esters and sulphonic acids such as dinonyland dioctyl-sodium sulphono-succinates and alkali and alkaline earth metal salts of high molecular weight sulphonic acid derivatives such as sodium and calcium lignosulphonates. Examples of suitable solid 35 diluents or carriers are aluminium silicate, talc, calcined magnesia, kieselguhr, tricalcium phosphate, powdered cork, absorbent carbon black and clays such as kaolin and bentonite. Examples of suitable liquid diluents include water, acetophenone, cyclohexanone, isophorone, toluene, xylene, and mineral, animal, and vegetable oils (these diluents may be used alone or in combination).

Herbicidal compositions according to the present invention may also contain, if desired, one or more conventional adjuvants such as adhesives, protective colloids, thickeners, penetrating agents, stabilisers, sequestering agents, anti-caking agents, colouring agents and corrosion inhibitors. These adjuvants may also serve as carriers or diluents.

Preferred herbicidal compositions according to the present invention are suspension concentrates and especially suspo-emulsions.

The aqueous suspension concentrates, which are applicable by spraying, are prepared in such a way as to obtain a stable fluid product (by fine grinding) which does not settle out and they usually contain from 10 to 75% of combination, from 0.5 to 15% of surface acting agents, from 0.1 to 10% of thixotropic agents, from 0 to 10% of suitable additives such as antifoams, corrosion inhibitors, stabilisers, and water or an organic liquid in which the active substance is sparingly soluble or insoluble. Some organic solid substances or inorganic salts can be dissolved in order to assist in preventing sedimentation or as anti-freeze 20 for the water.

Herbicidal compositions according to the present invention may also comprise clomazone and diflufenican in association with, and preferably homogeneously dispersed in, one or more other pesticidally active compounds and, if desired, one or more compatible pesticidally 25 acceptable diluents and carriers.

Preferred herbicidal compositions according to the present invention which comprise clomazone and diflufenican in association with other pesticides, e.g. herbicides, are those wherein the other herbicide is for example terbutryn, metosulam, flumetsulam, 30 imazethapyr, MCPA, ethametsulfuron methyl and sulfentrazone.

The compositions of the invention may be made up as an article of manufacture comprising clomazone and diflufenican and optionally other pesticidally active compounds as hereinbefore described, and as is 35 preferred, a herbicidal composition as hereinbefore described and preferably a herbicidal concentrate which must be diluted before use, comprising the clomazone and diflufenican within a container for the aforesaid clomazone and diflufenican or a said herbicidal composition and instructions physically associated with the aforesaid container, setting out the manner in which the aforesaid clomazone and diflufenican or herbicidal composition contained therein, is to be used to control the growth of weeds. The containers will normally be of the types conventionally used for the storage of chemical substances and concentrated herbicidal compositions, which are solids or liquids at normal ambient temperatures, for example cans and drums of plastics materials or metal (which may be internally-lacquered), bottles of glass and plastics materials; and when the contents of the container is a solid, for example a granular herbicidal composition, boxes, for example of cardboard, plastics material, metal or sacks. The containers will normally be of sufficient capacity, to contain amounts of the active ingredients or herbicidal compositions sufficient to treat at least one hectare of ground, to control the growth of weeds therein but will not exceed a size which is convenient for conventional methods of handling.

Instructions will be physically associated with the container, for example by being printed directly thereon or on a label or tag affixed thereto. The directions will normally indicate that the contents of the container, after dilution if necessary, are to be applied to control the growth of weeds at rates of application from about 120g to about 480g of clomazone and from about 35g to about 100Og of diflufenican per hectare in the manner and for the purpose hereinbefore described.

.ooooi According to a further feature of the present invention there is provided a method for controlling the growth of weeds at a locus which comprises applying to said locus a synergistic herbicidally effective amount of:clomazone, and diflufenican.

They are generally applied at application rates of about 120 to about 480 g/ha of(a) and from about 35 to about 100 g/ha of(b), preferably from about 120 to about 240 g/ha of and about 37.5 to about 50 g/ha of The method of the invention may be used to control a very wide spectrum of grass weeds in crops, for example cereal crops (such as wheat, barley and rye); and especially for pulse crops (such as lupins, field peas, chick peas) and oil seed crops (such as canola); without causing significant permanent damage to the crop. The combined use described above offers both foliar and residual activity and consequently can be employed over a long period of crop -6development, i.e. from pre-weed pre-crop emergence to post-weed postcrop emergence. Preferably the combination is applied pre-emergence (of weeds) and post-sowing of crops.

By the term 'pre-emergence application' is meant application to the soil in which the weed seeds or seedlings are present before emergence of the weeds above the surface of the soil. By the term 'post-emergence application' is meant application to the aerial or exposed portions of the weeds which have emerged above the surface of the soil. By the term 'foliar activity' is meant herbicidal activity produced by application to the aerial or exposed portions of the weeds which have emerged above the surface of the soil. By the term 'residual activity' is meant herbicidal activity produced by application to the soil in which weed seeds or seedlings are present before emergence of the weeds above the surface of the soil, whereby seedlings present at the time of application or which germinate subsequent to application from seeds present in the soil, are controlled. Weeds that may be controlled by this method include: broad-leafed weeds, for example, Abutilon theophrasti, Adonis microcarpa, Ageratum conyzoides, Bidens pilosa, Brassica toumefortii, Chenopodium album, Commelina nudiflora, Emex australis, Galinsoga 20 parviflora, Galium aparine, Lactuca serriola, Lamium amplexicaule, Polygonum spp, Portulaca spp, Raphanus raphanistrum, Rapistrum rugosum, Sida spp, Solanum nigrum, Sinapis arvensis, Sisymbrium officinale, Sisymbrium orientale; e °and grass weeds, for example Brachiaria plantaginea, Cenchrus 25 echinatus, Digitaria sanguinalis, Echinochloa crus-galli, Eleusine indica, Rottboellia exaltata, Setaria spp, Lolium perenne; and sedges, for example Cyperus esculentus, Cyperus iria and Cyperus rotundus, and Eleocharis acicularis.

The pattern of persistence of clomazone and diflufenican allows 30 the method of the present invention to be practised by the time-separated application of separate formulations.

In accordance with the usual practice, a tank mix may be prepared prior to use by combining separate formulations of the individual Sherbicidal components.

The following Experiments illustrate the present invention.

-7- EXPERIMENTAL PROCEDURE Clomazone and Diflufenican The experiments were carried out post planting of the crop and pre- emergence of the weed species at a research farm in Mallala, South Australia. A tank mix comprising clomazone and diflufenican (referred to as DFF) was dissolved in water to give a 650ml solution containing the appropriate concentration of active ingredients. Clomazone (as the commercial formulation "Command", trade mark, a soluble concentrate) and diflufenican (as the commercial formulation "Brodal", trade mark, an aqueous suspension concentrate) were also weighed out individually and dissolved in water to give a 650ml solution containing the appropriate concentration of active ingredient. Each solution was mixed and applied at a spray volume of 50 litres/hectare to a plot 3 metres by 10 metres comprising the weed population, which was naturally occurring, and crop species which was sown 5 days prior to the treatment. Four replicates were performed. A control plot was sprayed with a solution not containing test compound. Visual assessment of phytotoxicity was made 14, 28 and 42 days after crop emergence for 20 each weed species based on a comparison with the control plot on a •scale of 0 to 10 (whereby 10 represents complete control of the weed).

The tables below show the observed control of the weed species (on a scale of 0-10) by each combination, with the figure in brackets representing the predicted value using the Colby formula where it is 25 possible to calculate such values.

RESULTS

Weed Population: Annual Ryegrass 14 Days after Emergence Table 1 Clomazone Dose g/ha 0 180 0 5.25 75 8.75(5.25) 100 0.00 8.88(5.25)

DFF

5* 9 28 Days After Emergence Table 2 Clomazone Dose g/ha 0 180 0 5.75 75 8.75(5.75) 100 0.00 8.25(5.75)

DFF

42 Days After Emergence Table 3 Clomazone Dose g/ha 0 180 0 5.00 75 7.80(5.00) 100 0.00 7.25(5.00)

DFF

Note that in the above trials DFF alone is inactive at doses up to 150g/ha.

Throughout this-specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form or suggestion that that prior art forms part of the common general knowledge in Australia.

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Claims (7)

1. A herbicidal composition comprising a synergistic herbicidally effective amount of:- clomazone, which is 2-(2-chlorobenzyl)-4,4-dimethyl-1,2-oxazolidin-

3-one; and difluenican, which is N-(2,4-difluorophenyl)-2-[3- (trifluoromethyl)phenoxy]-3-pyridinecarboxamide; in association with a herbicidally acceptable diluent or carrier and/or surface active agent. 2. A composition according to claim 1 in which the weight ratio of is from 13.7:1 to 1.2:1. 3. A composition according to claim 1 or 2 in which the weight ratio of is from 6.4:1 to 2.4:1.

4. A method for controlling the growth of weeds at a locus which comprises applying to said locus a synergistic herbicidally effective amount of:- clomazone, which is 2-(2-chlorobenzyl)-4,4-dimethyl-1,2-oxazolidin- 3-one; and difluenican, which is N-(2,4-difluorophenyl)-2-[3- 20 (trifluoromethyl)phenoxy]-3-pyridinecarboxamide. A method according to claim 4 using from 120 g/ha to 480 g/ha of clomazone and from 35 g/ha to 100 g/ha of diflufenican.

6. A method according to claim 4 or 5 using from 120 g/ha to 240 g/ha of clomazone and from 37.5 g/ha to 50 g/ha of diflufenican.

7. A method according to claim 4, 5 or 6 in which the weed species controlled include grass weed.

8. A method according to claim 7 in which the grass weed is Annual ryegrass (Lolium perenne). 30 9. A method according to any one of claims 4 to 8 in which clomazone and diflufenican are applied pre-emergence. A composition according to claim 1 substantially as hereinbefore described.

11. A method according to claim 4 substantially as hereinbefore described. DATED this 28 th day of August, 2003 Rh6ne-Poulenc Agro by DAVIES COLLISON CAVE Patent Attorneys for the Applicant