GB1576221A

GB1576221A - Chemical treatments in agriculture

Info

Publication number: GB1576221A
Application number: GB159/77A
Authority: GB
Original assignee: Manchem Ltd
Current assignee: Manchem Ltd
Priority date: 1976-01-05
Filing date: 1977-01-05
Publication date: 1980-10-01
Also published as: NZ182991A; ZA7753B

Description

(54) CHEMICAL TREATMENTS IN AGRICULTURE We THE HONOURABLE LAURIE JOHN FERGUSON, Minister for Public Works for the State of New South Wales of State Office Block, Phillip Street, Sydney, New South Wales, 2000, Australia and Manchem Limited, a British Company of Borax House, Carlisle Place, London, 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: The present invention relates to chemical treatments for use in agriculture.

The present invention in one aspect is applicable to dealing with the problems of ectoparasites on animals.

Hitherto many materials have been used for combatting ectoparasite attack on animals as well as the treatment of stored food stuffs for the purpose of at least reducing the extent to which the animal or food stuff is likely to be adversely affected.

In the case of the sheep industry, many different materials have been used either to repel blowflies (Lucilia cuprina, wied) or alternatively to act as an insecticide. Usually the materials have been applied to sheep by dipping, showering or hand-jetting the sheep with a solution or aqueous suspension of the repellent or toxic material. Not only are these techniques expensive in terms of labour and cost of materials but also the material if of a toxic character may contaminate the environment. Furthermore the wool in the fleece may retain a residual quantity of chemical and in any case the technique may be less than completely successful. Economically it is very important to limit the effect of blowfly maggots which feed on the flesh causing local staining of the wool fibre and, due to a reaction, a weakening of the fibres over most of the animal. The fleece is of lower quality due to fibre breakage and comprises less useable wool. Therefore, it is necessary to cut away the wool around local infestations in order to treat the skin and remove the maggots.

Similar problems exist for example with cattle a particularly important ectoparasite being ticks (Boophilus microplus; Canestrini).

In the last 25 years, various synthetic insecticides have been tried for blowfly control but a major problem has been the fact that over a period of a few years, it has been found that the blowfly develops a resistance to the insecticide. Hitherto, several organo-phosphorous insecticides have been used because as the resistance to one insecticide has built up, it has been necessary to develop another synthetic insecticide to take is place. All organophosphorous insecticides that have been tried on blowflies exhibit cross-resistance.

Untortunately little has been done in the way of further developments since 1965 when resistance to the chemical Diazinon in the blowfly was confirmed. Prior to 1965 it was found that the single application to a sheep was effective for approximately 6 to 8 weeks and this was an acceptable length of time as in Australia the worst time for blowflies is approximately mid-October to mid-December and February and March, the hottest month of January being too hot for significant blowfly activity. However, it has now been found that blowflies have developed so that the Diazinon is only effective for a shorter period of approximately 12 to 18 days.

The present invention is directed to implementing a new approach to treating ectoparasites and is based on the concept of a radically different approach and instead of using a toxic material as in the prior art, the present invention proposes altering the micro-climate in the regions susceptible to infestation with a material selected to reduce significantly the available moisture by gelling and film forming.

In the treatment of animals, the material is applied by passing a discharge head through the coat of the animal at susceptible zones of the animal's skin or the entire external surface if desired while discharging through the head a fine spray of treatment material.

Materials have been developed which ut3 reduce significantly the available moisture and tests have shown that this reduction in moisture correlates with a reduced infestation rate.

Use of the present invention does not necessarily completely prevent infestations, but an improved and reduced rate of infestation compared with what would have occurred in the absence of the use of the invention generally occurs.

Although a reduction in available moisture of the order of ten per cent may be a useful improvement, in general a higher moisture reduction is preferred such as at least twenty percent by weight, for example of the order of twenty five to thirty per cent. It would be desirable in many applications of the invention if a higher reduction in available moisture could be achieved and it may be possible to develop materials which in the use of the present invention can achieve such results.

The present invention provides a method of treating animals for the purpose of reducing the effects of ectoparasites comprising passing a discharge head through the coat of the animal at the regions of the animal to be treated while discharging through the head a fine spray of treatment material, the treatment material comprising a solution of an organic material capable of being thinly coated over the fibres of the coat of the animal, being substantially inert relative to the fibres of the coat of the animal and being gel-forming in the presence of moisture whereby the microclimate adjacent the skin of the animal is modified to reduce substantially the attractiveness of the site to the ectoparasite.

In the case of the treatment of animals for such ectoparasites as blowfly in sheep, obligate parasitic sheep lice (damalinia Sp.) and ticks in cattle, the material selected is adapted to be applied to the exterior of the animal and react with moisture present on the animal to form a gel, preferably within a few days e.g. less than one week whereby the material is effectively retained on the hairs and/or fleece of the animal thereby causing a lowering in the available moisture.

In presently preferred embodiments of the invention, the material applied is an organic material for example an organic metal oxide in a hydrocarbon solvent whereby the material is sprayed onto the animal.

In the case of treatment of sheep it is preferable to use a fine spray mist using of the order of 150 mls of the material, the discharge nozzle being "combed" through the areas of the fleece which are susceptible to strike. For speed of operation a multi nozzle dispensing head may be used and the nozzle is designed so that the discharged material is in the form of a fine mist which will penetrate between the fine wool fibres and form a film thereon. It is not necessary for the film to be uniform and providing a complete coverage of the wool fibres.

It has been found that in the specific example hereinafter described, the use of about 150 mls of a twenty per cent solution of the organic aluminium compound is sufficient to treat the critical areas of marino sheep.

Not only should the gellant material be selected to suit the particular conditions, but also the solvent used to permit spraying of the material should be selected so that a relatively flexible and soft film is produced. The applicant's work has shown that better results are obtained from some hydrocarbon solvents or mixtures of solvents than others. Specifically, the applicant has found that a useful combination of hydrocarbon solvents is that sold by Esso Australia Ltd under the Trade Mark Isopar C and Isopar E. However, the use of Isopar E alone has been found to be less useful since the films appear to be stiff and brittle.

Use of the present invention for treating sheep against blowfly attack has demonstrated that effective protection lasting for the order of twelve weeks is obtained, this period being dictated substantially by the fact that the wool fibres are growing and after about twelve weeks a significant length of new fibre adjacent the skin occurs and this of course is untreated. It is believed that the reason for the effectiveness of the present invention particularly in the case of blowfly is that the eggs are laid at the tips of the wool fibres and on hatching the new maggots have to travel down over a period of hours to reach the skin, where in the next phase of development the maggot begins to feed on the flesh. A reduction in the available moisture during the critical period before the maggot can begin to feed results in a substantially greater death rate than would occur in untreated sheep.

Organic aluminium compounds can be particularly useful in the present invention and one formulation of particular use comprises six per cent oxides of aluminium, two per cent oxides of zinc and the balance being fatty acids and alcoholic esters.

The percentages of oxides of aluminium and zinc being expressed in terms of metal content relative to the formulation. The formulation may be modified or substituted by using oxo aluminium stearate with an equal amount of ispropyl stearate.

Additionally or alternatively, the process can use a formulation comprising oxo aluminium stearate together with a small proportion of ester and a low adour paraffinic solvent added.

Preferably the method includes forming a solution in a suitable hydrocarbon solvent whereby the material is readily atomised and sprayed onto the animal so that it is capable of penetrating, for example, the fleece of a sheep, gelling taking place subsequently by reaction with moisture in the fleece of the sheep, the material preferably being located as near to the skin of the animal as possible.

Suitable materials for use in the present method may be those prepared from compounds of the following types:

where R1 and R2 are alkyl groups containing 3 to 5 carbon atoms; X is an acyloxy group from a carboxylic acid, HX containing from 5 to 22 carbon atoms.

British Patents 806,113 and 825,878 describe the production of compounds of the form (O=AlX)n wherein n is an integer. In the case of compound (1) above the compound is heated with water and alcohol is distilled off or in the case of compound (2), the compound is heated to a temperature at which breakdown occurs to give the product (O=Al-X and RX where R is an alkyl group containing 3 to 5 carbon atoms.

It has been found that compounds of the type (O=AIX)n react with substances containing hydroxyl groups such as water and glycols and with carboxylic acids to produce gels, the materials furthermore being soluble in hydrocarbon solvents.

It is believed that materials of the type (O=A1-X), may also be modified by the inclusion of modifiers of the general formula O=A1-X, where Xis a different radical from that in the main gelation compound. An alternative modifier is that described in British Patent 972,804 which has the general formula

where each X is an acid radical and M is a divalent metal.

The present invention is based on the appreciation that the micro-climate adjacent the skin of an animal if altered to provide a drier climate is advantageous in controlling ectoparasites. The inventor has conducted experiments with different strains of merino sheep and has examined wool from different portions of the fleece and in each case it has been found that the lower the moisture content, the lower is the incidence of blowfly strike.

It has been found that different portions of the fleece are inherently of greater moisture content and these are most susceptible to blowfly strike and furthermore, some strains of merino have a lower moisture content in the fleece and significantly fewer blowfly strikes are found in the research undertaken to date.

In connection with sheep, the present invention is concerned with moisture control adjacent the skin which is the site of blowfly infestation. In this instance the source of moisture is sweat or, to use the correct term "suint". The effect of rain and dew is not significant to the moisture content adjacent the skin.

Although the invention may be practiced utilizing materials having the general structural formula (O=AIX)n it is believed that improved flexibility and adhesion may be obtained by including other components in the material. For example one or more esters of the formula RY may be included where R is an alkyl group and Y, which may be the same as X, is a carboxylic acid group containing three to twenty-five carbon atoms.

A useful mixture of this type is one containing from forty to ninety per cent by weight of (O=AlX)n and from five to sixty per cent by weight of the ester RY.

Additionally some unconverted aluminium compound of the formula ROAlX2 may be included, where R is a alkyl group containing from three to five carbon atoms and X is a carboxylic acid group containing from five to twenty-two carbon atoms.

Furthermore the mixture may include another aluminium containing compound which contains another metal. For example a compound as described in British Patent 972804 and having the following general formula may be utilized: B - M - 0 - AIB - 0 - AlB - 0 - M - B in which M is a divalent metal selected from calcium, magnesium, zinc and strontium and each B, which may be the same or different, is a carboxylic acid group containing from three to twenty-two carbon atoms.

Such materials are believed to have a greatly improved degree of strength, flexibility and adhesion yet may be sprayed when dissolved in suitable solvents such as hydrocarbons, fluorocarbons and halogenated hydrocarbons such as methylene dichloride.

The carboxylic acid group X, Y and B may be derived from aliphatic, aromatic, cycloaliphatic monocarboxylic acids or from the half esters of dicarboxylic acids. The ester RY may be either the ester RX produced in the preparation of (O=Al-X)n and/or another ester, for example isopropyl myristate, or a mixture of several esters.

The above described developments or improvements based on materials of the general structural formula (O=Al-X)n, have been developed by Manchem Limited and form part of the disclosure of pending British Patent Application 49010/75 (Serial No. 1556376).

For illustrative purposes only, an example of the invention will now be given.

Example 1 The treatment of the sheep to reduce blowfly strike was investigated using a formulation containing an organic aluminium compound comprising six per cent oxides of aluminium based on the general structural formula (O=AlX)n, two per cent oxides of zinc and the balance being fatty acids and alcoholic esters. This compound was diluted so as to be a twenty per cent solution in a mixture of hydrocarbon solvents, the mixture comprising Isopar C and Isopar E supplied by Esso Australia Ltd.

Trials have been undertaken using the organic aluminium compound in the hydrocarbon solvent which was atomised and sprayed on to the fleece of sheep, compressed air being used for atomising.

In the solution to be atomised, concentrations of the organic aluminium compound in the formulation in the range 15% to 30% have been tried. It has been found that a concentration of about 20% seems to be the optimum, whereby the gel formed on the fleece is pliable but retained readily on the fibres of wool, The quantity of solution used was approximately 100 ml. per animal, the solution being sprayed over the back and body area.

A comparison was made between sheep treated by the method according to the present invention, sheep treated by conventional jetting with the insecticide Diazinon and a control sample of sheep which were untreated. The sheep were all left in the same paddock, the sheep being merino ewe weaners.

Observations were conducted over a period of 5 weeks for evidence of blowfly strike and the following percentages indicate the percentage of sheep of each group in which some blowfly strike was observed: Control sample (untreated) 20.8% Diazinon jetted (0.04% diazinon) 10.9% Present invention 4.8%.

The trials mentioned above demonstrate that the use of the present invention with organic aluminium compound showed approximately an 80% improvement over the untreated control sample and approximately 60% improvement over conventional jetted Diazinon.

Experiments have shown that the use of the present invention reduces the available moisture content by approximately 30% compared with untreated sheep.

The present invention is fundamentally different to the use of insecticides and thus can offer fundamental advantages principally the fact that there can be no increase of resistance in the blowfly generations as the system does not rely on any toxic effect and thus, the material will not become progressively more ineffective. Therefore, expenditure on seeking the optimum material will be well justified as the material when found will not have simply a short useful commercial life. Another major advantage is that there is no ecological disturbance and no pollution from the insecticide used in the prior art.

Furthermore, it has been found that wastage of material is small as there is no possibility of the material dripping off the sheep after jetting and no deleterious effects have been found in either the wool or the tissue of the animal.

Other trials have been conducted with cattle and an increase d drop-off rate of adult ticks on infested cattle has been found. However, a better time to treat the cattle would be at the stage when lavae attach to the animal.

It is believed that the reduction in available moisture in the skin area of the animal makes the area unattractive to several parasites which rely on moisture to support life.

WHAT WE CLAIM IS: 1. A method of treating animals for the purpose of reducing the effects of ectoparasites comprising passing a discharge head through the coat of the animal at the regions of the animal to be treated while discharging through the head a fine spray of treatment material, the treatment material comprising a solution of an organic material capable of being thinly coated over the fibres of the coat of the animal, being substantially inert relative to the fibres of the coat of the animal and being gel-forming in the presence of moisture whereby the microclimate adjacent the skin of the animal is modified to reduce substantially the attractiveness of the site to the ectoparasite.

2. A method as claimed in claim 1 wherein the solution is formed from a hydrocarbon solvent.

3. A method as claimed in claim 1 or claim 2 wherein the organic material is an organic metal oxide.

4. A method as claimed in claim 3 wherein the organic metal oxide is an aluminium compound.

5. A method as claimed in claim 4 wherein the aluminium compound has the general structure (O=Al-X)n, where 0 is oxygen, Al is aluminium, n is an integer and X is an acyloxy group from a carboxylic acid.

6. A method as claimed in claim 5 wherein said aluminium compound is mixed with at least one ester of the formula RY where R is an alkyl group containing from three to five carbon atoms and Y is the same or a different carboxylic acid group containing from three to twenty-five carbon atoms.

7. A method as claimed in claim 6 and further comprising an aluminium compound of the formula ROAlZ2 wherein R is an alkyl group containing from three to five carbon atoms, 0 is oxygen, Al is aluminium and Z is a carboxylic acid group containing from five to twenty-two carbon atoms.

8. A method as claimed in any one of claims 4 - 6 wherein said material further comprises an aluminium compound containing another metal and of the general formula B - M - 0 - Al(B) - 0 - Al(B) - O - M - B where Mis a divalent metal selected from calcium, magnesium, zinc and strontium and each B which may be the same or different is a carboxylic acid group containing from three to twenty-two carbon atoms.

9. A method as claimed in any one of claims 5 - 8 wherein in said material the carboxylic acid groups are derived from any one or more of aliphatic, aromatic, cycloaliphatic monocarboxylic acids or from the half esters of dicarboxylic acids.

10. A method as claimed in claim 4 wherein said material comprises seventy percent by weight oxo-aluminium ethylhexoate and thirty percent by weight isopropyl ethylhexoate, this mixture being diluted by twenty-five percent by weight by a compound of the structure BZnO-Al(B)-O-Al(B)-OZnB, where B is the oleate radical, and the resulting material being dissolved in a fluorocarbon solvent prior to spraying.

11. A method as claimed in claim 5 wherein the material comprises a mixture of oxo-aluminium ethylhexoate (seventy percent by weight) and isopropyl ethylhexoate (thirty percent by weight).

12. A method as claimed in any one of the preceding claims wherein the fine spray is provided by atomizing under compressed air.

13. A method as claimed in any one of the preceding claims wherein said material has the characteristic of gelling in less than one week and reducing the available moisture adjacent the skin of the animal by at least twenty percent by weight.

14. A method as claimed in claim 13, wherein said material comprises by weight six percent of an aluminium compound as claimed in claim 4, two percent oxides of zinc and the balance being fatty acids and alcoholic esters, this material being dissolved in a hydrocarbon solvent system to form approximately a twenty percent solution by weight before spraying, the above percentages being in terms of the proportion of metal relative to the whole formulation.

15. A method as claimed in claim 1 substantially as herein described.

16. A method as claimed in claim 1 substantially as herein described with reference to the Example.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. on infested cattle has been found. However, a better time to treat the cattle would be at the stage when lavae attach to the animal. It is believed that the reduction in available moisture in the skin area of the animal makes the area unattractive to several parasites which rely on moisture to support life. WHAT WE CLAIM IS:

1. A method of treating animals for the purpose of reducing the effects of ectoparasites comprising passing a discharge head through the coat of the animal at the regions of the animal to be treated while discharging through the head a fine spray of treatment material, the treatment material comprising a solution of an organic material capable of being thinly coated over the fibres of the coat of the animal, being substantially inert relative to the fibres of the coat of the animal and being gel-forming in the presence of moisture whereby the microclimate adjacent the skin of the animal is modified to reduce substantially the attractiveness of the site to the ectoparasite.

15. A method as claimed in claim 1 substantially as herein described.

17. Animals when treated by a method as claimed in any of claims 1 to 15.