IE61109B1 - Compositions including herbicidal combinations of the glyphosate and the phenoxybenzoic type - Google Patents

Abstract

Compsn. contains at least one glyphosate type herbicide (A) and at least one phenoxybenzoic-type herbicide (B) at wt. ratio (B):(A) of 1:12-80, pref. 1:15-50. Compsns. are applied post-emergence at 0.3-0.9 (esp. 0.5-0.7) kg (A)/hectane plus 0.005-1 (esp. 0.02-0.08) kg (B)/hectane. [ES2007741A6]

Description

The present invention relates to new herbicidal compositions based on a glyphosate-type herbicide and a phenoxybenxo’ic-type herbicide. It also relates to a process for the treatment of undesirable plants using these compositions, Glyphosate (or N-phosphonomethylglycine) and its salts are well-known wide-spectrum herbicides which are active against annual and perennial weeds. This class of herbicides is especially known for its post-emergence efficacy and is used for agricultural applications and for garden activities. Nevertheless, it is still desirable to improve the herbicidal activity of these compounds, However, it is known that glyphosate-type herbicides act relatively slowly. In, fact, a period of approximately three weeks is generally required before the effects are observed.

In order to overcome this disadvantage, the PCT Patent Application WO 84/03607 indicates that, in the specific case of application to amateur gardens, th© addition of a certain quantity of acifluorfea or one of its salts to glyphosate-type herbicides increases the speed os action of glyphosate-type herbicides- la this context, an effective quantity of glyphosate-type herbicide ia employed and acifluorfea is added so that the ratio by weight is practically between 1/8.33 and 4.2. However, it is observed that the compositions described reveal a marked antagonism in many eases, which results in the efficacy of the glyphosate-type herbicide being adversely affected. The use of extemporaneous mixtures of glyphosate and acifluorfen against weeds of field crops such as soyabean, and not of garden weeds, has also been proposed. Thus, the publication Proceedings, Southernwoods Science Society, 38th annual meeting, Sanberg et al., 1985, pages 86 to 89, indicates that a 430 g/ha dose of glyphosate combined with 70 g/ha of acifluorfen shows a marked antagonism against the weeds tested, this antagonism decreasing, moreover, when the glyphosate:acifluorfen ratio decreases, that is to say when the quantity of acifluorfen is increasedA second publication, ibid., pages 64-67, Frost et al., also confirms the fact that it is necessary to increase the dose of acifluorfenIt is also seen from the latter publication that the spectrum of activity of glyphosate is reduced, especially against graminaceous plants.

Another disadvantage related to the mode of action of glyphosate or of its derivatives lies in the fact that it can very easily be leached. That is to say that, if there is a heavy rainfall a few hours after its application, a large part of it is removed. It is also desirable to improve the action of glyphosate-type herbicides on plants whose growth is slowed down by low temperatures and/or a low humidity, or on plants which are at the end of the growth cycle.

In an unexpected way, the present invention enables these disadvantages to be overcome and, more particularly, it enables one or more of the following objects to be achieved: - to increase the speed of action of glyphosatetype herbicides? to improve the activity spectrum of glyphosatetype herbicides? - to improve the herbicidal properties of glyphosate-type herbicides? to prevent glyphosate-type herbicides from being leached? and - to improve the activity of glvphosate-type herbicides on plants whose growth is slowed down by low temperatures and/or a low humidity or on plants which are at the end of the growth cycle. According to the present invention, th® herbicidal composition includes at least one herbicide of the glyphosate type (I) and at least one herbicide of the phenoxybenzoie type (VIII) and is characterized in that the (VIII)/(I) weight ratio is between 1/12 and 1/80 and preferably between 1/15 and 1/50.

This is equivalent to a molar ratio (VIII,/(I), taking into account the molar equivalence calculated on the basis of the acid for (I) as well as for (VIII), of between 1-2/12 and 1,2/80 and preferably between 1-2/15 and 1.2/50, DETAILED DESCRIPTION OF THS INVENTION 10 Glviohosate-type herbicides The glyphosate-type herbicides which may be employed in the present invention are compounds which correspond to formulae I and la below, as well as their metabolites and derivatives. The said compounds are defined by formulae I and la belows OR* ί O«P-CH2-NH-CS2-Z (tj OR2 in. which Z is a cyano group or a group COOR; R is a hydrogen atom or else is chosen from the lower alkyl, lower alkenyl or lower alkoxyalkyl groups: aryl groups containing β to 10 carbon atoms and optionally carrying 1 to 3 substituents chosen independently from the lower alkyl, lower alkoxy, halo, trifluororaethyl, nitro and cyano groups? or else is ra compatible cation, capable of forming a salt; Rx and. Rs are identical or different and are hydrogen atoms or are chosen from the lower alkyl, aryl, substituted aryl or biphenyl groups; or else are compatible cations capable of forming salts. 7ORJ Z *.? - CH, - N H, - CH, - Z1 (la) U , * oio W * OR* in which B Is a compatible anion, capable of forming a salt; R3 and R* are identical or different and represent hydrogen atoms or lower alkyl or aryl groups, which can be substituted, or biphenyl groups; Z1 is' a cyano group or a group COOR5; R5 may have the same meanings as those given for R, 5 except as regards a cation.

Xn formulae I and la, the valued compounds are those in which· Z and Z' are groups COOR and COOR3 respectively. With regard to formula (X), the valued compounds are those in which R, R1 and R3, which may be identical or different, are hydrogen atoms or compatible cations. Organic ammonium salts corresponding to formula (I) , especially those In which R is a cation derived from isopropylamine, give good results, and are commercially available. Organic sulphonium or sulphoxide salts (for IS example those in which Rx and/or Ra are the trimethylsulphonium cation or trimethyl sulphoxide) are also suitable. An example of a compound corresponding to formula I or la is the isopropylamine salt of N(phosphonoinethyl) glycine which is the active ingredient in 'the herbicide marketed by Monsanto under the trade name Roundup.

With regard to formula la, the valued compounds are those in which R3 and R\, which may be identical or different, represent lower alkyl or aryl groups, and in which Zx is a group COOR5, Rs feeing a lower alkyl or aryl group.

The cations and anions which are compatible from a herbicidal point of view are cations or anions forming part of a salt of formula X or la which do not alter the 30 herbicidal properties of the compound. The salt form is generally more soluble in water and more advantageous than the free acid or the corresponding free base., Examples of compatible cations include alkali metal cations such as sodium or potassium, alkaline-earth metal cations such as calcium or magnesium; cations of copper, zinc, iron, nickel, manganese, ammonium or organic ammonium, phosphonium, sulphonium or sulphoxide, these cations preferably having a molecular weight lass than 300. The organic cations of ammonium which are suitable include amine derivatives, especially aliphatic, cyclic or heterocyclic amines having 1 or 2 amine groups, such as alkylamines, alkyleneamines, alkenylemines and alkanolamines. Examples of amine derivatives include methylamine, ethylasaine, n-propylamine, isopropylamine, n-butylamine, isobutylasaine, sec-butylamine, n-amylamine, iso-emy lamine*, hexylemine, heptylamine, octylamise, nonylamine, decylamine, undecvlamine, dodecylamine, tridecylaaiae, tetradecylamine, pentadecylamine, hexaIQ decylamine, heptadecylamine, octadecvlamine, methylethylamine, methylisopropyl&mine, methylhexyland.se, raethylnonylamine, methylpentadecylamine, methyloctadecylamine, ethyIbutylaaine, ethylheptylamine, ethylocty lamine, hexylheptylamine, hexyloctylamine, IS dimethvlamine, diethylamine, di-n-propyl&mine, diisopropylamine, di-n-amylamine, diiso-anrylamine, dihexylamine, diheotylamine, dioetvlamine, trimethylamine , triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobuty lamine, tri-sec20 butylamine, tri-n-amylamine, n-sropanolamiae, isopropanol&mine, diethanolamine, Ν,Ν'’-diefchylethanolamine, 93-ethylpropanolamine, N-butylethanolamine, allylamine, n-butenyl-2-amine, n-pentenyl-2-amine, 2,3dimethylbutenyl-2-amine, dibutenyl-2-amine, n-hexenyl-225 amine and propylenediamine, primary aromatic amines such as aniline, methoxyaniline, ethoxyaniline, ortho-, metaand para-toluidine, phenylenediaaine, 2,4,6-tribromoaniliae, benzidine, naphthylssdne, ortho-, meta- aaa parachloroaailine, and the like^ heterocyclic amines such as pyridine, morpholine, piperidine, pyrrolidine, isdoline and azepine» Aaaosg suitable organic sulphoniua and sulpaoxide cations are Cx-Cie alkyl (preferably C3-C3 lower alkyl) sulphonium cations and C,-Ch@ alkyl (preferably lower alkyl) sulphoxide cations, such as triaethylsulphonium, efchyIdimethyIsulphoaium, tripropylsulphonium, trimethyl snlpfeoxide, triethyl sulphoxide and the like- These salts are described in particular is united States of America Patent So. 4.315.765. Suitable ohosohonium cations include those represented by the formula Rb Rffi — P - R C ia which K®, Rb and Re, which may he identical cr different, represent phenyl or C, to C10 alkyl radicals, preferably lower alkyl. These salts are described in united States of America Patent No.. 4,341,549. Other examples of suitable cations are described in united States of America Patent No. 3,799,758. Compatible anions which are suitable include the chloride, bromide, fluoride, sulphate, sulphite, bisulphite, phosphate, orthophosphate, carbonate, bicarbonate, acetate, butyrate, benzoate and maleate anions.

Compounds of formulae (I) and (la) are described, for example, in United States of America Patents Nos. 3,799,758, 3,835,000, 3,950,402, 4,067,719, 4,008,296, 4,147,719 and 4,369,142.

A large number of compounds which are metabolized by green plants or which function in a manner equivalent to that of the active part (from a phytotoxic point of view) of glyphosate may also be employed. These compounds include, for example, compounds represented by formulae I and la, and by the following formulae. os1 I a O-P-CH-N-Z (1X3 L· a5» OR3 z3I - P - CH - KH - Z i 3 2 3 (lib) OiV 1 0 - P - in2 OR1 I CH2 OR* - H - l· cr - H - Cl·? L z GF»1 I 1 - P - 0 i 2 OR (ΙΠ) 1 0 - ? 1CH2 - H -CH2 1 - P - 0 1 (XV) OS2 Z* OR2 1 OR 1 zi5 1 1 o · p . a 1 ' - N - 0 (V) '2. I 6 OS CH, -S R’-a | OR3 I 1 0 *» P 1 - o - P - 0 (VX) J Z3 - *NK3 - CK2 CH2 - HH, - Z 3 2 : ’ Z" " 2 2 . R -0 Q-R1 I I O-P-O-P-O (V2X) Z - S3H CH„ CH - HR - Z 4 in which; 23, R3, R3, R3 and R4 correspond to the definitions mentioned above? S'4 is a group CHaCN? COSiSOB (or its tautomeric form, 5 -C(OB)~NOB); CB,COOR, in which δ has the meaning mentioned above; CONR’R*, in which R7 and R", which may be identical or different, also have the same meanings as those given for H? Z3 is a group -CB,-CN; -CONBOB (or its tautomeric form 10 -C(OS)-NOH); ~CS2? -COOR8 or -CQNR’R’ in which the different groups R\, which may be identical to or different from one another, have one of the meanings mentioned above, δ8® is a lower alkyl, lower alkoxy, hydroxy, lower alkanoyl, optionally substituted aryl8 carbonyl, trifluoroacetyl, lower alkylthio, lower alkanoyl? amino, alkylamino, nitro or nitroso group, or a radical -COOR®, -OCH? COOP10, -CH2P(O)0PlS (OR23), -S(0)mRu, -SO-X-R or -CO-S (0) m-Ri2, in which R® is a lower alkyl, lower alkenyl or optionally substituted aryl group, Ru is a lower alkyl or optionally substituted aryl group? X represents -O- or -S-; R12 is chosen from lower alkyl, lower alkenyl, lower alkynyl, optionally substituted aryl or optionally substituted (lower) arylalkyl groups? m is equal to 0, 1 or 2? Rls, R2S and R30 have the same meanings as those mentioned above for R*, R’3 is a hydrogen atom or a lower alkyl group? an optionally substituted aryl, optionally substituted lower aryl or optionally substituted lower arylalkyl group; a group COORS or -P(0) (OR3) (OR*) in which R3, R* and Rs correspond to the definitions mentioned above.

Products corresponding to formulae II to VII above are generally known and may be prepared by known methods or else methods similar to known methods. These products and methods are described in United States of America Patents Nos. 4,035,177, 4,175,946, 4,251,258, 4,231,782, 4,322,238, 4,322,239, 4,323,387, 4,300,942 and 4,300,943; the United States of America Search Report No. 220,001 (Derwent No. 73,821 E/35); United Kingdom Patent No. 2,090,596? Belgian Patent No. 888,001? Japanese Patents Nos. 56,139,408, 57,120,595 and 57,099,597? European Publication No. 39,310? and German Federal Republic Patent Application No. 2,361,382.

Among (phenoxy-substituted) benzoic derivatives, acifluorfen-sodium and -potassium are preferred.

According to the present invention, the new agrochemical compositions may contain mixtures of active substances and common ingredients known in practice such as surfactants, carriers and diluents. If the composition contains two substituents, the systemic herbicide and the phenoxvbenzoic derivative, or more than two substituents, it is desirable that the compositions mentioned above are suitably mixed, in a homogeneous and/or uniform manner, which mixing can be achieved by means of a particular type of agitation. The compositions may be mixed in a container or premixed, in particular premixed.

The present invention also relates to a weederadication process consisting in applying an effective quantity of a herbicidal composition to plants which must be destroyed. This treatment process is destructive in object and enables, in particular, weed growth to be controlled and, where appropriate, the weeds to b® destroyed totally or partially.

The herbicidal compositions or mixtures of active substances, such as have been described above and can be used according to the present invention, are applied in a suitable manner to plant leave© and ia particular to weeds to be destroyed, for example when the latter have a green foliage.

The herbicidal compositions may also be applied shortly before the harvest in order to kill weeds having roots which are persistent in the soil after the harvest. Thus, it is possible to plant shortly after th® harvest without having to carry out mechanical weeding operations (manually or otherwise). However, this method is reserved for the cases in which the herbicides applied do not leave residues and/or are selective with regard to the crop to be planted after the harvest.. la general, the systemic compound of the glyphosate type is applied to plants at doses from 0.3 to 0.9 kg/ha, preferably fro® approximately 0.4 to approximately 0.8 kg/ha and especially from approximately 0.5 to approximately 0.7 kg/ha.

Acifluorfen-sodium is used as . a chemical substance which modifies membranes; a dose which is advantageously between 0.005 and 0.1 kg/ha and preferably between 0..02 and 0,.06 kg/ha is applied.

The herbicide of the phenoxybensoic type/ herbicide of the glyphosate type weight ratio is between 1/12 and 1/80 and preferably between 1/15 and 1/50.

Using the compositions of the present invention, an effective control of the following weeds is observed: Dicotyledonous plants: Xanthiuai, Iporaoea, Sesbania, Abutilon, Polygonum, Amaranthus, Chenopodiura, Sinapis, Datura, Solanum, Euphorbia, Bidens and Galinsoga. Monocotvledonous plants; (graminaceous plants) Setaria and Schinochloa.

The process according to the present invention makes it possible to control a wide spectrum of monocotyledonous or dicotyledonous annual and perennial weeds. The weeds may be destroyed by the processes and the compositions of the present invention, enabling the field to be left in a good condition for the subsequent growth of crops such as cereals, wheat, rice, cotton, soyabean, beets (especially sugarbeets), sunflower, rapeseed, sugarcane and vegetable crops, and for achieving as effective weed eradication in perennial crops (vines and orchards).

As the herbicidal effect appears and becomes effective shortly after treatment (much earlier than with the glyphosate-type herbicide alone (when employed in higher doses)), the process and the composition according to the present invention also make it possible to control plants, especially weeds, quickly.

The process according to the present invention also makes it possible to prevent glyphosate or its derivatives from being leached. The invention also relates to a process which makes it possible to prevent glyphosate or one of its derivatives corresponding to formula (I) mentioned above from being leached, the said process consisting in applying glyphosate or one of its derivatives of formula (I) in combination with a compound of the phenoxybenzoic type, according to the doses and the weight ratios defined above.

When the process of the present invention is put into practice, the herbicidal compositions most frequently contain one or more ingredients other than the compounds of the glyphosate type and their derivatives (hereinafter referred to as active ingredients). These compositions, which may be employed as herbicidal agents, contain the active ingredients in combination with solid or liquid carriers which are acceptable in agriculture and surface-active agents which are acceptable in agriculture. Common inert carriers and common surfaceactive agents may be employed. These compositions also form part of the present invention.

These compositions may also contain other ingredients .such as protective colloids, adhesives, thickeners, thixotropic agents, agents which facilitate penetration, activators, stabilizers, sequestering agents and the like, as well as other known active ingredients having pesticidal properties (especially insecticides, fungicides or herbicides) or having plant growthregulating properties. More generally, the compositions employed in the present invention may contain all the solid or liquid additives corresponding to conventional methods of formulation.

In the following description of the present invention, unless otherwise stated, the percentages are expressed on a weight basis.

The activators are compounds which are not normally herbicidal at normal doses (0,5 to 5 kg/ha), but which have a capacity to increase significantly the herbicidal activity of glyphosate-tvpe compounds. Most of these activators are well known. As described below, some activator® are surfactant®, especially polyethoxylated derivatives of phenol, of alcohol or of amines- Some activators are ammonium salts, especially chlorides, sulphates and inorganic or organic ammonium phosphates. Other activators may be employed. The quantity of activators employed in the compositions of the present invention may be between 0-1 % and 500 % of the quantity of the glyphosate-type compound and preferably between 50 and 350 %. This percentage depends on the specific nature of the activators employed.

The doses of compounds employed in the present invention may vary within wide limits, especially depending on the nature of the plants to be suppressed and/or the degree of infestation of the crops by the weeds, In general, the compounds according to the present invention usually contain 0.05 to 95 % of one or more active ingredients according to the present invention, 1 to 95 % of one or more solid or liquid . 5 carriers and, optionally, 0.1 to 50 % of one or more surface-active agents. i The compositions preferably contain 10 % to 50 % by weight of the combination of the two active substances of formulae (I) and (VIII) and preferably 15 I to 30 %, In accord with what was mentioned, above, the active ingredients employed in the present invention are generally combined with carriers and optionally with surface-active agents.

In the description of the invention, the term IS carrier denotes a natural or synthetic organic or inorganic ingredient with which the active ingredients are combined in order to facilitate application to the plant, to seeds or to the soil. Therefore, this carrier is generally inert and it must be acceptable in agriculture, especially with respect to the plant treated™ The carrier may be solid (clays, natural or synthetic silicates, silica, resins, waxes, solid fertilizers and the like) or liquid (water, alcohols, especially butanol); esters, especially merhylglycol acetate; ketones, especially cyclohexanone and isophorone? petroleum fractions; aromatic or paraffinic hydrocarbons, especially xylenes; chlorinated aliphatic hydrocarbons, especially trichloroethane, or chlorinated aromatic hydrocarbons, especially chlorobenzenes; water30 soluble solvents such as dimethylformamide, dimethyl sulphoxide or N-methylpyrrolidone; liquefied gases and the like.

The surface-active agent may be an emulsifying *1 , dispersant or wetting agent of ionic or nonionic type, or else a mixture of these surface-active agents. Examples include polyacrylic acid salts, lignosulphonic acid salts, phenolsulphonic or naphthalenesulphonic acid salts, products of polycondensation of ethylene oxide with fatty alcohols, fatty acids or fatty amines, - 13 substituted phenols (especially alkylphenols or arylphenols), sulpboscccinic acid ester, salts, tacrine derivatives (especially alkyl taurates|, phosphoric esters of alcohols or of products of polycosdensatios of ethylene oxide with phenols, esters of fatty acids with polyols, .and derivatives having sulphate, sulphonate and phosphate funtionality of the above compounds. The presence of at least one surface-active agent is generally valued.

For thexs· application, the .active ingredients employed ia the present invention .are generally is the fora of compositions. These compositions according to the present invention are themselves ia different solid or liquid forms* Perms of ccapositions of the present invention include water-soluble powders (having an active ingredient content which aay reach 80 t| and watersoluble granules, especially those obtained by extrusion, ccssoactiag, impregnation of a granular carrier, or else by granulation starting with a powder (the -active ingredient content in these granules being between ¢3.5 and 80 % in the latter cases), and aqueous solutions* The water-soluble concentrates or .solutions (especially powders or granules) also most frequently contain 5 to BO % of active ingredients, whereas the emulsions or solutions which are ready for application generally contain 0.01 to 20 % of active ingredients. Xs addition to the solvent, the solutions or concentrates say contain 2 to SO % of suitable additives such as stabilizers, surface-active agents, agents facilitating penetration, corrosion inhibitors, colorants or adhesives.

Irrespective of the concentration required, emulsions which are particularly suitable for application to plants may be prepared from these concentrates by diluting with water.

Ml these aqueous dispersions or solutions or mixtures for spraying may be applied to crop plants to be weeded, by aay suitable means, for example by spraying, at rates which are generally of the order of Z00 to 1,200 litres of spraying mixture per hectare» The compositions according to the present invention are suitably applied to the vegetation and especially to the weeds to be eliminated, when the latter have a green foliageί The non-limiting examples which follow illustrate the present invention and the way in which it can be applied in practiceExample 1/Application of the _hegbicidal_composition after the emergence of different species of plants (under.glass) x 7 x 8 cm pots are filled with light sand for cultivating, and a certain number of seeds, depending on the plant species and th© seed thickness, is planted.

The seeds are then covered with an approximately mm thick layer of soil, and the seeds are allowed to germinate until they reach a suitable stage of growth. The treatment stage for plants of the graminaceous type is the second-leaf formation stage. The treatment stage for dicotyledonous plants is the 'cotyledon unfolding and first -rue leaf development" stage.

The pots are then treated by spraying a quantity corresponding to an application dos© of 500 1/ha by volume, containing the active substances at their desired concentrations. The spraying mixture contains a tank mix prepared by mixing: - water, - an aqueous solution containing 240 g/1 of acifluorfen-sodium (the concentration in g/1 as well as the doses in g/ha refer to the acid form of acifluorfen), and - as aqueous solution containing 360 g/1 of the isopropylammonium salt of N-phosphonomethylglycine (which is the acid form of glyophosate; the concentration in g/1 as well as the doses ia g/ha refer to the acid form), <·* which also contains 15 % of surfactant of the polyethoxylated derivative type.

Different active substance concentrations of the spraying liquid are employed, corresponding to different doses of active substances applied The treated pots are then placed in tanks designed to receive irrigation water by sub-irrigation and they are maintained at ambient temperature for 24 days ,at a relative humidity of 70 %.

At 13 and 29 days after treatment, the number of live plants in the pots treated with the spraying liquid containing the‘active substance to be tested are counted and ths number ox live plants in a control pot treated according to the same conditions, but with a spraying liquid which does not contain active substances, is also counted. A percentage equal to 100 % indicates that there is a total destruction of the plant species under consideration, and a percentage equal to 0 % indicates that the number of live plants in the treated pot is identical to that in the control pot.

The plant species used in Example 1 ares common morning-glory (Ipomoea ourourea) and common purslane (Portulaca oleracea) ., The tests carried out demonstrate the remarkably early herbicidal effect of the compositions according to the present invention in post-emergence treatments. (see Tables X and II at the end of the description). Example 2: Field experiments The field was divided into 5 square metre plots.

Several species were sown in each plot, in rows 15 cm apart. These species included the following monocotyledonous plants: wild oat: Avana fatua (AVEFA) cockspur grass: Echinoehloa crus-galli (ECHCG) Italian rye grass: Lolium multiflorum (LOLMU, pros© millet: Panicum miliaceum (PANMI) and the following dicotyledonous weeds: redroot amaranth: Amaranthus^retroflexusIAH&RE) charlock: Sinapis.,arvensis (SINAR) When all the plants reached the 2-3 leaf stage, i.e. approximately three weeks after the sowing, treatments were applied by preparing tank mixes of active ingredients at suitable concentrations and spraying them on the rows of plants at a volume of 500 1 per hectare in order to obtain adequate rates.. An untreated plot was placed in contiguity with . each treated plot for comparison and rating. The ratings were carried out at J different times after the treatment and are expressed as percentages of destruction for each species, in J comparison ’with the same species in an untreated plot.

Herbicidal effect is observed 5 days after treatment. The same active ingredients and doses as in the previous example were used. A remarkable early herbicidal effect was observed, as indicated in Table III at the end, of the description.

In this example, rain (20 mm of water) fell on the plants 15 hours after treatment.

Claims (8)

1.CLAIMS 1,.. Herbicidal composition including at least one herbicide of the glyphosate type according to formula 1 0 - P - C’rf 2 - NH - CH, - Z ( j j OR 2 in which 2 is a cyano group or a group COOR; R is & hydrogen atom or else is chosen from the lower alkyl, lower alkenyl and lower alkoxyalkyl groups; aryl groups containing 6 to 10 carbon atoms and optionally carrying 1 to 3 substituents chosen independently from the lower alkyl, lower alkoxy, halo, trifluoromethyl, nitro and cyano groups; or else is a compatible cation, capable ox forming a salt; R 1 and R a are identical or different and are hydrogen atoms or are chosen from the lower alkyl, aryl, substituted aryl or biphenyl groups or else are compatible cations, capable of forming salts; or else the herbicide of the glyphosate type according to formula la OR I 0 W p - CH, z 2 N H + 2 - CH - Z CIS) OR 20 in which Z a is a compatible anion, capable of forming a salt; R 3 and R* are identical or different and represent lower alkyl or aryl groups, substituted lower alkyl or alkyl, or biphenyl groups? 25 Z l is a cyano group or a group COOR 3 ; B, 3 is a hydrogen atom or else is chosen from the lower alkyl, lower alkenyl and lower alkoxyalkyl groups; aryl groups containing S to 10 carbon atoms and optionally carrying 1 to 3 substituents chosen independently from the lower alkyl, lower alkoxy, halo, trifluoromethyl, nitro and cyano groups? and at least one herbicide of the phenoxy ben zoic type chosen from acifluorfen or the potassium or sodium salt of acifluorfen, characterized in that the herbicide of the phenoxybenzoic type/herbicide of th® glyphosate type weight ratio is between 1/12 and 1/80.

2. - Composition according to Claim 1, characterized in that the herbicide of the phenoxybenzoic type/ herbicide of the glyphosate type weight ratio is between 1/15 and 1/50.

3. Composition according to Claim 1 or 2, characterized, in that the compound of the phenoxybenzoic type is acifluorfen-sodium.

4. Composition according to one of Claims, 1 to 3, characterized in that it is in the form of a ready-to-use mixture.

5. Process for the post-emergence treatment of weeds, consisting in applying to the latter an effective quantity of a herbicide of the glyphosate type and a quantity of a herbicide of the phenoxybenzoic type according to one of Claims 1 to 4, characterized in that th® dose of herbicide of the glyphosate type is between 0.3 and 0.9 kg/ha, preferably between 0.4 and 0,.8 kg/ha and advantageously between 0.5 and 0.7 kg/ha, and the dose of herbicide of the phenoxybenzoic type is between 0.005 and 0.1 kg/ha, preferably between 0.02 and, 0.08 kg/ha, the herbicide of the phenoxybenzoic type/ herbicide of the glyphosate type weight ratio being between 1/12 and 1/80, preferably between 1/15 and 1/50.

6., Composition based on a herbicide of the glyphosate type having a good resistance' to leaching by rain, especially when it is present on plant leaves, characterized in that it is in accordance with any one of Claims 1 to 4. v

7. Composition based on a herbicide of the glyphosate type having a strong activity with regard to plants which are at the end of the growth cycle and/or whose growth is slowing, characterized in that it rs xn - 22 accordance with any one of Claims 1 to 4.

8. Composition according to any one of Claims 1 to 4, which-is intended to be diluted in water for the purpose of being applied to plants, characterized in that 5 it comprises 10 % to 50 % by weight of the combination of the two active substances of formula (I) and of the phenoxybenzoic type, preferably 15 to 30 %. 5. A herbicidal compostion substantially as hereinbefore described with reference to the accompanying Examples.