GB1594634A

GB1594634A - Fungicidal compositions

Info

Publication number: GB1594634A
Application number: GB151178A
Authority: GB
Original assignee: Philagro SA
Current assignee: Bayer CropScience SA
Priority date: 1977-02-09
Filing date: 1978-01-13
Publication date: 1981-08-05
Also published as: PH13830A; FR2408305B1; FR2408305A1

Description

(54) NEW FUNGICIDAL COMPOSITIONS (71) We, PHILAGRO, a French Body Corporate of 14.20, Rue Pierre Baizet, Lyon 9e, France, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to fungicidal compositions which can be used for the protection of plants, and especially of fruit trees, against fungal diseases, and to a method for the anti-fungal treatment of plants by means of these compositions.

Fungicidal compositions based on alkyl phosphites, which can be used especially for the protection of vines against mildew, as well as for the protection of other plants, such as tobacco, hop, strawberry, avocado and pineapple plants, against diseases due to fungi, especially Phycomycetes, have been described in British Patent Specification No. 1449394.

It has also been known for a long time that certain fungal diseases, especially scab and alternariosis, of fruit trees, and especially of apple trees and pear trees, can be effectively combated by treatment using captan [N-(trichloro-methylthio)tetrahydrophthalimide However, the activity of this compound is not always sufficient in certain regions, because of the sensitivity of certain plant varieties and the virulence of the fungi responsible for these diseases.

As a result of research and experimentation it has now surprisingly been found that if mixtures of certain alkyl phosphites and captan are used, the relative amounts of the constituents of the mixtures being as specified below, the anti-fungal activity of the mixtures is substantially greater than expected. In fact, the compositions exhibit synergism, i.e. the anti-fungal protection afforded by the mixtures is not only greater than that of the alkyl phosphite or captan used alone, but also greater than the theoretical sum of the protection which is obtained with each of the constituents used separately at the same rates as in the mixture.

The new fungicidal compositions of the invention comprise as an active material, at least one monoester of phosphorous acid of the general formula:

wherein R represents a straight- or branched-chain alkyl radical containing from 2 to 4 carbon atoms, M represents an alkali metal atom, an alkaline earth metal atom or an aluminium atom, and n is an integer from 1 to 3 equal to the valency of NM, and N-(trichloromethylthio)tetrahydrophthalimide, the ratio of alkyl phosphite to N (trichloromethylthio)tetrahydrophthalimide being 1:0.1 to 1.2, preferably 1:0.5 to 1, by weight.

The compositions of the invention are preferably applied by leaf spraying. For a spraying delivery of the order of 1,000 1/aha, the compositions preferably contain from 50 to 400 g/hl of alkyl phosphite and from 20 to 400 g/hl of captan.

The following Tests illustrate the synergistic fungicidal properties of the compositions according to the invention.

Test 1: Open air experiments on scab Plots containing 4 adult apple trees ("white Calville" variety) were artificially contaminated at the end of April, 1976, by spores of Venturia (sp). The plots were then treated nine times, at an average interval of 15 days from 7th April to 29th July 1976, with aqueous dispersions having the following compositions: (i) 150 g/hl of aluminium ethyl phosphite (wettable powder containing 80% w/w active material); (ii) 150 g/hl of captan (wettable powder containing 83% w/w of active material); and (iii) 75 g7hl of aluminium ethyl phosphite and 75 'g/hl of captan (wettable powder).

Spraying was carried out by means of sprayers with deliveries of the order of 800 I/ha.

The development of the scab attack on the foliage was observed and counts of the invaded surface of the leaves were carried out regularly.

A series of contaminated plots was kept without treatment by way of comparison.

For each count the percentage contamination of the surface of treated leaves was determined, and compared to that of the control trees, contaminated under the same conditions. This proportion of contamination was expressed as a percentage. Then the remainder from one hundred of the figure obtained was calculated to express the percentage of protected surface.

The following Table gives the results obtained on 12th July.

TABLE I Aluminium ethyl phosphite Captan % of surface g/hl g/hl protected 150 - 94 - 150 88 150 88 75 75 100 The results in Table I make it possible to establish, firstly, that captan has a good but incomplete activity at its recommended usage rate, secondly, that aluminium ethyl phosphite also has a good but insufficient activity at the same rate, and finally, that a mixture of one part of each of the above constituents, at an overall rate which is equal to that of each of them taken separately, has a complete protective action which is superior to each of the activities of the single constituents.

This provides a good illustration of the synergistic character of the compositions according to the invention.

Test 2: Open air experiments on alternariosis Several series of three tomato seedlings (Marmande variety) were planted out on 10th June. On each plot, older plants attacked by Alternaria solani were placed above the seedlings. The seedlings were then watered a tew times in order to cause some cases of infection. Parasitism set in rather slowly but became very virulent from 15th August, the climatic conditions then being very favourable for it.

Eight spraying treatments were carried out from 8th July at an average interval of 10-12 days. The treatments were carried out by means of aqueous dispersions of a wettable powder containing, respectively, 150 g/hl of aluminium ethyl phosphite, 75 g/hl of captan, and a mixture of 225 g/hl of a mixture of one part by weight of aluminium ethyl phosphite and 0.5 part of captan.

Checks were carried out on 1st and 17th September relative to untreated comparison plants which were destroyed by the fungus by the beginning of September.

The Table below gives the results expressed as the percentage protection of the seedlings relative to the comparison plants: TABLE II Aluminium ethyl phosphite Captan % protection of the g/hl g/hl seedlings 150 ~ 4 75 86 75 86 150 75 96 This Table clearly shows, firstly, that aluminium ethyl phosphite is inactive against Alternaria solani in this experiment, secondly, that captan has a good but incomplete action against the same fungus, and finally, that the mixture surprisingly has an activity which is superior to the sum of the activities of each of the constituents taken separately at the same rate as in the mixture.

This behaviour clearly demonstrates the synergistic character of this type of mixture.

Further experiments, carried out with the same mixture on Alternaria mali on 12 year old apple trees ("Starking delicious" variety), revealed analogous behaviour of the mixture and excellent protection of the crops treated.

These Tests clearly show the remarkable action of the mixtures according to the invention against fungal diseases, such as scab and alternariosis, of plants, especially of fruit trees and, in particular, of apple trees and pear trees.

Valuable results have been obtained for mixtures containing from 0.1 to 1.2 parts by weight, and preferably from 0.5 to 1 part by weight, of captan per part of alkyl phosphite.

For use in practice, the mixtures according to the invention containing, as active material, an alkyl phosphite of general formula I and captan, are rarely employed alone. The active material, containing alkyl phosphite and captan, is generally employed in association with at least one carrier or diluent and/or at least one surface-active agent compatible with the active material and suitable for use in agricultural fungicidal compositions. In such compositions, which are a feature of the present invention, the content of the active material can be from 0.05 to 95% by weight according to the form of presentation.

The term "carrier" for the purpose of the present description denotes an organic or inorganic, natural or synthetic material with which the active material is combined to facilitate its application to the plant, or to the soil, or to facilitate its transport or its handling. The carrier can be solid (e.g. clays such as kaolin or bentonite, natural silicates such as talc, or synthetic silicates, calcined magnesia, kieselguhr, tricalcium phosphate, powdered cork, absorbent charcoal, resins, waxes and solid fertilisers) or liquid (e.g. water, alcohols, ketones, petroleum fractions, chlorinated hydrocarbons or liquefied gases).

The compositions in the form of suspensions, emulsions or solutions generally contain a surface-active agent. The surface-active agent can be an emulsifying agent, dispersing agent or wetting agent, which can be ionic or non-ionic, for example, salts of polyacrylic acids and of ligninsulphonic acids, sulphoricinoleates, esters of benzenesulphonic and naphthalenesulphonic acids, quaternary ammonium salts, condensates of ethylene oxide with fatty alcohols, fatty acids or fatty amines, and especially products based on condensates of ethylene oxide such as the condensates of ethylene oxide with octylphenol or nonylphenol, or esters of fatty acids and anhydrosorbitols which have been rendered soluble by etherification of the free hydroxy radicals by condensation with ethylene oxide. It is preferable to use agents of the non-ionic type because they are not sensitive to electrolytes.

The compositions according to the invention can be prepared in the form of wettable powders, dusting powders, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.

The wettable powders are usually prepared so that they contain from 20 to 95% by weight of active material and they usually contain, in addition to a solid carrier, from 0 to 5% by weight of wetting agent, from 3 to 10% by weight of a dispersing agent and, where necessary, from 0 to 10% by weight of one or more stabilisers and/or anti-caking agents, dyestuffs, and other additives. By way of example, the composition of a wettable powder is given below, the percentages being expressed by weight: Example 1 active material 50% calcium lignosulphonate (deflocculating agent) 5% anionic wetting agent 1% anti-caking silica 5% kaolin (filler) 39% Aqueous dispersions and aqueous emulsions, for example compositions obtained by diluting a wettable powder or an emulsifiable concentrate with water, are included in the general scope of the present invention. These emulsions can be of the water-in-oil type or of the oil-in-water type and they can have a thick consistency, like that of a "mayonnaise".

The fungicidal compositions according to the invention can be applied by any means usually employed in agriculture.

The present invention also includes within its scope a method for the treatment of plants, especially fruit trees, against fungal diseases which comprises applying to the plants a fungicidal composition according to the invention.

WHAT WE CLAIM IS: 1. Fungicidal compositions comprising as an active material at least one monoester of phosphorous acid of the general formula:

wherein R represents a straight- or branched-chain alkyl radical containing from 2 to 4 carbon atoms, M represents an alkali metal atom, an alkaline earth metal atom or an aluminium atom, and n is an integer from 1 to 3 equal to the valency of M, and N-(trichloromethylthio)tetrahydrophthalimide, the ratio of alkyl phosphite to N (trichloromethylthio)tetrahydrophthalimide being 1:0.1 to 1.2 by weight.

2. Compositions according to claim 1 wherein the ratio of alkyl phosphite of general formula I depicted in claim 1 to N-(trichloromethylthio)tetrahydrophthalimide is 1:0.5 to 1 by weight.

3. Compositions according to claim 1 or 2 wherein the alkyl phosphite of general formula I depicted in claim 1 is aluminium ethyl phosphite.

4. Compositions according to claim 3, wherein the ratio of aluminium ethyl phosphite to N-(trichloromethylthio)tetrahydrophthalimide is 1:1 by weight.

5. Compositions according to any one of the preceding claims which comprise in addition to the active material a carrier or diluent and/or a surface active agent compatible with the active material and suitable for use in agricultural fungicidal compositions.

6. Compositions according to claim 5 in which the content of the active material is from 0.05 to 95% by weight.

7. Compositions according to claim 5 or 6 in which the carrier is water and the composition contains a surface active agent.

8. Compositions according to claim 5, 6 or 7 in which the carrier is liquid and which contain from 50 to 400 g/hl of alkyl phosphite of general formula I depicted in claim 1 and from 20 to 400 g/hl of captan.

9. Compositions according to claim 5 in which the carrier is a solid.

10. Compositions according to claim 9 in which the content of the active material is from 20 to 95% by weight.

11. Compositions according to claim 10 in the form of a wettable powder which comprise, in addition to the solid carrier, from 0 to 5% by weight of wetting agent, from 3 to 10% by weight of dispersing agent and from 0 to 10% by weight of one or more stabilisers and/or other additives.

12. Compositions according to claim 1 substantially as hereinbefore described.

13. Compositions according to claim 1 substantially as hereinbefore described with especial reference to Example 1.

14. Method for the treatment of plants against fungal diseases which comprises applying to the plants a composition according to any one of the preceding claims.

15. Method for the treatment of fruit trees against fungal diseases which comprises

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Example 1 active material 50% calcium lignosulphonate (deflocculating agent) 5% anionic wetting agent 1% anti-caking silica 5% kaolin (filler) 39% Aqueous dispersions and aqueous emulsions, for example compositions obtained by diluting a wettable powder or an emulsifiable concentrate with water, are included in the general scope of the present invention. These emulsions can be of the water-in-oil type or of the oil-in-water type and they can have a thick consistency, like that of a "mayonnaise". The fungicidal compositions according to the invention can be applied by any means usually employed in agriculture. The present invention also includes within its scope a method for the treatment of plants, especially fruit trees, against fungal diseases which comprises applying to the plants a fungicidal composition according to the invention. WHAT WE CLAIM IS:

1. Fungicidal compositions comprising as an active material at least one monoester of phosphorous acid of the general formula:

9. Compositions according to claim 5 in which the carrier is a solid.

12. Compositions according to claim 1 substantially as hereinbefore described.

applying to the fruit trees a composition according to any one of claims 1 to 13.

16. Method for the treatment of apple trees or pear trees against scab or alternariosis which comprises applying to the trees a composition accordilig to any one of claims 1 to 13.

17. Method according to claim 14, 15 or 16 substantially as hereinbefore described.