FR2759249A1 - Solid insecticidal composition effective against termites - Google Patents

Abstract

Novel solid compositions (A) comprise a water-insoluble cellulose derivative (I) and at least one 1-aryl pyrazole (II). Preferably (I) is cellulose acetate and (II) is fipronil.

Description

Device for the protection of rice against harmful species
The subject of the present invention is a fibrous sheet for the protection of rice, in particular against harmful species, the sowing boxes comprising it as well as a method of protecting rice using said boxes.

 Sowing boxes, also known in English as "seeding box" or "nursery box" are commonly used by rice farmers to obtain, after sowing, rice seedlings which are then conveniently transplanted (or transplanted) into submerged rice fields, generally by mechanical means.

 It is very desirable to apply one or more agrochemicals to the rice seedlings, when these are in the sowing boxes, in particular to avoid a subsequent treatment in submerged paddy fields, for which a greater quantity of products is generally necessary, and thus better respect the aquatic environment.

 Agrochemical is understood to mean any product which makes it possible to better ensure the development of grains and rice plants, whether it is a growth regulator, or a pesticide, such as nematicide, acaricide, moluscicide, fungicide or insecticide.

 A conventional technique thus consists in applying the pesticide in the form of granules on the rice seedlings, in the seed boxes, between 1 and 3 days before transplanting. This technique however requires a very important work of the rice cultivator, who must treat very quickly a large number of seedling boxes (up to 100). It also has the disadvantage that it is difficult to apply a precise quantity of agrochemical product, and uniformly on the box, especially for active pesticides at low doses, which can lead to a lack of regularity in the control of the harmful species and therefore a lack of effectiveness.

 Japanese patent application JP 01-019002 has proposed to remedy these drawbacks by placing in the nursery box, between 2 layers of soil (a lower layer and an upper layer) a sheet of a paper-type material which is soluble in water. water, and has previously been impregnated or coated with pesticide, and on which the rice grains are sown. The solubility in water of this leaf allows the rapid dispersion in the soil of the agrochemical product, and avoids, thanks to watering, any problem of rooting of the seedling.

 Such a problem generally results from the difficulty of the roots from the seeds to pass through paper, especially paper that is not soluble in water. The growth of the roots then results in lifting the seed above the upper soil layer of the seedling box, which is likely to harm its germination and the development of the later seedling. Such a phenomenon is qualified in English as "root up".

 The paper type sheet described in JP 01-019002, however, presents risks of exposure to the agrochemical product not only for the people who carry out its manufacture, but also for the farmers who handle them in large numbers, due to the presence of generally, but not exclusively, produced in the form of crystals, between the fibers and / or on the surface of the fibers. It also has the drawback of rapidly dispersing the agrochemical product in the sowing box.

 An object of the present invention is to avoid rice farmers any risk of exposure, in particular by skin contact, with an agrochemical product.

 Another object of the present invention is to provide rice growers with a support in the form of a tablecloth, comprising an agrochemical product and allowing, after introduction into the nursery box at the time of sowing, the delayed release of the agrochemical product into the sowing box. , and, the continuation of this release after transplanting into the rice field.

 Another object of the present invention is to provide rice growers with a simple, precise and convenient means of applying an agrochemical product when sowing rice in the nursery box, and offering substantially the same duration of protection of the rice in the rice field only when the said product is applied just before transplanting the seedlings.

 Another object of the present invention is to provide rice growers with a support in the form of a tablecloth comprising an agrochemical product, for introduction into a sowing box, and not causing root-up during germination of the seeds.

 Another object of the present invention is to allow rice growers an agrochemical treatment in a seedling box requiring less work.

 Another object of the present invention is to provide rice growers with a support making it possible to apply an insecticide during sowing in the "nursery box", said insecticide still protecting the rice after transplanting.

 Another object of the present invention is to provide rice growers with a support making it possible to apply an agrochemical product during sowing in the "nursery box", said support forming by interpenetration with the roots of the seedlings a mat which can be cut by mechanical means used for transplantation.

 Another object of the present invention is to provide rice growers with a support making it possible to apply an agrochemical product during sowing in the "nursery box", said support gradually disappearing after transplanting into the rice field.

 It has now been found that these objects can be achieved in whole or in part by means of the web according to the present invention.

 The subject of the present invention is therefore a sheet having a weight per unit area of between 5 and 100 g / m2, preferably between 10 and 70 g / m2, and comprising fibers of a polymer insoluble in water, said fibers fibers comprising an effective and homogeneously distributed amount in the fiber of at least one agrochemical product.

 The sheet according to the invention can be woven or non-woven. According to a preferred variant of the invention, the sheet is non-woven.

 Said tablecloth is very simply placed by the rice cultivator in a sowing box. For this, it suffices to place it on a first layer of soil, generally between 1 and 5 cm in height. The rice grains are sown on the tablecloth, and the whole is covered with a second layer of soil, generally between 0.5 and 2 cm in height. The sowing box is placed in conditions favoring the germination of seeds: after 3 days, the percentage of root up observed is advantageously less than 15%, and preferably less than 10%. Such a rate is considered by the rice farmer to be perfectly acceptable. The term “root-up percentage” is understood to mean the number of seeds having given rise to the root-up phenomenon described above divided by the total number of seeds sown.

 The sheets according to the invention are advantageously free of agrochemical product between the fibers and on the surface of the fibers, so that they can thus be handled in large numbers easily and quickly, and without any risk of skin contact with the agrochemical product for the farmer. This sheet gives rise to a carpet resulting from its interpenetration with the roots and / or rootlets resulting from the germination of the seeds and the development of the seedlings. Said carpet can be easily cut by the machines generally used for transplanting in rice fields. After this same transplanting, the release of the agrochemical product into the rice field makes it possible to maintain a substantially effective control of the species harmful to rice, whether it be in particular an insect or a phytopathogenic fungus.

 According to a preferred variant of the invention, the fibers of the sheet are made of a substantially biodegradable polymer. The term "biodegradable" means the ability of the polymer used to decompose or degrade under the action of agents present in the environment such as ultraviolet rays, heat, air, microorganisms. A material is advantageously used, the biodegradability rate of which is greater than 60%, preferably 95% after 6 months.

These percentages are percentages by weight / weight, it is the same for any other percentage given in the present text, in the absence of contrary indication.

The rate of biodegradability is defined according to the ASTM 12520991 method, described in the "Annual Book of ASTM Standards" published by the American
Society for Testing and Materials, 1991 edition. This method is based on the exposure of the polymer to microorganisms coming from sludges from a municipal wastewater treatment plant, and the determination of the quantity of carbon dioxide formed, at the end of a fixed period of time. More specifically, the supernatant liquid resulting from the sedimentation of a suspension of said sludge, and containing between 106 and 20 × 10 6 microorganisms per ml, is used as inoculum. After adding to the said liquid a determined weight of a sheet sample according to the invention, and stirring, CO2-free air is introduced into the solution, bubble to bubble, at a rate of 50 to 100 ml / min. The amount of CO2 produced is measured. The rate of biodegradability (expressed in%), at a given time, is obtained by dividing the weight of carbon corresponding to the cumulative weight of CO2 produced, by the weight of carbon initially present in the sample analyzed.

 According to a preferred variant of the invention, the fibers used have substantially no pores, and the agrochemical product is therefore not located in pores, but is mixed with the solid material of the fiber in the form of a solid solution. , in other words of a molecular dispersion. By the expression "having substantially no pores" is meant to mean that the fibers have a pore diameter of less than 10 nanometers, preferably less than 1 nanometer. Such a characteristic can in particular be observed by means of a scanning electron microscope.

 The agrochemical distributed in the fibers may be soluble or insoluble in water, preferably insoluble in water. The term “water-insoluble agrochemical” is understood to mean a product whose solubility is less than 50 ppm, preferably less than 10 ppm.

 According to a preferred variant of the invention, this same agrochemical product can be an insecticide or a fungicide.

Among the insecticides, mention may in particular be made of vamidothion, imidacloprid, benfuracarb, carbosulfan, cartap, furathiocarb, pymetrozine, nitenpyram, acetamiprid still known by the code NI25, as well as l- arylpyrazole of formula (I):

in which:
R1 is a halogen atom or a CN or methyl group;
R2 is S (O), R3 or 4,5-dicyanoimidazol-2-yl or haloalkyl;
R3 is alkyl or haloalkyl;
R4 represents a hydrogen or halogen atom; or a radical NR5R6, S (O), R7, C (O) R7 or C (O) O-R7, alkyl, haloalkyl or OR8 or a radical N = C (R9) (R10)
R5 and R6 independently represent the hydrogen atom or an alkyl, haloalkyl, C (O) alkyl, S (O) rCF3 radical; or R5 and R6 may together form a divalent alkylene radical which may be interrupted by one or two divalent heteroatoms, such as oxygen or sulfur
R7 represents an alkyl or haloalkyl radical
R8 represents an alkyl, haloalkyl radical or a hydrogen atom
Rg represents an alkyl radical or a hydrogen atom;
R10 represents a phenyl or heteroaryl group optionally substituted by one or more halogen atoms or groups such as OH, -O-alkyl, -S-alkyl, cyano, or alkyl;
X represents a trivalent nitrogen atom or a C-R12 radical, the other three valences of the carbon atom being part of the aromatic ring;
Ru let R12 represent, independently of one another, a hydrogen or halogen atom and optionally CN or NO2;
R13 represents a halogen atom or a haloalkyl, haloalkoxy group,
S (O) qCF3 or SF5;
m, n, q, r represent, independently of one another, an integer equal to 0.1 or 2;
provided that, when R1 is methyl, then either R3 is haloalkyl,
R4 is NH2, R1 is Cl, R13 is CF3, and X is N; or R2 is 4,5dicyanoimidazol 2-yl, R4 is Cl, R11 is Cl, R13 is CF3, and X is = C-Cl.

 The alkyl radicals of the definition of formula (I) generally contain from 1 to 6 carbon atoms. The ring formed by the divalent alkylene radical representing R5 and R6 as well as by the nitrogen atom to which R5 and R6 are attached, is generally a 5, 6 or 7-membered ring.

 Among the fungicides, mention may also be made in particular of iprodione, fosetyl-Al, bromuconazole, (4-S) 4-methyl-2-methylthio-4-phenyl-1phenylamino-2-imidazoline-5-one, 4 -chloro-3- (3,5-dichlorophenyl) 1Hpyrazole, hymexazol, metalaxyl, methasulfocarb, chlorothalonil, benomyl, tolclofos-methyl, probenazole, isoprothiolane, tricyclazole, azoxystrobin also called HERE At 5504, furametpyr, thifluzamide, SSF126 also called (E) -2- (Methoxyimino) -N-methyl-2- (2-phenoxyphenyl) acetamide.

These insecticides or fungicides are mostly known and described in the Pesticide Manual (10th edition) edited by Clive Tomlin and published by the British
Crop Protection Council in 1994. Acetamiprid or NI-25 is described in at least one of the international applications WO 91/04965 or WO 93/24004. (4-S) 4methyl-2-methylthio-4-phenyl-1-phenylamino-2-imidazoline-5 -one is prepared according to a process described in application EP 0629616. 4-chloro-3- (3,5dichlorophenyl ) lH-pyrazole is described in the international patent application
WO 93/22287. The azoxystrobin or ICI A 5504 is methyl- (E) -2- (2- [6- (2-cyanophenoxy) pyrimidin-4-yloxy] phenyl} -3-methoxyacrylate which is described in international application WO 9208703. Furametpyr is 1H-Pyrazole-4carboxamide, 5-chloro-N- (1,3-dihydro-1,1,3-trimethyl-4-isobenzofuranyl) - 1,3dimethyl, described in particular in European patent application EP 315502 . The
SSF-126 is described in European patent application EP 398692.

 The preparation of compounds of formula (I) can be carried out according to one or other of the methods described in patent applications WO 87/3781, 93/6089, 94/21606 or European patent 295117, or any other method relating to the skill of a person skilled in the art of chemical synthesis.

 According to a preferred variant of the invention, the agrochemical is a 1-arylpyrazole of formula (I). The compounds of formula (I) are particularly advantageous for combating various rice parasitic insects and nematodes. The tablecloth according to the invention comprising at least one compound of formula (I) is particularly advantageous since it makes it possible to fight against said insects and nematodes attacking or liable to attack rice seedlings or seedlings as well in seed trays, as for a certain period after transplanting in submerged rice fields of up to 2 months, preferably 1 month.

 A preferred class of compounds of formula (I) consists of the compounds such that R1 is CN, and / or R3 is haloalkyl, and / or R4 is NH2, and / or R11 and R 12 are independently one of the another a halogen atom, and / or R13 is haloalkyl.

A compound of formula (I) very particularly preferred in the invention is the
1- [2,6-C12 4-CF3 phenyl] 3-CN 4- [SO-CF3] 5-NH2 pyrazole,
also known as fipronil.

 According to a preferred variant of the invention, the polymers which can be used for the fibers are either polymers of natural origin, chemically modified, such as starch and cellulose derivatives, or synthetic organic polymers such as polyesters and their derivatives such as polylactides or polycaprolactones, or polyester amides.

 According to a more particularly advantageous variant of the invention, the polymer used as material for the fibers is a cellulose ester because of their advantageous biodegradability. Cellulose acetate is particularly preferred. A cellulose acetate having a degree of acetylation of between 1.2 and 2.8, preferably between 1.9 and 2.5, is even more advantageous because of its improved properties, in particular of biodegradability.

 The agrochemical is incorporated into the fibers by mixing the said product in organic solution with an organic solution of the constituent polymer of the fibers. The mixture is then extruded through an appropriate die, generally metallic, and solidified by evaporation of the solvent (s). The fiber thus prepared is cut into fragments of size generally between 2 to 30 mm, preferably between 6 to 18 mm.

 The fibers of the sheet according to the invention may have a cross-section of various shape, such as circular, in "Y", in "X", or in "I". Their weight per unit of length varies from 1 to 25 decitex. A range of 1 to 5 decitex is more particularly preferred for a more effective release of the agrochemical product over time. A decitex is the weight expressed in grams of 10,000 m of fiber.

The corresponding diameter is generally substantially between 10 and 100 clam, preferably from 15 to 50 μm.

 The effective amount of agrochemical product distributed in the fibers is such that it generally corresponds to an amount per unit area of the sheet according to the invention, between 0.1 to 25 preferably from 1 to 5 g / m2. The amount of agrochemical in the fibers is generally between 0.05 and 25%, preferably 0.1 to 15% by weight.

 Woven or nonwoven webs can be obtained from the fibers as described above, according to one or more methods well known to those skilled in the art.

 The nonwoven sheets according to the invention contain, in addition to the fibers comprising the agrochemical product, any additive known for the manufacture of nonwoven sheets, such as a binder or a dye.

 Among the binders used, a binder soluble or dispersible in water is preferred, generally in the form of cut fibers. Such binders are well known in the art. These are water-soluble or water-dispersible polymers, which are either natural polymers such as polysaccharides, or semisynthetic polymers such as carboxymethylcellulose and its salts, or synthetic polymers, such as polyvinyl alcohol or polyvinylpyrrolidone. Polyvinyl alcohol is particularly preferred.

 The weight ratio of binder / weight of fibers comprising the agrochemical product is generally between 1 and 20%, preferably between 5 and 15%.

 The sheets according to the invention, in particular the non-woven sheets, have a thickness of between 0.05 and 1 cm, preferably between 1 and 5 mm.

 The present invention also relates to sowing boxes comprising a sheet according to the invention, as defined above.

 Preferably, the sowing box successively comprises, from the bottom, a first layer of soil, the sheet according to the invention on which the rice seeds are sown, and finally a second layer of soil.

 The soil used in the seed boxes is natural or reconstituted soil or potting soil. It usually includes clay and sand and possibly fertilizers.

 The height of the first layer of soil is generally between 1 and 5 cm. The height of the second soil layer, also called the surface layer, is advantageously between 0.5 and 2 cm, preferably between 1 and 2 cm.

 According to a preferred variant of the sowing boxes according to the invention, the bottom of the box is covered, under the first layer of soil, with a paper usually qualified in English as "liner" of weight per unit of suitable surface. This variant is particularly advantageous when the seedling boxes are stored on the ground, during the period of time elapsing between sowing and transplanting. In fact, in the absence of such a layer of paper, the roots of the rice seedlings would be likely to cross the bottom of the box (pierced with multiple holes to facilitate the flow of the irrigation water), and to take root in the ground; which could damage the rice seedlings, and would considerably hamper the removal of the boxes for transplanting. The weight per unit area of the liner is generally between 20 and 80 g / m2, preferably between 30 and 50 g / m2.

 The size of the sowing box and the tablecloth is usually chosen to correspond to 100 to 300 boxes per hectare of culture, preferably 200 boxes. These boxes are generally rectangles of length usually between 50 and 65 cm, and of width between 20 and 35 cm. A rectangle of 58 by 28 cm is commonly used.

 The quantity of rice seeds contained in the boxes according to the invention corresponds to a sowing from 10 to 300 kg / ha, preferably from 20 to 200 kg / ha.

 The present invention finally relates to a method of protecting rice in a sowing box and in a submerged paddy field against harmful species, characterized in that a sowing box according to the invention is used.

 The harmful species are phytopathogenic fungi, and preferably insects and nematodes attacking or likely to attack nz.

 The following examples are given purely by way of illustration of the present invention and should in no way be interpreted as limiting the scope.

Example 1: Preparation of a nonwoven web of cellulose acetate fibers comprising fipronil:
A cellulose acetate is used, the degree of acetylation of which is 2.5, which is dissolved with fipronil in acetone, so as to obtain a spinning solution containing (percentage by weight):
cellulose acetate: 33%
fipronil: 2%
acetone: 65%
This viscous solution is extruded through a suitable die in an area where a stream of hot air circulates where a filament is formed by evaporation of the solvent.

 This continuous filament, of circular section, is cut into 12 mm fragments. These fragments have a diameter of about 80 Fm and a linear weight of 15 decitex. Sections of these fragments are examined by scanning electron microscopy with a magnification of 30,000: no pores or fipronil crystals are observed.

 The fipronil content of the fiber is 6%.

The preceding fragments are mixed with polyvinyl alcohol in the form of fibers 2 mm in length, at a rate of 10 g of polyvinyl alcohol per 100 g of cellulose acetate with fipronil. This mixture is treated by agglomeration using a paper-making machine. The nonwoven sheet obtained has the appearance of paper, has a thickness of 1.5 mm, a weight per unit area equal to 55 g / m2, and contains an amount of fipronil of approximately 3 g / m2.
Its biodegradability rate after 6 months is more than 80%.

EXAMPLE 2 Effect of the Application in a Sowing Box of the Nonwoven of Example 1 on the Protection of Rice in Submerged Rice Field Against the Leafhopper (Nilaparvata lugens) and the Leaf Winder (Cnaphalacrosis medicalis)
28 × 58 cm rectangles are cut from the tablecloth prepared according to example 1.

 The bottom of sowing boxes (28 x 58 cm inside dimensions) and 3 cm high is lined with 37 g / m2 density paper on which a first layer of soil 2 cm thick is spread. height. The rectangular sheet according to the invention, previously cut, is placed on this layer.

 250 g of rice grains (Koshihikari variety) are then sown, then a second layer of soil 1 cm high is placed to cover the grains.

Each seedling box thus prepared contains 0.5 g of fipronil.

 The seed boxes are then placed for 3 days in an enclosure at a temperature of 30 "C and a relative humidity of 100%.

 We observe, 3 days after sowing, a root-up rate substantially equal to 0%.

 The seed boxes are then placed in a greenhouse for 11 days, at an average temperature of 20 "C, and a relative humidity of 60%.

 Fourteen days after sowing, the rice seedlings are transplanted into a submerged paddy field.

 Thirty-nine days after transplanting, 2 whole rice plants are removed from the rice field, which are introduced into a test tube at the bottom of which has been placed a cotton pad soaked in water. The infestation is then carried out by introducing into the said test tube 10 insect pests known under the English term "brown planthopper", also under the Latin name Nilaparvnta lugens, or in French "leafhopper".

 Three days after the infestation, we count the number of dead insects which we divide by the number of insects introduced and we obtain a mortality rate of 74%.

Also thirty-nine days after transplanting, 2 sheets of rice plants are taken from the rice field, which are placed in a Petri dish. The infestation is then carried out by introducing into the so-called Petri dish 5 larvae of insect pests known under the English term "rice leaffolder", in Latin
Cnaphalacrosis medicalis, or in French "leaf rewinder".

 Five days after the infestation, count the number of dead larvae which is divided by the total number of introduced larvae and a mortality rate of 62% is obtained.

 This example shows that the tablecloth according to the invention applied conveniently at the time of sowing does not harm the germination of the seeds and moreover provides rice plants, more than a month after transplanting in submerged paddy fields, good protection against insects harmful.

Example 3
Example 1 is repeated, by preparing a fiber containing 13% by weight of fipronil, by cutting fiber fragments with a length of 6 mm, and by preparing a nonwoven web of weight per unit area equal to 25 g. / m2.

 This tablecloth is 1 mm thick and contains approximately 3 g / m2 of fipronil. Its biodegradability rate after 6 months is also greater than 80%.

EXAMPLE 4 Laboratory Study of the Root-Up of Rice Seeds Sown on the Tablecloths Prepared According to Examples 1 and 3
For the purpose of this laboratory study, micro-boxes of specific seedlings, of dimensions 1 1 by 16 cm and height 3 cm are used. Such sowing boxes are not usually used under practical conditions by rice growers.

 A non-woven sheet prepared according to Example 1 and a non-woven sheet prepared according to Example 3 are applied in a similar manner to that described in Example 2 in each of these two micro-boxes.

 400 grains (13.3 g) of rice grains (Koshihikari variety) are sown in each case. Such a sowing density is about half that of what is usually practiced by farmers, and generally results in a greater root-up phenomenon.

 In both cases, the height of the lower soil layer, located under the nonwoven web, is 2 cm, and the height of the upper soil layer, covering the seeds, is 0.8 cm. This height of the surface layer, less than the minimum height of 1 cm generally recommended, is usually a factor aggravating the phenomenon of root-up.

 These 2 sowing boxes are placed for 3 days in an enclosure at a temperature of 28 "C and with a relative humidity of 100%.

 3 days after sowing, we measure by estimation the number of grains of rice that gave rise to the root-up phenomenon, that is to say the number of seeds which, because of the growth of their root, were raised above the top soil layer, which number is divided by the number of seeds sown, to get a root-up rate.

We thus obtain for the prepared tablecloth:
- according to example 1, a root-up rate of 9%; and
- according to Example 3, a root-up rate of 4%.

 Example 4 shows that, even under severe application conditions, in the sense that they normally favor a high root-up rate, the layers according to the invention give rise to an acceptable root-up rate. by the rice farmer.

Claims (21)

 1. A sheet having a weight per unit area of between 5 and 100 g / m2, preferably between 10 and 70 g / m2, and comprising fibers of a water-insoluble polymer, said fibers comprising an effective amount and homogeneously distributed in the fiber of at least one agrochemical product.  2. Tablecloth according to claim 1, characterized in that it is non-woven.  3. Tablecloth according to one of claims 1 or 2, characterized in that the polymer is substantially biodegradable.  4. Tablecloth according to claim 3, characterized in that the rate of biodegradability of the polymer is greater than 60%, preferably 95% after 6 months.  5. Tablecloth according to one of claims 1 to 4, characterized in that the fibers have substantially no pores.  6. Tablecloth according to one of claims 1 to 4, characterized in that the agrochemical is insoluble in water.  7. Tablecloth according to one of claims 1 to 6, characterized in that the agrochemical product is an insecticide chosen from the group comprising vamidothion, imidacloprid, benfuracarb, carbosulfan, cartap, furathiocarb, pymetrozine, nitenpyram, acetamiprid, as well as 1arylpyrazole of formula (I):

R4 is NH2, R1 is C1, R13 is CF3, and X is N; or R2 is 4,5dicyanoimidazol 2-yl, R4 is Cl, R1 l is C1, R13 is CF3, and X is = C-Cl.  provided that, when R1 is methyl, then either R3 is haloalkyl,  m, n, q, r represent, independently of one another, an integer equal to 0, l or 2; S (O) qCF3 or SF5;  R13 represents a halogen atom or a haloalkyl, haloalkoxy group,  Ru let R12 represent, independently of one another, a hydrogen or halogen atom and optionally CN or NO2;  X represents a trivalent nitrogen atom or a C-R12 radical, the other three valences of the carbon atom being part of the aromatic ring  Rlo represents a phenyl or heteroaryl group optionally substituted by one or more halogen atoms or groups such as OH, -O-alkyl, -S-alkyl, cyano, or alkyl;  R9 represents an alkyl radical or a hydrogen atom  R8 represents an alkyl or haloalkyl radical or a hydrogen atom;  R7 represents an alkyl or haloalkyl radical  R5 and R6 independently represent the hydrogen atom or an alkyl, haloalkyl, C (O) alkyl, S (O) rCF3 radical; or R5 and R6 may together form a divalent alkylene radical which may be interrupted by one or two divalent heteroatoms, such as oxygen or sulfur;  R4 represents a hydrogen or halogen atom; or a radical NR5R6, S (O) mR7, C (O) R7 or C (O) O-R7, alkyl, haloalkyl or OR8 or a radical N = C (R9) (R10)  R3 is alkyl or haloalkyl;  R2 is S (O) nR3 or 4,5-dicyanoimidazol-2-yl or haloalkyl;  R1 is a halogen atom or a CN or methyl group;  in which:  8. Tablecloth according to one of claims 1 to 7, characterized in that the agrochemical product is 1-arylpyrazole of formula (I) as defined in claim 7.  9. Tablecloth according to one of claims 7 or 8, characterized in that the 1-arylpyrazole of formula (I) is such that R1 is CN, and / or R3 is haloalkyl, and / or R4 is NH2, and / or R11 and R 12 are independently of each other a halogen atom, and / or R13 is haloalkyl.  10. Tablecloth according to one of claims 7 to 9, characterized in that the 1 -arylpyrazole of formula (I) is 1 - [2,6-Cl2 4-CF3 phenyl] 3-CN 4- [SO-CF3 ] 5 NH2 pyrazole.  11. Tablecloth according to one of claims 1 to 6, characterized in that the agrochemical is a fungicide chosen from the group comprising iprodione, fosetyl-Al, bromuconazole, (4-S) 4-methyl- 2-methylthio-4phenyl- 1 -phenylamino-2-imidazoline-5-one, 4-chloro-3- (3,5-dichlorophenyl) 1H-pyrazole, hymexazol, metalaxyl, methasulfocarb, chlorothalonil, benomyl, tolclofos-methyl, probenazole, isoprothiolane, tricyclazole, azoxystrobin, furametpyr, thifluzamide, (E) -2- (Methoxyimino) -Nmethyl-2- (2-phenoxyphenyl) acetamide.  12. Tablecloth according to one of claims 1 to 11, characterized in that the polymers which can be used for fibers are polymers of natural origin, chemically modified.  13. Tablecloth according to one of claims 1 to 12, characterized in that the polymer is a cellulose ester, preferably cellulose acetate.  14. Tablecloth according to one of claims 1 to 13, characterized in that the polymer is a cellulose acetate having a degree of acetylation of between 1.2 and 2.8, preferably between 1.9 and 2.5 .  15. Tablecloth according to one of claims 1 to 14, characterized in that the weight per unit length of the fibers is between 1 and 25 decitex, preferably between 1 and 5 decitex.  16. Tablecloth according to one of claims 1 to 15, characterized in that the effective amount of agrochemical in the fibers corresponds to an amount per unit area of the sheet of between 0.1 to 25 g / m2, preferably from 1 to 5 g / m2.  17. Seedling trays comprising a sheet according to one of claims 1 to 16.  18. Sowing boxes according to claim 17, successively comprising, from the bottom, a first layer of soil, the sheet on which the rice seeds are sown, and a second layer of soil.  19. Sowing boxes according to one of claims 17 or 18, characterized in that the height of the surface layer is between 0.5 and 2 cm, preferably between 1 and 2 cm.  20. Sowing boxes according to one of claims 17 to 19, characterized in that the bottom of the box is covered, under the first layer of soil, with a paper whose weight per unit area is between 20 and 80 g / m2, preferably between 30 and 50 g / m2.  21. Method for protecting rice in a sowing box and in a submerged paddy field against harmful species, characterized in that a sowing box is used according to one of claims 17 to 20.