EP0077399A1 - Produit de pesticide systemique et procedes de fabrication et d'utilisation de celui-ci - Google Patents

Produit de pesticide systemique et procedes de fabrication et d'utilisation de celui-ci

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Publication number
EP0077399A1
EP0077399A1 EP82901877A EP82901877A EP0077399A1 EP 0077399 A1 EP0077399 A1 EP 0077399A1 EP 82901877 A EP82901877 A EP 82901877A EP 82901877 A EP82901877 A EP 82901877A EP 0077399 A1 EP0077399 A1 EP 0077399A1
Authority
EP
European Patent Office
Prior art keywords
pesticide
product
systemic
spikes
soil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82901877A
Other languages
German (de)
English (en)
Other versions
EP0077399A4 (fr
Inventor
Michael J. Cousin
William T. Lawhon
Richard G. Sinclair
Barney W. Cornaby
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Spike Inc
Original Assignee
International Spike Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Spike Inc filed Critical International Spike Inc
Publication of EP0077399A1 publication Critical patent/EP0077399A1/fr
Publication of EP0077399A4 publication Critical patent/EP0077399A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
    • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
    • A01N25/34—Shaped forms, e.g. sheets, not provided for in any other sub-group of this main group

Definitions

  • pesticides includes insecticides, fungicides, herbicides, miticides, nematocides and bactericides.
  • U.S. Patent No. 3,269,900 discloses a slow release pesticide product made by enclosing a pesticide in a polyurethane foam. The foam is decomposed by microorganism to release the pesticide. The release of the pesticide from the product disclosed in the Rubin patent is therefore dependent on the particular soil and microorganisms present therein.
  • systemic pesticides In order to maintain adequate levels of pesticides in the sap of the plants, the systemic pesticides must be frequently resupplied into the soil. The repeated applications of the systemic pesticides increases labor expenses. In addition, the accumulation of certain pesticides in the soil can cause health hazards.
  • a further object of the present invention is to form a product which rapidly begins to release the pesticide and continues to gradually release it for a prolonged period of time.
  • the products of the present invention generally comprise from about 25 to about 99 and preferably about 25 to about 95 weight per cent of the binder and 1 to 75 and preferably 5 to 75 weight per cent of the systemic pesticide.
  • Optional ingredients include plasticizers, fillers, colorants and a coating.
  • the use of fillers produces a product which is less expensive.
  • the coating makes the product safe to handle and provides an additional control over the release rate of the pesticide.
  • the present invention provides a method for using the products without creating health hazzard.
  • the products are formed into spikes that can be driven into the soil without sustaining damage. Once the products are inserted or driven into the soil in the vicinity of the plant, the moisture of the soil penetrates the coating (if any) and disolves the polymeric matrix and the pesticide released as the result of the disolving of the matrix. The pesticide is transported by the soil moisture to and absorbed by the roots of the plant into the sap making it poisonous to pests.
  • FIGURE 5 shows a diagram of a presently preferred commercial method of manufacture of spikes of the present invention.
  • FIGURE 6 is a side-elevational view of presently preferred commercial embodiment of the insecticide spike for household plants, made in accordance with the present invention.
  • FIGURES 8-10 are diagrams depicting profiles of the release of the systemic pesticide as a function of time from products made in accordance with the present invention.
  • the present invention provides a controlled-release systemic pesticide product which is safe to handle even by the general public.
  • the product of the present invention When inserted into the ground in the vicinity of a plant, the product of the present invention rapidly begins killing pests on the plant and continues to kill them for a prolonged period of time and/or prevents infestation of the plant by pests for a prolonged period of time, substantially without adverse effects on the plant.
  • the product of the present invention is designed to release a sufficient dosage of systemic pesticide to kill pests on the nearby plants within a relatively short period of time or to prevent infestation of a healthy plant and then continue to supply the pesticide to the plant gradu ally at a controlled rate for a prolonged period of time.
  • the additional ingredients that can be included in the composition include 0 to 5 weight percent of plasticizer, 0 to 70 weight percent of a filler, 0 to 2 weight percent of a colorant and 0 to 20 weight percent of a protective coating which is preferably water permeable.
  • the preferred amounts of plasticizers, fillers, colorants and protective coatings are 2, 43, 2 and 7 weight percent of the product.
  • systemic pesticides used in the product of the present invention should:
  • the LD 50 of the systemic pesticides should preferably be in the range from about 20 to 100.
  • the oral LD 50 should preferably be less than 500 mg/kg.
  • the binder must be water soluble at rates that permit a prompt release of the systemic pesticide upon initial contact with the moisture in the soil and a sustained controlled release of the systemic pesticide thereafter. In order to accomplish a rapid initial release of the systemic pesticide from the product, the binder should be hydrophilic and water soluble. A.ddi.tionally the binder should: (1) inflict no phytotoxic effects on plants;
  • the binder should preferably be non-toxic to humans.
  • composition of the present invention can be formed into spikes that can be driven into the soil without breaking or shattering.
  • the composition is rugged enough to maintain its integrity during packaging, transportation and in storage, and it is stable under normal atmospheric conditions so that it can be stored for prolonged periods of time. If coating is applied to the surface of the composition of the present invention, the resulting composition can be handled even by consumers during storage, transportation and planting into the soil without the danger of poisoning.
  • the spikes made in accordance with the preferred embodiment of the present invention are safe for consumer handling not only because of the protective coating and the use of a polymer matrix to shield the pesticide but also because during normal use they emit practically no toxic fumes and have low dermal and inhalation human toxicity.
  • Pesticides include water-soluble thiocarbamates, phosphocarbamates and thiophosphocarbamates that satisfy the criteria set forth above.
  • the binders suitable for use in the products of the present invention are those that satisfy the general criteria set forth above.
  • Two types of polymers have been found to be superior in the fabrication of the product of the present invention and were found to produce spikes which meet the objectives of the present invention and are drivable into the soil without breaking or shattering.
  • the first type is polyethylene oxide)s
  • the second is poly(ethylene glycol)s.
  • Poly(ethylene oxide)s are preferred because they allow the fabrication of the pesticide composition of the present invention by either melt extrusion or by injec tion molding.
  • poly(ethylene glycol)s are used as the binder, the product cannot be fabricated by melt extrusion. The reason for it is that melted poly(ethylene glycol)s do not provide sufficient green strength to allow for the formation of a uniform rod of material that can then be cut into desired shapes.
  • poly(ethylene oxide) binders available from Union Carbide include: "Polyox WSR N-80”, “Polyox WSR N-750", “Polyox WSR 205" and “Polyox WSR 1105", having average molecular weights of 200,000; 300,000; 600,000 and 900,000, respectively.
  • Fillers can be used in the pesticide products of the present invention to reduce the cost of the products. Fillers are significantly less expensive than binders; therefore replacing some of a binder with a filler reduces the overall cost.
  • Examples of fillers suitable for use with the composition of the present invention include clay and corn cob. Clay is especially preferred because, surprisingly, it has been found to improve the hot melt strength and the viscosity of the molten composition during fabrication. As a result, during processing a hot extruding rod can be subj ected to tensile stresses without breaking.
  • An example of useful clay is Spray Satin Clay commercially available from Englehard Minerals and Chemicals Corporation, Iselin, New Jersey. Corn cob can be purchased from The Andersons in Maumee, Ohio.
  • Plasticizers are used as a fabrication aid. They lower the viscosity of the composition at melt stage.
  • the presently preferred plasticizers include poly(ethylene glycol)s having an average molecular weight from about 400 to about 6000. Especially preferred is polyethylene glycol having an average molecular weight of 4000. This poly(ethylene glycol) is commercially available under the trade name designation "PEG 4000" from Union Carbide, New York, New York.
  • a coating applied on the surface of the product serves several functions. First, it protects the user of the product from accidentally absorbing some of the insecticide through the skin. Second, it enhances the stability of the product because it prevents the spike from absorbing moisture from the air during routine handling.
  • Suitable coatings include biodegradable polymers, such as cellulose acetate, alkyd resins, alkydacrylic copolymers, and poly(vinyl acetate)s.
  • the use of a biodegradable coating which is water-soluble provides an important additional advantage. Namely, it significantly slows down the rate at which systemic pesticide is released into the soil.
  • An example of a water insoluble biodegradable coating is cellulose acetate.
  • the presently preferred systemic pesticides are is O,S-dimethyIacetylphosphoramidothioate, commonly known as acephate and O,S-dimethylacetylphosphoroamidothioate.
  • the former is available as a wettable powder under the trade name ORTHENE®, from Chevron Chemical
  • ORTHENE® preferably 20 percent by weight of the spike should be ORTHENE®, but the amount of ORTHENE® used may range from 1 percent to 75 percent by weight of the spike. The present most preferred range of insecticide is between 10 and 30 percent.
  • the dry ingredients are first blended together using a conventional blender until a substantially uniform mixture is formed.
  • the mixture is then fed into a hopper of a conventional screw type extruder. From the hopper the mixture is transported into the heated barrel of the extruder. As the mixture is conveyed by the action of the screws, it is simultaneously heated and compressed. The temperature of the barrel is generally maintained between about 65°C and 75°C. As the mixture is compressed and heated it forms a substantially homogeneous melt which is forced through a die at the end of the barrel opposite from the hopper. The die temperature is maintained in the range from about 70°C to about 80°C.
  • the specific die size depends on the composition of the specific insecticide, the size of the extruder and the flow rate of the melt.
  • the dies used in our experiments had diameters of 0.195 and 0.240.
  • the dies were used in a single screw extruder having an L/D ratio of 20:1 manufactured by C.W. Brabender Instruments, Inc., Southhackensack, New Jersey.
  • the invention will now be further described in connection with a preferred commercial process of the present invention shown in FIG. 5.
  • the process uses Orthene rather than Standak as the preferred systemic pesticide because ORTHENE® has already been cleared for use as a systemic insecticide in the United States.
  • Material Source Referring now to FIG. 5, the starting materials shown thereon and the source of these materials are as follows: Material Source
  • the materials introduced into the mixer are thoroughly mixed preferably using an intensive mixer that assures break up of lumps and agglomerates and then is fed from the mixer into an extruder.
  • Twin screw extruders available, for example, from Cincinnati Milacron or Krauss Maffei, are presently preferred.
  • the moisture from the soil penetrates the coating and begins to erode the matrix releasing the systemic pesticide.
  • the pesticide is gradually released into the soil, it is absorbed by the roots into the sap of the plant.
  • the pesticide makes the sap of the plant poisonous to insect thereby kills the insects which attempt to feed on the plant and protecting the plant from infestation.
  • the binder, coating and optional ingredients that are not normally a part of the soil of the preferred embodiments are biodegradable; accordingly, they decompose so that there is no debris left in the soil as the result of the application of insecticide spikes of the present invention.
  • Criteria used in selecting the "best" insecticides included (1) high toxicity to insects, (2) low toxicity to humans, (3) usability on ornamental plants, (4) availability in the U.S.A., and (5) numerous chemical and physical properties.
  • Insecticide A killed up to approximately 80 percent of the original mealybug population after 24 hours and up to approximately 100 percent after 96 hours (Table 3). With these four "best" insecticides, total kill was accomplished after 11 days of treatment. From
  • Insecticide A was effective in all three concentrations with a total kill occurring after 11 days. During the first 24 hours a difference did exist between concentrations, with approximately 25 percent, 70 percent, and 75 percent of the population being killed by the respective low, medium, and high dosages. However, after 96 hours all three concentrations appeared to be equal in effect, with low concentrations eradicating 94 percent of the original population and middle and high concentrations killing approximately 95 percent of the baseline population.
  • Insecticide B was equally effective in all three concentrations, killing about approximately 85-90 percent of the mealybug population within 24 hours. After 95 hours the low dosage resulted in a 92 percent drop in population, and the medium and high dosages killed 97 percent drop in population. Total kill occurred after 11 days.
  • Insecticide C exhibited an opposite effect to that exhibited by A, B, D, and F.
  • the population had increased after 11 days by approximately 30 percent above the baseline population. After 24 hours there was no change, while after 48 and 96 hours there were small drops in the population, i.e., 3 percent (48 hours) and 37 percent
  • Insecticide E like C, showed no to little effect on population reduction of mealybugs. With the low, medium, and high concentrations the respective populations of mealybugs increased up to 123 percent above the baseline population count after 11 days. Plants treated with low and high dosages of E contained mealybug populations at 65 percent and 122 percent above their respective treatment day populations. The medium dosages resulted in a small 4 percent reduction of the original population count.
  • Insecticide F though not initially as effective as A, B, and D, caused 100 percent kill after 11 days at all dosages. After 24 hours all three dosages appeared equally effective, killing approximately 55-65 percent of the population. A difference in the effectiveness of dosages began to appear after 48 hours, at which time 75, 86, and 100 percent of the original populations had been killed for the respective low-, medium-, and high-dosage groups.
  • Numerical phytotoxicity ratings are shown in Table 4. Substance A caused moderate to strong phytotoxicity. The degree of phytotoxicity appears to be a function of concentration as well as time. The first effects were observed 7 days after treatment, at which time the low, medium, and high dosages exhibited average ratings of 2, 3, and 3 respectively (Table 4). Thus, moderate to large leaf loss or change of leaf color occurred. At 14 days after treatment, the average ratings were 3, 4, and 4 respectively, meaning large to total leaf loss or change of leaf color. Also, one of the plants (receiving the high dosage) received a rating of 5, indicating that the plant was dead.
  • Insecticide B was highly phytotoxic in all concentrations, killing medium- and high-dosage plants 8 days after treatment and all plants except one (which had a rating of 4 and was dying) after 14 days. Insecticide B was the fastest acting pesticide, exhibiting its effects only 4 days after initial application of the pesticide. Even at the low concentration it caused moderate to large leaf loss (rating of 3), and large if not total leaf loss or leaf death in the medium to high concentrations (rating of 4). By day 8, all middle and high-dosages plants were dead, and all plants (with the above exception), were dead at 2 weeks.
  • Insecticide C also was moderately phytotoxic to coleus. The first visible effects were not observed until one week after administration of the pesticide, at which time the low-dosage plants had lost several leaves (rating of 2) and others had brown edges. The medium-dosage plants had no visible adverse effects. However, two weeks after treatment, C caused large leaf loss in two of three plants in the medium-dosage plants and total leaf loss or leaf death (rating of 4) in all the low- and in one medium-dosage treated plant.
  • Insecticide E exhibited a small to moderate phytotoxic effect; the effects varied proportionally with time as well as with concentration.
  • the low-dosage plants exhibited either no effect or edges of leaves were turning brown.
  • the medium-dosage plants exhibited a loss of several leaves in addition to color change in leaves still on the plants.
  • the plants in the high-dosage range were losing many leaves.
  • all plants were still alive.
  • the low-dosage plants still exhibited only small leaf loss or brown-edged leaves (rating of 1).
  • the medium-dosage plants had lost several leaves (rating of 2) while the high-dosage plants had either lost many leaves or had a large number of dying leaves (rating of 3)).
  • Substances E and F produced the fewest phytotoxic effects of all insecticides tested. The first effects were not observed until day 8 when there was a turning of color in a few leaves in all plants at all concentration doses. By day 14 there was a loss of several leaves in 1 of 3 plants in the low-dosage group and in all 3 plants of the medium-dosage group. In the high concentration range all plants had lost many leaves. The controls received ratings of 0 (no effect) consistently throughout the 14-day experiment.
  • Insecticide D like B, killed a large portion of the mealybug population, i.e., 80 to 85 percent in just 24 hours. Again, however, like B, it was lethal to coleus after 8 days in three of the high-dosage group and in one medium-dosage group. By day 11 all insects were dead, but so were the plants.
  • Insecticide C and E appeared to be similar in their limited effectiveness in killing insects, but C was slightly more phytotoxic, causing large if not total leaf loss after day 11. Substance E never caused more than the loss of one large leaf.
  • Substances F and A were similar in their insectkilling effectiveness, but differed in their phytotoxic effects. These two pesticides were moderate in their insect-killing ability after 24 hours. The medium and high dosages of A killed 70 to 75 percent of the bugs, while F killed 60 to 65 percent of the population in all concentrations. Neither pesticide exhibited any phytotoxic effect. Insecticide F appeared to be the superior of the two, because although both had killed all insects by day 7, A was more phytotoxic by day 11 (exhibiting a rating of 3 to 4 on the phytotoxicity scale).
  • Insecticide F is the best overall insecticide. It killed insects initially and its killing power was sustained. Substance F showed the least phytotoxic effect of all six insecticides were to some extent phytotoxic. By comparison, A, D and B killed (in the early part of the experiment) approximately equal numbers of mealybugs at all concentrations and the lower concentration are less phytotoxic than the medium and high dosages . This implies that even lower dosages would be less phytotoxic in effect but still maintain a toxicity for insects.
  • EXAMPLE NO. 2 The purpose of this experiment was to determine the amount of ORTHENE® that needs to be incorporated into each systemic insecticide spike to kill within 24 hours over 50 percent of the mealybug population on small coleus plants without causing visible phytopathological reactions to the coleus plants.
  • the second run the design was slightly modified to place more emphasis on the number of plants being exposed to a given dose of ORTHENE® in a spike.
  • the second design was comprised of 1 species of plant (coleus) X 5 individual plants 4 for the reference X 3 exposures (0, 15, and 25 percent loading of a.i. per spike X 7 sampling times (days 0, 1, 2, 4, 8, 13 and 16). At each measurement time the number of mealybugs larger than the first instar was counted on each plant.
  • the insecticide spikes were effective in reducing populations of mealybugs on small coleus plants.
  • a population averaging 58 and ranging from 18 to 113 mealybugs per plant represented the initial populations (Table 4A).
  • Mite populations were reduced from an average of over 30 mites per leaf at day 0 to about 16 mites per leaf by day 24 (Table 5). Plants that received 16 spikes showed more rapid declines in mites than did those plants receiving 8 spikes. The least rapid (slowest) decline in number of mites was observed by plants that had been exposed to 4 spikes. The reference population (0 spikes) showed more than an average of 10 mites per leaf through day 47 then decreased to about 7 by day 72. Thus, the dosages of 4, 8, and 16 spikes worked well to reduce. mite populations.
  • ORTHENE® caused some chlorosis with 4 spikes; chlorosis was found in upper leaves only. With 8 and 15 spikes, chlorosis was found in all leaves. In addition, plants which received 16 spikes had leaves with brown edges and greater leaf drop occurred in plants with 16 spikes than those receiving 4 and 8 spikes. There was an obvious gradual decline in plant health from 0 to 16 spikes of ORTHENE®.
  • the purpose of this experiment was to determine the number of spikes containing 25 percent of active ORTHENE needed to protect uninfested plants from colonization by mites and mealybugs when the uninfested plants were placed next to infested plants.
  • Mites were suppressed by day 17 on large mums (Tables 7 and 8).
  • the population of mites exposed to 4 spikes was slightly lower than the population exposed to 2 spikes.
  • the effectiveness of the insecticide spikes was apparent when the population pattern for 2 and 4 spikes was compared to the population level for 0 spikes. In the latter, mites in mean number greater than 5 per leaf were present on leaves as late as 51 days after exposure began. By contrast mites were suppressed by day 17 on plants receiving insecticide spikes.
  • the reference (O spikes) showed an average population of around 13 mealybugs at day 51. The average reference population was as high as 61 mealybugs per plant on day 28 compared to 1 or 2 insects per plant for pots that had received spikes.
  • the pattern of mealybugs on small mums was similar to the pattern .for mealybugs on large mums (Table 7).
  • the population had built-up suggesting that the invasion rate of mealybugs from adjacent donor plants was greater than the insecticides ability to control pests.
  • the reference plants exhibited mealybug populations higher than those plants that had received protection from spikes. For example at day 17 there were an average of 148 mealybugs per leaf and by day 52 there was a mean of 72 mealybugs per leaf. This latter value was about 5 X as high as that for the treated plant.
  • Mite populations were reduced to zero by day 51 on large scheffleras that received 2 spikes (Table 9). Scheffleras that received 4 spikes showed an average population of 4 mites per leaf. The reference exhibited an average population of about 8 mites per leaf. By contrast, all mites on small scheffleras were dead by day 17. This was true of plants receiving 0, 1, and 2 spikes. Apparently, small scheffleras do not meet habitat requirements for mites because all the mites died.
  • plaques approximately 1/8" thick containing the various polymer/insecticide combinations were fabricated by compression molding. These plaques were made using a 4" ⁇ 6" positive displacement mold. It was necessary to mold all the plaques, with the exception of those containing the poly(ethylene glycol) and poly(ethylene oxide) at a temperature which was higher than the melt/degradation temperature of the insecticide. The pesticide plaque containing CAB was excessively degraded. Similarly, all the plaques (Table 13) which were molded at the high temperature showed signs of substantial degradation (browning).
  • Polyox 10 80 20 (a) brittle
  • CAB 80 20 (b) Clear, strong & flexible
  • Methocel 80 20 (b) strong, but slightly brittle
  • Klucel 80 20 (b) very thin, flexible but brittle
  • spikes have been prepared that contain as little as 23% by weight of poly(ethylene oxide).
  • the remaining spike mass consisted of 20% Standak wet ⁇ able powder formulation, 1% carbon black filler/extender and 1% carbowax plasticizer/lubricant. It was, however, difficult to injection mold spikes using this formulation and it would be necessary to consider using more PEO to facilitate the eventual preparation of spikes by extrusion.
  • the relatively high cost of PED was the reason for using as little PEO in the spike formulation as possible.
  • the results using the high melting polymers generally were the same as with the molded sheets.
  • the spikes containing Gelvatol showed definite evidence of degradation while the spikes using poly(ethylene glycol) were weak and brittle.
  • the formulations with insecticide incorporated in Methocel (with and without a clay filler) and with poly(ethylene glycol) containing carbon black filler could not be successfully injection molded.
  • the melt fabrication of insecticide spikes requires high temperatures. It is important that the chemical integrity of the insecticide remain intact during this process. Therefore, an experiment was designed to determine whether the model insecticide, Standak, was degraded during the process of melt fabrication by injection molding.
  • Standak was removed from spikes prepared using the various binder candidates just described by a solvent extraction technique. Spikes were broken into small pieces and placed into a beaker containing a magnetic stirring bar. Approximately 100 ml of anhydrous ether was added and the mixture allowed to stire for 0.5 hours at room temperature. The mixture was vaccuum filtered and the ether allowed to evaporate under low heat. The insecticide residue was then collected and placed in a small glass vial. 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 Chroraatograph (LC-65 T Chromatography Module).
  • a mobile phase consisting of 15% acetonitrile in deionized water was used at a flow rate
  • a chromatogram showed that a purified Standak solution used as a control shows component separation withih one minute and insecticide appearance after two minutes. The same tendency can be observed in the chromatograms of the Standak extracted from the spikes prepared using poly(ethylene glycol) and poly(ethylene oxide) as the binders. This indicates that no discernable degradation of the Standak had occurred as a result of melt fabrication using these binders.
  • a primary objective of this experiment was to identify an optimum composition for the fabrication of the Systemic Insecticide Spike using the predicted manufacturing technique of melt extrusion.
  • Table 16 contains a list and the specific quantities of the ingredients used in the formulations of this experiment.
  • Non-toxic spikes were melt fabricated by extrusion utilizing two grades of PEO (WSR N-750 and WSR N-80), a single lubricant (Carbowax 4,000) and several types of filler (spray satin clay, sized corn cob and Raven 5250 carbon black). The preferred ingredients were weighed into a paper cup (4 ounce) and mixed by hand using a wooden tongue depressor. The mixture was subsequently fed into the water-cooled hopper of a single TABLE 16. EXTRUDED NON-TOXIC INSECTICIDE SPIKES
  • Composition Hinder PEO (a) Crade, Quantity, % Clay, (b) Lubricant, (c) Colorant, (d) Diameter,
  • the extruded rods were sliced into two inch spikes while still warm.
  • the physical properties of fabricated spikes of varying composition were subsequently determined. Mechanical tests were performed on the spikes to approximate some of the physical stresses that could be imposed upon the spike during fabrication, packaging, shipping, handling and use.
  • the extruded rod exits the die while still at a relatively high temperature.
  • the rod should have a sufficient hot strength to allow a tensile stress to be applied during the drawdown and/or pulling process of the conveyor on the way to the cutters.
  • Spikes must also display satisfactory strength properties when cool to avoid any undesirable damage to the product during packaging, shipping and use. For these reasons, extrusion--formed spikes were tested in order to determine their tensile strengths at both elevated and room temperatures using an Instron Testing Machine ( Instron Engineering Corp., Canton Massachusetts) having an electrically heated oven (Instron Oven, Instron Engineering Corp., Canton, Mass.). Procedure.
  • the tensile strength of extruded spikes were determined at 23 and 70 C using an imposed stress of 0.2 inches/minutes. It is important to note that the oven temperature for the hot tests varied in the range between 60 and 70 C as a result of the heat loss which occurred from opening and closing the oven door during placement and removal of a spike. The actual tensile testing was begun only after the oven was allowed to come to constant temperature (approximately five minutes). Three replicate samples of spikes containing two PEO grades were tested and the results, in pounds, were averaged. These results are listed in Table 17 along with the results of tensile tests performed on spikes at room temperature.
  • a heated spike apparently responds to tensile stress in a very different manner than a spike tested at room temperature.
  • the spikes containing WSR N-80 which have been exposed to temperatures approaching 70 C display low tensile strengths.
  • increasing the quantity of filler in a spike from 45 to 70% by weight caused a corresponding increase in the tensile strength at break from approximately zero to 2.0 pounds (p), respectively.
  • the tensile strength at room temperature generally decreased TABLE 17.
  • a usable spike having 50% filler and 20% insecticide would be analogous to the 70% filler referred to during this discussion. This approximate formulation appears at this time to both minimize the decrease in ambient tensile strength as a result of including filler as well as to maximize the poor tensile strength of an extruding rod when hot.
  • the flexural strength was determined using the 3 point loading apparatus of the Instron and is recorded as an average value of 5 replicates in terms of pounds of flexural stress required to break a spike.
  • the rate of applied bending stress was 0.2 inches per minute.
  • the resistance to impact displayed by standard non-toxic test spikes is data contained in Table 18.
  • the impact resistance was determined using an Impact Tester (Testing Machines, Inc., Mineoia, NY). Each 2-inch spike specimen was positioned vertically within a brass holder using a locking screw. It was subsequently impacted using a 2-lb pendulum weight and the 8
  • Air-driable alkyd or unsaturated polyester coatings were investigated and solvent was used as a dilutent to lower the initial viscosity.
  • Coated spikes were prepared by dipping preformed (injection molded) non-toxic spikes into the polymer solutions for approximately three seconds and subsequently placing them in an oven (40° C) to dry. Drying spikes were periodically tested in the oven in order to discern the time after application necessary to provide a coating which was tack-free to touch.
  • poly(vinyl acetate) should yield poly(vinyl alcohol) which is an EDA approved food additive. Both coatings could also yield acetic acid as a by-product. Acetic acid is the main ingredient in edible vinegar and is considered to be harmless to the environment at the quantities found on the spike.
  • Coating thickness should have important effects upon the ultimate efficiency of the spike product.
  • the thickness of the coating should directly affect the initial delivery rate by altering the diffusion path length. In other words, it can be expected that the thicker the coating barrier, the slower the initial rate of release of active ingredient from the spike and into the potted plant soil.
  • the following discussion contains a description of the experimental task designed to identify a procedure which could be used to coat spikes in order to prepare a reproducible coating thickness. Subsequent studies should attempt to identify the effect of variations of coating thickness on the release rate of toxicant from the spike product.
  • a 10% solution of cellulose acetate in ethyl acetate was used as the test coating system.
  • the average diameter of preweighed spikes (10) was determined using a micrometer having an accuracy of 0.01 mil.
  • the sized spikes were subsequently pierced at one end with a straight pin and suspended into the coating solution for approximately three seconds via attachment to a string.
  • the spikes were removed from the solution and allowed to dry in an oven at 40 C for 75 to 80 seconds.
  • the width of the coated spike was then measured and found to be approximately one mil greater.
  • the bottom portion of a suspended spike developed a greater thickness of between 1.5 and 2.0 mil due to excess buildup of polymer from flew while drying.
  • the insecticide spikes which were prepared contained either the commercial wettable powder formulation of Standak (Union Carbide Corp.) or Orthene (Chevron Chemical Company) as the active ingredient. The former was included at a weight percentage of 20% while the latter at 10, 20 or 30% by weight of the spike. Second, the cumulative weight of insecticide and clay was maintained at a constant level. Therefore, any reduction in the quantity of insecticide within a fab ricated spike was balanced with a corresponding increase in filler content. Third, all spikes were prepared to include a single colorant (green, Ferro). It was later determined from the marketing studies that brown or red-brown could be more desirable colors to the consumer. However, the actual identity of the colorant is not presently perceived as important to the preliminary experimental determination of the relative release rates.
  • spikes were coated with cellulose acetate to yield either a one or two mil increase in diameter. Only spikes which had been coated to the former thickness were tested in order to determine relative release rates. The spikes having the larger coating were retained for possible future evaluations using the laboratory and/or bioassay techniques.
  • Table 21 contains a description of the eight formulations prepared for the release rate studies.
  • the PEO, Carbowax, insecticide formulation, clay and colorant were placed together in a 4-ounce paper cup and dry-mixed until qualitative homogeneity was apparent (approximately 15-25 seconds) using a wooden tongue depressor.
  • the mixture was then fed directly into the heating chamber of the Watson-StiIiman Injection Molder and maintained at a temperature of 86-92 C for five minutes.
  • a ram pressure of 900 psi was applied to force the flowable mixture into the preheated mold (60 C, approximately 10 minutes).
  • the mold was capable of producing six spikes which were each two inches in length and having an outside diameter of 0.195 inches.
  • Butvar B-76 Poly(vlnylMonsanto, St. Ethylacetate 50 Not Soluble - butyral) Louis, MO " 25 Soluble 2 Isopropyl alcohol 50 Not Soluble - " 25 Soluble 3
  • Vlnac B-15 Poly(vlnylAir Products, Ethylacetate 50 Gel - acetate) All entown, PA " 25 Viscous 1.5-2 10 good 1.5-2 Isopropyl alcohol 50 Not Soluble - " 25 Not Soluble -
  • Uncoated Spikes An initial attempt to determine the rate of release of insecticide from a spike was carried out using an uncoated spike containing Standak. Complete dissolution of the spike was apparent in water after 24 hours.
  • the coating could serve two functions. First, the coating could provide a safety buffer between the active ingredient residing on the surface of the solid formulation and the person handling the device. Second, the coating could slow the rate of release of insecticide from the fastiy degradable spike. The following sections describe the experiments designed to determine the release rate of the insecticide from coated spikes.
  • the initial trend for a fast release of insecticide from the spike is generally followed by a slower delivery of active ingredient.
  • the initial trend for a fast release of active ingredient provides sufficient systemic insect toxicant to a plant to cause a significant reduction in the size of any existing pest population.
  • the subsequent change in trend towards a slow release could, then, act as a maintenance dosage to ensure that re-infestation will not occur during a desirable period of effectiveness of 30-60 days.
  • dip-coated spikes prepared from a water-soluble, thermoplastic binder containing an inert filler and a wettable powder formulation of either Standak or Orthene can maintain their physical form for up to 25 days in a standard experimental situation. This is in comparison to the short, one to two day, lifespan of uncoated spikes. It is important to note that the coating remained nearly intact after both the binder and insecticide content had been exhausted. This can be attributed to the fact that cellulose acetate is not water soluble. However, it is biodegradable and the rate of dissappearance should be evident in a soil environment where microorganisms can act.
  • Figure 9 displays another important feature of the way in which the eventual effectiveness of the insecticide spike could be controlled by varying the loading of active ingredient in the initial formulation. Increasing the relative loading levels within coated spikes from 10 to 30% by weight does not apparently result in a corresponding change in the relative release rate.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Pest Control & Pesticides (AREA)
  • Plant Pathology (AREA)
  • Agronomy & Crop Science (AREA)
  • Engineering & Computer Science (AREA)
  • Dentistry (AREA)
  • Wood Science & Technology (AREA)
  • Zoology (AREA)
  • Environmental Sciences (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)

Abstract

Des produits biodegradables liberent, lorsqu'ils sont introduits dans la terre, des pesticides systemiques a une vitesse controlee pendant une periode de temps prolongee. Les compositions biodegradables peuvent etre formees en pointes qui peuvent etre enfoncees dans le sol sans causer de degats. Les produits consistent en un liant polymere solide hydrophile soluble dans l'eau et en un pesticide systemique. Des ingredients optionnels comprennent des plastifiants, des materiaux de remplissage, des colorants et un revetement. Les produits sont fabriques en melangeant les ingredients secs et en faconnant le melange resultant par moulage a injection par extrusion ou autre procede approprie pour obtenir des formes appropriees telles que des pointes. Dans une variante, le melange obtenu est moule par injection pour former des produits ayant des formes desirees. Les produits formes peuvent alors etre enrobes d'un revetement permeable a l'eau. Les produits sont introduits ou enfonces dans la terre au voisinage de la plante. L'humidite du sol penetre dans le (l'eventuel) revetement biodegradable de la matrice et commence a dissoudre la matrice et le pesticide contenu a l'interieur. Le pesticide est libere au depart rapidement puis il est libere de maniere commandee pendant une periode de temps prolongee. Le pesticide libere est absorbe par les racines de la plante, dans la seve, la rendant veneneuse aux insectes nuisibles. La vitesse initiale rapide de liberation a pour effet de tuer rapidement au moins une grande partie des insectes nuisibles se trouvant sur les plantes au voisinage du produit et la liberation ulterieure controlee tue les insectes nuisibles restants et empeche que les plantes ne soient infestees de nouveau.
EP19820901877 1981-04-29 1982-04-28 Produit de pesticide systemique et procedes de fabrication et d'utilisation de celui-ci. Withdrawn EP0077399A4 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US25866681A 1981-04-29 1981-04-29
US258666 1981-04-29
US37030182A 1982-04-22 1982-04-22
US370301 1982-04-22

Publications (2)

Publication Number Publication Date
EP0077399A1 true EP0077399A1 (fr) 1983-04-27
EP0077399A4 EP0077399A4 (fr) 1983-09-02

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Country Status (11)

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EP (1) EP0077399A4 (fr)
JP (1) JPS58500613A (fr)
BR (1) BR8207666A (fr)
ES (1) ES8305559A1 (fr)
GR (1) GR75995B (fr)
IT (1) IT8248304A0 (fr)
MA (1) MA19462A1 (fr)
NO (1) NO824358L (fr)
OA (1) OA07290A (fr)
PT (1) PT74824A (fr)
WO (1) WO1982003747A1 (fr)

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* Cited by examiner, † Cited by third party
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ZA86705B (en) * 1985-04-19 1986-09-24 Int Spike Controlled release insecticide
JP2731796B2 (ja) * 1988-05-09 1998-03-25 株式会社児玉商会 害虫防除施工法
EP1045885A1 (fr) * 1998-02-06 2000-10-25 Union Carbide Chemicals & Plastics Technology Corporation Compositions polymeres d'oxyde d'alkylene
GB9810861D0 (en) * 1998-05-20 1998-07-22 Zeneca Ltd Solid composition
AU2002366316A1 (en) * 2001-12-19 2003-06-30 Exosect Limited Pest control device comprising a degradable material incorporating a pest control material

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Also Published As

Publication number Publication date
OA07290A (en) 1984-08-31
ES511782A0 (es) 1983-04-16
BR8207666A (pt) 1983-03-29
ES8305559A1 (es) 1983-04-16
WO1982003747A1 (fr) 1982-11-11
NO824358L (no) 1982-12-23
PT74824A (en) 1982-05-01
JPS58500613A (ja) 1983-04-21
IT8248304A0 (it) 1982-04-29
GR75995B (fr) 1984-08-03
MA19462A1 (fr) 1982-12-31
EP0077399A4 (fr) 1983-09-02

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Inventor name: CORNABY, BARNEY W.