OA10340A

OA10340A - Pyrethroid-containing crop protection bags

Info

Publication number: OA10340A
Application number: OA60945A
Authority: OA
Inventors: Ruben Villasante; Bing Chen; Maryellen Lavin; Charles A Tennesen; Rafael D Feo
Original assignee: Fmc Corp
Priority date: 1995-06-21
Filing date: 1996-12-26
Publication date: 1997-09-19
Also published as: FR2735656A1; CR5354A; CN1148061A; BR9602852A; FR2735656B1; GB9612957D0; JPH09100203A; CO4750704A1; BR9602851A; GB2302542A; AU5608696A; JPH09132679A

Abstract

Small quantities of bifenthrin are used in formulations of plastic or polymeric compositions to provide compositions that are resistant to insect attack. The bifenthrin may be introduced as a component of a masterbatch which may be used to prepare PVC cable sheath. Other polymers specified are polyethylene e.g. polyethylene wax and ethylene-vinyl acetate copolymers.

Description

-1- 010340

PYRETHROID-CONTAINING CROP PROTECTION BAGS 5 Background of the Invention

This invention relates to crop protection bags and other plastic film which are résistant to attack by pests. More particularly, this inventionrelates to crop protection bags having incorporated therein an effectiveamount of bifenthrin or other pyrethroid insecticide which provides 10 protection for crops against insect damage.

The practice of incorporating insecticides into plastics or polymeric mafcerials such as polyethylene (PE), polyvinyl chloride (PVC), andcopolymers such as ethylene/vinyl acetate is well-known. For example, fleacollars for dogs and ear tags for cattle repel insects as a resuit of the release 15 of the insecticide from the plastic and thereby protect the animal (US PatentNo. 5,437,869).

Among the types of insecticides that hâve been incorporated intospécifie plastics are certain pyrethroids. Pyrethroids such as cypermethrinhâve been incorporated into PVC cable sheath that insulates electrical wires 20 (British Patent No. 1,538,222). Here, the cable sheath itself is the structure tobe protected as it is susceptible to attack by underground termites. BritishPatent Application Publication No. GB 2,276,171A describes a masterbatchcontaîning cypermethrin for making termite-resistant cable sheath. Anotherpyrethroid, deltamethrin, has also been reported to be useful in protecting 25 electcâc cable (Australian Application No. 62173/90).

Banana bags are thin film plastic bags that are used to cover the flower and stem of the banana plants. The bags may serve a variety ofpurposes: they are known to improve the bunch weight and ripeningcharacteristics of bananas; opague bags reduce sunlight for those plants -2- 010340 along roads or otherwise overly exposed to the sun; and insecticide-impregnated bags offer protection to growing bananas against insect attack.

In current use for protection against insects are banana bagsimpregnated with the insecticide chlorpyrifos (available from Dow ChemicalCompany). UK Patent No. 1,480,125 describes the absorption of chlorpyrifosinto normally solid thermoplastic polymer pellets. The pellets, withchlorpyrifos uniformly incorporated therein, are suitable for extrusion andthe préparation of thin plastic films that may be used for crop protectionbags. The chlorpyrifos-impregnated bag is effective against a wide range ofinsects affecting banana fruit. This broad spectrum of insecticide activity,the fact that the fruit is protected without the spraying of insecticides, and itslow cost are major reasons why the chlorpyrifos bag has achievedwidespread use. Despite these advantages it is known that chlorpyrifos, dueto its toxicity, présents a safety risk to workers during the material handlingand extrusion process to make the bags and to farm workers handling thebags.

Surmnary of the Invention

In accordance with the présent invention, it has now been found thatpyrethroid insecticides can be effectively employed at extremely lowconcentrations in polymeric compositions used in plastic film for theprotection of crops against attack by insects. In a preferred embodiment,bifenthrin incorporated in banana bags is particularly useful in theprotection of bananas against insect attack.

Detailed Description of the Invention

The présent invention describes the use of bifenthrin and otherpyrethroid insecticides in formulations of plastic or polymeric compositionsuseful for making crop protection bags and other plastic film that arerésistant to insect attack. The pyrethroid is introduced as a component of amasfcerbafcch. The masterbatch may be used to form a concentrate which in -3- 010340 tum is used to préparé the final composition. This final composition may beextruded or injected to obtain the desired plastic, as in the banana bagpréparations shown below. Altematively, the masterbatch may be useddirectly to préparé a final composition without the intermediacy of aconcentrate. The formed product from the final composition is an insect-resistant plastic bag comprising an insecticidally effective amount of apyrethroid impregnated in a polymer suitable for preparing crop protectionbags.

The masterbatch of the présent invention is prepared by mixing asuitable pyrethroid with polyethylene (PE) wax. The PE wax component is apolyethylene homopolymer having an average molecular weight range ofbetween about 1000 and about 4000, preferably between 2000 and about 3000(available from Allied Signal Inc., Morristown, NJ, USA). A preferred PEwax is available from Allied Signal, Inc. under the name A-C 6A.

Bifenthrin is a pyrethroid insecticide described in US Patent No.4328,505. Available from FMC Corporation, Philadelphia, PA, USA,bifenthrin is characterized as having very high insecticidal potency, goodstability and as being relatively safe to handle (Farm Chemicals Handbook'95, Meister Publishing Company, Willoughby, OH). Bifenthrin has thefollowing Chemical structure:

The relatively low human toxicity of bifenthrin, especially in relationto the amount necessary to prevent insect damage, is a significant benefit inusing it as an insecticide in plastic.

The concentration of bifenthrin in the masterbatch of the présentinvention may range from about 0.1 to 30 wt %. It has been found that the -4- 010340 thermal stability of bifenthrin, which normally has a lower flash point thanthe température at which polyethylene is extruded, is enhanced when it isincorporated in the PE wax masterbatch. Technical grade bifenthrin has aflash point of 165 °C; however, bifenthrin as a 20 wt% component in PE waxwas found to hâve a flash point of 213 °C. In a preferred embodiment forpreparing banana bags, a masterbatch is obtained by mixing about 20 wt%bifenthrin in polyethylene wax. The resulting masterbatch has a meltingpoint of about 110 to 125 °C and, for banana bags, is extruded attempératures between 160 and 180 eC. This masterbatch may be readilyground into a powder for easy handling.

The bifenthrin/PE wax masterbatch may be mixed with one or morepolymers suitable to form a concentrate. The polymers employed in theconcentrate composition of the présent invention are polyethylene,ethylene/vinyl acetate copolymer, polypropylene or other polymers suitablein preparing crop protection bags.

For banana bags, the masterbatch is added to low densitypolyethylene to préparé the concentrate. The amount of masterbatch addedto préparé the concentrate may range from about 1 to 30 wt.%. As a resuit ofextrusion compounding, the concentrate is typically provided in the form ofpéllets. In a preferred embodiment to obtain a concentrate for preparingbanana bags, a concentrate in pellet form is obtained by mixing about 1 partbifenthrin/PE wax masterbatch with about 4 to 19 parts low densitypolyethylene. In this embodiment, the bifenthrin concentration in the pelletis about 1-4% by weight.

The pellet concentrate may be used to préparé banana bags or otherplastic films having various concentrations of bifenthrin uniformlyincorporated throughout the plastic. To achieve the desired concentration ofbifenthrin, the pellets are added to an appropriate polymer, such aspolyethylene, ethylene/vinyl acetate copolymer, or polypropylene, and -5- 010340 processed using procedures well-known in the art. For banana bags, anappropriate polymer is blown film grade low density polyethylene. Thebanana bags of the présent invention may be prepared from the abovepellets and the polye hylene to provide bags having bifenthrin 5 concentrations ranging from about 0.01 to 1.0 wt.%. For example, a bifenthrin concentration in banana bags as low as about 0.05 wt. % is veryeffective against a variety of pests that attack bananas such as ,Colaspissoldier fly, and scale insects.

Bifenthrin-impregnated plastic films may also be used to protect10 other plants and structures from insect attack. The banana bags described above, for example, may be used to prevent leafcutter ants from attackingyoung eucalyptus trees. Among the other pests which may be controlled bythe plastic films of the présent invention are: Mexican bean beetle (Epilachnavarivestis Muls.), beet armyworm (Spodoptera exigua), corn earworm (Heliothis 15 zea), cabbage looper (Trichoplusia ni), southem armyworm (Spodoptera eridania), tobacco budworm (Heliothis virescens), milkweed bug (Oncopeliusfasciatus), subterranean termites, (Coptotermeo curuignathus and Reticulitermesspp.), pea aphid (Acyrthosiphon pisum), and two-spotted mites (Tetranychusurticae). 20 As exemplified with bifenthrin, other pyrethroids may be used in the présent invention. Pyrethroids that are generally suitable hâve the followingpropertîes: (1) photostability; (2) a flashpoint greater than about 180 °C whenmixed in the masterbatch; (3) effectiveness in controlling insects at very lowconcentrations; and (4) very low or no dermal toxicity to humans. Examples 25 ai such pyrethroids that may be used in the présent invention include pennethrin (3-phenoxybenzyl 3-(2,2-dichloroethenyl)-2,2- dimethylcyclopropanecarboxylate), cypermethrin (a-cyano-3- phenoxybenzyl 3-(2,2-dichloroethenyl)-2,2- dSmethylcyclopropanecarboxylate), alpha-cypermethrin (a racemate -6- containing (S)-a-cyano-3-phenoxybenzyl (lR)-cis-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate and (R)-a-cyano-3-phenoxybenzyl (1S)-cis-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropane-carboxylate), zeta-cypermethrin ((S)- a-cyano-3-phenoxybenzyl (±)-cis/trans 3-(2,2- 5 dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate), deltamethrin ((S)-a-cyano-3-phenoxybenzyl (lR,3R)-3-(2,2-dibromoethenyl)-2,2-dimethvlcyclopropane-carboxylate), tralomethrin ((S)-a-cyano-3-phenoxvbenzyl (lR,3R)-3-(l,l,2,2-tetrabromoethyl)-2,2-dimethvlcyclopropanecarboxylate), lambda cyhalothrin (a-cyano-3- 10 phenoxybenzyl 3-(2-chloro-3,3,3-trifluoroprop-l-enyl)-2,2- dimethylcyclopropanecarboxylate), cyfluthrin (a-cyano-4-fluoro-3-phenoxybenzyl 3-(2,2-dichlôroethenyl)-2,2- dimethylcyclopropanecarboxylate), fenpropathrin (a-cyano-3-phenoxybenzyl-2,2,3,3-tetramethyl-cyclopropanecarboxylate), fenvalerate 15 (a-cyano-3-phenoxybenzyl-2-(4-chlorophenyl)-3-methylbutyrate), andfluvalinate (a-cyano-3-phenoxybenzyl N-(2-chloro-4-triftuoromethyl)phenyl-D-valinate).

Example

Bifenthrin-impregnated banana bags were tested for their efficacy in 20 protecting banana plants during growth. The trial was conducted in an areain Costa Rica heavily infested with Colaspis and scale insects, which were theprincipal pests at the time of testing.

Test Methods

The bags were formulated and extruded by either of two Methods: (a) 25 bifentthrin/PE wax pellets were physically mixed with low density polyethylene resin and this mixture was extruded in the manner discussed above to form the banana bags, and (b) bifenthrin was introduced in a liquid solvent to the polyethylene resin, which was then extruded to form the bags.

For etach of the methods (a) and (b), bags were prepared having three -7- concentrations of bifenthrin: 0.05,0.1 and 0.3 wt.%. Chlorpyrifos-impreganted bags having 1.0 wt.% active ingrédient were tested forcomparison. -8- 010340

Treatments

Treatment Number Description 1 Bifenthrin 0.3% pellets 2 Bifenthrin 0.1% pellets 3 Bifenthrin 0.05% pellets 4 Bifenthrin 0.3% liquid 5 Bifenthrin 0.1% liquid 6 Bifenthrin 0.05% liquid 7 No insecticide 8 Chlorpyrifos 1.0% a Treatments 1-3 used bags formulated by method (a) andtreatments 4-6 used bags formulated by method (b). Intreatments 1-8 only buds that had just emerged without anybracts open were bagged. In treatment 9 buds were baggedbetween 0-3 bracts open.

Stems on the banana plant were assigned to treatments (Tl, T2,, T8) and bagged in consecutive order (stem 1 was Tl, stem 2 was T2, etc.).Twenty stems were bagged per treatment, in the bud stage (embolseprematuro), in two cycles per week. There were six treatments withbifenthrin bags: three where the bags were formulated using Method (a)above (Treatments 1-3) and three where the bags were formulated usingMethod (b) above (Treatments 4-6). Treatment 7 was a control; i.e., bagswithout insecticide. Treatments 8 was performed with chlorpyrifos-impregnated bags. In ail Treatments 1-8 care was taken to bag only budsthat had just emerged and were without any bracts open. -9- 010340

Observations

Ail stems were harvested at 14 weeks after the emergence of shoots.

In the banana field, individual bananas are commonly referred to as 5 "fingers" and bunches of bananas as "hands." At harvest time the totalnumber of fingers ail hands, and the number of fingers with blemishes dueto Colaspis, scale, soldier fly, and Caterpillar were recorded. The number ofhands and fingers harvested and corresponding percentages that had insectdamage were thus determined. 10 Results

Colaspis damage to the hands was substantial in the control where noinsecticide was used and greatly reduced in ail the treatments withinsecticide-containing bags. The lowest percentage of hands damaged byColaspis occurred with the bags formulated with 0.1 wt.% and 0.3 wt.% 15 liquid bifenthrin (Treatments 4 and 5). The other bags containing bifenthrin (ΊΊ-3 and 6) were at least as effective as the chlorpyrifos bag with respect topreventing Colaspis damage to the hands.

Scale damage to the hands was significant in the control and in thetreatments with chlorpyrifos bags. Ail of the treatments with bags 20 containing bifenthrin greatly reduced scale damage to the hands. The mosteffective treatments were with the bags formulated with 0.1 wt.% and 0.3wt.% bifenthrin (Tl, 2,4, and 5).

Soldier fly damage to the hands was substantial in the controltreafcment and greatly reduced in ail the treatments with insecticide- 25 containing bags. The bag formulated with 0.3 wt.% bifenthrin (pellets) wasthe most effective. The other bifenthrin-containing bags and the chlorpyrifosbag were about equally effective with respect to soldier fly damage to thehands. -10- 010340

Caterpillar damage to the hands was minimal in the controltreatments. Ail of the treatments with insecticide-containing bags preventedCaterpillar damage and were about equally effective.

Colaspis damage to the fingers was substantial in the control where noinsecticide was used and greatly reduced in ail the treatments withinsecticide-containing bags. Treatment 1 using bags formulated with 0.3wt.% bifenthrin (pellets) appeared as an outlier since almost ail of thedamage in this treatment was due to one of the nineteen stems harvested.The other bifenthrin bags (T2-6) were at least as effective as the chlorpyrifosbag in controlling Colaspis damage to the fingers.

Scale damage to the fingers was significant in the control and in thetreatments with chlorpyrifos bags. Treatments 1, 2,4,5, and 6 greatlyreduced scale damage. Treatment 3 using bags containing 0.05 wt.%bifenthrin (pellets) reduced scale damage relative to the control andchlorpyrifos treatment, but to a lesser extent than the other bifenthrintreatments.

Soldier fly damage to the fingers was substantial in the controltreatment and greatly reduced in ail the treatments with insecticide-containing bags. The treatment with bifenthrin bags were at least aseffective as the treatment with the chlorpyrifos bag in preventing soldier flydamage to the fingers.

Caterpillar damage to the fingers was minimal in the controltreatments. Ail of the treatments with insecticide-containing bags preventedCaterpillar damage and were about equally effective.

The above résulte show that treatments with bifenthrin bags provideexcellent control of Colaspis, scale and soldier fly damage and compare veryfavorably to treatments with bags impregnated with a higher concentrationof chlorpyrifos. -11- 010340

It is apparent that various modifications may be made in theformulations and application of the présent invention without departingfrom the inventive concepts herein, as defined in the daims.

Claims

1. An insect-resistant plastic bag comprising an insecticidally effectiveamount of a pyrethroid impregnated in a polymer suitable for preparingcrop protection bags.

2. A bag of claim 1 wherein the polymer is selected from the groupconsisting of polyethylene, ethylene/vinyl acetate copolymer, andpolypropylene.

3. A bag of claim 1 wherein the pyrethroid is selected from the groupconsisting of bifenthrin, cypermethrin, alpha-cypermethrin, zeta-cypermethrin, deltamethrin, tralomethrin, lambda cyhalothrin,cyfluthrin permethrin, fenvalerate, fenpropathrin and fluvalinate.

4. A bag of claim 1 wherein the pyrethroid is bifenthrin.

5. A polymer masterbatch useful for making insect-resistant plastic bagscomprising an insecticidally effective amount of pyrethroid and apolyethylene wax homopolymer having an average molecular weight inthe range between about 1000 and about 4000.

6. A masterbatch of claim 5 wherein the pyrethroid is bifenthrin.

7. A masterbatch of claim 5 wherein the pyrethroid concentration is about0.1 to 30 wt.%.

8. A masterbatch of claim 5 wherein the pyrethroid concentration isbetween about 15 and 30 wt.%.

9. A bag of claim 1 wherein the bag is a banana bag.

10. A bag of claim 1 wherein the concentration of bifenthrin in the bag isabout 0.01 to 1.0 wt.%.

11. A bag of claim 1 wherein the concentration of bifenthrin is about 0.05 to03 wt.%.

12. A method for protecting banana plants from insect damage whichcomprises dre step of covering the banana plants to be protected with abag of claim 9. -13- 010340

-12- 010340 CLAIMS:

13. A method for preparing insect-resistant crop protection bags whichcomprises the steps of 1) adding an insecticidally effective amount ofpyrethroid to polyethylene wax to form a masterbatch, (2) adding themasterbatch to low density polyethylene to form a mixture, (3) 5 extruding the mixture of step 2 to form a concentrate, and (4) processing the concentrate with blown film grade polyethylene to form a thinplastic film to be used to make crop protection bags.

14. A method of claim 13 wherein the pyrethroid is bifenthrin.

15. A method of claim 14 wherein about 15 to 30 wt.% bifenthrin is présent 10 in the masterbatch.

16. A method of claim 14 wherein about 0.01 to 1.0 wt.% bifenthrin inprésent in the plastic film.

17. A method for insect control which comprises covering the situs wherecontrol is desired with a bag of claim 1. 15

18. A method for insect control which comprises covering the situs where control is desired with a bag of claim 9.