GB2299509A - Fungicidal composition based on prochloraz and bromuconazole - Google Patents

Description

2299509 1 Fungicidal composition based on prochloraz and on a triazole

compound The subject of the present invention is a fungicidal composition which is useful for treating fungal attacks on crops and which is based on prochloraz and on bromuconazole. It also relates to a process for treating crops having the same aim.

The effectiveness of prochloraz in controlling eyespot of cereals is known. This disease, due to the fungus Pseudocercosporella herpotrichoides, is the cause of significant damage, mainly on winter cereals. However, for some years, prochloraz has been known to be unsatisfactory in its effectiveness and regularity of action, due to the appearance of strains exhibiting a degree of resistance.

The effectiveness of prochloraz in controlling fusarium disease of wheat ears is also known, this disease being caused mainly by 2 phytopathogenic fungi known as Fusarium roseum and Microdochium nivale. However, it is always desirable to improve this effectiveness, in particular by decreasing the dose of prochloraz necessary for controlling this disease or alternatively by widening the possibilities of choice offered to the farmer, in order for the latter to find the solution which is best suited to his particular problem.

An aim of the invention is thus to supply a 2 new fungicidal composition which is useful for the problem described above.

Another aim of the invention is to provide a new fungicidal composition which is useful in the treatment of eyespot of wheat and of fusarium diseases of wheat ears.

It has now been found that these aims could be achieved in all or part by virtue of the fungicidal composition according to the present invention.

The fungicidal composition according to the invention is characterized in that it comprises prochloraz and bromuconazole.

Prochloraz and bromuconazole are 2 active materials which are well known to the person skilled in the art and which are described in the work: "The Pesticide Manual", 10th edition, by Clive Tomlin, published by the British Crop Protection Council. The use of bromuconazole in controlling cereal diseases such as eyespot and fusarium disease of the ear is also known.

The bromuconazole/prochloraz ratio by weight in the composition according to the invention is generally between 0.25 and 4 and preferably between 0. 25 and 0.75. Bromuconazole is also known for its use against eyespot. The composition according to the invention is advantageous by reason of the spectrum of activity and the low doses which can be used for the active materials, the latter quality being particularly 3 important for easily understandable ecological reasons. Thus, the composition according to the invention makes it possible to observe notable synergic effects. These synergic effects are in particular evidenced by application of the Tammes method, "Isoboles, a graphic representation of synergism in pesticides", Netherlands Journal of Plant Pathology, 70(1964), p. 73-80.

The fungicidal composition according to the invention usually contains from 0.5 to 95 % by weight of a mixture of prochloraz and of bromuconazole.

It can be the concentrated composition, that is to say the commercial product combining the two active materials. It can also be the dilute composition ready to be sprayed on the crop to be treated. in this latter case, dilution with water can be carried out either from a commercial concentrated composition containing the two active materials (this mixture is known as "ready mix") or by means of the mixture prepared at the time of use (known as "tank mix") of two commercial concentrated compositions each containing one active material.

The composition according to the invention can additionally comprise all the usual additives or adjuvants of plant-protection compositions, especially vehicles, surface-active agents, adhesion agents and flow-improving agents.

In the present account, the term "vehicle" denotes a natural or synthetic, organic or inorganic 4 material with which the active materials are combined to facilitate their application on the plant. This vehicle is thus generally inert and it must be acceptable in agriculture, especially on the treated plant. The vehicle can be solid (clays, natural or synthetic silicates, silica, resins, waxes, solid fertilizers and the like) or liquid (water, alcohols, ketones, petroleum fractions, aromatic or paraffinic hydrocarbons, chlorinated hydrocarbons, liquefied gases, and the like).

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 acids, 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 esters of sulphosuccinic acids, taurine derivatives (especially alkyltaurates) or phosphoric esters of polyoxyethylenated phenols or alcohols. The presence of at least one surface-active agent is desirable to promote dispersion of the active materials in water and their ready application on the plants.

This composition can also contain any kind of other ingredients such as, for example, protective colloids, adhesives, thickening agents, thixotropic agents, penetrating agents, stabilizing agents, sequestering agents, pigments, dyes or polymers.

More generally, the composition according to the invention can include all the solid or liquid additives corresponding to the usual techniques for the formulation of plant-protection products.

The composition according to the invention can be in the solid, gel or liquid form and, in the latter case, in the form of solutions or suspensions or emulsions or emulsifiable concentrates. Liquid compositions are preferred, due both to their convenience of use and to their simplicity of manufacture.

There may be mentioned, as forms of solid compositions, powders for dusting or dispersion (with an active compounds content which can range up to 100 M, wettable powders and granules for dry spreading, as well as dispersible or soluble granules.

Wettable powders (or powders to be sprayed), as well as dispersible granules, generally contain 20 to 95 % by weight of active materials and, in addition to the solid vehicle, from 0 to 5 % by weight of a wetting agent, from 3 to 10 % by weight of a dispersing agent and, when necessary, from 0 to 10 % by weight of one or more stabilizing agents and/or other additives, such as pigments, dyes, penetrating agents, adhesives, or anticlumping agents, and the like. It is well understood that some of these compositions, such as 6 wettable powders or dispersible granules, are intended to constitute liquid compositions at the time of application.

There may be mentioned, as forms of liquid compositions, solutions, in particular water-soluble concentrates, emulsifiable concentrates, emulsions, suspension concentrates, aerosols or pastes.

The emulsifiable or soluble concentrates generally comprise 10 to 80 % by weight of active materials, the emulsions or solutions ready for application containing, for their part, 0.01 to 20 % by weight of active materials. In addition to the solvent, the emulsifiable concentrates can contain, when necessary, 2 to 20 % by weight of suitable additives such as the stabilizing agents, surface-active agents, penetrating agents, corrosion inhibitors, dyes or adhesives mentioned above. From these concentrates, it is possible to obtain, by dilution with water, emulsions of any desired concentration, which are particularly suitable for application on the aerial parts of the plant to be treated. 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, come within the general scope of the present invention. The emulsions can be of the water-in-oil or oil-in-water type and they can have a thick consistency, like that of a "mayormaise".

7 The suspension concentrates, also applicable by spraying, are a stable fluid product, which does not thicken or form a sediment after storage, and they generally contain from 10 to 75 % by weight of active materials, from 0.5 to 15 % by weight of surface-active agents, from 0.1 to 10 % by weight of thixotropic agents and from 0 to 10 % by weight of suitable additives, such as pigments, dyes, antifoaming agents, corrosion inhibitors, stabilizing agents, penetrating agents and adhesives and, as vehicle, water or an organic liquid in which the active materials are insoluble or nearly insoluble: certain organic solid materials or inorganic salts can be dissolved in the vehicle to aid in preventing sedimentation or as antigels for water.

The composition according to the invention is prepared according to processes known per se.

Thus, to obtain powders to be sprayed or wettable powders, the active materials are intimately mixed, in suitable mixers, with the additional substances and the mixture is milled with mills or other grinders. Powders to be sprayed are thereby obtained with advantageous wettability and suspensibility; they can be suspended in water at any desired concentration and these suspensions can be used very advantageously, in particular for application on the aerial parts of the plants.

Pastes or suspension concentrates can be 8 produced in place of wettable powders. The conditions and modes of production and use of these pastes are similar to those of wettable powders or powders to be sprayed, part of the milling operation necessary simply being carried out in a liquid medium.

The dispersible granules are generally prepared by agglomeration or extrusion or compacting, in suitable granulation systems, of compositions of wettable powder type. The granules for dry spreading are generally obtained by impregnating a granulated vehicle with a solution or an emulsion of the active materials.

The invention finally relates to a treatment process intended to control or prevent fungal attacks on crops, characterized in that an effective and non- phytotoxic dose of a composition according to the invention is applied on the aerial parts of the plants.

This composition is advantageously used so that the prochloraz dose applied is between 250 and 500 g/ha and preferably between 300 and 450 g/ha and the bromuconazole dose applied is between 180 and 280 g/ha and preferably between 200 and 250 g/ha. This dose is a function of the nature of the disease, the stage of growth of the plant treated, the degree of infestation and the weather conditions.

The fungal attacks are especially those caused by eyespot (Pseudocercosporella herpotrichoides), fusarium diseases of the ear 9 (Pusarium roseum and Microdocbium nivale), septoria diseases (Septoria tritici, Septorla nodorum), rusts (Puccinia strlifo=is, Puccinia recondita) and mildews (Erlsyphe gram-inis).

Crops which are suitable for the treatment process according to the invention are cereals, in particular barleys, wheat, rye or triticale, preferably wheat.

The following examples are given purely by way of illustration and without implied limitation of the advantageous properties of the compositions according to the invention. Example 1: In vitro test of a composition comprising a mixture of bromuconazole and of prochloraz on is Pseudocercosporella herpotricholdes responsible for eyespot of wheat: A nutrient medium consisting of maize flour and agar is introduced in the supercooled state into a series of petri dishes (20 ml per dish). During the filling of the dishes, injection is carried out of 200 gl of a solution of the active materials to be tested (alone or as a mixture) in acetone, so as to obtain the desired final concentration. 25 In the case of active materials as a mixture, the bromuconazole/prochloraz ratio by weight is 0.25, 0.33, 0.5, 1, 2, 3 and 4. Petri dishes analogous to the above, into which similar amounts of a nutrient medium not containing active material are poured, are taken as control.

After 24 hours, a pellet with a diameter of 5 mm, comprising a fragment of mycelium, withdrawn from a Pseudocercosporella herpotricholdes stock culture, is deposited at the centre of each dish. The petri dishes are stored at 201C for 3 weeks.

The growth of the fungus (measured by the diameter of the mycelial growth) in the dishes containing the active material or the mixture of active materials to be tested is then compared with that of this same fungus in the dish used as control. The results obtained are shown in the form of points, corresponding to the inhibition of 50 % of the mycelial growth of the parasite, placed in a Tammes diagram which contains, on the abscissa, the prochloraz doses expressed in mg/1 and, on the ordinate, the bromuconazole doses, also in mg/1. 20 The diagram of Figure 1 is obtained in which it appears that the addition of a bromuconazole dose of less than 0.15 mg/1 (which corresponds to the dose of bromuconazole alone which it is necessary to apply in order to obtain the destruction of 50 % of the parasite) makes it possible, in an entirely unexpected way, to lower the prochloraz dose necessary for the destruction of 50 % of the parasite below 0.05 mg/1 (this value corresponding to the dose of prochloraz alone which it is necessary to apply in order to obtain this same percentage of destruction).

The arrangement of the points obtained therefore indicates a bilateral effect, described according to the Tammes method mentioned above as a "two-sided effect". This arrangement corresponds to a type-III isobole according to the said method (page 75 of the corresponding bibliographical reference already mentioned) and is characteristic of a synergy. Example 2: In vitro test of a composition comprising a mixture of bromuconazole and of prochloraz on Microdochium nivale, responsible for fusarium. disease of wheat ear:

A nutrient medium consisting of maize flour and agar is introduced in the supercooled state into a series of petri dishes (20 ml per dish).

During the filling of the dishes, injection is carried out of 200 gl of a solution of the active materials to be tested (alone or as a mixture) in acetone, so as to obtain the desired final concentration.

In the case of active materials as a mixture, the bromuconazole/prochloraz ratio by weight is 0.33, 0.5, 1, 2 and 3.

Petri dishes analogous to the above, into which similar amounts of a nutrient medium not containing active material are poured, are taken as control.

12 After 24 hours, a pellet with a diameter of 5 mm, comprising a fragment of mycelium, withdrawn from a Microdochium nivale stock culture, is deposited at the centre of each dish. The petri dishes are stored at 200C for 7 days.

The results are then observed and the Tammes diagram is then constructed as described in Example 1.

Figure 2 is thus obtained, which figure is characteristic of a bilateral effect analogous to that observed in Figure 1 of Example 1 and is thus also characteristic of a synergy.

Claims (1)

13 CLAIMS

1. Fungicidal composition, characterized in that it comprises prochloraz and bromuconazole. Fungicidal composition according to Claim 1, characterized in that the bromuconazole/ prochloraz ratio by weight is between 0.25 and 4 and preferably between 0.25 and 0.75.

3. Fungicidal composition according to either of Claims 1 and 2, characterized in that it contains from 0.5 to 95 % by weight of mixture of prochloraz and of bromuconazole.

4. Treatment process intended to control or prevent fungal attacks on crops, characterized in that an effective and non-phytotoxic dose of a composition according to one of Claims 1 to 3 is applied on the aerial parts of the plants.

5. Process according to Claim 4, characterized in that the composition dose is such that the prochloraz dose applied is between 250 and 500 g/ha and preferably between 300 and 450 g/ha and the bromuconazole dose applied is between 180 and 280 g/ha and preferably between 200 and 250 g/ha.

6. Process according to either of Claims 4 and 5, characterized in that the fungal attacks are those caused by eyespot, fusarium diseases of the ear, septoria diseases, rusts and mildews.

7. Process according to one of Claims 4 to 6, characterized in that the targeted crops are 14 cereals, in particular barleys, wheat, rye or triticale.

8. Process according to one of Claims 4 to 7, characterized in that the targeted crop is wheat.

9. Fungicidal composition according to claim 1 substantially as hereinbefore described in Example 1 or 2.

10. Process according to claim 4 substantially as hereinbefore described in Example 1 or 2.