NO824358L - SYSTEMIC PESTICIDE PRODUCT AND PROCEDURES FOR PREPARING AND USING THEREOF - Google Patents

Description

The present invention relates to pesticide-releasing preparations. In particular, it concerns the s"am^ns^OTiTrge"r""soiti^gSlowly and controlled release of a systemic pesticide to the soil.

Farmers and plant growers have always faced a problem of partial or total loss of crops or plants due to plague. Over the years, a number of pesticide preparations have been developed to remove harmful organisms from crops or plants. As used herein, the term includes

ket "pesticides" insecticides, fungicides, herbicides, miticides, nematocides and bactericides.

Different approaches have been used to deliver pesticides to the plants. A common way has been to spray or otherwise deposit pesticides on the upper side of the plants. A number of patents describe different pesticides and methods for applying them directly to the surface of the plants. See e.g. US-PS 3,992,227 in the name of Bradburne and US-PS 4,102,991 in the name of Kydonieus.' However, this path has certain shortcomings. Firstly, the task of depositing pesticides on individual plants is expensive and time-consuming. Because the pesticides are usually toxic, and the task of applying pesticides to plants is also usually associated with a health risk for the worker. Because in the end the pesticides are thinly spread over the surface of the plants, they are exposed to the atmosphere and quickly lose their pesticidal properties. The pesticide is often washed off or otherwise removed from the surface of the plants by rain or wind. This necessitates frequent reapplication of the pesticides.

Another approach is to carry the pesticide to

the soil near the plates to destroy pest organisms at the plant root. E.g. US-PS 1,038,316 in the name Dokkenwadel describes this method. However, this method suffers from several shortcomings. Firstly, such pesticides do not protect the part of the plant that is above ground. In addition, such pesticides tend to dissolve quickly after they have been introduced into the soil. Accordingly, it is extremely difficult to maintain the concentration of pesticides at a sufficiently high level to continuously destroy pest-

organisms without poisoning the entire area.

In order to increase the lifetime of the pesticides, a number of slow-release products have been proposed. E.g. US-PS 4,007,258 in the name of Cohen et al describes a delayed-release pesticide product that includes a pesticide, a biological binder in a matrix of water-insoluble but water-swellable hydrophilic polymer. The biological binder binds the pesticide and prevents immediate release, but allows gradual release. The problem with this method is that a suitable biological binder must be found for a given pesticide. This can be a formidable task and in some cases an impossible task.

US-PS 3,074,845 in the name of Geary describes a controlled release pesticide product which is prepared by encapsulating, impregnating or coating the pesticide with an amido-aldehyde type resin. CA-PS 846,785 in the name of Allen indicates a number of problems associated with the products made according to the invention described in the Geary patent. In particular, the amido-aldehyde resins must be decomposed by microorganisms in the soil to effect release of the pesticide. Accordingly, the release rate is low and non-uniform because it depends on the type of microorganisms present at that particular location. The amido-aldehyde resins are also incompatible with many desirable pesticides and the polymerization reaction has repeatedly destroyed some of the potentially useful pesticides.

US-PS 3,269,900 in the name of Rubin describes a slow-release pesticide product by encapsulating a pesticide in a polyurethane foam. The foam is decomposed by microorganisms to release the pesticide. The release of the pesticide from the product described in the Rubin patent is therefore dependent on the particular soil and the microorganisms present therein.

US-PS 3,248,288 in the name of Wilder et al. discloses a pesticide product made by mixing a hydrocarbon solution of a pest control material with a polymeric material and cooling the resulting mixture to form the product. The liquid hydrocarbon evaporates and carries the pesticide with it. Allen's CA-PS 846,785 reports that this method of operation is unsatisfactory for general application of the pesticides because hydrocarbons are usually toxic. Therefore, evaporation of volatile components represents safety problems during the manufacture of the product and also during transport, storage and use of the product.

Some of the problems in connection with the application of pesticides on the surface of the plants or in the soil are offset by the use of systemic pesticides. A systemic pesticide is applied to the soil surrounding a plant. The plant absorbs the pesticide through the root system and carries it from there to the leaves. Insects and other pest organisms that come into contact with or feed on the leaves absorb the pesticide from the plant sap, either by ingestion or by absorption through external organs. Thus, a systemic pesticide can be applied to the soil rather than to each individual surface of the plant. They generally remain active for a longer period of time than pesticides applied directly to plant surfaces. Because the pesticides are in the plant sap, the plant is ultimately protected against attacks on the root system as well as attacks on leaves and stems. See e.g. GB-PS 679,631 in the name Ripper.

Despite the numerous benefits of systemic pesticides, their acceptance has not been overwhelming due to a number of serious problems. Probably one of the most serious problems is that systemic pesticides quickly dissolve in the soil so that most of the pesticide is available to the plants immediately after application. However, the plant can only absorb a limited amount of pesticide. The remaining portion is washed away and is no longer available for absorption in the plant's root system. Because the majority of the systemic pesticides are washed away before they can be utilized by the plant, the use of systemic pesticides is extremely expensive. If a large excess of a systemic pesticide is added to the vicinity of the plant, the pesticide can cause phytotoxicity to the plant and thereby cause its partial or total destruction. In order to maintain sufficient levels of pesticides in the plant sap, the systemic pesticides must be frequently re-introduced to the soil. Repeated applications of systemic pesticides increase labor costs. In addition, the accumulation of certain pesticides in the soil can cause health risks.

Another problem stems from the fact that systemic pesticides are generally harmful to humans. This makes the treatment and application of systemic pesticides in the soil risky for workers' health.

An attempt to eliminate these problems is described in US-PS 2,759,300 and 2,809,469, both in the name of Hartley. These patents describe a device comprising a shaft and a head of solid material attached to one end of the shaft. The material includes systemic insecticide covered with a water-soluble coating. If a liquid pesticide is used, the material may also include an inert carrier such as gypsum. The shaft is pushed into the soil until the head is below the surface. The moisture in the ground gradually dissolves the coating and exposes the insecticide. The insecticide material then penetrates the soil and is absorbed into the soil.

The Hartley patents' attempted solution to the above-mentioned problems has not been entirely successful because the coating several times delays the delivery of insecticide to the soil.

Once the coating is dissolved, all insecticidal material is immediately made available to the plant. According to this, the deficiencies in connection with excess insecticides made available to the plant are not eliminated. In addition, Hartley's device includes a non-biodegradable metal shaft that contaminates the soil each time insecticide is applied.

The Allen patent describes controlled release pesticide products that include a pesticide in a thermoplastic polymer material. Some of the pesticides described in the Allen patent are systemic pesticides. The thermoplastic material is hydrophobic and according to this the pesticide is released from the polymer matrix by a method of molecular diffusion of the molecules through the molecular latex in the polymer. The problem with this approach is that the release is rather slow and the infected plants can be seriously damaged or even destroyed by the attack before the pesticides start to work

kill the cause of the attack. The problems with delayed action of the pesticide are particularly serious when the pesticide is used on small sensitive plants, such as common household plants. Because such plants are small, pest infestations can multiply and cause damage to the plant before the pesticide has any significant effect on the pest population. Another problem in connection with products described in the Allen patent is that the product uses expensive binders. The total cost of the product makes it uneconomical to sell to consumers.

There is therefore a long-felt and unsatisfied need for a systemic pesticide product that does not suffer from the above-mentioned shortcomings.

An object of the present invention is to recognize the problems associated with the known technique and to provide a solution to these.

A further object of the invention is to define a class of compounds and a method for selecting and combining these to provide a systemic pesticide product which does not suffer from the shortcomings of the known products.

A further object of the invention is to provide a product which quickly begins to release the pesticide and which continues to gradually release this over a longer period of time.

A further object of the invention is to provide a systemic pesticide product which has the structural strength and integrity to retain its shape and which is shaped to facilitate introduction into the soil and provide an effective safe method of introduction of the product into the soil.

A further object of the invention is to provide a systemic pesticide product which can be released in a regulated manner and which can be produced without health risks, and which effectively kills a wide spectrum of plague organisms for a longer period of time, which can be easily treated__a^_menr^esJce^^and ^ which can easily be introduced into the soil.

A further object of the invention is to provide a controlled release systemic insecticide product which rapidly kills the pest organisms commonly found on household plants substantially without harming the plants, wherein the product once applied continues to kill such pest organisms for an extended period of time and which prevents attacks on healthy plants due to plague.

Other objects of the invention will be obvious to those skilled in the art upon study of the following description.

The present invention provides inexpensive products which, when introduced into the soil near the plant's root system, rapidly release a sufficient dose of a systemic pesticide into the soil to rapidly kill the plague attack on the plant and/or rapidly prevent attack on a plant, and then quaternize the pesticide at regulated speed for an extended period of time.

The products according to the invention comprise a matrix of a water-soluble, hydrophilic, polymeric binder and a systemic pesticide dispersed in the matrix. When the product is introduced into the soil near a plant's root system, the moisture in the soil through the hydrophilic matrix. The matrix begins to dissolve and at the same time the systemic pesticide dissolves in the soil water and is transported to the plant's roots. It then dissolves in the plant sap and is transported with this through the plant. This release mechanism allows rapid delivery of the pesticide to the plant so that pest can be eliminated before it causes serious damage to the plant. The matrix is then further eroded due to the moisture in the soil and continues to provide a gradual supply of the systemic pesticide to the plant to kill remaining pest organisms bg/or to prevent infection.

The products according to the invention generally comprise from approx. 25 - approx. 99 and preferably approx. 25 - approx. 95% by weight binder and 1-75 and preferably 5-75% by weight systemic pesticide. Optional ingredients include plasticizers, fillers, dyes and a coating. The coating makes the product safe to handle and provides additional control over the release rate of the pesticide.

The invention also provides methods for manufacturing the products without creating health risks. The ingredients are mixed. The resulting mixture is subjected to sufficiently high temperature and/or pressure to form a continuous rod. The rod is then cut into suitable shapes such as staples. The preferred method for forming the rod is by melt extrusion. In an alternative, the resulting mixture is injection molded or otherwise shaped to give products of the desired shape. The products can then be coated with a preferably biodegradable coating.

In addition, the invention provides a method for using the products without creating a health risk. According to one feature of the invention, the product is formed as staples which can be pushed into the soil without

get hurt. When the products are introduced into the soil near the plant, the moisture in the soil penetrates through any coating present and dissolves the polymer matrix and the pesticide is released as a result of the matrix's dissolution. The pesticide is transported due to the soil moisture to and absorbed by the plant's root system into the sap and makes the plant toxic to plague-causing organisms.

The preferred systemic pesticide product according to the invention comprises the dimethyl phosphate of 3-hydroxy-N-methyl-cis-crotonamide, 0,0-dimethyl-O-(2-methylcarbamoyl-1-1-methylvinyl)-phosphate or 0,0-dimethyl-S-( N-methylcarbamoylmethyl) phosphorodithioate, 0,0-dimethylacetylphosphoramidothioate or 0,S-dimethylacetylphosphoramidothioate. In a polymer matrix of polyethylene oxide or polyethylene glycol. The product, when introduced into the soil near a houseplant, is effective in rapidly killing pest-causing organisms commonly found on houseplants and prevents infection of the plants for an extended period of time, substantially without harming the plants.

Fig. 1 is a side view of a preferred embodiment

form of an insecticide stick according to the invention.

Fig. 2 is a cross-section of the pin according to fig. 1 along the line 2-2. Fig. 3 shows a flowchart for a first preferred method for producing staples according to the invention. Fig. 4 is a diagram of a second preferred method for producing staples according to the invention. Fig. 5 is a diagram of a currently preferred commercial method for the production of a-v sticks according to the invention, Fig. 6 is a side view of a currently preferred commercial embodiment of the insecticide stick for household plants, produced according to the invention. Fig. 7 is a cross section of the pin according to fig. 6 along the line 7-7. Fig. 8 - 10 are diagrams showing profiles for the release of systemic pesticide as a function of time, from the products manufactured according to the invention.

The present invention provides a controlled release systemic pesticide product that is safe to administer even to the general public. Introduced into the soil near a plant, the product according to the invention quickly begins to kill plague organisms on the plant and continues to kill these for a long time and/or "prevents infection of the plant due to plague organisms for a long time, essentially without adverse effects on the plant The product according to the invention is intended to release a sufficient dose of systemic pesticide to kill pest organisms on the nearby plants within a relatively short time, or to prevent infection of a healthy plant and then continue to add pesticide to the plant gradually at a regulated rate for a long time.

The products according to the invention include a systemic pesticide and a hydrophilic, water-soluble binder. The binder forms a matrix that holds the pesticide and prevents sudden release of the pesticide to the soil. The relative amounts of pesticide and binder may vary depending on the desired properties of the product and the specific binder and pesticide used^^^ The amount^ of binder in the product must be sufficient to hold the pesticide and prevent immediate release to the soil, and to retain the shape of the product. The binder generally comprises from approx. 25 - approx. 99 and preferably from approx. 25 - approx. 95% by weight of the product. The systemic pesticide includes from approx. 7 5 - approx. 1 and preferably from approx. 75-5% by weight of the product.

The most preferred product includes from approx. 30 - 70% by weight binder and from approx. 70 - approx. 30% by weight pesticide.

The other components that can be incorporated into the product comprise 0 - 5% by weight. plasticizer, 0-70% by weight filler, 0-2% by weight of a dye and 0-20% by weight of a protective coating which is preferably water permeable. The preferred amounts of plasticizer, fillers, dyes and protective coating are 2, 43, 2 respectively. 7% by weight of the product.

It has been discovered that adding fillers to the compositions to replace the binder not only results in savings due to lower costs, but also provides a product that is stronger and more durable.

It has also been found that the protective coating according to the invention not only makes the product treatment-safe for the consumer, but can also be used for further control of the release rate of the pesticide from the product. It is preferred that all components of the product according to the invention are degradable or common soil components. Accordingly, the preferred product according to the invention does not contain soil polluting materials.

The systemic pesticide product according to the invention includes a systemic pesticide in a matrix of polymeric binder. It has been discovered that systemic pesticides and binders must satisfy a number of specific criteria in order to be used in products according to the invention. In particular, the systemic pesticide must: (1) be stable at the manufacturing temperature of the product; (2) have sufficient solubility in water to be easily dissolved and transported to and in

the plant sap; ^ _

(3) remain stable and active at the normal pH range found in both soil and plants; and (4) have the ability to kill the desired pest organisms.

Preferably, the systemic pesticides used in the product according to the invention must: (1) have a vapor pressure at ambient temperature that is sufficiently low to essentially avoid the formation of toxic vapors; (2) have a half-life that allows prolonged release from the product; (3) not increase the physical strength and integrity of the binder at the desired concentration so that the product breaks down and/or crumbles when introduced into the soil; (4) has a melting point above the maximum manufacturing temperature; (5) has a LDrr. which is low enough to be usable;

beer)

and

(6) has a minimal effect on mammals, bees, wildlife and humans.

If the products are molded by extrusion, the production temperature for the products according to the invention is usually 50°C. According to this, the systemic pesticide should preferably be stable at least above and have its melting point below approx. 50°C. The preferred systemic pesticide that satisfies the vapor pressure requirements are those with a vapor pressure below approx. 10 mm Hg at - room temperature (approx. 20 oC).

The preferred systemic pesticides have water solubilities in the range of 1.0 - 100 g of pesticide per 100 ml of water. The systemic pesticides according to the invention are stable at pH ranges from approx. 4 - 9, the general range of the pH value

in soil and plants. The preferred half-life is within the range of 15 - 30 days. To satisfy the sixth requirement, the systemic pesticide should preferably be solid at temperatures at which it is applied to plants. (generally 10 - 40°C) .

The preferred systemic pesticides show toxicity against a wide range of plague-causing organisms and particularly good toxicity against aphids, cyclamen mites, fungus gnats, leaf miners, mealy bugs, millipedes, red spiders mites", "scales", "thrips", "two-spotted spider mites", and "whiteflies". The most preferred are the systemic pesticides which effectively kill aphids, "spider mites" and "mealy bugs". The LDj-Q value for systemic pesticides is preferably within the range from approx. 20 - 100 mg/kg. The oral LD[-q should preferably be less than 500 mg/kg. The binder must be water-soluble in quantities that allow a rapid release of the systemic pesticide upon first contact with moisture in the soil and a delayed controlled release of the systemic pesticide thereafter. In order to achieve rapid and initial release of the systemic pesticide from the product, the binding agent should be hydrophilic and water-soluble. In addition, the binder should: (1) not cause phytotoxic effects on plants; (2) be capable of being mixed with the systemic pesticide without the pesticide becoming fugitive; (3) not react with the pesticide in a manner that destroys the effectiveness of each of them in the product; (4) have a softening temperature below the decomposition temperature of the systemic pesticide; and (5) provide sufficient strength to the manufactured product to maintain it substantially intact during packaging, storage, transportation and introduction into the soil.

When forming, the binder should preferably not be toxic to humans.

The present invention offers numerous advantages. First, the product rapidly releases a sufficient dose of the systemic pesticide shortly after it is introduced into the soil to kill disease-causing organisms and then continues to release the systemic pesticide at a controlled rate to eliminate remaining disease-causing organisms if present, and to prevent infection or new infection. Because the composition according to the invention releases the systemic pesticide in a gradual and regulated manner, the pesticide is effectively utilized and lasts for a long time. The pesticide is gradually added to the plant in quantities that do not harm the plant. In addition, the gradual and controlled utilization of the systemic pesticide prevents an accumulation of unused pesticides in the soil. Because the pesticide is effectively utilized, it lasts for a longer time and thereby saves product and labor which is necessary to keep the pesticide level in the soil near the plants sufficiently high to prevent attack.

Another advantage of compounders according to the invention is that they can be shaped into pins that can be driven into the ground without being crushed or broken. The compositions are coarse enough to maintain their integrity during packaging, transport and storage, and are stable under normal atmospheric conditions so that they can be stored for a longer period of time. If a coating is applied to the surface of the composition according to the invention, the resulting product can also be treated by consumers during storage, transport and introduction into the soil without risk of poisoning.

It should be pointed out that the staples produced according to the preferred embodiment of the invention are safe for consumer use, not only because of a protective coating and the use of a polymer matrix to encase the pesticide, but also because in normal use they do not, so to speak, emit toxic vapors and has a low dermal and inhalation toxicity to humans.

Further advantages of the preferred products according to the invention are that they are biodegradable and that they are "self-administered", i.e. that they contain a pre-determined amount of a systemic pesticide and they require no measurement, mixing or other treatment by the product user.

Other benefits will be^ openba^ re_ f or^fa<g>ma nnen

upon closer study of the description.

The components used in the products according to the invention will now be described separately.

The systemic pesticides include water-soluble

equal thiocarbamates, phosphocarbamates and thiophosphocarbamates that satisfy the criteria stated above.

A currently preferred systemic pesticide is 0,S-dimethylacetylphosphoramidothioate which is manufactured by Union Carbide Co. under the name "Standak". Another preferred systemic pesticide is 0,S-dimethylacetyl phosphate oramidothioate, commonly known as acephate. It is available as a wettable powder under the trade name "Orthene" from Chevron Chemical Company, San Francisco, California. Less effective than the two preferred but still acceptable systemic pesticides is 0,0-dimethyl-0-(2-methylcarbamoyl-1-methylvinyl)phosphate, commonly known as monocrotophos and sold under the name "Azodrin"

and 0,O-dimethyl-S-(N-methylcarbamoylmethyl)-phosphorodithioate, commonly known as dimethoate and sold under various trade names including "Cygon".

In general, the binders which are suitable for use in the products according to the invention are those which satisfy the above stated general criteria. Two types of polymers have been found to be superior in making the product of the invention and were found to provide staples which met the object of the invention and which can be driven into the soil without breaking or crumbling. The first type is polyethylene oxides, the second is polyethylene glycols. Polyethylene oxides are preferred because they allow the production of pesticide compositions according to the invention, either by melt extrusion or by injection molding. When polyethylene glycols are used as the binder, the product cannot be produced by melt extrusion. The reason for this is that molten polyethylene glycol does not provide sufficient raw strength to allow the formation of a uniform rod of material that can be cut into desired shapes.

The currently preferred binders are solid polyethylene oxides with molecular weights in the range _approx. 100 .jjO 0 j^_ c a. 900,000. Particularly preferred is polyethylene oxide with an average molecular weight of approx. 100,000 and a narrow molecular weight distribution. Such binders are today commercially available under the trademark "Polyox WSR N-10" from Union Carbide Corporation, New York, New York. Other polyethylene oxide binders available from this manufacturer include "Polyox WSR N-80", "Polyox WSR N-750", "Polyox WSR 205" and "Polyox WSR 1105", with average molecular weights of 200,000, 300,000, 600,000, respectively. 900,000.

Examples of polyethylene glycols that can be used

in conjunction with. the invention includes "Carbowax 4000", "Carbowax 6000" and "Carbowax 14000", commercially available from Union Carbide Corporation, New York, New York.

Fillers can be used in the pesticide products according to the invention to reduce the costs of the products. The fillers are significantly less expensive than the binders, replacing some of the binders with fillers thus reduces the total costs. Examples of fillers suitable for use in the compositions of the invention include clay and corn cob. Clay is particularly preferred because, surprisingly, it has been found to improve the hot-melt strength and viscosity of the molten composition during manufacture. As a result, during processing, a hot-extruded rod can be subjected to tensile stresses without breaking.

An example of a useful clay is "Spray Satin Clay", commercially available from Englehard Minerals and Chemicals Corporation, Iselin, New Jersey. "Corn cob" can be obtained from The Andersons in Maumee, Ohio.

Plasticizers are used as manufacturing aids. They reduce the viscosity of the composition in the melting stage. The currently preferred plasticizers include polyethylene glycols with average molecular weights from approx. 400 - approx. 6000. Particularly preferred is polyethylene glycol having an average molecular weight of 4000. This polyethylene glycol is commercially available under the trade name "PEG 4000" from Union Carbide, New York, New York.

A dye can be added to improve the appearance of the product. Examples of colorants include brown iron oxide sold as "Brown M Oxide" by Hercules, Inc., Wilmington, Delaware; soot, sold as "Raven 5250" by Cities Service Co., Atlanta, Georgia; "corn cob," sold by The Andersons, Maumee, Ohio; iron III ammonium ferrocyanide, sold as "MiloriBlue" from American Cyanamid, Bound Brook, New Jersey; a mixture of zinc and cobalt oxides, sold as "Green V-116 55" by Ferro Colors, Cleveland, Ohio; red iron oxide sold as "Iron Oxide" by Pfizer, Inc., New York, New York; clay sold as "Spray Satin Clay" by Englehard Minerals & Chemicals, Iselin, New Jersey; and titanium dioxide, sold as "Unitane" by American Cyanamid, Wayne, New Jersey. Other colorants will be obvious to those skilled in the art.

Brown iron oxide is today preferred because it has been found particularly acceptable by consumers.

A coating applied to the surface of the product serves several functions. Firstly, it protects the user of the product from accidental absorption of the insecticide through the skin. Second, it increases the stability of the product because it prevents the staple from absorbing moisture from the air during routine processing. Suitable coatings include biodegradable polymers such as cellulose acetate, alkyd resins, alkyd-acrylic copolymers and polyvinyl acetates. The use of a biodegradable coating which is water soluble provides an important additional benefit, namely that the rate at which a systemic pesticide is released into the soil is substantially reduced. An example of a water-insoluble biodegradable coating is cellulose acetate. The coating is generally applied in liquid form and dried on the surface to form a solid coating. Solvents such as ethyl acetate can be used to form a solution for coating the product. Other solvents will be apparent to those skilled in the art. The preferred coating today is a 10% solution of cellulose acetate dissolved in ethyl acetate. The preferred cellulose acetate is commercially available under the trademark "AC6555" from Eastman Chemical Products, Kingsport, Tennessee.

The invention will now be described in connection with

the preferred embodiment of the product shown in the drawings. With reference to fig. 1 there is shown a systemic insecticide stick constructed in accordance with the present invention and generally indicated by the reference numeral 10. The stick 10 includes a generally cylindrical body 12 and a beveled portion 14 terminating in a tip 16. The shape of the stick facilitates its driving into the soil. Depending on the size of the pin and the soil conditions, the pin can be manually pushed into the soil or it can be driven in using a hammer or other suitable tools. A removable plastic or metal cap (not shown) can be placed on the body at the end furthest from the tip 16 to prevent chipping of the pin when it is hammered into the soil.

As shown in fig. 2, the pin 10 includes a coating

21 and a preparation 19. The preparation 19 comprises a systemic

insecticide, a binder, a plasticizer, a filler and a coloring agent. The general and preferred weight percentages for each component and the preferred types of each component are the same as those indicated above for the pesticide compositions.

The currently preferred systemic pesticides: are 0,S-dimethylacetylphosphoramidothioate, generally known as acephate, and 0,S-dimethylacetylphosphoramidothioate. The former is available as a wettable powder under the trademark "Orthene" from Chevron Chemical Company, San Francisco, California. The latter is manufactured by Union Carbide under the name "Standak". If "Orthene" is used, preferably 20% by weight of the staple should be "Orthene". but the amount of "Orthene" used can range from 1% to 75% by weight of the staple. Today's most preferred range for the insecticide is between 10 and 30%.

A preferred method for producing insecticide sticks will now be described with reference to fig.

3. As shown in fig. —3, the dry ingredients are first mixed together using a conventional mixer until a substantially uniform mixture is formed. The mixture is then fed to the bin, in a conventional screw-type extruder. From the bin, the mixture is fed to the jjppy-armed barrel in the extruder. As the mixture is transported under the influence of the screw, it is simultaneously heated and compressed. The temperature during the run is generally kept between approx. 6 5 and 75°C. As the mixture is compressed and heated, a substantially homogeneous melt is formed which is forced through a nozzle at the end of the barrel opposite the bucket end. The nozzle temperature is kept in the range approx. 70 - approx. 80°C. The specific nozzle size depends on the composition of the specific insecticide, the size of the extruder and the flow rate of the melt. The nozzles used in the applicant's experiments had diameters of 0.495 and 0.610 cm. The dies were used in a single screw extruder with an L/D ratio of 20:1, manufactured by C.W. Brabender Instruments, Inc.,

South Hackensack, New Jersey.

The molten preparation emerges from the extruder i

shape of a rod of material. The rod is cut into sections and can be shaped into tubular pins that are beveled at one end towards a point.

The product can preferably be coated with a biodegradable and impermeable, but insoluble, coating, such as cellulose acetate. Such a coating can be applied in any usual way such as e.g. by spraying or dipping the product in a solution of the coating material. The product can then either be dried in air or in an oven.

It has been found that the coating is dried in an oven held at approx. 40°C for 1 - 2 minutes.

The second preferred method for the production of the product according to the invention shall be described with reference to fig. 4. As shown in fig. 4, the dry starting materials are mixed together using a conventional mixer until a substantially uniform mixture is obtained. The mixture is then passed through a heating zone which is maintained at a sufficiently high temperature to melt it. The temperature is usually between approx. 80 and 100°C and preferably between approx. 85 and 95°C. The desired temperatures can e.g. achieved in heating chambers by a Watson Stillman injection molder. The molten mixture is forced under pressure into the worm. The resulting product is removed from the mold and cooled. On cooling, the product becomes solid.

The solid product is then coated with a preferably biodegradable and water-permeable, but water-insoluble, coating of the type and in the manner described in connection with the extrusion process.

The invention will now be further described in connection with a preferred commercial process according to the invention as shown in fig. 5. The method uses "Orthene" instead of "Standak" as the preferred systemic pesticide because "Orthene" is already cleared for use as a systemic insecticide in the United States.

With reference to fig. 5, the starting materials shown there and the source for these are as follows:

As shown in fig. 5, polyethylene oxide, polyethylene glycol, clay and color are weighed or dosed and then added to a mixer in the predetermined proportions. The materials can be transported to the mixer and through the process by screw conveyors, pneumatic carriers and transportable bins.

The materials supplied to the mixer are thoroughly mixed, preferably using an intensive mixer which ensures the breaking up of lumps and agglomerates, and are then fed from the mixer to an extruder. Twin screw extruders, e.g. available from Cincinnati Milacron or Krauss Maffei, are today preferred.

Waste from the extruder is ground up in a suitable device and returned to the mixer. Acceptable extruded products are coated with a mixture of ethyl acetate/cellulose acetate solution, mixed in a mixer and introduced from a storage tank. The coating is applied to the extruded product by dipping the product into the mixture. The coated product is then dried and cut and the coating is applied to the cut ends of the product by dipping after which the coating is dried. Waste is returned to grinding devices and then returned to the mixer. Solvent is recovered from the coating and drying step and stored for later use. The commercially preferred staple 30 for houseplants is shown in fig. 6 - 7 and includes the preparation 30 and a coating 37.

The procedure for using the product according to the invention will now be described in connection with staples as shown in fig. 1 - 2 and 6 - 7.

The staples are packaged and distributed to plant growers. Because the staples do not decompose easily, nor do they break or crush, they can be stored and transported without structural damage. Because they have a protective coating and are manufactured using non-volatile systemic pesticides and non-toxic binders, they can be handled safely during packaging, storage and distribution.

Growers insert the pin into the soil near the plant's roots to protect against insects and to kill insects on an infected plant. Depending on the size of the pin and the soil conditions, the pin can either be pushed or hammered in. The composition in the pin according to the invention has sufficient strength to avoid breakdown or crushing while it is hammered into the ground.

The grower can treat the staple without risk of poisoning because the systemic P^^icid^eXr^^iiSii-.^11116 closed in the matrix formed by the binder, and the matrix in turn is covered by a coating composition 21 that does not allow the user to get in contact with the active ingredient.

Once the pin is in the soil, moisture from the soil penetrates through the coating and begins to erode the matrix releasing the systemic pesticide. As the pesticide is gradually released into the soil, it is absorbed by the roots and penetrates into the plant sap. The pesticide makes the plant sap toxic to insects and thereby kills insects that try to graze on the plants and protects the plants from contamination.

The binder, the coating and any components that are not normally part of the soil are in the preferred embodiments biodegradable, according to this they are decomposed so that no residues are left in the soil as a result of the use of the insecticide sticks according to the invention.

The following examples shall be given to further describe the invention. These are given only to illustrate the invention and shall not limit it in any way.

Example 1

The purpose of this experiment is to determine the effectiveness of six selected systemic insecticides in killing insects within 24 hours when applying the pesticide product in the soil to a potted plant.

(A) Selection of plant and insect species

Coleus was chosen as the plant for this experiment because

it is a typical houseplant and it is easy to grow, both in natural and fluorescent light. "Mealybugs" were selected as pest species because they are a common pest for coleus and because they can be seen and counted with the naked eye.

Several hundred healthy coleus plants were purchased from a garden center (Boulevard Gardens) in Columbus, Ohio. About. 100 coleus, heavily infested with "mealybugs", were obtained from a second source at Ohio State University. The plants were 15 - 20 cm tall. Each was transplanted into an approx. 10 cm pot inside

holding commercial flower soil (Bacto^potting_ medium) .

A portion of the non-infected plants were brought into contact with the infected plants in a growth chamber. After approx. After 10 days, the insect population had spread to the new host plants. Plants infected with mealybugs were kept in growth chambers under the following conditions: temperature = 27°C; light intensity = 2,000 ft. candles (mix of cold white and fluorescent bulbs); day length = 12 hours. The plants were watered daily by subirrigation with distilled water and once per week with a quarter-strength Hoagland's solution. Infected plants were kept in a chamber separately from the healthy control plants.

(B) Selection of systemic insecticides

About. 60 systemic insecticides were identified and

tested for potential use in a planting pen during the first trial phase. The following six systemic insecticides were selected as the best candidates:

The criteria used to select the "best" insecticide included (1) high toxicity to insects, (2) low toxicity to humans, (3) usability on ornamental plants, (4) availability in the U.S. and (5) numerous chemical and physical properties.

(C) Experimental design

The following experimental guidelines were

used for the study:

(a) Six systemic insecticides; (b) Three dosage levels for each insecticide; (c) Three replicates of each condition; and (d) Two conditions for the plants; with insects

and without insects.

The study used 108 plants plus 10 control plants. The control plants were infected with "mealybugs", but not treated with insecticide.

Three dosage levels were used: low, medium and high concentration for each of the six insecticides. The dosages were determined on the basis of several factors. Firstly, the percentage of active ingredients as indicated on the insecticide's label was written down. Then the concentration range of the systemic insecticide in two 1000 mg sticks (assuming two are recommended for a 10 cm pot) was determined to be between 0% and 80%.

As an approximation for low, medium and high concentration, it was decided to assume 10, 30 and 60% by weight systemic insecticide. This gave 200, 600 and 1200 mg of systemic insecticide. Because none of the systemic insecticide samples contained 100% active ingredients, it was necessary to weigh out sufficient combined active and inactive ingredient to ensure 200 mg of active ingredient. Table 1 indicates these weight proportions for 10, 30 and 60% by weight concentrations.

Before adding the insecticides, each pot was placed in a separate glass Petri dish with a diameter of 15 cm and then placed so far apart that there was no contact between the plants. The insecticides were then distributed so

evenly as possible in the top of the soil in each pot and then incorporated into the soil with a glass rod. 50 ml of distilled water was added to each pot to wash the insecticide into the soil. Washed liquids and insecticide were retained in the Petri dish. The highest dosage of substance C, 120 g, proved to be too much to mix into the soil and therefore this treatment was not carried out.

All data collection consisted of visual observation. Before treatment, the number of large "mealybugs" was counted to obtain a baseline for comparison for later results.

In the phytotoxic sample, the first observations were qualitative color changes, leaf loss or leaf death. The observations were entered using code numbers identified in Table 2.

The observations were carried out on the day of treatment with insecticides (day 0), as well as 1, 2, 4, 7 and 11 days after treatment. Further toxicity readings were carried out 8, 10 and 14 days after treatment. All plants were photographed 7 and 14 days after treatment.

(D) Results

(1) Effects of insecticides on mealybug populations

As shown in Table 3, four of the six systemic insecticides, namely A, B, D and F, were effective in killing mealybugs. On the other hand, the insecticides C and E had little effect on this population.

Insecticide A killed up to approx. 80% of the original fish population after 24 hours and up to approx. 100% after 96 hours (Table 3). With these four "best" insecticides, a total eradication of the pest was achieved after 11 days of treatment. From table 3 it can be seen that in general there was little difference between low, medium and high treatment. When looking at B, killed e.g. the low concentrations killed 83% of the fish after 24 hours, while the medium concentration killed 88% and the high concentration 84%. Thus, a presentation of the results suggests that the three dosages are roughly equivalent.

Insecticide A was effective in all three concentrations with total eradication after 11 days. During the first 24 hours there was a difference between the concentrations as approx. 25%, 70% respectively 75% of the population was killed at low, medium or high dosage. After 9 6 hours, however, all three appeared. concentrations to be equivalent in effect as the low concentration exterminated 94% of the original population and the medium and higher concentration killed approx. 95% of the base population.

The insecticide B was equally effective in all three concentrations and killed approx. 8 5 - 90% of the population within 24 hours. After 96 hours, the low dosage resulted in a 92% drop in the population and the medium and high dosage killed 97%. Total eradication occurred after 11 days.

The insecticide C showed an opposite effect -than-that which was the case_with A, B, D and™F. In the group with low concentration dosage, the population had increased after 11 days by about 30% above the baseline population. After 24 hours there was no change, while after 48 and 96 hours there were small drops in the population, namely 3% after 48 hours and 37% after 96 hours. The narrow fall followed by a large increase in population ..was due to:.probably, a combination of causes. For example, there was probably a small effect of the pesticide, but the increase in population over time was greater and the net result was a population increase in the size class of insects counted. On the other hand, the mid-dose concentration of C was effective to some extent in controlling this population as approximately 40% of the baseline population was killed after 11 days. ;After 24 hours, D was equally effective in all the tested concentrations, as 82% at the low, 84% at the medium and 81% at the high concentration were killed of the original population. However, a small effect difference seemed to emerge after 96 hours where the low dose * had killed approx. 90% of the original population while the medium dose had killed 98% and the high had killed 100%.

In the same way as C, the insecticide E showed little effect on reducing the population of mealybugs. With low, medium and high concentration, the population increased up to 123% above the baseline population after 11 days. Plants treated with low and high dose of E had populations of 65%

and 122% above the respective treatment day populations. The medium dosages resulted in a small reduction of 4%

of the original population census.

Insecticide F, although initially not as effective as A, B and D, caused 100% eradication after 11 days at all dosages. After 24 hours, all three dosages proved equally effective and eradicated approx. 55 - 65% of the population. A difference in dosing efficiency began to appear after 48 hours,

during which period 75, 86 respectively. 100% of the original

equal population had been killed in low, medium and the high-dose group.

|(2) Effects of insecticides on plant populations

(phytotoxicity)

The phytotoxicity of the six insecticides was studied and judged on a scale from 0 (no effect) to 5 (total plant death) as described in table 2. All six pesticides, compared to controls, were phytotoxic to coleus plants. Phytotoxicity varied from the loss of some leaves or browning of the edges in case F, to the death of the entire plant as occurred in cases D or B.

A, E and C showed moderate to strong phytotoxicity. Only in 2 experiments was no phytotoxic effect recorded during the first 6 days after treatment and thus the phytotoxic effect was manifested 6 or more days after treatment.

Numerical phytotoxicity data are shown in Table 4.

Substance A caused moderate to strong phytotoxicity. The degree of phytotoxicity appeared to be a function of concentration and time. The first effects were observed 7 days after treatment at which time the low, medium and high doses showed different assessments of 2, 3

respectively 3 (Table 4). Thus, moderate to severe leaf loss or a change in leaf color occurred. 14 days after treatment, the average assessments were 3, 4 respectively. 4, which strongly indicated total leaf loss or change in leaf colour. Furthermore, one of the plants (which received a high dose) gave a rating of 5, which indicated that the plant was dead.

Insecticide B was highly phytotoxic at all concentrations, killing medium- and high-dose plants 8 days after treatment and all but one plant (which had a rating of 4 and was lethal) after 14 days. Insecticide B was the fastest-acting pesticide and showed its effect only 4 days after the first application of the pesticide. Even at low concentrations it caused moderate to severe leaf loss (rating 3) and large, if not total, leaf loss or death at medium to high concentrations.

(rating 4) . By the 8th day, aJlJ^jslaryie^ taken medium and high doses were dead and all plants (with the exceptions noted above) were dead after 2 weeks.

Insecticide C was therefore moderately phytotoxic to coleus. The first visible effects were not observed until 1 week after administration of the pesticide, by which time the plants receiving the low dosage had lost several leaves (score 2) and others had brown edges. The medium-dose plants had no visible adverse effects. However, two weeks post-treatment caused C severe leaf loss in two of three plants in the medium dose group and a total leaf loss or death (score 4) in all plants in the low dose group and one plant in the medium dose group.

The substance D ..., like B, was strongly phytotoxic in all concentrations and showed effects just four days after application of the pesticide. At this point, the leaf edges of low- and medium-dose plants began to turn brown, while the high-dose plants lost leaves. On day 8, all high-dose plants were dead and on day 10, all plants in all concentration groups were dead, with the exception of one (which received a rating of 4).

The insecticide E showed a small to moderate phototoxic effect, the effect varying proportionally with time and with the concentration. On the 7th day, the low dose plants showed neither effect nor brown edges. The medium dose plants showed a loss of several leaves in addition to discoloration in the leaves that were still on the plants•The plants x high dose area lost many leaves. On the 14th day, all the plants were still alive. The low-dose plants still showed only a small loss of leaves or brown-edged leaves (rating 1). The medium-dose plants had lost more leaves (score 2) while the high-dose plants had either lost many leaves or had a high number of dying leaves (score 3).

Substances E and F produced the fewest phytotoxic effects of all the tested insecticides. The first effects were not noted until after 8 days when there was a color change in a few leaves in all plants at all concentrations. On the 14th day there was a loss of f l ere J^t in^ one_ ay^three plants in the low-dose group and all in all three plants in the medium-dose group. In the case of the high concentration group, all the plants had lost many leaves.

The controls had a rating of 0, no effect, for the entire duration of the experiment of 14 days.

(3) Comparison of insect-phytotoxic effect

All the pesticides killed mealybugs and all showed

some phytotoxic effect on coleus. Substances B and D

had the strongest effect on both the insect and plant populations. Insecticide E had the least effect on the insect population, while E and F had the least phytotoxic effect.

Insecticide B had the strongest effect, killing up to 90% of the weevil population after 24 hours and showing a moderate to high phytotoxic effect (2 - 4 on the rating scale) on the 4th day after treatment. The substance was lethal to plants already 8 days after treatment, with a total eradication of the pest in between 4 and 7.

Insecticide D, in the same way as B, killed a large proportion of the weevil population, namely 80 - 85% within 24 hours. In the same way as B, however, D was lethal to coleus after 8 days in three of the high-dose group and for one in the medium-dose group. On the 11th day all the insects were dead, but so were the plants.

Insecticides C and E appeared to be similar in their limited effectiveness for killing insects, but C was somewhat more phytotoxic and caused large, if not total, leaf loss after day 11. Substance E never caused more than one large leaf loss blade.

Substances F and A were similar in their insecticidal effect, but differed in their phytotoxic effect. The two pesticides were moderate in terms of insecticidal ability after 24 hours. Medium and high doses of A killed 70 - 75% of the lice while F killed 60 - 65% of the population in all concentrations. None of the pesticides showed any phytotoxic effect. Insecticide F appeared to be superior to the two because although both had killed all insects by the 7th day, var

A more phytotoxic at the 11th day jyi ste a judgment on

3 - 4 on the phytotoxicity scale).

(E) Conclusions

This trial tested the effects on only ullus and

coleus plants.

Several of the six insecticides killed 60 - 80% of the lice within 24 hours and four insecticides killed 100% of the lice within 11 days, B, D, A and F. The insecticide F is the best overall insecticide. It killed the insects to begin with and the killing power was maintained.

Substance F showed the least phytotoxic effect. All six insecticides were phytotoxic to a certain extent.

By comparison, A, D and B (in the early part of the experiment) killed approximately equal amounts of ullus at all concentrations and the lower concentrations were less phytotoxic than medium and hly. This implies that even lower dosages would be less phytotoxic in effect, but still retain a toxicity against insects.

Thus, the experiments showed that the insecticide F is the best. Insecticide A is second best while D is third. The fourth is B. Neither C nor E killed lice during the 11-day trial.

Example 2

The purpose of this trial is to determine the amount of "Orthene" that is necessary to incorporate into each systemic insecticide stick to kill over 60% of the woolly louse population on small coleus plants within 24 hours without causing visible phytopathological reactions on the coleus plate.

The trial scheme consisted of two departments.. In the first, the scheme was: 1 plant species (coleus) x 2 individual plants (4 for reference) x 4 exposures (=, 2.5, 10 and 30% concentration "Orthene." x 4 test times ( 0, 1, 2 and 9 days).This represents a total of 40 measurements. At each measurement, each number of ullus was greater than the first value counted on each plant and pot surroundings and two or three leaves were removed from each plant for analysis of radioactive content. In the second section, the scheme was slightly modified to place more emphasis on the number of plants exposed to a given dosage of "Orthene" in a stick. This second scheme consisted of 1 plant species (coleus) x 5 individual plants, 4 for reference x 3 exposures (0, 15 and 25% loading of active ingredient per stick) x 7 test times (day 0, 1, 2, 4, 8, 13 and 16). At each measurement time, the number of ullus was greater than the first value counted on each plant.

Fresh plants were obtained from a nursery in Columbus, Ohio. The plants were in 10 cm pots and were approx. 15 cm high. The plants were grown in a medium consisting of 33% vermiculite, 33% sand and 33% peat. The coleus plants were kept in temperature-regulated greenhouses and given normal watering. Ullus were obtained from infected plants in nurseries and maintained on large host plants. At the start of the experiment, coleus plants of the same size with the same infection level of ullus were selected.

The sticks were prepared according to the procedure detailed in Example 6. Briefly, "Orthene" was melt-blended into a polymer matrix. The mixture was then poured into molds to form staples which were then coated with a clear polymer. The pins were placed in airtight containers and used in the above-mentioned experiments within a few weeks of manufacture.

(B) Results

(1) First attempt

The insecticide sticks were effective in reducing the population of aphids on small coleus plants. A population with an average of 58 and a number from 18 - 113 wool lice per plant .represented the original population (Table 4A). Within 24 hours, up to 80% of the aphids can be killed or displaced from the plants tested with the highest dosage (1 stick with 30% active "Orthene").

Ullus populations exposed to staples containing 30% active "Orthene" fell from an average of 80 individuals per plant to 40 individuals per plant (about 50% less) within 24 hours (Table 4B). After 48 hours, the average number of ullus was 14 individuals, this was approx. 20% of the original population. The response at 10 wt% was less dramatic. The populations were reduced from an average of 52 to 35 (day 1) and from 35 to 20 (day 2). Expressed as a percentage, this was a 33% drop (day 0 to day 1) and a 43% drop (day 0

to day 2). Finally, there was no reduction in number for staples containing 2% by weight "Orthene". As expected, the reference population tended to increase over the observation period. E.g. the average initial population was 39 and on day 9 it was 48 individuals. Thus, staples containing 30% by weight and 10% by weight "Orthene" were the most effective.

(2) Second attempt

In the second experiment, dosages of

15 and 25% by weight active "Orthene". Ullus populations decreased on treated plants. Populations on plants dosed with 25% by weight decreased from an average of 118 ullus per plant to 84 insects (day 1) and to 24 (day 8). This represented a 30% reduction in the number of insects within 24 hours and an 80% reduction within 8 days. The plants which received the staples containing 15% by weight of active "Orthene" also showed a reduction in the number of ullus. The initial average of 76 ullus (Table 4B) decreased to 72 (day 1), but had decreased to 51 (day 2) and then reached 23 (day 8). Thus, there was an approximately 10% reduction between day 0 and day 1. The fall between day 0 and day 2 was approx. 30% and between day 0 and day 8 approx. 70%. In contrast, ullus receiving staples containing 25% by weight "Orthene" were killed more rapidly in the first days, but thereafter (days 5, 8, 13 and 16) the percentage of kill was approx. the same for the 15 wt% staples. The reference populations expanded during the 16-day period. To begin with, the average population was 92. Although there was a slight reduction to 78 ullus per plant on the second day, the population had reached 110 on the 4th day, 216 on the 3rd day and continued to expand thereafter. Thus, the insecticide foundations were effective in reducing plague-causing populations.'

(3) Phytopathological effects

Some leaf loss was observed on coleus plants

which were exposed to the insecticides, but leaf loss also occurred on the references. There did not appear to be any appreciable effect on the coleus of the above stated staple dosages.

Example 3

The purpose of this experiment is to determine how many insecticide sticks containing 25% by weight of active "Orthene"

which were necessary to regulate mites and lice on two plant species, mums and scheffleras.

The experimental plan consisted of 1:, plant species (mums and scheffleras) x 1 size (large in 15 cm pots) x 3 individual plants x 4 exposures (0, 4, 8 and 16 staples per large pot) x an average of 7 test times. Thus, there were a total of 84 measurements. At each measurement time, the number of mites and lice was counted on the upper and lower surfaces of 3 leaves per plant.

Healthy plants were obtained from a plant center in Columbus, Ohio. Large scheffleras plants were in 15 cm pots with a height of approx. 50 cm. Mums was grown in a potting medium consisting of 33% vermiculite, 33% peat and 33% sand. Scheffleras were grown in a medium whose exact composition was not determined, but which consisted of a mixture similar to that of mums. The plants were watered regularly. Mites were obtained from infected plants from a nursery and then maintained as a colony on host plants in much the same way as ullus were maintained on coleus host plants.

The insecticide sticks were effective for

to reduce the mite and aphid population on host plants to 0

in most cases (tables 5 and 6). Doses of 4, 8 and 16 staples each containing 25% "Orthene" killed mites and lice on large scheffleras and on large mums within 24 days of exposure. There were dramatic reductions that began a day or two after exposure.

The mite population was reduced from an average of over 30 mites per leaf at day 0 to approx. 16 mites per leaf on day 24 (Table 5). Plants that received 16 staples showed a more rapid reduction in the number of mites than_the^j)J^ anter^ soin received 8 staples. The most rapid (slowest) final reduction in mite numbers was observed in plants exposed to 4 staples. The reference population (0 staples) showed more than an average of 10 mites per leaf at day 47 and the value then dropped to approx. 7 on day 72. Thus, the dosages of 4, 8 and 16 staples worked excellently to reduce the mite population.

The ullus population was almost reduced to 0 on day 10 (Table 5). There appeared to be no difference in the pattern of death for ullus as a function of dosage; the pattern of reduction for 4, 8 or 16 staples was similar.

As a comparison, the reference population initially decreased and then expanded, reaching an average of 25 ullus per day the 45th day. On the 73rd day, the ullus population averaged 11 individuals per leaf, which suggested a reduction in the number of individual pest individuals. After 73 days a few ullus were observed on scheffleras, probably the effectiveness of "Orthene" was reduced on the 73rd day after which the population could expand.

The mite population was reduced to 0 on day 2 with

4, 8 and 16 pin exposures (Table 6). The mite population began to decline within a day of exposing the plants to the insecticide sticks. 16 staples caused a more rapid reduction in the plague population than both 8 and 4 staples. In contrast, the reference population expanded during the rapid reduction on the treated plants, then began to decline, reaching a mean of 16 mites per plant.

magazine on the 21st day.

Ullus population decreased on plants treated with 4,

.8 and 16 pins (Table 6) . On the 20th day, no live ullus was observed on mums. There was a somewhat faster response with 16 staples compared to 8. Mite populations were initially low on plants receiving 4 staples and the population was driven to near 0 by the 8th day. The reference population of mites remained significantly higher than the population on

the treated plants. On the 21st day, when all aphids on treated plants had died, the aphid population on the reference

anseplantene 13 individuals per blade.

Phytotoxic tests were carried out 36 days and 40 days, 61 days and 65 days and 120 days and 124 days after healthy scheffleras and mums plants were dosed with insecticide sprays. In scheffleras (pesticide and no insects) "Orthene" caused some chlorosis with 4 staples, chlorosis was found only in upper leaves. With 8 and 16 staples pale chlorosis found in all leaves. In addition, plants receiving 16 staples had leaves with brown edges, and greater leaf drop was observed in plants with 16 staples than in those receiving 4 and 8. There was no apparent gradual decrease in plant health from 1 to 16 staples "Orthene" .

On other Schefflera plants with insects and pesticides there were signs of mite damage, even though mites were not present. Furthermore, there were signs of phytotoxicity in the upper leaves (4 spikes), , upper and middle leaves (8 spikes) and all leaves (16 spikes). The mite damage was more obvious in the lower leaves, but the "Orthene" damage was more obvious in the upper leaves. A second effect (noted only in this group) was a curling of the new tender leaves for plants receiving 8 and 16 staples. The worst plant in this group was one of the plants that got 4 staples, it was practically dead. In the reference plants, scheffleras (no insects and no pesticides) were generally worse in appearance than the above groups of plants. All plants had leaves with brown edges and white spots. Surprisingly, however, none of the plants in this group were dead.

After 61 and 65 days the scheffleras (pesticide and not insects) were still affected by "Orthene". With 4 staples, about half of the leaves were chlorotic. With 8 and 16 staples, the entire plant was affected. In addition, plants that received the higher doses had curled leaves, leaves with brown edges and leaf drop. Even new leaves with high doses (8, 16) were slightly affected. —"Orthene" damage seemed to spread rather than decrease. Scheffleras that had insects and received pesticides had less evidence of mite damage. Chlorosis and leaf curling were evident at all three exposure levels, but were more predominant at higher ex g one ri n g^ New leaves were good in appearance for 4 staples and only minor effects on new leaves at 8. There were no new leaves on plants exposed to 16 Staples. The newest leaves on the scheffleras (no insects, no pesticide) were rather healthy. Necrosis or death was observed on older leaves.

Signs of lice, mites and whiteflies were present on most plants^. These plants looked healthy and were not dying.

Scheffleras continued to show phytotoxic effects 120 and 124 days after exposure. The plants that received 4 staples showed chlorotic leaf edges on about one-eighth of the leaves, new shoots were present. The plants exposed to 8 staples also showed new shoots, but a large number (about 1/3) of the leaves were chlorotic at the edges. About. half the leaves were chlorotic in plants that had received 16 staples and new shoots and leaflets were curled, the plant still looked unhealthy. In contrast, the reference plants had some leaves die and new shoots did not look healthy, "spider" mite damage was obvious.

In chrysanthemums (insects and pesticides) it was difficult to notice differences between 0, 4, 8 and 16 stamens because all plants were in a state of senescence. However, it appears that more of the leaves in the 16-staple plants were dead than for the 8-staple plants, i than those with 4-staples and those with 0-staples.

In reference mums plants, it was difficult to determine the differences between the 4-, 8- and 16-pin treatments.

No investigations were carried out on mums at these two observation times because all the plants were dying.

Example 4

The purpose of this experiment is to determine the number of staples containing 25% by weight of active "Orthene" necessary to protect uninfected plants against colonization by

> mites and lice when non-infected plants are placed near infected plants.

The experimental setup consisted of 2 species of plants (scheffleras and mums) x 2 sizes of plants (large and small): x 4 individual plants x 3 exposures (0, 2 and 4 pegs per large pot and 0, 1 and 2 pegs per . small pot) x 8 test times. Thus, there were a total of 384 measurements. At each measurement time, the number of mites and lice was counted on the lower and upper surface of 2 leaves per plant.

Fresh scheffleras and mums plants were obtained from a plant center in Columbus, Ohio. Large scheffleras were in 15 cm pots and had a height of approx. 50 cm. Small plants were in 10 cm pots with a height of approx. 15 cm. Big mums and little mums had heights of approx. 50 cm or 15 cm. Mums was grown into a potting medium consisting of 33% sand, 33% vermiculite and 33% peat. The plants were kept under regular watering. Mites were obtained from infested plants from a plant center and then maintained as a colony on host plants in the same manner as ullus were maintained on host plants.

The insect sticks were effective in terms of controlling mites and lice on mums (tables 7 and 8). In general, the control of mites was best observed on large as opposed to small mums. The ullus population was suppressed on both large and small mums.

Mites were suppressed on the 17th day on large mums

(tables 7 and 8). The population of mites exposed to 4 staples was somewhat lower than the population exposed to 2 staples. The efficacy of the insecticide sticks was evident when the population pattern for 2 and 4 sticks was compared to the population level for 0 sticks. In the latter case, the average number of mites was greater than 5 per person. leaf present on leaves up to 51 days after the start of exposure. In contrast, mites were suppressed by day 17 on plants receiving insecticide sticks.

Ullus was suppressed on both large and small mums

(tables 7 and 8). On large mums, the population of wool lice was suppressed on the 17th day. On large plants suppress 4 insecticide sticks per pot populations of ullus on the 17th day. However, 2 staples did not kill all the ullus because after

51 days a small population was still present. The reference (0 pins) showed an average population of approx. 13 ullus on the 51st day. The average reference population was up to 61 ullus per plant on the 28th day compared to 1 or 2 insects per plant for pots that had received staples.

The pattern for ullus on small mums was similar to the pattern for ullus on large mums (table 7). A staple suppressed the ullus population, causing their average number of individuals per leaf decreased from approx. 36 on day 7 to approx. 7 on day 28. By day 51, the population had built up, which suggested that the invasion rate of ullus from adjacent standing donor plants was greater than the insecticide's ability to control the population. In contrast, the reference plants show aphid populations higher than the plants that had received protection from staples. On day 17 it was e.g. average 148 ullus per leaf and on day 52 there was an average number of 72 ullus per blade. This latter value is approximately 5 times higher than the value for treated plants.

The insect sticks were effective in controlling mites and lice on scheffleras (tables 9 and 10). The most dramatic control was observed with ullus on small scheffleras. The mite population was reduced to 0 on the 51st.

day on large scheffleras that received 2 staples (Table 9). Scheffleras that received 4 staples showed an average population of 4 mites per blade. The reference showed an average population of approx. 8 mites per blade. In contrast, all mites on small scheffleras were dead by the 17th day. This applied to plants that received 0, 1 and 2 staples. Apparently small plants of this type did not satisfy the bb requirements for mites because all the mites died.

On the 51st day, ullus was still observed on large scheffleras (Table 9). Reference populations on day 51 were highest with an average of approx. 7 ullus, compared to an average of 2 for 2 staples and 4 for 4 staples. Thus, ullus on large scheffleras was partially controlled by the insecticide sticks. In contrast, aphids were eliminated on small treated scheffleras plants (Table 10). Exposure to 1 and 2 staples -resulted in a strong reduction of the wool louse population on the 28th day. During this count, no ullus was observed on small scheffleras. Ref^ejra nseplant ene, on the other hand, showed average populations exceeding .37 ullus per leaf from the 6th - 52nd day.

A phytotoxicity study was conducted 73 days after healthy scheffleras and mums plants were exposed to insecticide sticks. Scheffleras exposed to 2 staples showed chlorosis on the edges of a few leaves. More upper than lower leaves were affected. Some leaves had brown tips and some new leaves curled.

Plants that had received 4 staples showed chlorosis on the edges of some leaves. Some leaves appeared healthy, but some new leaves curled. The references (no insects and no pesticide) showed older leaves with discolouration. Some of the new leaves were overgrown. ... Small scheffleras showed patterns too. The plants that received 1 pin showed chlorotic edges in about a third of the leaves, some of the leaves were misshapen. New leaves were also present and looked healthy. With 2 staples, almost all leaves had chlorotic edges. Some of the new leaves seemed healthy. On the reference plates (no pesticide) all leaves were brown with yellow areas.

Only small mums were examined because large ones died for reasons unrelated to the pesticide. With 1 pin, the plants appeared to be healthier than the reference plants. With 2 staples, the upper third of the leaves curled and curved upwards. The reference plants had shoots that were up to 33 cm, while the plants exposed to the insecticide sticks had an average of approx. 57 cm (dose of 1 pin) and approx. 70 cm (dose of 2 staples). Thus, the insecticide appeared to cause accelerated growth in small mums plants.

Example 5

The purpose of this experiment was to find binders that would give a product that satisfied the object of the invention. Initially, attempts were made to

casting films from a methylene chloride solution containing the polymer and carefully purified "Standak". The insecticide was isolated from the commercial formulation followed by solvent extraction, repeated filtration and recrystallization. However, no conclusions could be drawn from these data. Therefore, several films were produced using commercial wettable powders using compression molding.

The data obtained from these investigations seemed more favorable. As shown in Table 11, "Elvanol" (PVA, Dow Chemical Company), "Gelvatol" (PVA, Monsanto), "Methocel"

(methyl cellulose, Dow Chemical Company), Cellulose Acetate Butyrate (CAB, Eastman Chemicals), "Polyox" (polyethylene oxide, Union Carbide Company), "Carbowax" (polyethylene glycol, Union Carbide Company) and "Klucel" (hydroxypropyl cellulose, Hercules Inc.) investigated for potential use as binders to incorporate the wet powder to form films.

In addition, polymer pesticide films were produced using clay fillers and polymeric plasticizers. The various combinations are listed in Table 12. The results of these investigations indicated that films prepared using only CAB binder had the best qualitative characteristics in terms of strength, clarity and flexibility. However, biodegradability in houseplant soil may be at a minimum for staples prepared using CAB.

Plates with a thickness were then produced

of approx. 3.17 mm of the different polymer/insecticide combinations by compression molding. These plates were produced using a 10 cm x 15 cm positive displacement mold. It was necessary to cast all the plates except those containing polyethylene glycol and polyethylene oxide at a temperature that was high

ere than the melting/decomposition temperature for the insecticide. Pesticide plates containing CAB- were degraded to a great extent.

Similarly, all plates (table 13) that were cast at high temperature showed signs of significant degradation (browning).

Molded films of polyethylene glycol and polyethylene oxide containing "Standak" appeared both weak and brittle. However, incorporation of 1% carbon black ("Raven" 5250) and 1% plasticizer/lubricant ("Carbowax" 4000) significantly increased the strength of the polyethylene oxide film. In contrast, no apparent qualitative increase in strength could be seen in the polyethylene glycol foil. Thus, the polyethylene oxide/insecticide combination seemed most promising and was later used as a "Standak" binder during the injection molding studies.

A special mold was fabricated to allow the formation of 6 pins with dimensions 4.76 mm x 49.21 mm. The pin models were produced using a Watson-Stillman injection molder. The polymer/pesticide formulations were cast

using a suitable piston pressure of between 43 and 63 kg/cm 2.

Initially, many different formulations were extruded to create optimal extrusion conditions. The different polymer/insecticide formulations that were evaluated are listed in Table 14.

As a result of the data obtained in these die casting studies, polyethylene oxide/pesticide formulations containing different ratios of carbon black to clay fillers were investigated as possible prescriptions for systemic staples. Table 15 contains the first results from these assessments.

It can easily be seen that staples containing up to 23% by weight of polyethylene oxide were produced. The remaining sticking compound consisted of 20% "Standak" wettable powder formulation, 1% carbon black filler/stretcher, 53% filler and 1% "Carbowax" softener/lubricant. However, it was difficult to injection mold pins using this formulation and it would

be necessary to consider the use of more PEO to facilitate the eventual production of staples by extrusion. The relatively high cost of PED was the reason why as little PED as possible was used in the stick formulation.

The results using high melting polymers were generally the same as for the cast films. The sticks containing "Gelvatol" definitely showed signs of degradation while the sticks using polyethylene glycol were weak and brittle. In addition, formulations with insecticide incorporated in "Methocel" (with and without clay filler) and with polyethylene glycol containing carbon black could not be successfully injection molded.

Melt production of insecticide sticks requires high temperatures. It is important that the chemical integrity of the insecticide remains intact during this process. Therefore, an experiment was set up to determine whether the model insecticide, "Standak", was broken down during the melt production process by injection molding.

"Standak" was removed from staples made^wood

using different binder options as just described using a solvent extraction technique. The pins were broken into small pieces and placed in a beaker containing a magnetic stirrer. About 100 ml of anhydrous ether was added and the mixture was stirred for half an hour at room temperature. The mixture was vacuum filtered and the ether evaporated under low heating. The insecticide residue was then collected and placed in a small glass ampoule. A 100 ppm aqueous solution was then prepared using 100 mg of the residue.

A 20 microliter sample was injected into a High Performance Liquid Chromatograph (LC-6 5 T Chromatography Module). A mobile phase consisting of 15% acetonitrile in deionized water was used at a flow rate of 20 ml/min. A UV detector was used at a wavelength of 210 nm

to record the presence of the insecticide. The results were recorded using a 10 mV printer with a paper speed of 30 cm/hour showing 0.08 absorbance units at full scale (AUFS).

A chromatogram showed that a "Standak" solution used as a control showed component separation within one minute and insecticide appearance after 2 minutes. The same tendency can be observed in chromatograms of "Standak" extracted from staples prepared using polyethylene glycol and polyethylene oxide as binders. This suggests that no recordable degradation of "Standak" had occurred as a result of melt production using these binders.

Example 6

The primary object of this trial was to identify an optimal composition for the manufacture of the systemic insecticide stick using the suggested melt extrusion manufacturing technique.

Because the experiment did not concern the effect of the insecticide, the extrusion tests were carried out without systemic insecticide in the formulation. Table 16 contains a list and the specific amounts of the ingredients used in the formulations of this example.

Non-toxic staples were melt-extruded using two grades of PEO (WSR N-750 and WSR N-80), a single lubricant ("Carbowax" 4000) and several types of fillers ("spray satin" clay, powdered corncobs) and "Raven -5250" soot). The preferred ingredients were weighed into a paper cup in an amount of approx. 113 g and mixed by hand using a wood chip depressor. The mixture was then fed to a water-cooled hopper in a single-screw (20:1 L/D) extruder (Brabender Extruder, C.W. Brabender Instruments, Inc., South Hackensack, N.J.).

The running temperature in the extruder was maintained between

60 and 70°C with thermostatic regulation of two internal heating devices. The nozzle temperature was kept between 70 and 80°C using an external 1-bore-torier rheostat of the Variac type. Two nozzles with internal diameters of 6.1 and 5.0 mm were used .

The extruded rods were cut into 5 cm long staples in the hot state. The physical properties of the manufactured staples of varying composition were then determined.

Mechanical tests were carried out on the staples to estimate some of the physical loads that could be placed on the staples during manufacture, packaging, shipping, processing and use.

Tensile strength

During extrusion, the extruded rod exits the die in a still relatively hot state. The rod should have sufficient heat strength to allow a tensile stress to be applied during pulling and/or pulling of the conveyor on its way to the cutting device. The staples must also show satisfactory strength properties when cooled to avoid unwanted damage to the product during packaging, shipping and use. For these reasons, extruded staples were tested to determine tensile strength at both elevated and room temperature using an Instron Testing Machine (Instron Engineering Corp., Canton, Mass.) with an electrically insulated oven

(Instron Oven, Instron Engineering Corp;w_Carij^nLi__Mass.) .

Procedure. The tensile strength of extruded staples was determined at 23 and 70°C using an applied load of 5 mm/min. It is important to note that the oven temperature for the heat samples varied within the range of 70 - 70°C as a result of the heat loss that occurred due to the opening and closing of the oven door during placement and removal of staples. The actual tensile testing began only after the oven was allowed to come to constant temperature (about 5 minutes).

Three replicate samples of staples containing two PEO grades were tested and the average was calculated in kg. These results are listed in table 17 together with results of tensile strength tests carried out on pins at room temperature.

All results are expressed as the tensile load in kg required to break a pin. This should help the understanding of the physical properties of manufactured staples and filled polymer staples. It must also be kept in mind that these -diagramniex-visex -tendencies, the pt not absolute measures. Each of the stated data represents the average of 3-5 sample replicates and can be considered a reliable indication of tendencies in variations in the physical properties.

Results. A heated pin responds to tensile loading in a very different way from a pin tested at room temperature. Staples containing "WSR N-80" and exposed to temperatures approaching 70°C showed low tensile stresses. However, an increase in the amount of filler in a pin from 45 - 70% by weight caused a corresponding increase in the tensile strength at break from approx. 0 - approx. 0.9 kg. On the other hand, the tensile strength at room temperature generally decreased from 41.5 kg at 2.5% filler content (lubricant and dye) to about 13.2 kg at 70% filler content.

Discussion - A possible reason for these apparently contradictory tendencies can be seen by considering the molecular structure of PEO. Chain mobility and the relaxation of internal stress can be induced when the polymer approaches its characteristic melting temperature and near zero tensile strength in the heating chamber. Chain relaxation can cause specimen contraction which manifests itself as an increase in tensile strength. In addition, the application of a small tensile load can induce chain alignment. Some of the energy in the stress can then be transferred to the filler. This will be realized as an apparent increase in the strength of an extruded pin in the tensile direction. An increase in the filler content should then result in an increase in the hot tensile strength up to the point where the staples can no longer be produced.

The same thinking can be used to predict the effect of pulling an extruded bar down a conveyor to the cutters. An increase in the initially hot tensile strength can be expected from increasing the amount of filler. However, this trend must be balanced against the trend of a reduction

tion of the tensile strength with increased filler content when stressed at room temperature. In this latter case, the clay acts as a true filler and serves to reduce the overall strength of the polymer. A recommendation based on the results of these tests would be to produce staples with a filler content of between 60 and 70% by weight. It should be pointed out that the insecticide used in the formulations was considered a proportion of the filler during these studies. A suitable stick with 50% filler and 20% insecticide would be suitable with the 70% filler mentioned during the discussion. This approximately-

formulation appears at present to both minimize the reduction in ambient tensile strength as a result of the incorporation of filler as well as to maximize the poor tensile strength when extruding the rod when hot.

Bending strength

The inherent bending strength of a manufactured pin only needs to be measured at room temperature because the bending stress that can be placed on a pin only occurs during placement in the plant soil. These data are listed in table 18.

The flexural strength was determined using an Instron 3-point strain apparatus and was recorded as an average value for 5 replicates expressed in pounds of flexural strength required to break a pin. The load was applied with 5 mm per minute.

It can be seen that an increase in the filler content in

a pin is detrimental to the ultimate bending strength. Lucky-

vis, even the most strongly filled staples apparently showed sufficient qualitative strength data to be able to be placed in moist soil. It should be pointed out that pins produced with a smaller diameter had proportionally less mass and were more susceptible to breakage when subjected to bending stresses. However, in each situation there is a small change in the apparent flexural strength when the filler concentration is increased from 40 to 70% by weight. A combination of the information gleaned from these test data and qualitative observations suggests that a stick containing up to 70% filler may be an acceptable formulation. Inclusion of this approximate amount of filler in the stick formulation should permit the manufacture of a product of acceptable strength at minimal cost.

It should once again be pointed out that the insecticide is considered a filler in this discussion. The data found in Table 19 suggest that staples can be filled with 70% filler and insecticide and still have sufficient flexural strength. Although these staples were produced by an injection molding technique rather than an extrusion technique, similar conclusions can be drawn. Polyethylene oxide can be heavily filled during a melt fabrication process. There are indications that the incorporation of a wet powder insecticide ("Orthene") as part of the filler has little apparent effect on the final physical properties of the product.

Impact resistance

Manufactured staples can be inadvertently subjected to many impact stresses. The pins are exposed when they are packed and during shipping or storage. It is therefore important to identify a formulation that can withstand most of the "usual" stresses that can be expected. A description of the tendency in the impact strength as a function of the filler content should serve as a good starting point for the data concerning

-the lifetime of a foundation—today—is—unavailable. -

The impact resistance exhibited by standard non-toxic test pins is listed in Table 18. Impact strength was determined using an Impact Tester (Testing Machines, Inc., Mineola, NY). Each 50 cm pin test was

brought into position vertically in a brass holder by use of a locking screw. It was then processed using a 0.9 kg pendulum weight and the results are given for an average of 3-4 pins expressed in foot-pounds of force required to break a pin.

The impact strength shown by manufactured staples is generally reduced when the amount of filler incorporated into the polymer is increased. It should be remembered that the staples are no longer produced easily when the filler content of the original mixture is increased to over 70%. As a result, strength data can only be given to describe staples containing up to,

but not more than, 70% by weight filler (spray satin clay).

There is little or no detectable variation in the minimum strength when the filler content is varied within the range of 60-70%. A qualitative assumption of these highly filled polymer systems provides a basis for recommending that the filler can be incorporated up to 70% of the formulation and still provide an acceptable strength for the impact resistance that may occur for a gasket. Specific tests must be conducted using the packing equipment available for these staples to determine the ability of manufactured staples to withstand the impact and wear and tear imposed by the outboard. Further adjustments to the filler content can then be made.

Summary

The results of the physical testing part of the research show that a formulation containing polyethylene oxide and up to 70% of an inert clay filler and insecticide produces staples that show adequate physical properties

at minimal costs for materials. The insecticide in the form of a wettable powder is considered to be equivalent to filler.

Example 7

This trial was conducted to identify and develop a procedure for coating the pesticide stick.

The most convenient laboratory procedure for the preparation of coated sticks containing an active systemic insecticide was to dip "pre-coated" sticks in a dryable solution of coating polymer in a volatile solvent. Each coating polymer candidate was placed in three possible solvents to identify a workable solution viscosity and drying time. Attempts were made to prepare coating solutions with initial ratios of coating to diluent solvent on a weight basis of 50:50, 25:70 and 10:90. The latter was found to be most suitable for preparing fast-drying polymer solutions.

Air-drying alkyd or unsaturated polyester coatings were investigated and the solvent was used as a diluent to reduce the initial viscosity. Coated staples were produced by dipping preformed (injection molded) non-toxic staples in polymer solutions for approx. 3 seconds and then place them in an oven at 40°C for drying. The drying of the staples was periodically tested in the oven to determine the time after application required to produce a coating that was tack free.

The drying time is an important factor because it can be the speed-limiting factor in manufacturing. It is desirable that the coating dries during the time it takes to move it all down the conveyor to the cutters. In addition, the staples must be kept separate to avoid agglomeration during the drying phase. This can be difficult to achieve with long drying times. Therefore, the shortest drying times are the most desirable.

A complete set of coating candidates is shown in Table 20. A 10% solution of cellulose acetate ("AC 6555", Eastman Chemical Products, Kingsport, TN) in ethyl acetate dried and provided a tack-free coating for 1.0 - 1.5 minutes in an oven at 40°C. This turned out to be. the fastest that was tried. An alternative choice is a 10% solution of polyvinyl acetate

("Vinac B-15", Air Products, Allentown PA) in ethyl acetate which dried for about the same amount of time. The use of alkyd resins as a coating does not seem to be suitable at this time. The resin must dry via a slow chemical reaction. In contrast, the solvent only needs to evaporate from the polymer solution when cellulose acetate is used.

The cellulose acetate coating formulation is advantageous over polyvinyl acetate because the former compound is a derivative of a natural product while the latter is commercially produced using a petroleum-derived chemical feedstock. Of course, the breakdown products for both must be harmless to plants and animals. E.g. should cellulose acetate be broken down into natural fibrous cellulose and possibly into glucose. Similarly, polyvinyl acetate should yield polyvinyl alcohol which is an FDA approved food additive. Both coatings should also give acetic acid as a by-product. Acetic acid is the main ingredient in edible vinegar and is considered to be harmless to the environment in the quantities it is found in the staples in

The coating thickness should have important effects on the final efficiency of the staple product. The thickness of the coating should directly affect the initial release rate by changing the length of the diffusion path. In other words, can

it is expected that the thicker the coating barrier, the lower the initial release rate of active ingredient from the staple to the plant soil. The following discussion contains a description of the experimental setup intended to establish a procedure that can be used to coat staples to produce a reproducible coating thickness. Subsequent studies are intended to identify the effect of variations in coating thickness on the release rate of the active agent from the manufactured stick.

A 10% solution of cellulose acetate in ethyl acetate was used as the sample coating system. The average diameter of pre-weighed pins (10) was determined using a micrometer with an accuracy of 0.00025 mm. The measured pins were then pierced at one end with a straight stick and suspended in the coating solution for approx. 3 seconds via attachment to a string. The pins were removed from the solution and allowed to dry in an oven at 40°C for 75-80 seconds. The dimension of the coated pin was then measured and found to be approx. 0.025 mm thicker. On the other hand, the bottom part of a suspended pin developed a greater thickness of

between 0.038 and 0.05 mm due to a stronger build-up of polymer due to flow during drying.

A subsequent trial was carried out to double the coating thickness. The desired increase in coating thickness was achieved by dipping pins for 3 seconds in the coating solution, removing them for 3 seconds, dipping them once more for another 3 seconds and then transferring them to an oven for drying. Staples coated to a total increase in diameter of 0.05 mm were found to have increased their weight by an average of 0.07 g. In other words, approximately 3.178 kg of cellulose acetate in 28.60 kg of recoverable ethyl acetate is required to apply a 0. 0254 mm thick coating on 45.4 kg insecticide stick.

Example 8

The object of this experiment was to determine the rate and profile of release of active ingredient from products manufactured according to the invention in potting soil.

Several stick formulations were prepared and the rate of release of the insecticide from the stick was then determined. An initial rapid rate of release was observed. This was followed by a slower release. In addition, the insecticide was apparently depleted from the staple within a 25- to 30-day period. It must be recognized here that the real duration of the biological effectiveness of the staples can only be determined during a biotest phase for the project. Laboratory tests discussed here are intended to provide estimates for the experimental direction for identifying optimal formulations.

The following sections contain descriptions of the products used and results obtained from tests performed to determine the profile of the relative rate of release of the insecticide from the staples.

Manufacture of insecticide sticks

Insecticide sticks produced contained either the commercial wettable powder formulation "Standak" (Union Carbide Corp.) or "Orthene" (Chevron Chemical Company)

as an active ingredient. The former was incorporated in a percentage by weight of 20% while the latter was incorporated in amounts of 10, 20 or 30% by weight of the staple. Second, the cumulative weight of insecticide and clay was maintained at a constant level. _ Therefore, any reduction in the amount of insecticide in the manufactured stick was balanced by a corresponding increase in the filler content. Third, all staples were produced with a single dye (green, Ferro). It was later determined from market studies that brown or red-brown would be more desirable colors for the consumer. However, the actual dye was not determined or considered important to the preliminary experimental determinations of the relative release data. Finally, the staples were coated with cellulose acetate to give either an increase of 0.025 or 0.05 mm. Only staples coated to these thicknesses were tested to determine the relative release rates. The pins with the largest coatings were retained for possible later assessments using laboratory and/or bioassay techniques.

Table 21 contains a description of the 8 formulations that were prepared for studies of the release rate. The PEO, "Carbowax", insecticide formulation, clay and dye were placed together in a 100g beaker and dry mixed until qualitative homogeneity was apparent (about 15 - 25 seconds) using a wood chip depressor. The mixture was then fed directly to the heating chamber of a Watson-Stillman Injection Molder and held at a temperature of 86-92°C for 5 minutes. A pressure of 63 kg/cm was applied to force the flowable mixture into the preheated mold (60°C, about 10 minutes). The mold was capable of producing 6 pins each 5 cm long and having an outer diameter of 5 mm. The hot mold was removed from the press and allowed to cool for approx. 1 minute. The pins were removed from the mold and excess film cut away using a razor blade.

Then some of the pins were coated by suspension from straight pins and dipping in a 10% solution of cellulose acetate in ethyl acetate solution for 3 seconds. The dipping procedure was repeated to achieve twice the coating thickness. The wet sticks were placed in an oven at 40°C for 75 seconds, removed and set aside to determine the relative release rate of insecticide from the product.

General test procedure

A 1:1 weight ratio mixture of an alpha-cellulose fiber mat (Hawkesbury Sulfite, International Pulp Sales Company) and 20 g of distilled water was spun in a Waring mixer. The mass of 40 g was then placed in a 400 ml beaker to simulate household soil with 25% moisture content. Pre-weighed pins were individually placed in the simulated environment and the top covered using "Saran" plastic wrap, double secured with a rubber band. One pin was removed from each of 11 cups after 0.25, 1, 2, 3, 5, 7, 10, 13, 16, 20 and 25 days. The amount of remaining nitrogen was then determined and used as a measure of the amount of pesticide that had been released. The specific analytical procedures used are discussed below as well as the development of the test procedure and the knowledge gathered regarding the mechanism and effectiveness of the staple's performance.

Uncoated staples. A first attempt was made at

to determine the release rate of insecticide from a stick and was carried out using an uncoated stick containing "Standak". A complete dissolution of the staple was evident in water after 24 hours.

A total of 22 cups containing pulp were produced to house 11 staples containing "Orthene" (85% by weight active ingredient in the form of wettable powder) in PEO "WSR N-80" and a corresponding number of staples were produced with 4.5% by weight % .as. clay filler f_... St if tene_ var. not coated. Each pre-weighed s"tift was' introduced"! "the cup dg care was taken that it was completely covered with mass. Every pin had to be removed

for analysis according to the previously set timetable. However, the staples were almost completely dissolved by the end of the first day of exposure. The experiment was therefore discontinued.

Valuable information can be gleaned from this mortified attempt. An average household soil with a moisture content of 25% is likely to be sufficient to allow total dissolution of a rootstock within one or two days. Thus, all the insecticide will be released during this short period of time. The initial high insecticide dose would meet the general criteria_for_Jiurj:ig_ release of the desired short-term kill (over a period of 24-48 hours). However, the duration of the formulation's effectiveness could not be expected to significantly exceed the actual duration of the active ingredient itself.

These results indicated that the application of a biodegradable coating in the staples could serve two functions. Firstly, the coating could provide a safe buffer between the active ingredient on the surface of the solid formulation and the person handling the device. Second, the coating could reduce the release rate of insecticide from the rapidly degradable stick. The following sections describe the experiments conducted to determine the release rate of insecticide from coated staples.

Coated staples. Figs. 8-10 graphically show the data obtained from experiments intended to determine relative differences in release rates for coated staples containing "Standak" and coated staples containing various amounts of "Orthene". It was found that the 0.0254 mm cellulose acetate substantially extended this physical life of the staples containing insecticide to at least 25 days after application. In other words, relatively intact staples could be removed from the simulated environment up to this time period, but not after this. This improvement provided a method for determining the amount of insecticide released into the environment.

The staples were removed at predetermined intervals

as described above from the simulated environment using tweezers and then^ placed in pre-weighed glass ampoules. Any large amounts of residual mass adhering to the staples were carefully removed and the ampoules placed in an oven maintained at 40°C for drying. The ampoules were removed after a constant weight had been achieved and the residual nitrogen content was determined using the Kjeldahl technique. The amount of nitrogen that remained in the staples after exposure to moist mass could be used to determine the amount of insecticide that had been released into the sample surroundings.

The data shown in f^ j^^ j^^^^^ S^ ÅSi^^^ l.,^^. 3 as indicative of the relative release rates and profiles of coated staples. E.g. shows fig. 8 the data obtained in an attempt to determine relative release rates for coated staples containing 20% "Standak" or "Orthene". The apparent difference in the rate of loss of insecticide from the staples need not be present. Thus, they may be due to a spread of the data points.

The initial trend for a rapid release of insecticide from the staples is generally followed by a slower release of active ingredient. The first trend of rapid release of active ingredient provides sufficient systemic insecticide toxic to a plant to cause a substantial reduction in the size of any existing pest population. The subsequent change in the trend towards a slow release can then act as a maintenance dosage to ensure that new infection does not occur during an effectiveness period of 3.0 - 60 days.

Another important point is that dip-coated staples made from a water-soluble thermoplastic binder composition containing an inert filler and a wettable powder of either "Standak" or "Orthene" can maintain their physical form for up to 25 days in a standard experimental situation.. This in comparison with the short, namely 1 or 2 days, lifetimes for uncoated staples. It is important to note that the coating is retained somewhat close to intact both after the binder and insecticide content has been depleted. This may be due to the fact that cellulose acetate is not water-soluble. However, it is biodegradable and the rate of disappearance should be obvious in soil environments where microorganisms can work.

The rate at which water diffuses through the coating into the active matrix and back out through the coating to the environment probably determines the release rate of the insecticide from the stick. The strong contrast between water solubility for the two insecticides can be misleading when interpreting the data shown in fig. 8. Water present in the release environment should be considered to

be in great surplus. Thus, there is a sufficient amount to completely dissolve the small amounts of insecticide found in a stick.

The data contained in fig. 9 shows another important feature of the way in which the eventual effectiveness of the insecticide stick can be controlled by varying the load of active ingredient in the original formulation. Increasing the relative loading levels in coated staples from 10 to 30% by weight does not appear to result in any corresponding change in the relative release rates.

Of course, this does not mean that there is no change in the amount of insecticide released. The results from the experiments suggest that a change in the initial loading of insecticide in a stick will result in a corresponding change in the cumulative release of the insecticide. This can be seen in fig. 10 where the amount of insecticide released from the stick is plotted against time. A general tendency can be seen where an increase in the initial load results in an apparent linear increase in the amount of insecticide released. In other words, a variation of the initial load of insecticide in a stick will affect the amount of insecticide available to a plant at any given time. This should be a means of predictably changing the apparent duration of effectiveness.

Many changes and modifications will be apparent to those skilled in the art upon a study of this description. All such changes and modifications falling within the spirit of the invention as defined by the accompanying claims are intended to be within the scope of the invention.

Claims (24)

1. Product for the controlled release of a systemic insecticide to the soil, characterized in that it includes: a systemic pesticide; and a matrix for holding the systemic pesticide, said matrix comprising a solid hydrophilic polymer binder which is water soluble to allow moisture in the soil to erode said matrix and cause an initial rapid release of the systemic pesticide from the product into the soil and then a slower controlled release thereof systemic pesticide. 2. Product according to claim 1, characterized in that the pesticide is a systemic insecticide. 3. Product according to claim 1, characterized by -that the system mix- -pesticide -ex -sx-ab_il_t at the production temperatures "for the product, has a sufficient solubility in water to to be able to dissolve and be transported to and into the plant's sap, past stable and active in the normal pH ranges found in both soil and plants, and has the ability to kill the desired plant, and in which, the binding agent does not cause phytotoxic effects on the plants, are able to be mixed with the systemic pesticide in an unlimited way, does not react with the pesticide in a way that destroys each individual's role in the product, has a softening temperature below the decomposition temperature and provides sufficient strength to the manufactured product to maintain it substantially intact during packaging, storage, shipping and introduction into the soil. 4. Product according to claim 1, characterized in that the pesticide is the dimethyl phosphate of 3-hydroxy-N-methyl-cis-chrontonamide. 5. Product according to claim 1, character i se r^E in that the pesticide is--0,0-dimethyl-O-(z-methylcarbamoy 1-1- 1-methylvinyl) phosphate. 6. Product according to claim 1, characterized in that the pesticide is O,O-dimethyl-s-(N-methylcarbamoylmethyl)-phosphorodithioate. 7. Product according to claim 1, characterized in that the pesticide is 0,0-dimethyl-acetyl phosphoramide thioate. 8. Product according to claim 1, characterized in that the pesticide is 0,S-dimethylacetylphosphoramidothioate. 9. Product according to claim 1, 4, 5, 6, 7 or 8, characterized in that the binder is polyethylene oxide. 10. Product according to claim 1, 4, 5, 6, 7 or 8, characterized in that the binding agent is polyethylene glycol. 11. Product according to claim 7, characterized in that the systemic pesticide comprises from approx. 70 - approx. 30% by weight of the product and in which the binder is polyethylene oxide containing from approx. 30 - approx. 70% by weight of the product. 12. Product according to claim 8, characterized in that the systemic pesticide comprises from approx. 70 - approx. 30% by weight of the product and in which the binder is polyethylene glycol containing from approx. 30 - approx. 70% by weight of the product. 13. Product according to claim 12, characterized in that it further comprises: from approx. 0 - approx. 5% by weight of a plasticizer; from approx. 0 - approx. 70% by weight of a filler; from approx. 0 - approx. 2% by weight of a dye, the softener, filler and dye being thoroughly dispersed in the binder and in the insecticide; and from approx. 2 - approx. 20% by weight of a biodegradable coating that covers the surface of the product. 14. Systemic pesticide stick, characterized in that it includes: a hydrophilic water-soluble polyethylene oxide polymer; and a systemic insecticide, in that the polymer forms a matrix that holds the systemic insecticide so that when the pesticide is introduced into the soil, it is initially quickly released to the soil under the influence of the soil moisture and is then removed in a controllable manner from the matrix due to the soil's moisture, as the pin can be driven into the ground without it breaking or crushing. 15. Systemic insecticide stick according to claim 14, characterized in that it further comprises: from approx. 0 - approx. 5% by weight of a plasticizer; from approx. 0 - approx. 70% by weight of a filler; from approx. 0 - approx. 2% by weight of a dye; and from approx. 0 - approx. 20% by weight of a protective coating. 16. Method for producing a systemic pesticide product with delayed release, characterized in that it includes: (a) mixing from approx. 25 - approx. 99% by weight of a polymer binder, from approx. 1 - approx. 75% by weight of a systemic pesticide to form a dry mixture; (b) applying sufficiently high temperature and • pressure to said dry mixture to melt it into the desired shape. 17. Method according to claim 16, characterized in that it further comprises applying a bee egg to the surface of the product. 18. Pesticide product with delayed pesticide release, characterized in that it is produced by the method according to claim 16. 19. Method for producing a systemic insecticide product with delayed release, characterized in that it comprises: (a) mixing approx. 25-95% by weight of a polymer binder, 5'-75% by weight of a systemic pesticide, 0-70% by weight of a filler, 0-5% by weight of a plasticizer and 0-2% by weight of a dye; (b) heating the dry mixture obtained in (a). until it melts; (c) forming the molten mixture to form a stick; (d) allowing the staple to at least partially solidify; (e) Coating the pin with a biodegradable polymer. 20. Pesticide product with delayed pest life, characterized in that it is produced using the method according to claim 19. 21. Procedure for eliminating plague from a plant, characterized in that it includes: to introduce into the soil near the roots of the plant a product comprising a systemic pesticide and a solid, water-soluble, hydrophilic polymer binder, the binder forming a matrix that encloses said systemic pesticide so that the moisture from the soil dissolves the matrix and the binder and quickly releases a sufficient amount of said systemic pesticide from said matrix to the soil to kill at least a sufficient number of plague organisms and then to control the release of said systemic pesticide to allow the plant to continuously adsorb into its plant sap to kill the remaining plague infestation and to prevent re-infection. 22. Method according to claim 21, characterized in that 0,S-dimethylacetyl phosphoramidothioate is used as systemic insecticide. 23. Method according to claim 21 or 22, characterized in that the binder is polyethylene oxide. 24. Method according to claim 21 or 22, characterized in that the binding agent is polyethylene glycol.