GB2279252A - Fungicidal seed treatment using phosphorous acid or its salts - Google Patents

Description

2279252 1 Fungicidal seed treatment using DhosRhorous acid or its salts.

The present invention relates to the protection of plant seeds and propagation material.

including more especially monocotyledon plant seeds. against attacks from fungal diseases. and to compositions useful for this purpose.

It Is known that it is possible to control fungal diseases of plants by foliar application of phosphorous acid and its derivatives (Patent GB 1,459,539) but this application has not been used in practice because of the phytotoxicity of compositions containing these ingredients (European Patent Application 230,209).

It has now surprisingly been found that it is possible to obtain compositions having a good protective effect on seeds ' and plants resulting from the germination of these seeds# by protecting the seeds with phosphorous acid or a derivative thereoff without 20 this protection being disturbed by excessive phytotoxicity.

2 As used herein, the term 11seedsve includes any generative part (propagation material) of the plant which can be used for the reproduction of the latter. This includes not only seed grains (seeds within the narrow meaning), but also roots, rhizomesy fruits, tubers, bulbs, plant parts, germinated plants, young seedlings resulting from any method of propagation from seed grains, cuttings, cell cultures and artificial seeds such as, for example, those described in Patent Applications PR 9305192 or PCT/FR 91/00984 (published under the number WO 92/10087).

The present invention more specifically provides natural or artificial seeds# preferably of monocotyledon plants, and other propagation material comprising, on or inside, as fungicide phosphorous acid or a salt thereof. The presence of another fungicide is not necessary, and in particular the triazole 2-(4chlorobanzylidens)-S,S-dimethyl-l-(IH-lp2l4-triazollylmethyl)-l-cyclopentanol (the use of which with a second fungicide which may be inter alia phosphorous acid or a phosphite salt is described in European Specification No. 467792) is not used, but the presence of other fungicides is optional as described below.

Phosphorous acid# also known as phosphonic acid, has the formula 31-P (0) (OR) 2 (abbreviated as H3PO3) Its salts are known as phosphites, and can be mono- or disalts, preferably alkali metal or ammonium salts, in particular Na2HPO3, X2HPO3 or NH4H2Po3.

0 3 On a practical level, the effective amount of phosphorous acid or salt thereof is generally between I g/q and I kg/q (q is the abbreviation of quintal 100 kg), preferably between 5 and 500 g/q.

The seed grains are preferably coated in a proportion of I to 500 g of active material per quintal of seed grain and preferably 5 to 300 g/quintal. The active material of phosphorous type is preferably chosen such that its solubility in water at 200C is greater than 0.1 g/l, more preferentially still greater than 0.5 g/1 and more preferentially still greater than 50 g/l. Active materials of lower solubility can also be used but it is then necessary to use fairly complicated formulations, for example wettable powders or aqueous suspensions. The use of active materials of sufficiently high solubility as it has just been defined is advantageous in that it makes it possible to treat seeds using simple solutions, which is extremely economic.

According to a first variant, the invention further relates to young plants resulting from the germination of the seeds which have just been defined, these young plants being at the one- or two-leaf stage.

That such young plants are obtained is all the more remarkable since it could be expected that the residual phosphorous acid has a phytotoxic effect with respect to plants resulting from the germination, in the same way that it had a phytotoxic effect in foliar 4 treatment.

The invention is particularly advantageous in protecting, against fungal diseases, seeds corresponding to crops included in the group comprising cereals, in particular wheat, barley, rye, winter barley, oats, triticale, maize or rice.

The invention is particularly advantageous in protecting seeds against diseases belonging to the group comprising Pvthium arrhenomanes. Rythium graminicola, Rythium torulosum. Pvthium vantervoolii, Rythium mvriotylUM. Rythium Periiium, Rythium aristosporum, Rythium LiLRhanidermatum. damping-off, root rot, young plant collar rot.

The invention further relates to fungicidal compositions intended for protecting seedsl preferably of monocotyledon plants, against fungal diseases, characterized in that they contain:

at least one active material chosen from the group consisting of phosphorous acid or its salts, at least one inert vehicle which is acceptable in agriculture and, optionally a surface-active agent which is acceptable in agriculture, the various constituents of these compositions being other than the triazole 2-(4chlorobanzylidene)-515-dimethyl-l-(IH-1.2.4-triazol-lylmethyl)-icyclopentanol.

The compositions according to the invention commonly contain between 0.5 and 95% (by weight) of active material of phosphorous type. Preferably, the amount of active material of phosphorous type in these treatment formulations is greater than 5% (by weight).

The present invention also relates to a process for protecting seedst preferably of monocotyledon plants, against fungal diseases, characterized in that an effective amount of fungicidal active material and/or of fungicidal compositions as defined above is applied to the said seeds. According to this process of the invention, application of the fungicidal active material of phosphorous type is carried out using compositions comprising at least S% of active material of phosphorous type, preferably at least 10%.

In the present account,, the term levehicle" denotes a natural or synthetic, organic or inorganic material with which the active material is combined to facilitate its application to the seed. This vehicle is thus generally inert and it must be acceptable in agriculturej especially on the treated seed. The 2S vehicle can be solid (clays, natural or synthetic silicates# silica, resins, waxes, solid fertilizers and the like) or# preferably, liquid (water, alcohols, ketones# petroleum fractions, aromatic or paraffinic 6 hydrocarbons, chlorinated hydrocarbons, and the like). As has been said above, liquid vehicles are preferred, in particular those in which the phosphorous active material is soluble, more especially water and aqueous solutions.

The surface-active agent can be an emulsifying, dispersing or wetting agent of ionic or nonionic type. There may be mentioned, for example, salts of polyacrylic acids, salts of lignosulphonic acidsp salts of phenolsulphonic or naphthalenesulphonic acids, polycondensates of ethylene oxide with fatty alcohols or with fatty acids or with fatty amines, substituted phenols (especially alkylphenols or arylphenols), salts of asters of sulphosuccinic acids, is taurine derivatives (especially alkyltaurates)p or phosphoric asters of polyoxyethylenated phenols or alcohols. The presence of at least one surface-active agent is often required.

These compositions can also contain any kind of other ingredients such as, for example, protective colloids, adhesives, thickening agents, thizotropic agents, penetrating agentse stabilizing agents, sequestering agents, pigments,, dyes or polymers.

Nora generally, the compositions according to 2S the invention can be combined with all the solid or liquid additives corresponding to the conventional formulating techniques for application of seed treatment in particular.

1 0 7 While on this subject, it will be noted that, in the vocabulary of those skilled in the art, the term seed treatment in fact mainly relates to the treatment of seed grains.

The application techniques are well known to those skilled in the art and they can be used without disadvantage in the context of the present invention.

Mention may be made, for example, of filmcoating or coating. coating is preferred in the invention because of its simplicity; it is sufficient to stir or mix the seed to be treated with the fungicidal compositions according to the invention.

Among the compositions, solid or liquid compositions may generally be mentioned.

There may be mentioned, as forms of liquid compositions or those intended to constitute liquid compositions at the time of application, solutions, in particular water-soluble concentrates, emulsifiable concentrates, emulsions, suspension concentrates or wettable powders (or powder to be sprayed).

The emulsifiable or soluble concentrates most often comprise 10 to 80% of active material while emulsions or solutions ready for application contain, for their part, 0.01 to 20% of active material.

Por example, in addition to the solvent, the emulsifiable concentrates can contain, when this is necessary, 2 to 20% of suitable additives such as stabilizing agents, surface-active agents, penetrating 1 8 agents, corrosion inhibitors, dyes or the abovementioned adhesives.

From these concentrates, it is possible to obtain, by dilution with water, emulsions of any desired concentration, which are particularly suitable for application to seeds.

The wettable powders (or powder to be sprayed) are generally prepared so that they contain 20 to 95% of active material, and they generally contain, in addition to the solid vehicle, from 0 to 5% of a wetting agent, from 3 to 10% of a dispersing agent and, when this is necessaryl from 0 to 10% of one or more is stabilizing agents and/or other additives, such as pigmentst dyes, penetrating agents# adhesivese anticlumping agentso and the like.

As has already been said, aqueous dispersions and emulsions, for example the compositions obtained by diluting a wettable powder or an emulsifiable concentrate according to the invention with water, are contained within the general scope of the present invention. Emulsions can be of the vater-in-oil or oilin-vater type and they can have a thick consistency# like that of a limayonnaise",, Among these compositions, a person skilled in the art will advantageously choose that or those which are suitable depending on the conditions of use.

In the invention, the phosphorous derivative can be used alone or as a mixture, in particular with 9 fungicides or insecticides, especially captan, thiram, aspirin or its salts and esters, salicylic acid or its salts and esters, guazatine, oxine-copper, tefluthrin, anthraquinone or metalaxyll and insecticides such as imidacloprid, lindane and endosulfan, as well as mixtures of these various products.

The following Examples illustrate the invention.

Example 1 g of barley seed grains were treated with 1.5 al of an aqueous phosphorous acid or sodium monophosphite (NaH2PO.) solution. The concentration of the treatment solution was calculated so as to obtain. on the seed& the dosage (in g/q) of product shown in is the Table below. Por a dosage of 100 g/q, the concentration of phosphorous acid in the water was 75 g/1.

The treatment was carried out by simple mixing/stirring, for 1 miny so as to obtain seeds comprising various concentrations of phosphorous acid as shown in the Table below.

These seed grains were deposited in pots containing a mixture of peat and pozzolana. One millilitre of Eythium mycolium ground preparation was inoculated into each pot by spraying the earth. There were approximately 20 seed grains per pot.

The seed grains germinated and. 15 days after sovingo the state of the plants was observed with is respect to control seed grains not treated with phosphorous acid and with respect to control seed grains not inoculated with Eythi All the plants which had survived had two leaves. No phytotoxicity was observed in any case.

The results were the following:

Fungicidal Dose in Efficiency expressed as agent g/q percentage LPythium Eythium arrhenomanes myriotylum Phosphorous 50 60 40 acid 100 100 60 sodium 100 75 20 monophosphite 200 100 70 400 100 100 800 100 100 Untreated 0 0 0 control inoculated with Pythi i.e. the number of surviving treated seedlings expressed an a percentage of the number of surviving seedlings which had received neither the fungicidal 20 agent nor the inoculation with 2Xthium, EXAMPle 2

1 11 Barley seed grains were treated. as in Example 1,, with aqueous dipotassium phosphite solution.

To obtain a dosage of 240 g/q of product on the seedor g of seeds were treated with 1.5 al of a solution containing 80 9/1 of 1C2RP03 The seed grains thus treated were sown in an open field and the state of the crop was observed 72 days after sowing with respect to an untreated control.

Both crops were affected by fungal attacks of Pythium arrhenomanes. As compared with the untreated plants. the plants treated according to the invention contained 2.8 times more roots and were greater in number by 24.3%. The weight of dry matter of the roots of the treated plants compared with the untreated plants was greater by 39%.

12 is

Claims (14)

1. Plant seedst and other propagation material.

comprising an fungicide phosphorous acid or a salt thereof.

2. Plant seeds according to claim 1 which are monocotyledonous.

3. Seeds according to claim 2 which are cereal seeds. in particular of wheat. barley. rye, winter barley. oatsy triticale, maize or rice.

4. Seeds according to claim 1# 2 or 3 which comprise phosphorous acid or an alkali metal or ammonium salt thereof.

5. Seeds according to claim it 2 or 3 which comprise a phosphorous acid salt having a solubility in water at 200C greater than 0.1 g/lt preferably greater than 0.5 g/1.

6. Seeds according to any one of claims 1 to 5.

which comprise from 1 g/q to 1 kg/qo and preferably from 5 to 500 g/qr of the phosphorous acid or salt thereof.

7. Seeds according to any one of claims 1 to 6.

which also comprise a second active material chosen from captan. thiram. guazatiner oxine-copper.

metalaxylo imidacloprid. lindane and endosulfan.

8. Seeds according to any one of claims 1 to 6.

which also comprise a second active material chosen from aspirin, its salts and enters and salicylic acid and its salts and esters.

1 i 13

9. Method for protecting seeds and other propagation material, preferably of monocotyledon plants, against fungal diseases, which comprises applying thereto an effective amount of phosphorous acid or a salt thereof.

10. Method according to claim 9 wherein the fungal disease is a disease caused by Rythi arrhenomanes,]Rythium graminicola, Pythium torulosum, ]Rythium vantergoolii, Eythium myriotylum. Pythium veriilum. Pythium aristosporum, or Pythi aRhanidermatum damping-off, root rot, or is young plant collar rot.

11. Young plants, resulting from the germination of seed according to any one of claims I to a or treated by the method of claim 9 or 10.

12. Fungicidal composition useful for protecting seeds and other propagation material comprising, as fungicide, at least one active material chosen from phosphorous acid and its salts, at least one inert vehicle which is acceptable in agriculture, and a surface-active agent which is acceptable in agriculture.

13. Composition according to claim 12, which 14 contains between 0.5 and 95% of the said active material.

14. Composition according to claim 12 or 13.

wherein the inert vehicle is liquid, preferably water.