DELIVERY DEVICE FOR AGRICULTURAL PESTICIDES

Abstract: A device for the controlled and/or altered release of pesticidal substances contained in solid or gel compositions for delivery to a plant comprising an inner water soluble or water dispersible film or bag to contain the composition and an outer protective layer which permits release of the pesticidal substance in use.

Description: Delivery Device for Agricultural Pesticides The invention relates to a new delivery device suitable for pesticides, and especially for hazardous pesticides. This is also applicable to eg. plant nutrients and antibiotics. The legal and environmental requirements are becoming more and more demanding in relation to the use of pesticides, and the concern for unmanaged residues of any kind in the working environment. In addition, risk incurred in the environment due to emptied containers and broadcast applications is of great concern to regulatory managers worldwide. Even though there are no specific laws, it is a natural need to make, use, manipulate and apply the pesticides in the safest possible way. The most common ways to apply pesticides are directly to the plant or the soil or the seed. In all these situations there are still instances where workers are in some substantial contact with the pesticides. It has also been described to use pesticides in water soluble bags, but these bags are intended to be dissolved or diluted in a dilution tank and the resulting solution then sprayed. The manipulation of the pesticides is thus reduced up to the time the diluted spraying mixtures are made, but that does not prevent the contact of the pesticide with the person who sprays the products on the plants. An object of the instant invention is to provide a delivery device for pesticides, as well as a cultivation method, whereby contact between the pesticides and the workers is still further reduced, i.e. a cultivation method which reduces worker exposure to pesticides. Another object of the instant invention is to provide a direct delivery device for pesticides to the plant, as well as a cultivation method, whereby the pesticide is easy to apply to the vegetal organism. The advantage of the invention is to deliver the pesticide, premeasured, so as not to exceed the labeled rate. Another object of the instant invention is to provide a direct delivery device for pesticides to the plant, as well as a cultivation method, which is simple and cheap, and which requires a very reduced amount of material for the application. It has now been found that these goals may be achieved, totally or partially, by means of the instant invention. The present invention provides a device for the controlled and/or altered release delivery of pesticidal substances, contained in solid or gel compositions, to a plant which device comprises an outer layer of perforated plastics film having eg. several holes generally small in size and an inner water soluble or water dispersible film or bag within the said outer layer. The solid or gel composition is such that it need not be diluted before use or application. The device generally contains a pesticidal solid or gel composition. By controlled and/or altered delivery it is to be understood that the delivery of the active ingredient comprised in the composition is made gradually in a time generally extending over a period of time of up to 4 weeks. In practice the time should generally not exceed four weeks; however this may be more depending on products or mixtures contained in the device. For example, a banana plant may be cut, and the device inserted into the mother plant. The device will release the active ingredient into the plant and this will then move into the daughter plant over a period of time. When the active ingredient does move into the daughter plant it can provide, for example, nematicide/insecticide protection to the plant over the next 180 days as it matures. Furthermore, undesired residues of pesticide in the fruit of the banana plant at harvest may be avoided or reduced. According to another feature, the instant invention provides a device (otherwise named as a container), which container contains one dose of pesticidal composition which is not to be diluted before use or application and which is appropriate for, or suitable for, or designed to the treatment of one vegetal system. The word vegetal in the instant specification, designates a plant or a tree or any intermediate vegetal organism such as a bush or the like. The solidity and/or rigidity of the container, when filled, of the instant invention is generally such that it does not substantially flex under pressure or under normal conditions. Flexing under pressure is not necessarily important but it must not burst under pressure in normal use before being put into a vegetal. The device of the invention may resemble a Ketchup packet, or a very small pillow. It is generally made from flexible packaging films and filled on a machine used for flexible packaging materials. Thus, the packets are not completely rigid. The film is somewhat flexible so there is not the rigidity seen with eg. condiments that are packaged in foil wrap. According to another feature, the instant invention provides a device having no space between the inner bag or film and the outer layer. Thus, there is no material such as active ingredients, adjuvant or carrier or the like in the space between the inner bag or film and the outer layer of plastic film. According to another feature, the instant invention provides a device wherein the inner bag or film is adhering to the outer layer. According to another feature, the instant invention provides a device wherein the inner bag or film is coated on the outer layer. According to another feature, the instant invention provides a device wherein the inner bag or film is applied as an ink would be applied on the inside surface of the outer layer. The ink-like water soluble or water dispersible material will seal off the small holes of the outer layer. The size of the container may vary in a large range according to the size of the vegetal to be treated and according to the amount of pesticide which is to be delivered to the said vegetal. Generally the container is smaller than 50 ml, preferably smaller than 20 ml. Typically, containers of the invention are from 1 to 6 cm wide and from 4 to 15 cm long. Preferred containers are from 2 cm wide and 4 cm long to 5 cm wide and 15 cm long. More preferred is a container such as a bag about 4 cm wide and about 7 cm long. The shape of the container may also vary in relation to the prescribed dose. Generally it may have a cylindrical, or cylinderlike shape in order to be able to be introduced easily in a soft plant, the section of the cylinder being not limited to a circle nor to a square or other polygonal form. The term cylindrical shape, indicates the general arrangement of the container, but some narrowing and/or some broadening of the cross section is possible. It may also be advantageous to have at least one extremity of the container having a conic shape. This general conic shape may have itself a round end, or a spike to aid in application to the vegetal. The container may also resemble a Ketchup packet, or a very small pillow as mentioned above. The shape of the container is advantageously such that the ratio longer size / smaller transverse size is in the range from 1 or 1.5 to 5, preferably 2 to 4. The material which constitutes the inner film or bag, may be any water dispersible or, preferably, water soluble polymer, such as PVOH, gelatin, starch, etc.. Polyvinyl alcohol (PVOH) is particularly preferred for its mechanical properties which work well from a handling and machinability view. It is also easily available and has outstanding odour barrier properties. In the future, new films suitable for use in the invention may also be developed. When it forms a bag inside the device, said bag is generally closed by at least one water soluble heat seal. The thickness of the walls of the inner water soluble bag or film may be determined to provide appropriate release of the pesticidally active ingredient in the vegetal. A thicker wall provides a slower release. A thinner wall may provide a quicker release. This is also useful to influence the amount of pesticide residue remaining in the plant at the harvest time. The thickness is also important to influence the rate of solubility of a water soluble material constituting the inner film or bag. The water solubility is generally such that the material constituting the inner water soluble film or bag may be dissolved at normal temperatures of cultivation of plants, that it is to say at temperature higher than 10°C, preferably higher than 15°C. It is not really necessary that the dissolving takes place rapidly in the plant. A lengthy dissolution due to a low solubility may be very convenient as providing a slower release of the pesticidal compound. The plastics film constituting the outer layer of the device according to the invention comprises at least one polymeric material, including polymers and copolymers and is preferably water insoluble and optionally biodegradable. A preferred polymer is polyethylene terephthlate (PET). The size and number of small holes is determined according to the desired delivery or release time. Preferably, the size of each small hole is from 0.025 to 0J25 cm (0.01 to 0.05 inches) and the number of small holes is at least 1 hole and no more than 25 per square cm of the plastics film surface. More holes can be used, for example up to 150, eg up to about 100. Holes are not necessarily identical as far as diameters are concerned. The aim of the outer plastics film is also to prevent the inner film or bag being dissolved, for instance by the user, and to prevent individual packets from sticking together for example during storage.. Alternatively, the plastic film may be replaced by a degradable material, eg paper, such as tea bag paper, made generally from a type of banana tree pulp, which therefore will be very degradable in for instance a banana plant. In this case, it would not require any holes. If desired holes could, of course be formed, eg stamped, in it. The inner bag may be also such that it is separated by an additional plastics sheet (either PVOH or PET or, in general, a water insoluble, water dispersible or water soluble material) thus leading to an inner bag having two compartments each of which having one different pesticide inside. The individual packet will therefore have a two cell unit that could hold two products. For example one part of the bag may contain a fungicide (such as fosetyl-Al) and the other part an insecticide (such as aldicarb). The advantages are obvious : less packaging material used, easier application (one device instead of two), less expensive to use in the method of the invention. The pesticidally active formulation which is contained in the container may be a solid or a gel. However, solid formulations are preferred because they are more favourable in reducing the risk of exposure of the people who are handling or manufacturing the said compositions or formulations. Still more preferable are the substantially dustless formulations, for example those whose particle size is more than OJ mm, preferably from 0.4 to 8 mm. The pesticidally active formulation which is contained in the device of the invention is preferably concentrated. The more concentrated the formulation the smaller the water soluble container can be and the less damage made to the vegetal when the containerisation device of the invention is introduced therein. Pure pesticidally active ingredient may be used and enclosed in the device, but, it is often desired to have the said active ingredient or pesticide incorporated in an appropriate formulation which may help the dissolving inside the vegetal, and/or the spreading of the said ingredient in the whole vegetal. It may also be desirable to have a formulation which itself controls the release of the active ingredient in the vegetal. Concentrations higher than 15 % (w/w) are thus generally used. Preferably the concentrations of these formulations are even higher than 20 % or even better, higher than 40 %. However, the main criterion is the water solubility of the pesticide rather than the concentration of the pesticide. In the case of banana treatment for instance, the release would not be intentionally delayed because there is only a short period of time before the mother plant will begin to die and as it dies, the ability to transfer the pesticide, as desired to the daughter plant will decrease. Fast release and transfer is desired. A phytotoxic response at this time is not a great concern since the mother plant has already been harvested and the release of the pesticide to the daughter plant will be somewhat gradual. According to another feature, the instant invention provides a delivery device as already defined which contains one or more pesticides which are naturally toxic at low dose for mammals, and/or which are at least partially soluble in water. According to another feature, the instant invention provides a delivery device wherein the active ingredient, or pesticidal substance, of the solid or gel composition is systemic. By systemic, is meant that the active ingredient is able to use the natural flow of material in the plant in order to move inside said plant. Preferably, the active ingredient is aldicarb. More advantageously, the composition is a composition comprising aldicarb and gypsum. Preferably, aldicarb is adsorbed on gypsum. However, other aldicarb formulations are suitable, such as aldicarb adsorbed on corn cob grits. The invention provides a method of treating a plant with a pesticide which method comprises inserting into a plant a device according to the invention. The device may, for example, be inserted into a hole cut or bored into the plant. According to another feature, the instant invention provides a method for vegetal cultivation, in which the said vegetal contains a soft part and at least one device as defined above is inserted into the vegetal by pressure and/or in a hole previously made in, eg bored or cut in the vegetal, eg the mother trunk in the case of a banana. In this cultivation method, the inner film or bag of the device is sufficiently dissolved so as to release the pesticide included therein directly inside the vegetal. The vegetal is soft enough so as to make possible the introduction of the said container inside the said vegetal without a substantial damage to the said plant. The method of the instant invention is especially suitable for banana or plantain trees, especially banana or plantain trees which have been cut after harvesting. The place of cutting is generally rather soft and well suited to the introduction of a delivery device therein. The introduction of the delivery device inside a banana plant then protects the next generation of plant which grows from the bottom of the said cut mother plant. Other plants or trees may of course be treated, eg date palms. Due to the controlled release which can be obtained by variation of different characteristics of the container as indicated hereabove, it is possible to have a variable release rate in the tree from very slow to a rapid release of product. Also, the method may involve more than one device per plant. Each device may be at separate locations in the plant, eg in bored or cut holes. Alternatively, for the method for treating banana or plantain plants one or more device as described above may be inserted by pressure and/or in a hole previously bored in the daughter trunk of a plant. This is particularly suitable when pesticides either have a short half life and/or require a limited preharvest interval. The pesticide of the instant invention may be for example a herbicide, a fungicide, a nematocide, a bactericide, an antibiotic, a plant growth regulator or plant nutrient or an insecticide or combination thereof. The invention is especially advantageous for pesticides having high acute or chronic toxicity for mammals at certain rates and in certain conditions. The invention is especially of interest for insecticides / nematocides. Pesticides which are well suited for use in the invention have some water solubility and systemic activity so as to be able to move inside the vegetal. Among the many pesticides which can be used, examples include methyl carbamates, such as aldicarb ; the 1-arylpyrazoles such as fipronil ; imidacloprid ; fosetyl-Al ; carbofuran ; benomyl ; terbufos ; oxamyl ; fosthiazate ; these active ingredients being well known to persons skilled in the art. One of the advantages of the device and method of the invention is illustrated by its use to deliver aldicarb to bananas: it minimizes the residue of aldicarb in the banana plant and contamination of the surrounding soil (more than 99% of the active ingredient goes into the plant and substantially no aldicarb goes into the soil). Therefore less material is needed and the speed of absorption by the plant is greatly accelerated. The aldicarb flows from a mother plant to a daughter plant without being applied to the soil or to the daughter plant directly. This limits the contamination of the soil by aldicarb and provides thus a safe and novel method of applying aldicarb to the new plant. It may be that a minimal amount of aldicarb may leave the plant through root exudates. Substantially no pesticide is expected to be released into the soil. However, depending on the nature of the active ingredient, there is a possibility that as the pesticide may move from mother to daughter plant and into the root system. A highly water soluble pesticide might partition into the soil if there was a very high concentration of water in the soil (for example during heavy rain). Example About 0.8 grams of aldicarb (as Temik ™ GG 15 % w/w on gypsum granules) were placed in a packet that is approximately 8 cm long by 3 cm wide and 1.5 cm thick. This packet was made of water soluble polyvinyl alcohol. The packet was filled and then sealed using a high temperature seaFer. This water soluble packet was itself put in a second packet made of a plastic film with several small size (about 0.075 cm (0.03 inches)) holes. The outer plastic packet is a little larger than the inner polyvinyl alcohol packet so as to enclose it without further substantial freedom of movement. The packet was placed into a freshly cut banana plant and left for about a week, after which time the granules were recovered. The percentage of aldicarb left on the granules was less than 2% by weight.

Claims: Claims : 1. A device for the controlled and/or altered release of pesticidal substances contained in solid or gel compositions for delivery to a plant comprising an inner water soluble or water dispersible film or bag to contain the composition and an outer protective layer which permits release of the pesticidal substance in use. 2. A device according to claim 1 for the controlled and/or altered release delivery of pesticidal substances contained in solid or gel compositions to a plant comprising an outer layer of perforated plastics film and an inner water soluble or water dispersible film or bag within the said outer layer. 3. A device according to claim 1 or 2 having no space between the inner bag or film and the outer layer. 4. A device according to claim 3 wherein the inner bag or film adheres to the outer layer. 5. A device according to claim 4 wherein the inner bag or film is coated on the outer layer. 6. A device according to claim 5 wherein the inner bag or film is applied like an ink on the inside surface of the outer layer. 7. A device according to any one of the preceding claims having a cylinder shape or a pillow shape. 8. A device according to claim 6 wherein the cylinder has a round or polygonal base at one end and a spike shape at the other end. 9. A device according to any one of the preceding claims wherein the inner film forms a bag and has at least one water soluble heat seal. 10. A device according to any one of the preceding claims wherein the inner film comprises polyvinylalcohol (PVOH). 11. A device according to any one of the preceding claims wherein the plastics film, optionally biodegradable, is preferably PET. 12. A device according to any one of the preceding claims wherein the perforations are holes from 0.025 to 0J25 cm (0.01 to 0.05 inches) in size and the number of small holes is at least 1 hole and no more than 25 per square cm of the plastic film surface. 13. A device according to any one of the preceding claims wherein the active ingredient of the solid or gel composition is systemic. 14. A device according to any one of the preceding claims wherein the active ingredient is aldicarb. 15. A device according to any one of the preceding claims wherein the composition comprises aldicarb and gypsum. 16. A device according to claim 15 wherein the aldicarb is adsorbed on gypsum. 17. Amethod of treating a vegetal with a pesticide which method comprises inserting into the vegetal a device according to any one of the preceeding claims. 18. A method according to claim 17 for treating banana or plantain plants wherein at least one device according to any one of the preceding claims is inserted by pressure and/or in a hole in the mother trunk of the plant. 19. A method according to claim 18 wherein the device is inserted inside the mother trunk once its fruits are harvested and its head is cut. 20. A method according to claim 18 or 17 using more than one device per plant, each device being in a separate hole. 21. A method according to claim 17 for treating banana or plantain plants ' wherein at least one device according to any one of claims 1 to 16 is inserted by pressure and/or in a hole in the daughter trunk of the plant. 22. A method according to claim 21 in which the pesticide either has a short half life and/or requires limited preharvest interval. 23. A method according to claim 17 in which the vegetal is a date palm.

Inventors: BOCANEGRA JUAN, CEPEDA JORGE, KNUDSEN GLENN C, BOCANEGRA, JUAN, CEPEDA, JORGE, KNUDSEN, GLENN, C.
Applicants: BOCANEGRA JUAN, CEPEDA JORGE, KNUDSEN GLENN C, RHONE POULENC AGROCHIMIE, BOCANEGRA, JUAN, CEPEDA, JORGE, KNUDSEN, GLENN, C., RHONE POULENC AGRO
Application year: 1998
Main classification: A01N25
IPC codes: A01N25