Improvements in or relating to copper based pesticides

Abstract

The effect of aqueous compositions of copper-based fungicides is improved by including a mixture of sodium dodecyl succinate and sodium lauryl sulfate surfactants in the aqueous composition which shou

Description

The present invention relates to the use of copper as an agrochemical and in particular to the use of copper as a fungicide and / or as an insecticide. Copper is widely used in agriculture and horticulture as a pesticide usually as an aqueous suspension of finely milled particles of copper compounds. The biologically active component is the Cu++ ion and examples of copper compounds that are used to provide the ions include copper sulphate, copper hydroxide, cuprous oxide, copper oxychloride, copper ammonium carbonate and copper octanoate. Whilst copper compounds are effective pesticides there are however concerns that their use can lead to the build-up of copper in soil causing the formation of undesirably high heavy metal deposits. There is therefore a need to improve the effectiveness of copper pesticides to enable the desired effect at lower treat rates. Copper is widely used in agriculture and horticulture as a fungicide and bactericide particularly to prevent or reduce the formation of scab and canker on apples and the formation of downy mildews, fire blight and late blights, Alternaria, Stemphylium, Taphrina and other leaf spot fungal and bacterial diseases on grapevines, hops, fruit and nuts, vegetables and ornamentals. It is also used on some arable crops such as potatoes for control of late blight, and on beet such as sugar beet and cereals for the control of leaf spot diseases. These fungi tend to be dispersed via airborne spores and via rain splash in the field, spreading from one plant or part of the plant to another; the copper is used to prevent or limit access of the fungi to the plant tissues. Copper is also used on many other crops such as citrus, olives, peanuts, cocoa, coffee, rubber, tea, tobacco and the like. Agricultural production worldwide is under permanent threat from numerous insects, mites, phytopathogenic fungi and bacteria. For the protection of yield and quality of produce and to avoid economic losses, the application of agents that control plant diseases is an absolute requirement. Although the need for pesticides is generally acknowledged there is an ongoing public concern about the negative impact of pesticides on the environment and on human health. There is a general concern about the environmental aspect of agrochemicals and the present invention provides a method whereby the amount of copper required for effective treatment may be reduced perhaps by as much as 50% at any particular time during the growing season. Copper is typically applied to vegetation during the growing season and is applied to both the foliage of the plants and the fruit as they develop during the growing season. Copper acts preventively, through direct contact of the Cu++ ions to the pest (fungal spores or hyphae) on the plant surface. Generally the amount of copper that is applied per hectare increases throughout the growing season as the size of the plant (both foliage and produce) increases. Regulatory pressure, notably in Europe, is increasingly restricting the use of copper-based products to limit the total amount of copper applied per hectare in a year or successive years. This is leading to reduced numbers of applications allowed per crop and season for existing products. Copper use as an agrochemical is typically by spraying of an aqueous composition of the copper compound containing various adjuvants and in the case of vegetation onto the leaves and produce of the crop. The preferred composition is an aqueous dispersion of finely milled particles of the copper compound. Typically solid or concentrated compositions of the copper compound are supplied to the grower who will mix the formulation with water in a spray tank and then spray the suspension or solution onto the vegetation. Additionally the formulation may contain other agrochemicals such as other fungicides and insecticides. Most aerial vegetation, particularly leaves and stems, has a thin waxy surface layer, the cuticle, which is highly hydrophobic. Some of the aqueous spray compositions of copper products that are sprayed onto the vegetation will not be retained on the vegetation and will simply run off the plant surfaces. This can result in inadequate treatment of the vegetation or the requirement of larger amounts of products to be applied in order to obtain the desired protection of the crop. Additionally the lack of retention of the composition on the vegetation often results in uneven distribution of the copper across the vegetation resulting in untreated areas which will not be protected from fungal infections. The present invention addresses these problems. PCT publication WO2018 / 036579 relates to a preparation for use as a plant protection agent which has at least one copper containing component, at least one basic component and at least one wetting agent and the wetting agent is selected from docusate sodium or a combination of docusate sodium and sodium dodecyl sulfate and the basic component is potassium hydrogen carbonate and / or sodium hydrogen carbonate. According to WO2018 / 036579 the combination of copper hydroxide with the basic component increases the free availability of the copper ions whereas previously it was considered that the availability of free copper ions could only be achieved by acidification. The active mechanism is said to be the formation of intermediary carbonate / copper complexes with a hydrogen carbonate before it is fixed as basic copper carbonate. WO 2018 / 036579 does not describe the function of the wetting agent although the patentee states that the presence of the wetting agent can further increase the availability of copper when WO2018 / 036579 uses a mixture of docusate sodium and sodium dodecyl sulphate together with potassium bicarbonate. Furthermore WO2018 / 036579 does not consider the amount of the mixture of the two surfactants that should be employed in the formulation and additionally does not consider the ratio of the two surfactants that should be employed. We have now found that providing from 15 % to 300 % by weight of a mixture of docusate sodium and sodium dodecyl sulphate based on the weight of copper metal and that providing the mixture contains the two surfactants in a ratio of from 2:1 to 1:2 the effectiveness of an aqueous composition of a copper containing pesticide can be increased without the need to include a basic bicarbonate salt. The present invention therefore provides a pesticide preparation comprising an aqueous composition containing 0.015 wt % to 3 wt % of copper metal 0.0025% to 10% of a mixture of docusate sodium and sodium dodecyl sulphate in a ratio of from 2:1 to 1:2 parts by weight And which is free of bicarbonate salts, such as potassium and sodium bicarbonate. The composition is preferably an aqueous suspension of finely milled particles of the copper compound. Preferably the particles are of average particle size of from 1 to 15 microns, more preferably 2 to 5 microns. We prefer to use from 0.001% to 6 wt % of the surfactant mixture in the aqueous composition and we have found that by using this amount of the surfactants in the preferred ratios the amount of surfactant is optimised to achieve the desired wetting of the crop and thus the amount of copper metal that is required to be applied to achieve a particular effect is reduced. In WO2017 / 037277 we describe how a combination of sodium dioctylsulfosuccinate and sodium lauryl sulfate may be used with the fungicide potassium bicarbonate to control the surface tension and contact angles of the spray droplets and the crystal size of the potassium bicarbonate that is deposited on the vegetation once the water used in the spray solution has evaporated. The use of the surfactant mixture of this invention improves the retention of the copper containing aqueous composition on vegetation when the composition is sprayed onto the vegetation. By retaining the composition on the vegetation, more copper remains on the vegetation when the water of the aqueous composition evaporates and less runs off and is wasted providing more copper compound on the vegetation to provide the Cu++ ions that have the pesticidal effect. This results in a more efficient use of the copper enabling a smaller amount to be used to obtain a desired degree of treatment. The use of the surfactant mixture also improves the distribution of the aqueous composition on vegetation when it is applied onto the vegetation. By improving the distribution on the vegetation a more uniform pattern of the copper compound is formed when the water of the aqueous spray evaporates thus resulting in more uniform treatment across the whole surface of the vegetation providing improved treatment for a given amount of the copper compound. The pesticides envisaged by this invention may be insecticides or fungicides and for formulations of the invention are useful for inhibiting, ameliorating, preventing or treating a plant and / or soil for insect infestation such as treatment for aphids and / or fungal disease such as scab, downy mildew, late blight, Alternaria, Stemphylium, Taphrina, Septoria and other leaf spot diseases, mites, flies, scales, psyllids or thrips and the invention is particularly useful as a fungicide and in a preferred embodiment is used for the prevention of downy mildew on lettuce and for the prevention of Sclerotinia on oilseed rape. In preferred embodiments the formulations and the preparations used in the invention may include at least one further surfactant and an anionic surfactant is preferred as the further surfactant. The further surfactant may be one or more anionic surfactants selected from phosphate esters, substituted and non-substituted sulphonic acids, and their salts, monosulphate esters, naphthalene sulphonic acid derivatives, sulphonated vegetable oils, sulphonated esters of natural fatty acids, carboxylic acid derivatives, alkyl substituted succinic acid, polycarboxylic acid salts and many others. We prefer that the further surfactant is not an amphoteric surfactant and in one embodiment of the invention an amphoteric surfactant is excluded. The formulation of this invention and the preparation that is used in this invention comprise a copper compound and sodium dioctyl sulfosuccinate and sodium lauryl sulfate and it is preferred that the amount of the sodium lauryl sulfate present in the formulation is equal to, less than or greater than the amount of sodium dioctyl sulfosuccinate; the amount being by weight. The copper in the formulations and the preparations is preferably provided by a copper compound which is preferably selected from copper sulfate, copper hydroxide, cuprous oxide, copper oxychloride, copper ammonium carbonate and copper octanoate. Copper hydroxide is particularly preferred. Accordingly a preferred composition for mixing with water to produce an aqueous pesticide composition according to this invention comprises i) From 5 wt % to 30 wt % of copper metal ii) From 0.25 wt % to 60 wt % sodium dioctyl sulfosuccinate iii) From 0.25 wt % to 60 wt % sodium lauryl sulfate. iv) No bicarbonate salts More preferably the composition has the formulation i) From 5 wt % to 30 wt % of copper metal ii) From 3 wt % to 40 wt % sodium dioctyl sulfosuccinate iii) From 3 wt % to 40 wt % sodium lauryl sulfate. iv) No bicarbonate salts The copper metal being derived from a copper compound. These compositions can be mixed with water to provide a pesticide spray composition (a preparation) and a preferred preparation is one that contains from 0.015 % to 3 % copper metal, preferably 0.05 % to 0.3 % copper metal, more preferably 0.25 % to 1.5 % copper metal together with the surfactant mixture diluted respectively by the same amounts. As mentioned one feature of this invention is the recognition that the use of the surfactant combination of this invention enables the desired fungicidal effect to be achieved without requiring the presence of bicarbonate salts such as potassium or sodium bicarbonate. The treatment rate that should be used depends upon the nature of the crop being treated, the nature of the fungus to be treated and the stage of growth of the crop during the growing season. We have however found that in many instances the invention enables a reduction in the necessary treatment rate in copper metal to achieve a desired pesticidal effect of 40% or more typically 50% to 60%. The improved retention of the copper on the vegetation and the improved dispersion arises from the degree of wetting of the surface of the vegetation by the spray preparation. This in turn is determined by the surface tension and contact angle of the droplets on the vegetation as provided by the use of the mixture of surfactants. We have found that typically a contact angle from 40° to 60° is desirable. Additionally we have found that smaller angles typically result in over-wetting of surfaces with spray droplets running off the crop surface whilst angles above 60° result in incomplete wetting and areas left untreated. The present invention is illustrated by the following Examples Example 1 A formulation (comparative formulation) containing i. 708 grams per kilo of potassium bicarbonate ii. 100 grams per kilo of copper hydroxide to provide 65.15 grams per kilo of copper metal ill. 125 grams per kilo of a 2:1 mixture of docusate sodium and sodium dodecyl sulfate was compared with a formulation (inventive) containing i. 18.0 wt % copper hydroxide to provide 11.7 wt % copper metal ii. 22.5 wt % of a 2:1 mixture of docusate sodium and sodium dodecyl sulfate The copper hydroxide was milled to an average particle size in the range 1 to 5 microns. The formulations were mixed with water to provide an aqueous suspension of copper hydroxide and tested for control of the fungus Sclerotinia sclerotiorum on stems and pods of oilseed rape by spraying onto the oilseed rape 5 litres per hectare of the inventive preparation and 5 kilograms per hectare of the comparative (bicarbonate containing) preparation. Control of Sclerotinia disease on stems with the preparation of the inventive formulation was at least as good as that of the preparation of the comparative formulation, and better on pods than the preparation of the comparative formulation. The yields of rape seed from the crop sprayed with the preparation of the inventive formulation were considerably higher than the yields of the crop sprayed with the preparation of the comparative formulation. Example 2 The inventive preparation of Example 1 was applied to sugar beet at a treat rate of 5 kilograms per hectare to provide 570 grams per hectare of copper to investigate the control of the fungus Cercospora beticola. The crop was evaluated by counting the leaves of the middle crown of 25 plants showing symptoms prior to treatment and 14 days after treatment and after a further 14 days and again after 30 days. The results were compared with similar crops treated with the conventional fungicide Amistar 5 Pro and the results using the product of the invention were superior.

Claims

1. A pesticide preparation comprising an aqueous composition containing Cu++ ions comprising5 0.015 wt % to 3 wt % of a copper metal derived from a copper compound ofaverage particle size 1 to 5 microns and selected from copper sulfate, copper hydroxide, cuprous oxide, copper oxychloride, copper ammonium carbonate and copper octanoate0.0025% to 10% of a surfactant mixture of docusate sodium and sodium10 dodecyl sulphate in a ratio of from 2:1 to 1:2 parts by weightand which is free of bicarbonate salts, such as potassium and sodium bicarbonatewherein the surfactant mixture is present at 15 - 300 wt % of the copper metal.

152. A pesticide formulation for mixing with water to produce an aqueous pesticide spray preparation comprisingCM i. From 5 wt % to 30 wt % of copper metal derived from a copper compoundCM average particle size 1 to 5 microns and selected from copper sulfate, copper'1““ 20 hydroxide, cuprous oxide, copper oxychloride, copper ammonium carbonater-") and copper octanoateCO ii. From 0.25 wt % to 60 wt % of sodium dioctyl sulfosuccinate and from 0.25 wt% to 60 wt % sodium lauryl sulfate ill. No bicarbonate salts25 wherein the surfactant mixture is present at 15 - 300 wt % of the copper andthe SDS and SLS are present in the surfactant mixture in the ratio of 2:1 to 1:2.

3. A formulation according to Claim 2 comprising30 i. From 5 wt % to 30 wt % of copperii. From 3 wt % to 40 wt % sodium dioctyl sulfosuccinateiii. From 3 wt % to 40 wt % sodium lauryl sulfate.iv. No bicarbonate salts35 4. A pesticide spray composition comprising a formulation according to Claim 2 or Claim3 and water containing from 0.015 % to 3 % copper, preferably 0.05 % to 0.3 %copper, more preferably 0.25 % to 1.5 % copper together with the surfactant mixture diluted respectively by the same amounts.

5. The use of a pesticide preparation according to any of Claims 1 to 4 for inhibiting, 5 ameliorating, preventing or treating a plant and / or soil for insect infestation such astreatment for aphids, mites, flies, scales, psyllids or thrips.

6. The use of a pesticide preparation according to any of Claims 1 to 4 for inhibiting, ameliorating, preventing or treating a plant and / or soil for fungal disease such as 10 scab, downy mildew, late blight, Alternaria, Stemphylium, Taphrina, Septoria andother leaf spot diseases.

7. The use according to Claim 6 as a fungicide for the prevention or remediation ofdowny mildew on lettuce.

158. The use according to Claim 6 as a fungicide and for the prevention or treatment of Sclerotinia on oilseed rape.

9. The use according to Claim 6 as a fungicide and for the prevention or treatment of 20 Cercospora leaf spot on sugar beet.30 12 24