LU87872A1 - METHOD FOR CONTROLLING WEEDS IN CORN FIELDS USING A MIXTURE OF ACLONIFEN AND ANOTHER N-CHLORO ACETAMIDE HERBICIDE - Google Patents

Description

The invention relates to a new method for controlling weeds in corn fields using a mixture of aclonifen and another herbicide of the N-chloro acetamide type. cornfield. It also relates to the herbicidal compositions intended in particular for implementing the process.

All kinds of herbicides are known to weed all kinds of crops. However, practice shows that, despite the multiplicity of herbicides available, it is often difficult to properly weed a particular crop. Among the crops causing problems and requiring specific solutions, we can mention the weeding of corn.

An object of the invention is to provide a satisfactory means for weeding the corn, in particular with weed killers other than atrazine, the method according to the invention then having the advantage of leading to reducing the pollution of groundwater compared to known processes using atrazine and also being more effective for the destruction of certain weeds known to be resistant to said triazines.

Compositions based on aclonifen have already been described in European patent application No. 342 134, but these compositions illustrated a particular means for obtaining stable emulsions, this means being a derivative of titanium, and this state of the art did not provide any suggestion relating to the aims of the present invention and the means of achieving these aims.

The method according to the invention is characterized in that a mixture consisting of aclonifen and at least one chosen N-chloro acetamide herbicide is applied to the place where corn seeds have been sown, before their emergence. among acetochlor, alachlor, metholachlor, metazachlor, preferably alachlor.

According to a general procedure which is obviously only given as an indication and not limiting, it is considered that the application period varies according to the climatic conditions between 1 to 3 weeks approximately after sowing

Metholachlor is 2-chloro-6'ethyl-N- (2-methoxy-l-methylethyl) acet-o-toluidide. Acetochlor is 2-chloro-N-ethoxymethyl-6'-ethylacet-o-toluidide. Aclonifen is 2-chloro 6-nitro 3-phenoxyaniline. The alachlor is 2-chloro 2 ', 6'-diethyl N-methoxymethylacetanilide.

Preferred rates for alachlor 1 to 3 kg / ha of aclonifen 1 to 2.5 kg / ha of alachlor and more advantageously 1000 to 1500 g / ha of aclonifen 1500 to 2500 g / ha of alachlor Among the bad weeds that can be destroyed include Setaria sp Chenopodium sp Atriplex sp Mercurialis sp Digitaria sp Solanum sp

The processes defined above are most often carried out with only aclonifen and a single other herbicide, but it is also possible, without departing from the present invention, to associate therewith one or more compatible pesticides and, preferably , complementary.

For the implementation of the herbicidal processes according to the invention, it is advantageous to use ready-to-use products, most of the time in the form of compositions as will be described below, containing the two active materials. It is also possible (although not preferred) to use a packaging comprising an internal partition separating the two active materials in the form or not of composition. It is therefore in this case an extemporaneous mixture of active ingredients. A subject of the invention is also the herbicidal compositions intended in particular for implementing the method according to the invention. Most often, these herbicidal compositions contain the active materials according to the invention as described above in association with solid or liquid carriers, acceptable in agriculture and surfactants also acceptable in agriculture. In particular, the usual inert supports and the usual surfactants can be used. These compositions are also part of the invention.

These compositions can also contain all kinds of other ingredients such as, for example, protective colloids, adhesives, thickeners, thixotropic agents, penetrating agents, stabilizers, sequestering agents, etc. other known active ingredients with pesticidal properties (in particular insecticides, fungicides or herbicides) or with properties regulating plant growth. More generally, the compounds used in the invention can be combined with all the solid or liquid additives corresponding to the usual techniques of formulation. In general, the compositions according to the invention usually contain from 0.05 to 95% approximately of the active materials used according to the invention, from 1% to 95% approximately from one or more solid or liquid carriers and optionally from 0.1 to 50% (preferably 5 to 40%) of approximately one or more surfactants.

Preferably the aclonifen / alachlor weight ratio is between 1 / 2.5 and 3, advantageously 1 / 2.5 and 1.

By the term "support", in the present description, is meant an organic or mineral, natural or synthetic material, with which the active materials are associated to facilitate their application to the plant, to seeds or to the soil. This support is therefore generally inert and it must be acceptable in agriculture, in particular on the treated plant.

As solid supports (or fillers) mention may be made of mineral or synthetic fillers such as kaolin, attapulgite, montmorillonite, bentonite, talc, fuller's earth, diatomaceous earth, kieselguhr, calcium carbonates and magnesium, precipitated synthetic silica, alumina, alkali silicates and silicoaluminates, resins, waxes, solid fertilizers. It is also possible to use water-soluble fillers such as sodium or ammonium sulfates and urea.

As liquid carriers, mention may be made of water, alcohols (in particular butanol), esters (in particular methyl glycol acetate), ketones (in particular cyclohexanone and isophorone), petroleum fractions, aromatic hydrocarbons (in particular xylenes or paraffinics), chlorinated aliphatic hydrocarbons (in particular trichloroethane) or aromatic (in particular chlorobenzenes), water-soluble solvents such as dimethylformamide, dimethylsulfoxide, N-methyl-pyrrolidone. The surfactant can be an emulsifying, dispersing or wetting agent of ionic or nonionic type or a mixture of such surfactants.

As nonionic wetting agents, polyethoxylated alkylphenols (in particular octyl-, nonyl- and tributylphenols having from 6 to 18 oxyethylene units) can be cited, polyethoxylated fatty alcohols (in particular alcohols from C ^ g to C ^ g having from 6 to 18 oxyethylene units), polyethoxylated fatty amines (in particular tallow amine, or tall oil, having from 2 to 40 oxyethylene units), polyethoxylated esters of fatty acids and of polyols (of glycerin or sugar type) (in particular sorbitan laurate and stearate having from 5 to 20 oxyethylene units).

As anionic wetting agents, mention may be made of the alkylnaphthalene sulfonate ester salts (especially sodium or potassium isopropyl-, butyl- and dibutylnaphthalene sulfonate, fatty alcohol ester sulfate salts (especially sodium or potassium lauryl sulfates) , the sulfosucci'nate salt esters of fatty alcohols (in particular sodium or potassium dioctyl sulfosuccinates), taurine derivatives (in particular alkyltaurates, aryl-N-methyltaurides, sodium oleylmethyltauride).

As nonionic dispersing agents, mention may be made of polyethoxylated arylphenols (in particular di- and tri- (phenylethyl) phenols comprising 18 to 40 oxyethylene units).

As anionic dispersing agents, mention may be made of salified polycarboxylic polymers (such as polycarboxylate polymers and sodium polyacrylates), polycondensates of formaldehyde and diphenolsulfonates or of alkylnaphthalene sulfonates (in particular of sodium methylnaphthalene sulfonate), salt esters or acids phosphorics of polyoxyethylenated alkyl- or aryl-phenols (in particular phosphoric esters of nonylphenols having 6 to 18 oxyethylene units in acid or potassium salt form as well as phosphoric esters of di- or tri- (phenylethyl) phenol having 18 to 40 units oxyethylene in acid or salt form), phosphated polyoxyethylenated fatty alcohols (in particular fatty alcohols C · ^ to C ^ g having 6 to 18 oxyethylene units), alkali or alkaline earth lignosulfonates.

The compositions according to the invention, especially when it is self-dispersible granules, can also contain from 1 to 50% by weight of natural or synthetic binder.

As natural binder, mention may be made of starch and its derivatives (in particular modified starch and dextrin), cellulose derivatives (in particular carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose), sugars (such as lactose, mannitol, sorbitol), gums (such as gum arabic and xanthan gums).

As synthetic binder, mention may be made of polymers (in particular polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, alkaline polyacrylates), polycondensates (especially polyethers such as polyglycols; maleic anhydride copolycondensates; polycondensates of formalin and alkylnaphthalene sulfonates, such as polycondensate of formalin and sodium methylnaphthalene sulfonate), alkaline lignosulfonates.

The presence of at least one surfactant in the compositions according to the invention is generally essential because, on the one hand, the active materials and / or the inert support are not soluble in water and, on the other hand, the vector agent of the application is water.

For their application, the compositions according to the invention are in fairly diverse forms, solid or liquid; these are relatively dilute forms, while the compositions suitable for transport, trade and storage are rather concentrated compositions.

As forms of solid compositions, mention may be made of wettable powders and powders for dusting (with an active ingredient content of up to 100%) and granules (preferably self-dispersible), in particular those obtained by extrusion, by compacting, by impregnation of a granulated support, by granulation from a powder (the content of active materials of formula (I) and of group (II) in these granules being between 0.5 and 80% for the latter cases).

It is nevertheless preferred to use in the invention compositions in liquid form. Mention may be made of emulsifiable concentrates, concentrated suspensions and concentrated emulsions.

The concentrated suspensions, which are applicable in spraying, are prepared so as to obtain a stable fluid product which does not deposit (fine grinding) and they usually contain from 10 to 75% of active materials, from 0.5 to 15% of surfactants, 0.1-10% thixotropic agents, 0-10% suitable additives, such as defoamers, corrosion inhibitors, stabilizers, penetrating agents and adhesives and, as a carrier , water or an organic liquid in which the active ingredients are not very soluble or insoluble: certain organic solid matters or mineral salts can be dissolved in the support to help prevent sedimentation or as antifreezes for water. As an example, here is a concentrated suspension composition (Example 1): - active ingredients 500 g - polyethoxylated tristyrylphenol phosphate 50 g - polyethoxylated alkylphenol 50 g - sodium polycarboxylate 20 g - ethylene glycol (antifreeze) 50 g - oil organopolysiloxane (antifoam) 1 g - polysaccharide (thickener) 1.5 g - water 316.5 g

The emulsifiable or soluble concentrates most often comprise 10 to 80% of active material, the emulsions or solutions ready for application containing, for their part, 0.001 to 20% of active material.

In addition to the solvent, emulsifiable concentrates can contain, when necessary, 2 to 20% of suitable additives such as stabilizers, surfactants, penetrating agents, corrosion inhibitors, dyes or adhesives previously cited. From these concentrates, emulsions with any desired concentration can be obtained by dilution with water, which are particularly suitable for application to crops. As an example, here is the composition of some emulsifiable concentrates:

Example (formulation) 2: - active ingredients 400 g / 1 - alkali dodecylbenzene sulfonate 24 g / 1 - oxyethylated nonylphenol containing 10 molecules of ethylene oxide 16 g / 1 - cyclohexanone 200 g / 1 - aromatic solvent q.s.p. 1 litre

According to another formula of emulsifiable concentrate, the following are used:

Example F 3: - active ingredients 250 g - epoxidized vegetable oil 25 g - mixture of alkylaryl sulfonate and polyglycol ether and fatty alcohols 100 g - dimethylformamide 50 g - xylene 575 g

Concentrated emulsions are compositions in the form of stable liquid emulsions, the active material being in liquid form by itself or in form dissolved in a solvent. These emulsions are essentially aqueous and, in addition to water, usually contain 20 to 80% of active material, 0 to 35% of solvent (this solvent being simply useful for dissolving the active material if it is solid, and being generally used in the minimum quantity to achieve this goal), 1 to 15% (preferably 2 to 10% r of a water-soluble surfactant, optionally 1 to 12% (preferably 2 to 6%) of a hydrophobic or liposoluble surfactant, and possibly also various other adjuvants such as for example 1 to 10% of stabilizing agent for the emulsion, 0 to 5% of mineral or organic thickening agent and 0 to 10% of various agents such as defoamers, biocides, antifreezes, etc ... The preparation of these emulsions is carried out by adding the oily phase (that is to say organic liquid) to the aqueous phase with stirring, followed by homogenization for example using a colloid mill.

As regards the compositions suitable for storage and transport, they more advantageously contain from 0.5 to 95% (by weight) of active substance.

Thus, the compositions for agricultural use according to the invention can contain the active materials according to the invention within very wide limits, ranging from 0.05 to 95% (by weight). Their content of surfactant is advantageously between 5% and 40% by weight. The following example, given without limitation, illustrates the invention and shows how it can be implemented.

The tests are carried out on elementary plots of 30 m ^ each invaded naturally by a mixed grass + dicotyledonous flora.

Each treatment is repeated on two different plots, each adjacent to an untreated control plot. The application is made pre-emergence after sowing at the rate of 300 l / ha of spray.

A survey is carried out 8 weeks after emergence, the percentage of effectiveness is measured (100% = 100% of herbs destroyed).

The mixture is prepared, diluted with water and intended to be applied to plants, from the commercial concentrates of each of the constituents. In the results presentation table, the following abbreviations were used:

Weeds Abbreviations

AMARANTHUS SP AMA

ATRIPLEX PATÜLA ATP

BRASSICA NAPUS BRA

CHENOPODIUM SP CHS

DIGITARIA SP DIG

FALLOPIA CONVOLVULUS FAL

GALIUM APARINE GAP

MATRICARIA SP MAT

MERCURIALIS ANNUA MEA

POLYGONUM AVICULARE POA

POLYGONUM PERSICARIA POP

SETARIA SP SET

SINAPIS ARVENSIS SIA

SOLANUM NIGRUM SOUND

STELLARIA MEDIA STE

VERONICA PERSICA VER

Cultures

BUT BUT

The following results, expressed as percentage of destruction, were obtained by applying the aclonifen + alachlor mixture at the dose such that the aclonifen is applied at the rate of 1 kg / ha and the alachlor at the rate of 1.8 kg / ha .

Weeds Pre-emergent AMA 90 CHS 72 POP 90 DIG 84 SET 95

Crops BUT 5 At the dose of 1144 g / ha of aclonifen and 2056 g / ha of alachlor, the following results are obtained AMA 88 ATP 100 CHS 72 MEA 100 SON 67 DIG 58

A similar trial with a dose of 864 g / ha of atrazine and 2016 g / ha of alachlor gave the following results: AMA 88 ATP 90 CHS 18 MEA 100 SON 67 DIG 42

These corn weeding results correspond to satisfactory and equivalent performances or superior to those of mixtures of the atrazine-alachlor type, but the mixtures of the invention do not have the drawbacks due to atrazine with respect to the sheets. phreatic. Mixtures based on aclonifen and pendimethalin lead to equally equivalent herbicidal performances, and with a situation with regard to groundwater also favorable.

Claims (7)

1) Method for controlling weeds in corn fields, characterized in that a mixture consisting of aclonifen and at least one is applied to the place where corn seeds have been sown minus one herbicide chosen from Acetochlor, metazachlor, alachlor, metolachlor. 2) Method according to claim 1, characterized in that the herbicide is chosen from alachlor 3) Method according to claim 2, characterized in that one applies 1 to 3 kg / ha of aclonifen 1 to 2.5 kg / ha of alachlor. 4) Method according to claim 3 characterized in that one applies 1000 to 1500 g / ha of aclonifen 1500 to 2500 g / ha of alachlor 5) Method according to one of claims 1 to 4 characterized in that the weeds are chosen from Setaria sp Chenopodium sp Atriplex sp Amaranthus sp Mercurialis sp Digitaria sp Solanum sp 6) Herbicidal composition intended in particular for implementing the method according to one of claims 1 to 5, characterized in that it comprises 0.05 to 95% of active material 7) Composition according to claim 6, characterized in that the aclonifen / alachlor weight ratio is between 1 / 2.5 and 3, advantageously 1 / 2.5 and 1.