GB1580631A - Control of agricultural pests by controlled pesticide release particles - Google Patents

Description

(54) CONTROL OF AGRICULTURAL PESTS BY CONTROLLED PESTICIDE RELEASE PARTICLES (71) We, HERCULITE PROTECTIVE FABRICS CORPORATION, a corporation organised according to the laws of the State of New York, United States of America, of 1107 Broadway, New York, New York, United States of America, 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 the control of agricultural pests by controlled pesticide release particles.

Increased scrutiny of the effects of various pesticides has placed a greater emphasis on the utilization of already widely known agents whose effects have been studied over the years since it may take upwards of several years to bring to the marketplace a new and more effective agent that will meet the imposed governmental standards. It is increasingly attractive to utilize known agents for the control of agricultural pests. This could be done by decreasing the influence of environmental factors such as heat, humidity and rain upon the agent. Further, a desirable end result would be the extension of the active life of the agent in order to decrease the number of applications of the agent and the maintenance of the activity of the agent at a steady level such that the initial application activity would not be dangerously high followed by a period of the proper level followed by a period of low activity.

To provide an efficient delivery system for agents for the control of agricultural pests, a method has been developed whereby polymeric particles which release the agent in a controlled manner are applied to the environment of a plant or seed. The particles can be applied to the agricultural environment such that the absolute amount of agent per unit area is the same as that applied by previous delivery methods. However, distinct and important advantages are gained by the use of the present invention whereby the effective life of the agent is extended which may result in a lowering of the absolute amount of agent applied to the environment to achieve the same degree of agricultural pest control.

According to the present invention there is provided a method for the control of agricultural pests (as herein defined) comprising producing polymeric controlled pesticide release particles by granulating a laminated sheeting material comprising i) a first solid, non-porous polymeric sheet having adhered thereto ii) a polymeric core film containing a pest controlling active agent and having on the opposite side of the first sheet, adhered thereto iii) a second solid, non-porous polymeric sheet, said active agent being capable of migrating by molecular migration through at least one of said sheets to become available on at least one surface of said particles, and applying said particles to a location where it is desired to control pests.

In the context of the present invention "active agent" means substances capable of migrating into and through the polymeric materials used in the invention so that it becomes available on, at or from the surface of said polymeric materials. "Migration" indicates a mass transfer or diffusion in molecular form of material through a solid, non-porous polymer layer or material and excludes bulk transfer through pores or micropores. The active agents are materials capable of killing or affecting agricultural pests such that damage to the crop is lessened.

Although the present invention is especially effective in controlling insects, "pest" means insects, animals and all other lower forms of life undesirable in the context of the invention from an agricultural standpoint including mammals, birds, vertebrates, invertebrates, worms, fungi, molds, protozoa, viruses, bacteria and other organisms capable of reproducing or multiplying.

Particles of the general structures described in United States Patents 3,705,938 and 3,864,468 can be used in the method of the present invention. The particles can be formed by chopping, dicing or otherwise granulating laminated sheeting materials wherein the active agent is contained in an interior "reservoir-type" layer and is capable of migrating to the surface.

The polymeric laminated sheeting is preferably formed by providing a first sheet of a polymer which is substantially non-porous and can be any polymeric material which is capable of being formed into a self-supporting continuous sheet or film. This first sheet, which is non-porous but not necessarily impervious to migration of the agent, can be an of the available polymer sheetings, e.g., hydrocarbon polymers such as rubber and ole ins, for example, polyethylene and polypropylene, imide, amide, ester, urethane, carbonate, cellulosic, halocarbon, ionomer, vinyl, such as polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate and other polymers as well as their blends, interpolymers and copolymers, polyvinyl chloride being preferred. The thickness of the sheet is not critical, and articles of about 3 mm thick can be produced. Excellent results have been obtained with single sheets having a thickness of about 0.3 mm and with multi-ply laminates having a combined thickness of about 0.8 mm.

To the first sheet, a polymeric liquid composition containing the active agent is applied.

Although any liquid composition capable of being set to form a solid film of plastic can be used, the term includes plastisols, polymer solutions, polymer-in-liquid emulsions and 100% solid liquid polymers.

The laminate is completed by application of a second polymeric sheet to the liquid composition followed by a lamination step to form an integral laminate which can then be chopped, diced or otherwise granulated to produce the particles for the invention. A "blocking" layer may be added to slow or stop the agent migration. Further laminates include a structure whereby two agents are included in one or more "reservoir-type" layers. A structure could be formulated whereby one agent migrates to one surface while another agent migrates to the opposite surface with a barrier layer between two reservoir layers containing the respective agents. Thus, laminated structures, such as those described in Belgium Patent 807,146, of which one of the inventors of the present application is a co-inventor, can be used as the sheeting to be granulated.

A three-layered laminate is preferred wherein the outer layers have a thickness of the order of from 0.02 to 0.2 mm, the polymeric core layers have a thickness of the order of from 0.05 to 0.5 mm and the overall laminates have a total thickness of up to about 1 mm.

The agents in the invention include insecticides, rodenticides, acaricides, nematocides, moluscides, anthelmintic substances, insect, bird and animal repellants, fumigants, algicides, insect growth regulators, antimetabolites, chemosterialants, juvenile hormones, analogs and mimics; and such pest foods and food minics, any of the foregoing of which are capable of "migration". Active agents used in the dispensers described in Belgium Patent No. 820,284, of which one of the present co-inventors was the inventor, can be used in the particles.

Preferred agents include Diazinon which is 0,0-diethyl-0(2 -isopropyl-6-methyl4-pyrimidyl) phosphorothioate, and Thimet which is a trademark for a systemic insecticide based on 0,0-diethyl- S-(ethylthiomethyl) phosphorodithioate.

In general, the particles used in the present invention can be applied in an amount corresponding to the same amount of the active agent which is applied to that particular crop in a non-controlled release form, Examples 2, 3, 4 and 5 being examples of this procedure.

Lower amounts may be applied if found to be adequate in controlling the particular pest while higher amounts may be used in view of the lowered danger in view of the present invention, of the application of too high a concentration.

Additional agents or materials can be formulated in the particles of the present invention as an integral part of the particle itself or intermixed therewith. The outer layer of the particle may contain fillers, pigments, ultraviolet screening agents or other standard materials used in the polymeric technology.

Although release rates may vary according to the particular polymer and/or agent used, such rates can be easily determined and the release rates can be programmed for the entire growing season of the life cycle of the pest. The invention can eliminate over-spraying where extremely toxic chemicals are used or where crop growth or timing makes it impractical to return to the crops for additional application.

The particles can be applied to the soil environment of a plant or seed, at the surface, intermixed throughout or primarily at a desired depth, to the plant itself or to the seed as an admixture with the seeds before planting or in the furrow or hole provided for the seed.

The following Example demonstrates the preparation of a laminated sheeting.

A sheet of polyvinylchloride (PVC) film having a thickness of 0.1 mm was coated with a plastisol prepared by dispersing 100 parts of PVC resin in about 25 parts of dioctylphthalate and then adding 120 parts of chlorpyrifos, i.e., 0,0-diethyl 0-(3,5,6-trichloro-2-pyridyl) phosphorothioate. The coating was applied in a thickness of about 0.5 mm. The coating was overlaid with a second sheet of the 0.1 mm thick PVC and laminated under suitable conditions of heat and pressure. The laminate contained 30.8% chlorpyrifos insecticide.

The following examples indicate the utilization of particles formed from such laminates.

Example 1 A laminate was prepared as above with the substitution of chlorpyrifos by Diazinon such that Diazinon was 6% by weight. The sheet was chopped into small granules and compared with standard Diazinon 14G granules.

The polymeric laminated granules (hereinafter referred to as HERCON granules) and the standard Diazinon 14G granules were weighed to the correct rate and placed with 500 cc of air-dried top soil in a plastic bag and mixed. 25 ml of water were added and mixed. The treated soil was split into 250 cc aliquots and placed in 16-ounce wax-coated paper cups. 10 kernels of germinated corn were planted 1.5 centimeters deep in each cup and 10 four- to seven-day old Diabrotica balteata larvae were placed on the soil surface. The cups were sealed with a snap-on plastic lid and held at room temperature for 7 days at which time the soil was sifted through a No. 16 sieve having 1.19 mm openings to recover the larvae and determine their mortality. The soil was retained and placed in plastic bags to which 12.5 ml of water were added. After mixing, the soil was retested as above. Each treatment was replicated two times to yield 4 cups for a total of 40 larvae for each treatment.

As shown in Table A, at the rate of 1 part per million, all granules were effective at least 5 weeks. However, at the rate of 2 ppm, the HERCON Diazinon 6G was effective for 13 weeks while the standard Diazinon 14G was effective for only 7 weeks. Thus, as can be seen by the following Table A, the use of the present invention increased the duration of effectiveness of Diazinon by almost 100% at a substantially lower concentration.

TABLE A

Percent Mortality at Indicated Week Treatment Rate 1 5 7 11 13 15 ppm week week week week week week Diazinon HERCON 1 90 90 70 60 45 0 6.0% 2 75 90 100 95 80 35 (GA-4-587) 4 85 100 100 95 100 95 Diazinon 14G 1 75 80 60 25 25 0 2 90 100 95 30 20 10 4 4 100 70 95 85 90 30 Check #1 -- 15 0 20 25 30 0 Check - -- 10 15 15 25 20 5 Example 2 In this experiment particles are introduced to the environment of seeds during planting.

Pots were filled to within about 5 cm of the top with soil and dispensers containing Thimet where applied to the surface on a 7.5 cm line in the center. In addition to HERCON dispensers without Thimet and control pots, pots were prepared with HERCON particles containing Thimet and with standard Thimet 15G Attapulgite clay granules, attention being paid to the absolute amount of Thimet applied to each pot via the different delivery systems. 3 field corn seeds were placed on the line in each pot after which the pots were covered with 2.5 cm of soil, placed in a greenhouse and watered for good germination and growth. The plants were carefully thinned to one per pot when 5 to 7 cm tall.

When the corn plants were 15 to 18cm tall in about 17 days, the soil in each pot was lightly cultivated and 10 southern corn rootworm larvae (3rd instar) were placed on the soil adjacent to each plant. Feeding damage to the corn was classified as follows: 0 = no feeding 1 = slight feeding 2 = moderate feeding 3 = severe feeding Seven to 10 days following each damage rating, a new seeding of corn was carefully made in the same location as the original planting. This regime was followed for the duration of the experiment.

As shown in Table B, the method of the present invention utilizing controlled released polymeric particles gave good control against the southern rootworm (Diabrotica undecimpunctata howardii Barker) for 164 days when the experiment was completed. The standard formulation of Thimet designated as Thimet 15 G at the same rate of 7.5 mg was only effective for 73 days and completely ineffective thereafter. To obtain the same effectiveness as the controlled release dispenser, one would have to use 4 to 8 times as much Thimet in the form of the standard Thimet 15G.

TABLE B

Average Com Damage Rating Rate at Treatment Rate at (Days After Treatment) System Thimet 17 73 122 164 H-i - 3.0 3.0 3.0 3.0 Clay 7.5 1.0 0.3 3.0 3.0 15.0 1.0 0.0 3.0 3.0 30.0 0.0 0.0 0.7 1.7 H-1(Invention) 7.5 0.7 0.0 0.3 0.0 15.0 0.7 0.0 0.0 0.0 30.0 1.0 0.0 0.7 0.0 Control - 3.0 3.0 3.0 3.0 Example 3 To determine the effect of the Thimet to the corn plants themselves in Example 2, the systemic characteristics of the plants were determined.

When the corn plants of Example 2 were 15 to 18 cm tall, the second leaf from the bottom was excised for bioassay with western potato leafhopper (Empoasca abrupta DeLong). The rates for both delivery systems were 7.5, 15, 30 and 60 mg of actual Thimet present.

As shown in Table C below, the controlled release formulation in accordance with the present invention at the rate of 7.5 mgwas 100% effective for 124 days when the experiment was discontinued. The standard Thimet 15 G clay formulation gave 100 % control for only less than 73 days with no control thereafter. To obtain the same control as the invention by using the standard clay formulation, 4 to 8 times as much Thimet would have to be applied.

TABLE C

Average % Control of Leafhoppers Rate at Treatment Thtmet (Days After Treatment) System Thimet (Mg) After 24 73 96 124 H-i - 0.0 33 0.0 Clay 7.5 100 100 0.0 0.0 15.0 100 100 66 0.0 30.0 100 100 66 100 H-i (Invention) 7.5 100 100 100 100 15.0 100 100 100 97 30.0 100 100 100 100 Control ~ - 0.0 0.0 - 0.0 0.0 Example 4 This experiment compares Diazinon dispensers within and outside of the scope of the invention.

Sweet corn was sown in small plots at fortnightly intervals. After the plants were 3 weeks old, Diazinon insecticide was spread on the plants at the rate of 30 kilograms per hectare. The controlled release particles of the invention were 3-layered particles containing 10% Diazinon while the standard particles were 10% Diazinon calcite granules.

At intervals of 1, 7, 14 and 20 days atter the insecticide treatment, day old larvae of sweet corn borers (Sesamia nonagrioides) were placed on the plants. Since the granular materials tend to collect at the leaf axils, the larvae were placed at these axils at the rate of 30 larvae per plant. Ten days later the plants were uprooted and examined by counting the number of live larvae which penetrated the plant.

Table D below summarizes the results with standard 10%Diazinon calcite granules and the controlled release dispensers according to the invention (designated as "HERCON L 5328-2"). The particles according to the invention gave good control and were superior to the conventional granules. Although both were effective when the larvae were placed one day after treatment, an increase in the rate of live larvae was observed when placed one week after treatment, primarily on plants treated with the conventional granules. After 20 days, the invention was as effective as the standard formulation after one week. The controlled release formulation was not phytotoxic even at high temperatures of 40"C and at a very high relative humidity of 80 to 90% TABLE D

Number oflive larvae per 10 plants when larvae Treatment applied X days after plant treatment, where X = 1 7 14 20 HERCON L 53-28-2 0 16 16 46 Diazinon 10% 1 50 60 75 Check 96 185 120 122 Example 5 Granular form Diazinon insecticide according to the invention is compared to a standard formulation as they affect corn plant tolerances and corn silage yields at harvest when applied to the furrow at seed planting when exposed to northern corn rootworm larvae.

Insecticidal granules were placed with corn seeds into plowed and fitted soil to result in an in-furrow treatment. The standard was Diazinon 14G used in Example 1. The controlled release particles were 3-layered Diazinon formulations as previously described. Root ratings were obtained from 30 plants (10 plants per replicate, 3 replicates) by the Iowa State University System: 1 = no feeding damage 2 = feeding scars present 3 = at least one root pruned 4 = at least one full root node pruned 5 = at least two full root nodes pruned 6 = at least three full root nodes pruned A "pruned root" must have been pruned to within 1 1/2 inches of the plant. Brace roots are considered as a node if they are below the soil surface.

As indicated in Table E, the formulations according to the present invention gave average root rating damage indices and average silage yields which were superior to those of the standard granular Diazinon 14G. The index of phytotoxicity of the 4 runs was 0(0 =none, 10= 100% kill).

TABLE E Average Average Insecticide Granular Root Silage Material Application Application Ratings Yields Rate (Ibs. A mount/Plot Damage Tons/Acre ai/Acre) (1/1000 Acre) Index at 32% DM HERCON Diazinon 11.3G 1 4.53 g 3.0 25.20 Tns HERCON Diazinon 8.3G 1 5.89 g 2.1 26.60 Diazinon 14G 1 3.62 g 3.4 24.50 Untreated Check - - 3.8 20.81 Example 6 This experiment was conducted to compare granular insecticides against cabbage maggots when the granules are applied in-furrow with the seeds.

Diazinon 14G granules used in Example 1 and controlled release particles according to the invention were applied to respective furrows during cabbage seed plantings. The granules were in the form of banded granules and were incorporated 2 inch bands at a depth of 1/2 inch or less.

Ratings were made 1 month after treatment on the roots of 30 plants for each run (10 per replicate) after they had been removed and washed. The average weight per head was determined from 30 which had been cut about 50 days after treatment.

As indicated in Table F, the furrows treated by the invention gave far more root protection from maggot tunneling than the standard Diazinon 14G. Stand phytotoxicity for all runs was 0.

TABLE F Total Root Granule Maggot Insecticide Amount Damaged So Average Rate Ibs. Product Plants Clean Wt./Head Material ai/Acre lD & /Acre Out of 30 Plants (Ibs Diazinon 14G 1 7.0 16 46.6 1.75 HERCON 11.33% Diazinon 1 9.5 6 80.0 1.82 HERCON 8.8% Diazinon 1 12.0 5 83.3 1.64 Untreated Check - - 18 40.0 1.40 WHAT WE CLAIM IS: 1. A method for the control of agricultural pests (as herein defined) comprising producing polymeric controlled pesticide release particles by granulating a laminated sheeting material comprising i) a first solid, non-porous polymeric sheet having adhered thereto ii) a polymeric core film containing a pest controlling active agent and having on the opposite side of the first sheet, adhered thereto

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. TABLE E Average Average Insecticide Granular Root Silage Material Application Application Ratings Yields Rate (Ibs. A mount/Plot Damage Tons/Acre ai/Acre) (1/1000 Acre) Index at 32% DM HERCON Diazinon 11.3G 1 4.53 g 3.0 25.20 Tns HERCON Diazinon 8.3G 1 5.89 g 2.1 26.60 Diazinon 14G 1 3.62 g 3.4 24.50 Untreated Check - - 3.8 20.81 Example 6 This experiment was conducted to compare granular insecticides against cabbage maggots when the granules are applied in-furrow with the seeds. Diazinon 14G granules used in Example 1 and controlled release particles according to the invention were applied to respective furrows during cabbage seed plantings. The granules were in the form of banded granules and were incorporated 2 inch bands at a depth of 1/2 inch or less. Ratings were made 1 month after treatment on the roots of 30 plants for each run (10 per replicate) after they had been removed and washed. The average weight per head was determined from 30 which had been cut about 50 days after treatment. As indicated in Table F, the furrows treated by the invention gave far more root protection from maggot tunneling than the standard Diazinon 14G. Stand phytotoxicity for all runs was 0. TABLE F Total Root Granule Maggot Insecticide Amount Damaged So Average Rate Ibs. Product Plants Clean Wt./Head Material ai/Acre lD & /Acre Out of 30 Plants (Ibs Diazinon 14G 1 7.0 16 46.6 1.75 HERCON 11.33% Diazinon 1 9.5 6 80.0 1.82 HERCON 8.8% Diazinon 1 12.0 5 83.3 1.64 Untreated Check - - 18 40.0 1.40 WHAT WE CLAIM IS:

1. A method for the control of agricultural pests (as herein defined) comprising producing polymeric controlled pesticide release particles by granulating a laminated sheeting material comprising i) a first solid, non-porous polymeric sheet having adhered thereto ii) a polymeric core film containing a pest controlling active agent and having on the opposite side of the first sheet, adhered thereto

iii) a second solid, non-porous polymeric sheet, said active agent being capable of migrating by molecular migration through at least one of said sheets to become available on at least one surface of said particles; and applying said particles to a location where it is desired to control pests.

2. A method according to Claim 1, wherein said particles are intermixed with soil or are applied to the surface of soil in the environment of plants or seeds.

3. A method according to Claim 1 or 2 wherein said pest controlling active agent is an insecticide.

4. A method according to Claim 3, wherein said insecticide is 0,0-diethyl-0(2-isopropyl6-methyl-4-pyrimidyl) phosphorothioate, or 0,0-diethyl-S-(ethylthiomethyl) phosphorodithioate.

5. A method according to any one of Claims 1 to 4 wherein said first and second sheets i) and iii) are sheets of polyvinyl chloride and the polymeric core is a polyvinyl chloride plastisol.

6. A method according to any one of Claims 1 to 5 wherein said first and second sheets i) and iii) have a thickness of 0.02 to 0.2 mm and the polymeric core layer ii) has a thickness of 0.05 to 0.5 mm.

7. A method according to Claim 1 substantially as described in any one of Examples 1 to 6.