IE60076B1

IE60076B1 - Herbicidal compositions containing biscarbamates

Info

Publication number: IE60076B1
Application number: IE83187A
Authority: IE
Original assignee: Rhone Poulenc Agrochimie
Priority date: 1986-04-02
Filing date: 1987-03-31
Publication date: 1994-06-01
Also published as: CN1024445C; FI884524A0; EP0299961A1; CN87102237A; EP0299961B1; FI884524A; ES2004130A6; FR2596618B1; PL264906A1; DE3782937D1; GR870518B; IE870831L; WO1987005778A1; DD263221A5; DE3782937T2; FR2596618A1

Abstract

Liquid herbicidal compositions based on biscarbamate and usable particularly for weed-killing in beet root fields, characterized in that the biscarbamate has the formula X-C6H4(m)-NH-CO-O-C6H4(m)-NH-CO-O-R wherein (m) indicates that the aromatic radical is a radical meta-di-yl, X is a hydrogen atom or an alkyl radical comprising from 1 to 3 carbon atoms, R is an alkyl radical comprising from 1 to 3 carbon atoms, and in that said compositions comprise in weight percent from 10 to 50% of biscarbamate having the formula (I), from 20 to 60% of vegetable oil, from 5 to 40% of surface-active agents having emulsifying and dispersing properties, from 20 to 60% of water.

Description

The present invention relates to liquid herbicidai compositions based on meta-biscarbamates as } active substance and more particularly to compositions in the form of a dispersion of the active substance in » an organic/agueous emulsion.

The term m-biscarbamates used hereinafter refers to herbicides of the formula: X - CgH4(m)- NH - CO - 0 - CgH4(m)- NH - CO - 0 - R (I) wherein (m) indicates that the phenylene radical is a meta-phenylene radical, X represents a hydrogen atom or an alkyl radical containing from 1 to 3 carbon atoms, and R represents an alkyl radical containing from 1 to 3 carbon atoms.

Representative examples of herbicides of this family are phenmedipham (compound of formula (I) in which X = R = CH^) and desmedipham (compound of formula (I) in which X is a hydrogen atom and R is an ethyl radical). These compounds are especially useful in post-emergence weed control in beet crops.

These compounds, and especially phenmedipham, are generally used in the form of emulsifiable concentrates containing an organic solvent and a surfactant. These adjuvants are considered essential » because, without them, phenmedipham tends to crystallize » during application, which prevents it from penetrating into the plants and exercising its herbicidai action. -3The possibility of preparing agueous emulsions of phenmedipham has been mentioned, but not described specifically, in French Patent 1,536,108, Russian Patent 671,798 and European Patent Application No. 102,003, but agueous compositions which are stable and which have a good biological activity have not been available so far.

The present invention seeks to provide concentrated agueous compositions of biscarbamates and especially of phenmedipham. Concentrated aqueous compositions intrinsically have various advantages, especially in that they are generally less expensive and more conducive to safety.

The present invention also seeks to provide concentrated aqueous compositions of phenmedipham which, after dilution with water, lead to mixtures which have a good biological activity, i.e. exhibiting a good herbicidal effect, of the same order of magnitude as that of mixtures resulting from known emulsifiable concentrates.

The present invention also seeks to provide concentrated aqueous compositions of phenmedipham which, after dilution with water, do not lead to the formation of phenmedipham crystals of size greater than 40 microns. In fact, such a crystallization is harmful because microcrystals of size greater than 40 microns tend to block the nozzles of spraying equipment.

The present invention seeks to provide -4concentrated aqueous compositions which have a good physical-chemical stability over a period of time.

The present invention accordingly provides liquid herbicidal compositions which comprise, by weight: to 50% of a biscarbamate of formula (I), preferably phenmedipham; to 60% of vegetable oil; to 40% of surfactant with emulsifying and dispersing properties; and to 60% of water.

In practice, the compositions according to the invention are of a mixed liquid/liquid emulsion and solid/liquid dispersion nature.

Suitable vegetable oils are those contained in oil seeds and include linseed oil, sunflower oil, and preferably, rape seed oil and soya bean oil. They are generally obtained by extraction and/or pressing and/or crushing the oil seeds.

As mentioned above, the surfactant employed in the invention has emulsifying and dispersing properties. In practice, it is preferred to employ a mixture of two surfactants, one with dispersing properties and the other with emulsifying (or emulsioning) properties. Suitable surfactants with emulsifying properties are generally such that, if a mixture containing equal volumes of water and vegetable oil and 10%' by weight of -5the surfactant under consideration is stirred vigorously with a rotary stirrer this mixture does not separate back into two distinct liquid phases after allowing it to stand for 1 h. Suitable surfactants with dispersing properties are generally such that, if a mixture containing 100 g of phenmedipham, 1 litre of water and 50 g of surfactant is stirred vigorously with a rotary stirrer, the mixture does not reprecipitate after allowing to stand for 1 h.

According to another feature of the invention, a mixture of at least one ionic surfactant and at least one nonionic surfactant is used as the surfactant with dispersing and emulsifying properties.

When a surfactant comprising a mixture, either a mixture of a surfactant with emulsifying properties with a surfactant with dispersing properties, or a mixture of an ionic surfactant with a nonionic surfactant is used, the relative proportion by weight of the two types of surfactant in the mixture is usually from 1:9 to 9:1, preferably from 1:3 to 3:1. As surfactants with dispersing properties and surfactants which are ionic in nature, there may be mentioned polyacrylic acid salts, lignosulphonic acid salts, phenolsulphonic or naphthalene- 6 sulphonic acid salts, polycondensates of ethylene oxide with fatty acids and their salts, salified polycondensates of ethylene oxide with fatty amines, alkylbenzene sulphonates and alkylnaphthalene sulphonates, suIfosuccinic acid ester salts, taurine derivatives (especially alkyl taurates), phosphoric acid mono- or diesters of polycondensates of ethylene oxide with alcohol or phenol (especially polycondensates of ethylene oxide with di- or triphenylethylphenol). In most of these compounds, the alkyl chains have 6 to 20 carbon atoms and the ethylene oxide polycondensate chains generally have 6 to 30 ethoxy groups.

As surfactants with emulsifying properties or as nonionic surfactants, there may be mentioned polycondensates of ethylene oxide with alkylphenols or polyalkylphenols or polyarylalkylphenols (especially derivatives with alkyl groups containing from 8 to 12 carbon atoms), polycondensates of ethylene oxide with aliphatic alcohols (especially Cg to C2q), polycondensates of ethylene oxide with fatty acid esters (especially Cg to C2{p* polycondensates of ethylene oxide with anhydrosorbitol (= sorbitan) esters, polyoxypropylene glycols, polyconjdensates of ethylene oxide with polyoxypropylene glycols, and copolymers of alkylene oxide and esters of these polyethers. In most of these compounds, the ethylene oxide polycondensate or polyoxyalkylene chains generally contain from 2 to 30 ethoxy or oxyalkylene groups. - 7 The emulsifying activity of the surfactants with emulsifying properties which are nonionic in nature nay be enhanced, if required, with a surfactant of the ionic type, such as alkali aetal alkyl (Cg-C^g) benzenesulphonates or phosphoric acid esters of polyethers.

In addition to the constituents mentioned above, the compositions according to the invention may comprise from 0.01 to 52, preferably 0.05 to 12, of a hydrophilic heterppolysaccharide biopolymer with thickening properties.

The heteropolysaccharide type of hydrophilic biopolymers which can be used in the invention are known products. They have a molecular weight greater than 200,000 and preferably greater than 1,000,000; they have pseudoplasticity properties and are generally obtained by the action (i.e. fermentation) of bacteria of the genus Xanthomonas on carbohydrates. These biopolymers are also sometimes called by various other names such as: hydrophilic colloids of Xanthomonas; heteropolysaccharide gums; xanthan gums; extracellular heteropolysaccharides originating from Xanthomonas or froa bacteria of the family Pseudomonacea. The word biopolyaer is used in the sense that it refers to polymers resulting froa a biological process (bacterial fermentation in this case).

The bacteria used for. the preparation of these biopolyaers are generally Xanthomonas campestris but other species of Xanthomonas such as Xanthomonas carotae. - 8 Xanthomonas incanae, Xanthomonas begoniae, Xanthomonas malvacearum, Xanthomonas vesicatoria, Xanthomonas translucens, Xanthomonas vasculorum may also be used. Carbohydrates suitable for fermentation with Xanthomonas bacteria include glucose, sucrose, fructose, maltose, lactose, galactose, starch and potato starch.

As is usual in the field of preparing compositions for use in plant protection, any other known additive, especially antifreezes and/or antifoams, may be incorporated into the compositions according to the invention; these products facilitate the practical implementation and use of the compositions according to the invention without, however, being indispensable for the invention.

The preparation of the compositions according to the invention may be carried out by any means known per se for mixing the various liquid and solid constituents.

The handling of the compositions according to the invention does not give rise to any dust; these compositions do not constitute any fire hazard and avoid the use of organic solvents.

The present invention also relates to a method of controlling the growth of weeds at a locus particularly at the locus of a beet crop and especially of a sugar beet crop, which comprises the post-emergence application to the locus, for example to a field carrying a beet crop, of a composition prepared by the - 9 dilution with water of a composition according to the invention. According to the method of the invention, the diluted composition employed, generally contains 1 to 10 g of biscarbamate per litre of mixture applied (diluted with water), preferably 1.1 to 6 g/1; 150 to 2,000 g/ha of biscarbamate of formula (I), preferably 250 to 1,000 g/ha, are generally applied.

The following Examples illustrate the invention and show how it can be put into practice.

Examples: compositions, 1 litre in volume and each containing 100 g of phenmedipham, are prepared. The mixing is carried out using a grinder mixer. Before mixing, the phenmedipham employed was of a crystal size of between 1 and 30 microns.

The remaining constituents of each of these compositions are as follows: Composition No, 1: 500 g of rape seed oil g of mono- and/or diester of phosphoric acid with the polycondensate of ethylene oxide (18 units) with tris(phenylethyl)phenol g of a mixture of the polycondensate of ethylene oxide with tributylphenol (8 ethoxy units; 5 g) and the polycondensate of ethylene oxide with a C31 to C13 branched alcohol (10 ethoxy units; 8 g) - 10 2 g of heteropolysaccharide biopolymer g of propylene glycol (antifreeze) g of polysiloxane oil (antifoam) 307 g of water Composition No. 2 to 4; In composition No. 1, rape seed oil is replaced successively with a similar quantity of soya bean oil (No. 2), linseed oil (No. 3) and sunflower oil (No. 4). Composition No. 5; 300 g of rape seed oil 100 g of polycondensate of ethylene oxide (10 ethoxy units) with a linear alcohol g of the whole mixture of adjuvants (other than oil and water) used in composition No. 1.

By way of comparison, a composition No. 6 was also employed; this is a composition marketed under the name Betanal* which is an emulsifiable concentrate based on isophorone as the solvent.

These various compositions, which are stable for at least 6 months, were tested for physical and plant protection properties.

Physical properties; study of crystallization on dilution with water: A test is carried out to evaluate the tendency of the compositions to form crystals on dilution with water, it being understood that the formation of crystals of size greater than 40 microns is considered harmful. a The composition to be tested (20 cc) is added to ~ 11 water (980 cc) in the course of 40 seconds, with stirring (in order to homogenize). Precipitate formation is initiated by adding solid phenmedipham (300 mg). After 24 h, the mixture is filtered through a sieve with a pore size of 40 microns. The precipitate is washed for 1 minute with a jet of water. The precipitate is collected, dried and then weighed.

The test as described above is used for testing mixtures obtained by diluting compositions No.1 to 6 with water. Tests on these mixtures were carried out by diluting these compositions until a mixture containing 2.5 g/l of phenmedipham was obtained on the one hand and until a mixture containing 1.5 g/l of phenmedipham was obtained on the other. Such dilutions are approximately of the order of magnitude of dilutions of mixtures applied by farmers to crops in weed control treatments; whereas the concentrated compositions are those stored and handled before diluting to obtain a mixture.

None of the compositions No. 1 to 5 gave rise to the appearance of microcrystals of size greater than 40 microns.

In contrast, composition No. 6 leads to the appearance of microcrystals of size greater than 40 microns. At the 2.5 g/l dilution, 272 by weight of phenmedipham in the initial concentrated composition was found in the form of microcrystals of size greater than 40 microns; at the 1.5 g/l dilution, this percentage rose to 842.

Herbicidal properties: With a view to ensuring that the compositions of the invention had suitable herbicidal properties, the LD90 (lethal dose of application in g/ha at which 90Z of the plants of the species considered are destroyed) was measured. This measurement was carried out by applying mixtures of different concentrations obtained by diluting the concentrated compositions No. 1 to 6 with water. The following results were obtained: Polygonum bindweed Composition No. Setar ia Mustard Comp. No. 1 700 350 300 Comp. No. 2 300 320 300 Comp. No.3 1,200 600 400 Comp. No. 4 1,200 650 400 Comp. No. 5 330 350 300 Comp. No. 6 600 300 250 It is observed from the results above that the compositions according to the invention have a herbicidal effect of the same order of magnitude as the emulsifiable concentrate which is known and marketed, but have an - 13 important advantage of not having the tendency to form microcrystals which are too large.

By way of comparison, a composition No. 7, similar to composition No. 1, but in which the 500 g of vege5 table oil was replaced with 400 g of water, was also tested. The physical- properties of composition No. 7 were similar to the physical properties of composition No. 1; in contrast, with respect to herbicidal properties, composition No. 7 had an LD 90 of greater than 2,000 towards the three weeds mentioned above, which demonstrates a much lower herbicidal activity.

Claims

1. WE CLAIM

1. A liquid herbicidal composition which is in the form of a dispersion of the active substance in an aqueous/organic emulsion and which comprises, by weight: 10 to 50% of a biscarbamate of the general formula: X - CgH^(m)- NH - CO - 0 - CgH 4 (m)- NH - CO - 0 - R (I) wherein (m) indicates that the phenylene radical is a meta-phenylene radical, X represents a hydrogen atom or an alkyl radical containing from 1 to 3 carbon atoms, and R represents an alkyl radical containing from 1 to 3 carbon atoms; 20 to 60% of vegetable oil; 5 to 40% of surfactant with emulsifying and dispersing properties; and 20 to 60% of water.

2. A composition according to claim 1 wherein, in general formula (I), X and R both represent methyl.

3. A composition according to claim 1 or 2 wherein the vegetable oil is linseed oil, sunflower oil, rape seed oil or soya bean oil.

4. A composition according to claim 1 or 2 wherein the vegetable oil is rape seed oil or soya bean oil.

5. A composition according to any one of the preceding claims which comprises 0.01 to 5% of a heteropolysaccharide biopolymer.

6. A composition according to claim 5 wherein the biopolymer is obtained by fermentation of carbohydrate by a bacterium of the genus Xanthomonas. - 15

7. A composition according to any one of the preceeding claims wherein the surfactant comprises at least two surfactants one of which has dispersing * properties and the other of which has emulsifying 5 properties.

8. A composition according to claim 7 wherein the surfactant with emulsifying properties is a polycondensate of ethylene oxide with alkylphenol, polyalkylphenol or polyarylalkylphenol, a polycondensate 10 of ethylene oxide with aliphatic alcohol, a polycondensate of ethylene oxide with fatty acid ester, a polycondensate of ethylene oxide with anhydrosorbitol ester, a polyoxypropyleneglycol, a polycondensate of ethylene oxide with polyoxypropyleneglycol or a 15 copolymer of alkylene oxide, or an ester of such polyethers.

9. A composition according to claim 7 or 8 wherein the surfactant with dispersing properties is a polyacrylic acid salt, a lignosulphonic acid salt, a 20 phenolsulphonic or napthalenesulphonic acid salt, a polycondensate of ethylene oxide and fatty acid or a salt thereof, a salified polycondensate of ethylene oxide with fatty amine, an alkylbenzene sulphonate or « alkylnapthalenesulphonate, a sulphosuccinic ester salt, 25 a taurine derivative, a mono or diester of phosphoric acid with a polycondensate of ethylene oxide with alcohol or phenol. - 16 10. A composition according to claim 9 wherein the taurine derivative is an alkyl taurate and the polycondensate of ethylene oxide with alcohol or phenol is a polycondensate of ethylene oxide with di- or 5 triphenylethylphenol. 11. A composition according to claim 1 substantially as hereinbefore described. 12. A method of controlling the growth of weeds at the locus of a crop which comprises the post-emergence

10. Application of a composition obtained by the dilution with water of a composition according to any one of claims 1 to 11.

11. 13. A method according to claim 12 wherein the crop is a beet crop.

12. 15 14. A method according to claim 12 or 13 wherein the composition applied to the locus comprises 1 to 10 g/1 of biscarbamate. 15. A method according to claim 12 or 13 wherein the composition applied to the locus comprises 1.1 to 6 g/1 20 of biscarbamate.

13. 16. A method according to any one of claims 12 to 15 in which 150 to 2,000 g/ha of biscarbamate is applied to the locus.

14. 17. A method according to claim 16 in which 250 to 25 1,000 g/ha of biscarbamate is applied to the locus.

15. 18. A method according to claim 12 substantially as hereinbefore described.