HU194707B - Stabile, aquous fungicide composition containing aluminium-tris/ethyl-phosphonate/ as active component - Google Patents

Abstract

The fungicidal composition contains phosethyl Al (i.e. Al tris-(ethyl-phosphonate)) as the active ingredient and a salt of a weak acid and a strong base as the stabiliser. Aqueous solutions of the composition are preferably injected into the trunks of crop trees, such as avocado.

Description

FIELD OF THE INVENTION The present invention relates to a stable aqueous fungicidal composition containing aluminum tris-ethylphosphonate.

No. 2,254,276. French Patent No. 5,198,125 describes compositions for the treatment of fungal diseases of plants which contain at least one alkyl phosphoric acid salt as an active ingredient. These compositions are effective against many phytophagous fungi such as Phycomycetes, especially Plasmopara viticola and various species of Phytophthora. In practice, aluminum ethyl phosphite or aluminum tris (ethyl phosphonate) (fosetyl Al) is commercially available as a wettable powder and used as a fungicide by spraying on the leaf. Although this composition is quite effective under these conditions, especially in grapes, its efficacy will be more pronounced over time when used to treat tropical plants frequently attacked by Phytopthora, such as Phytopthora cinnamomi, which cause avocado or citrus germination.

In fact, the amount of active agent absorbed by the low-absorbing foliage is small enough and not enough to treat the trees already affected by the disease. This necessitates repeated spraying of plants, so that the treatment is only inhibitory, slow in every way, and the fungal disease is too severe to be effective.

It has been found that these diseases can be effectively treated with a stabilized aqueous solution of aluminum tris (ethylphosphonate), especially when injected into the tree trunk. However, the preparation of the aqueous solution poses a problem since the active ingredient is hydrolyzed in an aqueous medium, thereby significantly and increasingly decreasing its concentration, thus preventing the preparation of a concentrated aqueous solution which is stable over a longer period.

FIELD OF THE INVENTION The present invention relates to stable aqueous formulations of aluminum tris (ethylphosphonate) containing 0.33 to 1 mole of calcium acetate per mole of active ingredient as a stabilizer in addition to the active ingredient at a concentration of 1 to 120 g / l.

The particular amount of stabilizer used depends on the amount of aluminum tris (ethylphosphonate) in solution. If the stabilizer is present in too small a quantity or, conversely, too much, the solution is not clear, which indicates that the active ingredient is not sufficiently soluble. This results in a correspondingly limited efficacy of the formulation.

Surprisingly, it has been found that the most suitable amount of stabilizer is not the stoichiometric amount, but about half of the stoichiometric amount results in a stable, clear solution, whereas the addition of double this amount results in precipitation.

The amount of aluminum (tris-ethylphosphonate) in the composition according to the invention is preferably 10-110 g / l.

This solution can be applied to the plants by any suitable treatment, for example by spraying the leaves or soaking the roots. Excellent results can be obtained when injecting the strain into diseased trees such as avocados, but this method can be applied to other trees such as citrus, cocoa or rubber. The treatment is performed by first drilling holes in the tree trunk.

In the second step, a defined amount of aqueous aluminum tris (ethylphosphonate), which may vary from 0.1 to 5 g / m ² depending on the size of the ground covered by foliage, is injected into the wells with or without pressure.

The liquid is slowly absorbed and it is advantageous to keep it under pressure in the injection device. When the injection is complete, it may be desirable to seal the hole or holes with a material that does not attack the plant tissues, such as adjuvants, such as resin containing disinfectants, to reduce the risk of secondary infection. The treatment should be applied only a few times, especially when compared to the number of leaf sprays required. For example, for a severely ill tree, treatment can be effective if two injections are given in the first year, and one in the second and subsequent years, so that the tree remains healthy and heals. The effectiveness of this treatment is very valuable as heavily attacked trees can heal within 2 years. This is surprising since the other systemic fungicides, which are generally effective against these fungal diseases, are ineffective when injected into trees in a similar manner.

The following examples illustrate the preparation of the composition of the invention and the method of injecting it into the trunk of sick trees.

Example I

The following formulations were prepared by dissolving aluminum tris (ethylphosphonate) and, where necessary, calcium acetate in water. The numbers refer to units of mass.

Control Preparation of the Invention

2 3

Technical, 98% pure

foszetii-Al 102 102 102 102 Calcium acetate - 33 67 22 Water supplemented to 1 1 898 865 831 876

The amount of calcium acetate added corresponds to half of the stoichiometric amount for Formulation 1, while for Formula 2 it is equal to the total stoichiometric amount and for Formulation 3 it is one third of the stoichiometric amount.

The three solutions were kept at 50 ° C for 1 month, after which the disintegration of aluminum tris (ethylphosphonate) and the appearance of the solution were investigated.

The results are shown in the table below:

evaluation control According to the invention 1 2 3 preparation Decomposition of fosetyl-Al 100% 12% 12% 24% relative decay The appearance of the solution (initially clean) wet clear rain

The table above clearly shows that after one month at 50 ° C:

- In the control solution, fosetyl-Al was completely degraded to 2194707 and a precipitate formed in the solution. The solution is neither clear nor stable.

The decomposition of fosetyl Al in solutions 1, 2 and 3 of the invention is acceptable. While slight precipitation is observed in solution 2, solutions 1 and 3 are clear. Thus, solutions 1 and 3 are found to be satisfactory.

Example 2 was prepared by diluting Example 1 with Example 1. Thus, solutions containing 51 and 20.5 g of 98% purity aluminum tris (ethylphosphonate) and 16.5 and 8.25 g of calcium acetate were obtained. They have the same stability as formulation 1 of Example 1.

Example 3 15

Formulation 1 of Example 1 was injected into 5 cm deep wells distributed around ten-year avocado trees (21 planted trees). The trees are heavily infected

Phytophtora cinnamoni pest. For each injection, 20 ml of the composition is used and the number of injections is chosen so that 0.5 g / m ^{2 of} active ingredient is applied to the tree during such a circular treatment. Treatment is given twice in the first year (at 6-month intervals) and once in the second year. By the beginning of the third year, the trees are almost completely healed.

Claims (1)

Patent claim As an active ingredient, a stable aqueous fungicidal composition comprising an alkylphosphonic acid aluminum salt, characterized in that it is an aqueous solution of aluminum tris (ethylphosphonate) at a concentration of from 1 to 120 g / l and as a stabilizer to one mole of aluminum tris (ethyl phosphonate). It contains 0.33 to 1 mol of calcium acetate. (No drawing)