GB1578221A - Pesticidal compositions - Google Patents

Description

(54) PESTICIDAL COMPOSITIONS (71) We, THE BOOTS COMPANY LIMITED, a British Company, of 1 Thane Road West, Nottingham, NG2 3AA, England, 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 pesticidal compositions and methods of controlling pests.

A problem constantlly facing farmers with the need to control pests attacking crops is the build up of resistance to pesticides. There is always a need for improved materials which are not only more effective against particular pests but are also versatile and can be used to combat a wide spectrum of pests.

We have now discovered that mixtures of the pesticide, amitraz, with methomyl have valuable and unexpected properties. For example in the context of certain pests which attack crops we have observed that the pesticidal activity of the mixtures is greater than would be expected from merely combining them together and synergism is exhibited.

Accordingly the invention provides a pestividal composition comprising amitraz and methomyl.

Amitraz has the chemical formula 1,5-di (2,4 - dimethylphenyl) - 3 - methyl - 1,3,5- triazapenta - 1,4 - diene and methomyl has the structure S - methyl - N - (methyl carbamoyloxy) thioacetamidate commercially available for example as Lannate (Registered Trade Mark). It is preferred to employ a composition in which the active ingredients, amitraz and methomyl, are in the ratio range of from 8:1 to 1:80 by weight, especially from 3:1 to 1:40 by weight, for example from 1:1 to 1:10 by weight.

Naturally it is possible to obtain the advantages of the invention by the addition of other pesticides which do not affect the interaction between amitraz and methomyl.

As mentioned above, the mixtures of the invention are active against a wide range of pests, both insects and acarids, and one of their advantages stems from the fact that they can be applied to a crop attacked by pests at all stages of their life cycle. This is an important advantage since the timing of pesticide application is made less critical and there is a greater chance of obtaining good, overall, control of the pests in a single treatment. In addition to their synergistic activity we have observed an extension to the spectrum of control of pests resistant to methomyl. Amongst the pests the mixtures are effective against are insects such as aphids for example the green peach aphid Myzus persicae; the boll weevil Anthonomis grandis; and noctuid insects such as for example the bollworm Heliothis zea, pink bollworm Pectinophora gossypiella and cotton leaf worm Spodoptera littoralis; and acarids (pests of the order Acarina) such as for example spider mites Tetranychus urticae and Panonychus citri.

These pests attack many important crops and in doing so cause great economic damage.

Thus the mixtures find application on cotton, maize and soybean crops, soft fruit and top fruit such as apple, pear, peach and citrus crops.

The compositions of the invention can be employed in a wide variety of forms and can comprise a liquid or solid diluent optionally together with a surface active agent. They are often most conveniently prepared in aqueous form immediately prior to use, for example, as a spray on pest-infested crops or animals. One such method is commonly called "tank mixing" in which the pesticide ingredients in their commercially available forms are mixed together by the farmer in a quantity of water for direct application. The concentration of the active ingredients for application to a crop by conventional ground methods is preferably within the range of from 0.001 to 10 per cent, especially from 0.005 to 5 per cent by weight of the composition, but more concentrated compositions containing up to 20 per cent by weight may be desirable in the case of aerial sprays. When an aqueous preparation is required for treatment of animals by means of, for example, a spray race or dip the composition comprises an amount of active ingredients that is non-toxic to the host animal and is preferably from 0.001 to 1.0 per cent, especially from 0.005 to 0.5 per cent by weight of the composition.

The compositions of the invention include not only those in suitable form for direct application but also concentrated primary compositions which can be supplied to the user and which require dilution with a suitable quantity of water or other diluent before application. Such compositions may comprise a surface active agent in addition to the active ingredients and typical examples are an aqueous dispersion, an aqueous emulsion, an emulsifiable concentrate, a dispersible powder or a dusting powder. As a concentrated primary composition the concentration of active ingredients can vary widely and can be for example from 5 to 95 per cent by weight of the composition.

An emulsifiable concentrate, also known as a "miscible liquid", comprises a solution of the active ingredients in a water-immiscible solvent in association with one or more emulsifying agents. An emulsion is formed when the emulsifiable concentrate is mixed with water.

A dispersible powder comprises the active ingredients in finely divided form in association with one or more dispersing agents so that a stable aqueous dispersion of the active ingredients is formed on mixing the powder with water. A finely divided inert solid diluent such as kaolin or diatomaceous earth sold under the Registered Trade Mark CELITE is generally incorporated in the dispersible powder.

A dusting powder comprises the active ingredients intimately mixed with a solid pulverulent diluent, for example kaolin.

As a further aspect, the invention includes a method for controlling pests which com prises applying a composition comprising amitraz and methomyl to the locus of the pests, that is, the pests or their habitat. More particularly the invention comprises a method for protecting plants from insects and acarids by the use of such compositions applied most conveniently as a foliar spray at a rate, for example, of from 0.25 to 6.0 kilograms of active ingredient per hectare.

A wide variety of crops including cotton, maize, soybeans, soft fruit and top fruit can be protected by treatment with the pesticidal composition of the invention, but the method of the invention finds particular application to cotton crops. Thus the invention includes a method for controlling insects on a cotton crop which comprises applying a composition of the invention to the locus of the insect.

Some of the noctuid insects most harmful to cotton are bollworms, leaf worms and armyworms which can be controlled by application of the active ingredients preferably at a rate of from 0.25 to 5.0 kilograms per hectare for example from 0.5 to 2.5 kilograms per hectare. More than one application of pesticide may often be desirable and when cotton crops are concerned, treatment at intervals of 3 to 30 days is suitable.

The invention is illustrated by the following Example.

EXAMPLE The activity of pesticidal compositions against adults of Tetranychus urticae was tested according to the following procedure.

French bean leaf discs, 2 cm in diameter, were cut to retain the petiole which was kept in contact with water throughout the test.

Fifteen adult mites of Tetranychus urticae were placed on a leaf disc, which was then sprayed to the point of run-off with an aqueous solution or dispersion of amitraz and methomyl, both separately and together as mixtures. Percentage mortality was recorded after 72 hours.

The activity of each active component was read from dose response curves and an expected value for the mixture calculated. A comparison of these values with the observed data shows evidence that the mixtures have a synergistic effect.

Activity Activity Calculated Observed Amitraz mortality Methomyl mortality effect of effect of (ppm) (ç) (ppm) (g) mixture (g.) mixture ((4) 150 35 1500 37 72 98 120 31 300 7 38 69 40 6 100 0 6 15 25 2 250 0 2 19 10 0 400 16 16 24

WHAT WE CLAIM IS: 1. A pesticidal composition 'comprising amitraz and methomyl.

2. A pesticidal composition according to claim 1 in which the amitraz and methomyl are employed in a ratio of from 3:1 to 1:40 by weight.

3. A pesticidal composition in aqueous form suitable for direct application to a crop, comprising a pesticidal composition as defined in either of claims 1 and 2 in which the concentration of active ingredients is from 0.005 to 5 per cent by weight.

4. A method for controlling pests which comprises applying a composition according to any of claims 1 to 3 to the pests or their habitat.

5. A method for protecting crops selected from cotton, maize, soybeans, soft fruit and top fruit by application to the crop of a composition according to any of claims 1 to 3.

6. A method according to claim 5 in which the active ingredients are applied at a rate of from 0.25 to 6.0 kilograms per hectare.

7. A method according to either of claims 5 and 6 which comprises treating a cotton crop by foliar application.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. Activity Activity Calculated Observed Amitraz mortality Methomyl mortality effect of effect of (ppm) (ç) (ppm) (g) mixture (g.) mixture ((4) 150 35 1500 37 72 98 120 31 300 7 38 69 40 6 100 0 6 15 25 2 250 0 2 19 10 0 400 16 16 24 WHAT WE CLAIM IS:

1. A pesticidal composition 'comprising amitraz and methomyl.

2. A pesticidal composition according to claim 1 in which the amitraz and methomyl are employed in a ratio of from 3:1 to 1:40 by weight.

3. A pesticidal composition in aqueous form suitable for direct application to a crop, comprising a pesticidal composition as defined in either of claims 1 and 2 in which the concentration of active ingredients is from 0.005 to 5 per cent by weight.

4. A method for controlling pests which comprises applying a composition according to any of claims 1 to 3 to the pests or their habitat.

5. A method for protecting crops selected from cotton, maize, soybeans, soft fruit and top fruit by application to the crop of a composition according to any of claims 1 to 3.

6. A method according to claim 5 in which the active ingredients are applied at a rate of from 0.25 to 6.0 kilograms per hectare.

7. A method according to either of claims 5 and 6 which comprises treating a cotton crop by foliar application.