Pest control sheet.

, The présent invention relates to the field of pest control. Particularly, to a novel polymeric sheet and uses thereof in pest control in agriculture, horticulture and gardens.

Background of the Invention

The control of pests is a vast field which covers a plethora of methods, devices and compositions. The control of weeds via sheets which contain a herbicide are known in the art. U.S. Patent'No.5,181,952 discloses a herbicide-containing-geotextile which is used for preventing the entry of roots into soil. The geotextile can be mserted in the soil to form a barrier so that roots may not penetrate the banier, and thus, the soil beyond the barrier is protected from the intrusion of roots and subséquent damage which may resuit therefrom. The herbicide is distributed in various forms throughout the geotextile. U.S. Patent No. 5,575,112 discloses a similar fabric to that of USP 5,181,952 and use thereof for controlling root growth. Said fabric comprises an inorganic copper compound as a herbicide. USP 5,139,566 to Reemay Inc. describes a geotextile and use thereof, similar to the above-referenced publications. The sheets described in the prior art cannot be applied in agriculture as weed control sheets for protecting a field of crop. The manner in which the herbicide is dispersed throughout the sheets which are described in the prior art, is not suitable for said agricultural application. Applying said sheets would expose the crop to the herbicide which would resuit in damage to the crop and subséquent withering of the pLant.

Other methods of pest control in agricultural fïelds include pretreatment of the soil with , méthyl bromide. Méthyl bromide is a highly effective and controversial pest controlling agent. It is alleged to hâve hazardous impact on the environment, and thus will most • likely be ban for use in the future.

Furthermore, there are certain, crops which are highly sensitive to herbicides. For example cucurbitaceae (zucchini, cucumbers, melons, watermelons squash and the like) are very

-2012409 sensitive to herbicides. Thus, the only way for removing weeds from the a fîeld of cucurbitaceae is by manual means.

In view of the aforementioned there is a long felt need to develop a method and means for pest control which provides a solution to the aforementioned disadvatages. Further more there is a long felt need to develop a pesticide control sheet which can be effectively and safely applied for agricultural purposes.

It is therefore an objective of the présent invention to provide a pesticide control sheet which can be-used in agriculture.

It is another objective of the présent invention to provide a method for pest control in agriculture which provides highly effective pest control and is safe to the plant and crop.

A further objective of the présent invention is to provide a composition for preparing a pest control sheet.

It is yet another objective of the présent invention to provide a sheet and method for pest control that overcome the disadvantages of the known art.

Other objectives of the invention will become apparent as the description proceeds.

The term sheet is synonymous with film.

Sunamary of the Invention

The présent invention provîdes a sheet for pest control, wherein said sheet is of polymeric material and comprises at least two layers; a top layer and a bottom layer. The bottom layer contains a herbicide and optionally a pesticide selected from among insecticides and fongicides. The top layer is a protective layer to protect the plant parts, which can be harmed by the pesticide in the bottom layer, from coming in contact with tire bottom layer. Optionally, the top layer may contain an insecticide to protect the plant from insect

-3012.4 09 infestation and a fongicide to protect the plant from fongus attack. Said sheet may further optionally comprise an additional layer or layers which fonction as a bairier between the bottom layer and the top layer, hereinafter protective middle layer.

Further provided by the présent invention is a method for pest control in agriculture, horticulture and gardening, comprising covering the ground (soit) with the sheet of the présent invention. Hence, the bottom layer prevents the emergence of weeds and controls soi! borne pests. The top layer protects the sensitive plant parts from contacting the bottom layer. When the top layer contains an insecticide and/or fongicide, said layer 10 further proteets the plant from insect infestation.

Furthennore, the présent invention provides compositions comprising a polymer and a pesticide, hereinafter “master batch”, which are suitable for the préparation of polymeric sheets, and wherein the layers of the sheet of the présent invention are produced from said 15 master batch. The master batch may be in the form of a resin, wherein the pesticide is.

mixed into the resin, or in the form of pellets which contain the pesticide.

Throughout the description of the invention the term “pesticide” applies to .herbicides, fungicides and insecticides.

Description of the Drawings

Fig. I is a cross section of a particular embodiment of the sheet.

Fig. Π is a cross section of a crop field in which the-method of the présent invention has been applied.

Fig. ΙΠ is a schematic représentation of a process for preparing the sheet.

Detailed Description of a Preferred Embodiment of the Invention

The following description is illustrative of embodiments of the invention, with reference to the Figures. The following description is not to be construed as limiting, it being 30 understood that the skilled person may carry out many obvious variations to the invention.

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Throughout the description, percentage indicated are by weight.

According to an embodiment of the présent invention the sheet of the présent invention is of polymeric material which is suitable for use as a ground sheet. Said polymeric material selected from a group comprising homopolymers and copolymers of polyolefînes selected from a group comprising of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), ethylene vinyl acetate (EVA), ethylene methyl aciylate (EMA), dérivatives or mixtures and blends thereof. Other polymeric materiels can be used for the présent invention, as may be appreciated by the skilled artisan. The sheet is composed of-at least two layers of polymeric material wherein the bottom layer [Fig. 1,(1)] contains about 0.1% to 5% herbicide, and optionally 0.1% to 5% of one or more other pesticides, and the top layer (Fig.I,(2)] is a polymer layer which protects parts of the plants such as leaves and the shoot from contacting the bottom layer. Contact of the leaves or the shoot with the herbicide in the bottom layer would resuit in damage to the plant which subsequently could resuit in withering of the plant. The top layer may optionally contain a fongicide or insecticide, Control of weeds is provided in two manners; 1) weeds emerging from the ground contact the bottom layer and the herbicide in this layer and are thus eliminated 2) The herbicide is slowly released from the bottom layer and migrâtes into the soil, hence preventing the emergence of weeds from the soit The rate of release of the pesticide from the sheet is controlled so that by the end of the growing season most, and may be ail, of the pesticide has been released from the sheet. The rate of release of the pesticide from the sheet may be controlled by the amount and type of anti-block- fîller additives and type of polymer from which the sheet is prepared. Said additives described hereinafter.

According to a forther embodiment of the invention the bottom layer contains about 0.1% to 5% herbicide and about 0.1% to 5% insecticide and/or fongicide. Thus, the bottom layer controls weeds and exterminâtes soil dwelling insects which could be harmfol for the plant, and protects and controls fongus attack. According to the présent embodiment insect control is achieved by an insecticide which migrâtes from the bottom layer into the soil and/or via contact of the insect with the insècticide-containing bottom layer.

-5012409 _t. k* accordance to yet a further embodiment of the invention the top layer contains about

0.1% to 5% insecticide and/or fungicide. Hence, providing control of insects and disease » around the parts of the plant which are above the sheet. Insecte coming in contact with the insecticide in the top layer will accordingly be exterminated and the fongicide provides protection against fungi.

According to a further embodiment, the sheet of the présent invention may further comprise an additional layer or layers of polymeric film between the top and bottom 10 layer. Said profective middle layer being of a polymeric material which prevents the migration of herbicide from the bottom layer to the top layer and subsequently to the plant. Thus any migration of the herbicide or vapor thereof upwards is prevented, hence a “sealing” effect is obtained. The protective middle layer may be a polyamide, polyvinyly alcohol or any other polymeric material which provides said sealing effect.

Herbicides suitable for use in the présent invention are selected from a group comprising, but not limited to:

- Oxyfluorfen - 2-chloro-a,a,a-trifluoro-p-tolyl 3-ethoxy-4-nitrophenyl ether

Trifluralin — a,a,a-trifluoro-2,6-dinitro-N,N-dipropyI-p-toluidine

Benfluralin — N-butyl-N-ethyI-2,6-dinitro-4(trifIuoromethyI) benzenamine

Isopropalin — 4-isopropyl-2,6-dinitro-N,N-dipropylaniline

Oiyzalin - 3,5-dinitro-N⁴,N⁴ -dipropylsulfanilamide

Fluroxypyr — 4-amino-3,5-dichloro-6__LfLuoro-2-pyridyloxyacetic acid

Ethalfluralin — N-ethyl-a,a,a-trifluoro-N-(methylallyl)-2,6-dinitro-p-toluidine

Pendimethalin - N-(l-ethylpropyl)-2,6-dinitro-3,4-xylidine » Profluralin - N-(cyclopropylmethyl)- a,a,a-trifluoro-2,6-dinitro-N-propyl-p-toluidine

Diuron - 3 -(3,4-dichlorophenyl)-N,N-dimethylurea

Imazethapyr - (RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-inüdazolin-2-yl)nicotinic acid Imazaquin - (RS)-2-(4-isopropyl-4-methyl-5-oxo-2-imidazoIin-2-yl)quinoline-330 carboxylic acid

Glyphosate — N-(phosphonomethyl) glycine

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Simazine - 6-chloro-N,N’-diethyI-l,3,5-triazine-2,4-diamine ΤεΛπίτγη-Ν-(1₅1-άύηε^1ε^1)-Ν’-ε^1-6-(ωε^1ώΐο)-1,3,5-ίπΗζίηε-2,4-<ϋ3ΐηΐηε Metribuzin - 4-amino-6-tert-butyl-3-methyIthio-l ,2,4-triazin-5(4H)-one or sulfonyl urea herbicides selected from among (common names) triasulfuron, clorsulforon, tribenuron and rimsulforon.

Insecticides usefuî for the présent invention (noted according to the common names) are selected from among the following groups of insecticides comprising, but not limited to, the following insecticides: organophophorous insecticides: chlorpyrifos and diazinon; neonicotinoids: ' imidacloprid, acetamiprid, thiamethoxam; pyrethroid insecticdes: bifenthrin, lambda-cyhalothrin, tefluthrin and pennathrin. Further suitable insecticides are spinosad, indoxacarb, fipronil and insecticides of the group known as nematicides, such as cadusafos and fenamiphos.

Fungicides usefuî for the présent invention (noted according to the common names) are selected from among, but not limited to, a group of fungicides which are steroid déméthylation inhibitors (SDI). The group of SDI comprises hexaconazole, myclobutanil, propiconazole, triadimenol, tebuconazole, penconazole. Other usefuî fongicides are prochloraz, metalaxyl, dimethomorph, cymoxanil, propamocarb hydrochloride and fluazinam. Further fongicides usefol for the présent invention are of the group known as strobilurin type fongicides, such as: Azoxystrobin, Kresoxim-methyl, Trifloxystrobin, Metonimostrobin, Picoxystrobin, Pyraclostrobin, MA-20565 (development code of Mitsubishi)

According to a preferred embodiment, the sheet of the présent invention is transparent. This allows for the heating of the soil via the “green house effect”. This effect occurs when solar radiation pénétrâtes the sheet and is reflected from the soil. The reflected radiation in the infra-red range does not penetrate the sheet and is thus “trapped” between the sheet and the soil. This “trapped” radiation heats the soil. This is particularly important in cold countries of for crops that are grown during cold seasons.

) .

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The présent invention further provides a method for pest control. Said method may be applied in agriculture, horticulture or in garden maintenance. In agriculture and horticulture said method is applied as follows: subséquent to physically preparing the fîeld and soil for planting, e.g. plowing, fùmigating the soil and Iaying down of an irrigation System, the sheet is spread over the field so as to cover the soil [Fig. Π, (1)], and is then secured to the ground. The sheet [Fig. Π, (2),(3)] is then punctured at the spot where a seedling is intended to be planted so that a seedling [Fig. Π, (4)] may be inserted through the hole [Fig. II, (5)] and planted in the soil. The seedling is planted in such a manner that the roots are in the soil and the leaves are above the top layer in a manner that 10 they do not conte in contact with the bottom layer. Thus, the herbicide, and optionally the insecticide in the bottom layer, control weeds, and optionally insects, via contact of the weed or insect with the bottom layer or via slow release of the pesticides into the soil, hence controlling the emergence of weeds and exterminatmg insects in the soil. When the sheet contains a pesticide in the top layer, then pest control is maintained above the soil, 15 in the area of the plant. This may also help in protecting the fruit/vegetable itself. Said method can be applied in gardens in a similar manner as described above.

The method of the présent invention présents the following advantages:

1. The application of the sheet to the field is done before the plants are planted and is a single step application. Thus, there is no need to remove the sheet until after harvest time.

2. The sheet provides constant pest control throughout the entire growing season, without the need to reapply pesticides during the season.

3. The method provides a safe mode of pesticide application. The pesticides are released slowly directly into the ground or affixed to the sheet Hence the exposure of people working in the field is minimal. This is in comparison to other application methods which involve handling and mixing of toxic chemicals and spraying of these chemicals. The spraying créâtes a hazardous mist which may be harmful to the person working in the field and to the 30 environment.

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4. The pesticide release profile of the sheet is such that by the end of the season when the sheet may be collected from the field there is none, or minimal traces of pesticide in the sheet, which allows for the recycling of the polymeric sheet. This has its environmental advantages.

5. For crops which are sensitive to herbicides, the présent invention provides an effective substitute for methyl bromide which is allegedly harmfol to the environment and is often used for such crops.

6. The sheet further provides a green house effect.

In yet a further émbodiment of the présent invention the master batch comprises about 5% to 30% by weight pesticide, wherem the herbicide content in the master batch intended for the préparation of the bottom layer, contains about 5% to 30% herbicide and optionally 5% to 30% of insecticide and 5% to 30% of fongicide. According to an optional embodiment wherem the top layer comprises a fongicide and/or an insecticide, a 15 master batch intended for the préparation of the top layer comprises 5% to 30% of insecticide. Hereinafter a master batch without a pesticide is defined as “pre-mix”.

Accçrding to a particular embodiment of the invention the master batch is in the form polymeric pellets which contain a pesticide. According to a preferred embodiment of the 20 invention, the master batch for preparing the bottom layer (hereinafter “bottom master batch”) comprises polyethylene pellets containing about 5% to 30% oxyfluorfen in the pellet In yet a further embodiment, the bottom master batch comprises about 5% to 30% oxyfluorfen and about 5% to 30% insecticide selected from among diazinon, chloipyrifos and imidacloprid. The master batch for preparing the top layer, according to the 25 embodiment wherein the top layer comprises an insecticide, is defined as the top master batch and comprises about 5% to 30% insecticide selected from among diazinon, chloipyrifos and imidacloprid. The top master batch may be in the form polymeric pellets wherein the insecticide is dispersed throughout the pellet.

The master batch may be prepared during the manufacturing process of the sheet by directly adding the required amount of pesticide to the pre-mix in the

-9012409 polymer-sheet-preparing-apparatus which may be an extrader or any other ₍ polymer-sheet-manufacturing apparatus.

« The sheet of the présent invention may further be prepared by applying to a ready polymeric sheet which comprises a bottom and top layer, a pesticide. Thus, obtaining a sheet as described herein.

The pre-mix and master batches of the présent invention may further comprise additives that are intended for achieving the desired properties of the sheet. The group of additives 10 which are well known from the prior art comprises u.v. absorbents; anti-blocks which are based on amorphous and crystalline silicates; slip agents selected from among amides, oleamide, stearamide and dérivatives thereof; lubricants selected from among polyolefine waxes, PE waxes and PP waxes and métal stéarates; anti-oxidants. Other additives may be applied as may be appreciated by the skilled artisan.

Throughout the description, where herbicide, insecticide or fungicide is described in the invention, it also includes mixtures thereof.

The following description is for puiposes of illustration and is not to be construed as 20 limiting. The sheet of the présent invention can be produced from a pre-mix or a top master batch, and a bottom master batch according to a technique known by the skilled artisan as co-extrusion blown film technique. According to said technique, the bottom master batch and polymeric resin are fed to an extrader [Fig. HI,J1)], the are extruded under heat [Fig. ΙΠ, (2),(5)], while simultaneously, the top master batch or top pre-mix is 25 fed to a separate extrader together with polymeric resin [Fig. IH, (3)] and extruded under , heat [Fig. M, (4),(6)]. The final desired percentage of pesticide in each layer can be adjusted by controlling the amount of polymeric resin added to each mixture. Both • extruded mixtures are fed to the blowing tower [Fig. ΙΠ, (11)] wherein they are simultaneously blown into two films each blown through a separate die. The top master 30 batch or pre-mix is blown to fonn a balloon, hereinafter “outer balloon”, while simultaneously, the bottom master batch is also blown to from a balloon which is

-10012409 contained within the outer balloon. The dies through which the balloons are blown are arranged such that the inner die is set in the center of the outer die. The bottom layer of the sheet is formed through the inner die [Fig. Ht, (7)] and the top layer of the sheet is formed through the outer die [Fig. ΠΙ,(8)]. The films which form the balloon-within-a-balloon formation are pressed and flattened between rollers [Fig. ΙΠ, (9)] and rolled as a four layered sheet [Fig. ΙΠ, (10)]. The four layer pressed sheet is then eut and spread open to form the bi-layer sheet of the present invention. By cutting and spreading the four layer sheet, the inner two layers ofthe four layer sheet form the bottom layer of the sheet of the present invention, and the outer two layers of the four layer sheet form the top layer of the sheet of the present invention.

The foregoing technique is also suitable for preparing a sheet with more than. two layers. In such a case the co-extrusion is carried out with more than two master batches and/or pre-mix. Accordingly, a sheet with a protective middle layer may be produced by said technique.

Other polymer-sheet-forming techniques known in the art may be applied for the pmpose of preparing the sheet of the present invention.

While the method of the present invention may be broadly applied in the fields of agricultural and gardening, a particularly effective application of the method is for crops selected from among: cucurbitacea: melon, Zucchini, cucumber, watermelon, squash; solanaceae: tomato, pepper, eggplant; orchards and omamentals.

Examples

Example 1: Watermelon Crop

The sheet and method of the present invention hâve been applied to a watermelon crop. The experiments were conducted with three different concentrations of herbicide in the bottom layer. The results are presented in Table I.

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Table I

<td> Pesticide</td><td> % Pesticide</td><td> Development*</td><td> Weed contre</td>

<td> Oxyfluorfen</td><td> 0.5</td><td> 100</td><td> 100</td>

<td> Oxyfluorfen</td><td> 1</td><td> 100</td><td> 100</td>

<td> Oxyfluorfen</td><td> 2</td><td> 100</td><td> 100</td>

- weight % of pesticide in bottom layer ofsheet

- % of crop development in comparison to healthy crop on a scale of0-100,100 indicating a healthy crop. -% ofweed control on a scale of0-100, 100 indicating total prévention of weed émergence.

Example 2: Préparation of bottom master batch

The following is a description of the préparation of 100 kg master batch. 2.5 kg of a 10 composition of additives is prepared by mixing slip agents, anti-oxidants and lubricant in a weight ratio of about 2:2:6. 67.5 kg of EVA resin, 10 kg anti-block Apacet™ 10063 and 2.5 kg of the above additive composition are fed to the main feeding port of the extrader, thus forming a polymeric melt. Each component has a separate continuos-weight feeder. 20 kg oxyfluorfen is mixed with the polymeric melt in the center 15 of the extrader. The final polymeric melt obtained is fed through a perforated dise to foim “noodle like” polymeric strands which are slowly cooled and chopped and fed into a pelletizer/granulator.

While embodiments of the invention hâve been described by way of illustration, it will be 20 apparent that the invention may be carried out with many modifications, variations and adaptations, without departing from its spirit or exceeding the scope of the daims.