FR2735656A1 - PROTECTIVE BAG, HARVESTING, CONTAINING PYRETHROID - Google Patents

Abstract

The present invention describes the use of small amounts of bifenthrin or other pyrethroids in formulations of plastic or polymeric compositions, so as to obtain compositions resistant to attack by insects. The pyrethroid can be introduced individually into a masterbatch which can be used to prepare insect resistant plastic bags or films, which are useful in protecting crops.

Description

PROTECTIVE BAG, HARVESTING, CONTAINING A

PYRETHROID

  The present invention relates to crop protection bags and other plastic films which resist attack by pests. More particularly, this invention relates to crop protection bags which incorporate an effective amount of bifenthrin or other pyrethroid insecticide which protects crops from damage by insects. The practice of incorporating insecticides into plastics or polymers such as polyethylene (PE), poly (vinyl chloride) (PVC) and copolymers such as the ethylene / vinyl acetate copolymer is well known. For example, flea collars for dogs and ear tags for livestock repel insects as a result of the release of the insecticide from the plastic, and protect

  therefore the animal (US Patent No. 5,437,869).

  Among the types of insecticides which have been incorporated into specific plastics, there may be mentioned certain pyrethroids. Pyrethroids such as cypermethrin have been incorporated into PVC cable sheaths which insulate electrical wires (British Patent No. 1,538,222). In this case, the cable sheath itself is the structure to be protected because it is susceptible to attack by termites from the basement. British patent application N GB 2 276 171 A describes a masterbatch containing cypermethrin to make cable sheaths resistant to termites. Australian patent application N 62173/90 also indicates that another

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  pyrethroid, deltamethrin, is useful for protecting

electric cables.

  Banana bags are thin film bags of plastic that are used to cover the flowers and stems of banana plants. The bags can be used in many applications; they are known to improve the ripening and weight characteristics of bunches of bananas; opaque bags reduce sunlight on these plants located along roadsides or otherwise completely exposed to the sun; and insecticide-impregnated bags protect banana growth

  against insect attack.

  For protection against insects, banana bags impregnated with the insecticide chlorpyrifos (available from Dow Chemical Company) are commonly used. GB patent 1,480,125 describes the absorption of chlorpyrifos in normally solid thermoplastic polymer granules. The granules, in which the chlorpyrifos are uniformly incorporated, are suitable for the extrusion and preparation of thin plastic films which can be used for crop protection bags. The bag impregnated with chlorpyrifos is effective against a wide range of insects affecting bananas. This broad spectrum insecticidal activity, the fact that the fruit is protected without spraying with insecticides, and its low cost, are the main reasons why bags with chlorpyrifos are widely used. Despite these advantages, it is known that chlorpyrifos, because of its toxicity, poses a risk to the health of workers during the handling of the material and the extrusion process in order to

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  to produce the bags, and farmers handling

the bags.

  According to the present invention, it has now been found that pyrethroid insecticides can be used at extremely low concentrations in polymeric compositions used in plastic films for protecting crops from attack by insects. In a preferred embodiment, bifenthrin incorporated in banana bags is particularly useful for protecting bananas from attack by insects. The present invention describes the use of bifenthrin or other pyrethroid insecticides in formulations of plastic or polymeric compositions useful for producing crop protection bags and other plastic films resistant to insect attack. The pyrethroid is introduced individually into a masterbatch. The masterbatch can be used in the form of a concentrate which is in turn used to prepare the final composition. The final composition can be extruded or injected to obtain the desired plastic, as in the

  banana bag preparations listed below.

  Alternatively, the masterbatch can be used directly to prepare a final composition without going through a concentrate. The product formed from the final composition is an insect resistant plastic bag, comprising an insecticide effective amount of a pyrethroid impregnated in a polymer suitable for

  preparation of crop protection bags.

  The masterbatch of the present invention is prepared by mixing an appropriate pyrethroid with

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  polyethylene wax (PE). The polyethylene wax component is a polyethylene homopolymer having an average molecular weight of between about 1000 and about 4000, preferably between 2000 and about 3000 (available from Allied Signal Inc., Morristown, NJ, USA). A preferred PE wax is available from Allied Signal, Inc., under the

designation A-C 6A.

  Bifenthrin is a pyrethroid insecticide described in US Patent No. 4,328,505. Bifenthrin, which is available from FMC Corporation, Philadelphia, USA, is characterized by very high insecticidal power, good stability and relative safety when manipulation (Farm Chemicals Handbook '95, Meister Publishing Company, Willoughby, OH). Bifenthrin has the following chemical structure: O The relatively low toxicity to humans of bifenthrin, particularly in the amounts necessary to prevent insect damage, is a significant advantage when used as an insecticide in a plastic material. The concentration of bifenthrin in the masterbatch of the present invention can be between about 0.1 and 30% by weight. It has been found that the thermal stability of bifenthrin, which normally has a flash point below the temperature at which the polyethylene is extruded, is enhanced when incorporated into the masterbatch of

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  PE. Technical grade bifenthrin has a flash point of 165 C; however, bifenthrin in the proportion of% by weight in PE wax turns out to have a flash point of 213 C. In a preferred embodiment for the preparation of banana bags, a masterbatch is obtained by mixing the bifenthrin with due to% by weight in polyethylene wax. The resulting masterbatch has a melting point between about 110 and 125 C and, for bum bags, it is extruded at temperatures between 160 and 180 C. This masterbatch can be easily ground

  in powder so that its handling is easy.

  The bifenthrin / PE wax masterbatch can be mixed with one or more suitable polymers to form a concentrate. The polymers used in the concentrate composition of the present invention are polyethylene, ethylene / vinyl acetate copolymer, polypropylene or other polymers suitable in the preparation of

crop protection bags.

  For bum bags, the masterbatch is added to low density polyethylene to prepare the concentrate. The amount of masterbatch added to prepare the concentrate can be between about 1 and 30% by weight. As a result of mixing by extrusion, the concentrate is usually in the form of granules. In a preferred embodiment for obtaining a concentrate intended for preparing banana bags, a concentrate is obtained in the form of granules by mixing approximately 1 part of bifenthrin / PE wax masterbatch with approximately 4 to 19 parts of low density polyethylene. In this embodiment, the concentration of bifenthrin in the granules is approximately 1 to 4%

in weight.

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  The granular concentrate can be used to prepare bum bags or other plastic films having varying concentrations of bifenthrin uniformly incorporated throughout the plastic. To obtain the desired concentration of bifenthrin, the granules are added to an appropriate polymer, such as polyethylene, ethylene / vinyl acetate copolymer or polypropylene, and treated using procedures well known in the art. For bum bags, a suitable polymer is quality low density polyethylene for blown film. The bum bags of the present invention can be prepared from the above granules and polyethylene to obtain bags having a bifenthrin concentration of between about 0.01 and 1% by weight. For example, such a low concentration of bifenthrin in bum bags of about 0.05% by weight is very effective against many pests that attack bananas such as

  Colaspis, cantharides and scale insects.

  Plastic films impregnated with bifenthrin can also be used to protect other plants and structures from attack by insects. The banana bags described above, for example, can be used to prevent

  myrmics of attacking young eucalyptus plants.

  Among the other pests which can be controlled by the plastic films of the present invention, there may be mentioned: the Brazilian beetle (Epilachna varivestis Muls.), The beet moth (Spodoptera exigua), the caterpillar of the ears of corn ( Heliothis zea), the cabbage surveyor caterpillar (Trichoplusia ni), the armyworm caterpillar (Spodoptera eridania), the tobacco bud miner (Heliothis

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  virescens), milk bug (Oncopelius fasciatus), underground termites (Coptotermeo curvignathus and Reticulitermes spp.), pea aphid (Acyrthosiphon pisum), and red spider (Tetranychus urticae). In the present invention, other pyrethroids can be used than the example bifenthrin. The generally usable pyrethroids have the following properties: (1) photostability; (2) flash point greater than about 180 ° C in the masterbatch; (3) effective control of insects at very low concentrations; and (4) low or no dermal toxicity to humans. As examples of such pyrethroids which can be used in the present invention, mention may be made of

  permethrin (3- (2,2-dichloroethenyl) -2,2-

  3-phenoxybenzyl dimethylcyclopropanecarboxylate),

  cypermethrin (3- (2,2-dichloroethenyl) -2,2-

  -cyano-3- dimethylcyclopropanecarboxylate

  phenoxybenzyl), alpha-cypermethrin (racemate

  containing (1R) -cis-3- (2,2-dichloroethenyl) -2,2-

  (S) -a-cyano-3- dimethylcyclopropanecarboxylate

  phenoxybenzyl and (1S) -cis-3- (2,2-dichloroethenyl) -

  (R) - a-cyano-3- 2,2-dimethylcyclopropanecarboxylate

  phenoxybenzyl), zeta-cypermethrin (() -cis / trans-

3- (2,2-dichloroethenyl) -2,2-

  (S) -x-cyano-3- dimethylcyclopropanecarboxylate

  phenoxybenzyl), deltamethrin ((1R, 3R) -3- (2,2-

  dibromoethenyl) -2,2-dimethylcyclopropanecarboxylate (S) -a-cyano3-phenoxybenzyl), tralomethrin

  ((1R, 3R) -3- (1,1,2,2-tetrabromoethyl) -2,2-

  (S) -a-cyano-3- dimethylcyclopropanecarboxylate

  phenoxybenzyl), lambda-cyhalothrin (3- (2-chloro-

3,3,3-trifluoroprop-1-enyl) -2,2-

  x-cyano-3- dimethylcyclopropanecarboxylate

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  phenoxybenzyl), and cyfluthrin (3- (2,2-

  dichloroethenyl) -2,2-dimethylcyclopropanecarboxylate a-cyano-4-fluoro3-phenoxybenzyl).

Example

  We test the effectiveness of bifenthrin-impregnated bum bags to protect banana plants during their growth. The test is carried out in a place located in Costa Rica, heavily infested with Colaspis and mealybugs, which were the main animals

harmful during the test.

  Test Methods The bags are formulated and extruded by one of the following two methods: (a) physically mixing bifenthrin / PE wax granules with low density polyethylene resin, and extruding this mixture of the manner described above for forming the bum bags; and (b) the bifenthrin, dissolved in a liquid solvent, is introduced into the resin of

  polyethylene, then extruded to form the bags.

  For each of methods (a) and (b), bags are prepared having three concentrations of bifenthrin: 0.05, 0.1 and 0.3% by weight. For comparison, bags impregnated with chlorpyrifos having

1.0% by weight of active material.

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Treatments

Treatment number Description

  1 granules with 0.3% bifenthrin 2 granules with 0.1% bifenthrin 3 granules with 0.05% bifenthrin 4 liquid with 0.3% bifenthrin liquid with 0.1% bifenthrin 6 liquid with 0.05 % bifenthrin 7 no insecticide 8 1.0% chlorpyrifos Treatments 1 to 3 use bags formulated with method (a), and treatments 4 to 6 use bags formulated with method (b). In treatments 1 to 8, the bags contained only newly emerged buds, with no bracts. In treatment 9, the bags contained buds with

0 to 3 open bracts.

  Treatments (T1, T2, .., T8) are applied to the bunches on the banana tree, which are bagged in order (scheme 1 for T1, scheme 2 for T2, etc.). 20 diets are bagged per treatment, at the bud stage (immature stage), at the rate of two cycles per week. There are six treatments with bifenthrin bags: three treatments for which the bags are formulated with method (a) above (treatments 1 to 3), and three treatments for which bags are formulated with method (b ) above (treatments 4 to 6). Treatment 7 is a control, i.e. bags without insecticide. Treatment 8 is carried out with bags impregnated with chlorpyrifos. In all treatments 1

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  at 8, care is taken to bag only buds which

  have just emerged and no open bracts.

  Observations All stems are harvested after 14 weeks after the emergence of shoots. In the field of bananas, individual bananas are commonly called "fingers" and bunches are "hands". During the harvest, note the total number of fingers on all hands, and the number of fingers damaged by Colaspis, scale insects, cantharides and caterpillars. This determines the number of hands and fingers harvested and the corresponding percentages damaged

by insects.

  Results The damage by Colaspis to the hands is significant in the control without insecticide, and greatly reduced in all treatments with bags containing an insecticide. The lowest percentage of hands damaged by Colaspis is obtained with bags formulated with 0.1% by weight and 0.3% by weight of liquid bifenthrin (treatments 4 and 5). The other bags containing bifenthrin (T1 to T3 and T6) are at least as effective as the chlorpyrifos bag in preventing hand damage by Colaspis. Damage to mealybugs on the hands was significant in the control and in the treatment with chlorpyrifos sacks. All treatments with bags containing bifenthrin greatly reduce scale damage to the hands. The most effective treatments are those with bags formulated with 0.1% by weight and 0.3% by weight of

bifenthrin (T1, T2, T4 and T5).

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  The damage by cantharides to the hands is significant in the control treatment and greatly reduced in all treatments with bags containing an insecticide. The bag formulated with 0.3% bifenthrin (in granules) is the most effective. The other bags containing bifenthrin and the chlorpyrifos bag are equally effective in

  concerns damage by cantharides to the hands.

  Damage to the hands from caterpillars is minimal in control treatments. All treatments with bags containing insecticide prevent caterpillar damage and are about equally effective. The damage by Colaspis to the fingers is significant in the control without insecticide, and greatly reduced in all treatments with bags containing an insecticide. Treatment 1 using bags formulated with 0.3% by weight of bifenthrin (in granules) is not representative since almost all the damage in this treatment is due to one of the nineteen harvested regimes. The other bifenthrin bags (T2 to T6) are at least as effective as the chlorpyrifos bag in controlling damage

to the fingers by Colaspis.

  Damage by scale insects on the fingers was significant in the control and in the treatment with chlorpyrifos sacks. Treatments 1, 2, 4, and 6 greatly reduce the damage. Treatment 3, using bags containing 0.05% by weight of bifenthrin (granules), reduced the damage compared to the control and to the chlorpyrifos treatment, but to a lesser degree than the other bifenthrin treatments. Cantharid damage to the fingers is important in the control treatment and strongly

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  reduced in all treatments with bags containing insecticide. Treatments with bifenthrin bags are at least as effective as treatment with a chlorpyrifos bag in preventing cantharide damage to the fingers. Damage to the fingers from caterpillars is minimal in control treatments. All treatments with bags containing insecticide prevent damage by caterpillars and are approximately

also effective.

  The results above show that treatments with bags of bifenthrin allow excellent control of damage by Colaspis, cochineals and cantharides, and a comparison with treatments with bags impregnated with a higher concentration of chlorpyrifos is very favorable. It is obvious that various modifications can be made in the formulations and the applications of the present invention, without departing from the inventive concepts of the invention as they are.

defined in the claims.

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Claims (18)

  1. Insect-resistant plastic bag, characterized by an insecticide-effective amount of a pyrethroid impregnated in a polymer suitable for the preparation of crop protection bags. 2. Bag according to claim 1, characterized in that the polymer is chosen from the group consisting of polyethylene, the ethylene / acetate copolymer vinyl and polypropylene.   3. Bag according to claim 1, characterized in that the pyrethroid is chosen from the group consisting   by bifenthrin, cypermethrin, alpha-   cypermethrin, zeta-cypermethrin, deltamethrin, tralomethrin, lambda-cyhalothrin, cyfluthrin and permethrin.   4. Bag according to claim 1, characterized in that   that the pyrethroid is bifenthrin.   5. Masterbatch polymer useful for producing plastic bags resistant to insects, characterized by a quantity, effective from an insecticidal point of view, of a pyrethroid and of a polyethylene homopolymer wax having a molecular mass   average between about 1000 and about 4000.   6. Masterbatch according to claim 5, characterized in that the pyrethroid is bifenthrin. SR 12412 US / EE   7. Masterbatch according to claim 5, characterized in that the concentration of the pyrethroid   is between 0.1 and 30% by weight.   8. Masterbatch according to claim 5, characterized in that the concentration of the pyrethroid   is between 15 and 30% by weight.   9. Bag according to claim 1, characterized in that that the bag is a banana bag.   10. Bag according to claim 1, characterized in that the concentration of bifenthrin in the bag is   between 0.01 and 1.0% by weight.   11. Bag according to claim 1, characterized in that the concentration of bifenthrin is included between 0.05 and 0.3% by weight.   12. A method for protecting banana plants against damage by insects, characterized by the step of covering the banana plants to be protected by a bag according to the claim 9.   13. Method for preparing insect-resistant crop protection bags, characterized by the steps of (1) adding an insecticide-effective amount of pyrethroid to a polyethylene wax to form a masterbatch , (2) add the masterbatch to a low density polyethylene to form a mixture, (3) extrude the mixture from step (2) to form a concentrate, and (4) incorporate the concentrate into a quality polyethylene for film blown to form a thin film in SR 12412 US / EE   plastic material to be used to form   crop protection bags.   14. Method according to claim 13, characterized in that the pyrethroid is bifenthrin. 15. Method according to claim 14, characterized in that 15 to 30% by weight of bifenthrin is present in the masterbatch.   16. Method according to claim 14, characterized in that 0.01 to 1.0% by weight of bifenthrin is   present in the plastic film.   17. Method for controlling insects, characterized in that one covers the sites where one wishes to carry out this control with a bag according to the claim 1.   18. Method for controlling insects, characterized in that the sites where one wishes to carry out this control are covered with a bag according to the claim 9. SR 12412 US / EE