GB1576374A - Insecticidal compositions - Google Patents

Description

(54) INSECTICIDAL COMPOSITIONS (71) We, AMERICAN CYANAMID COMPANY, a corporation organised and existing under the laws of the State of Maine, United States of America, of Berdan Avenue, Township of Wayne, State of New Jersey, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to pesticidal compositions, and methods of preparing the same, said compositions containing a pesticide of the formula:

wherein R is -C2H5 or -C(CH3)3.

It is known that O,O-diethyl S-[(ethylthio) -methyl]phosphorodithioate and O,O-diethyl S-[(1,1-dimethylethylthio)methyl phosphorodithioate compounds are highly effective for the control of a broad spectrum of insects which attack and destroy agriculturally important food and fodder crops. Therefore, it is of advantage to utilize both of the above-identified compounds in various compositions useful in agriculture. Unfortunately, these otherwise highly effective pesticides are extremely toxic to mammals when introduced into the mammalian circulatory system. Although these toxicants may be introduced into the mammalian circulatory system via ingestion and/or inhalation, nonetheless, the most commonly encountered mode of entry by far is through dermal or skin absorption.

The use of compositions containing O,O-diethyl S-[(ethylthio)methyl] phosphorodiethioate and/or O,O-deithyl S-[(1,1-dimethylethylthio) methyl]phosphorodithioate for the control of soil insect pests (e.g. nematodes), therefore represents a distinct hazard to the individuals engaged in the use and application thereof. Similar hazards are encountered by those who are engaged in storing, transporting and distributing to the ultimate user the above referred-tocompositions.

It has been surprisingly found that, when solid granular carriers are coated or impregnated with the aforementioned pesticides together with shellac, resultant compositions possess a greater margin of safety due to their lowered mammalian dermal toxicity as compared to similar compositions not containing shellac while fully retaining their pesticidal activity.

Moreover, this advantageous effect may be accomplished in a relatively straightforward manner as will be described in greater detail below.

More specifically, the present invention in one aspect provides a granular pesticidal composition comprising a sorptive or non-sorptive granular carrier material coated or impregnated with (1) a pesticide of the formula:

wherein K Is the radical -(g2F15 or -L(Ln3)2, said pesticide being present in an amount ot trom 5% to 20%, by weight, based on the total weight of the composition; (2) shellac, in a pesticide-to-shellac ratio of 1:1 to 3:1, by weight; and (3) a glycol type deactivator selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol and mixtures thereof, said deactivator being present in an amount of from 4% to 6%, by weight, based on the total weight of the composition; and either (a) said composition comprising also from 1% to 10%, by weight, based on the total weight of the composition, of a finely divided sorptive substrate when the granular carrier is non-sorptive, or (b) said composition optionally comprising also from 1% to 10%, by weight, based on the total weight of the composition, of a finely divided sorptive substrate when the granular carrier is sorptive.

Preferred pesticidal compositions of this invention include one or more of the following features: (a) the pesticide is present in an amount of from 10% to 15% by weight, based on the total weight of the composition; (b) the pesticide-to-shellac ratio is 2:1 by weight; (c) the deactivator is propylene glycol or polyethylene glycol with a molecular weight of 6000, or a mixture thereof.

(d) the granular carrier is sorptive carrier selected from clays (particularly attapulgite and montmorillonite clays), pumice, brick chips, talc, volcanic cinders and corncob grits; or a non-sorptive carrier selected from sand and limestone chips; and (e) the sorptive substrate, when present, is selected from calcium silicate, diatomaceous earth and fumed silica (and mixtures thereof), and the amount of this component is within the range of 1% to 6% by weight, based on the total weight of the composition.

The deactivator serves to neutralize intrinsic acidity, whilst the sorptive substrate such as calcium silicate, help to prevent aggregation and to maintain the fluiditity of the composition by acting as a drying agent.

One preferred method of preparing the pesticidal compositions of this invention comprises adding the selected pesticide to a 20%to 30%w/v solution, of shellac, prepared from shellac and an inert solvent, such as a monohydric alcohol e.g. methanol or ethanol or a lower aliphatic ketone e.g. acetone, methyl ethyl ketone, methyl isobutyl ketone alone or in combination with methylene chloride. The glycol type deactivator is then added to the toxicant-shellac solution. The thus-prepared solution is sprayed on to the surface of the selected carrier granules while these are kept in constant motion by any known means. If necessary or desired a predetermined amount of drying-sorptive substrate compound is admixed with the carrier granules prior to spraying or added during the spraying operation.

Advantageously, a warm air stream is directed onto the surface of the granules while the latter are being sprayed with the shellac-toxicant solution so as to promote drying and to remove any solvent. With the spraying completed, the treated granules are kept in motion with mold heating at 50"C to 55"C and/or under an air stream until the desired product is freeflowing and dry.

The novel granular coated compositions of the present invention can alternatively be prepared in the following manner. The aforementioned pesticide and a liquid glycol type deactivator, preferably propylene glycol, are mixed and sprayed on the surface of the inert carrier granules. When all the liquid is absorbed, the granules are heated to from 500C to 55"C, then agitated and subjected to a surface spray of a 20%to 30%w/v solution of shellac in a solvent, such as a lower monohydric alcohol such as methanol or ethanol or a mixture or a lower alcohol, and methylene chloride, wherein said solvents are utilized in a 1:1 volume ratio. While treating said granules with the shellac coating solution, the granules are agitated at 50"C to 55 "C to aid in the evaporation of the solvent mixture. Simultaneously, if necessary or desired, small incremental amounts of a sorptive drying agent, such as calcium silicate are added to prevent aggregation and to maintain the fluidity of the formulation. When the coating of the granules with shellac has been completed, the granules may then be sprayed on the surface with a solution of a polyethylene glycol, such as polyethylene glycol (PEG) having an average molecular weight of 6,000 in methylene chloride. In practice, 1% to 5% PEG 6000 based on the weight of the granular or finished product is generally used so that the total amount of deactivator is within the range of 4 % to 6 % by weight of the finished composition.

The granules then are heated and agitated, while if necessary or desired sufficient small amounts of sorptive substrate such as calcium silicate are added until the coated granular formulation is free-flowing and dry.

The compositions of the present invention may be applied to soil by commercially available equipment designed to distribute solid pesticidal compositions.

The invention is illustrated by the examples which follow and in which, unless otherwise specified, all parts are by weight Example 1 Components Percent by Weight O,O-diethyl S-(ethylthio)methyl phosphorodithioate (technical, 88.5% real) 12.43 Propylene glycol 4.0 Shellac 5.0 Diatomaceous earth 4.2 Agro-Minerals Clay (India) 20/40 mesh (U. S. standard), q.s. ad 100.0 Shellac (5.0 g) is dissolved in methanol (20 ml) at 450C to 500C with stirring. To the above solution, 12.4 g of O,O-diethyl S-(ethylthio)methyl phosphorodithioate (88.5% real) and propylene glycol (4.0 g) are added and the mixture is stirred until a homogeneous solution results. Clay granules (g.s. ad 100) and diatomaceous earth (4.2 g) are next charged to a rotary blender. With the blender in operation, the above prepared methanolic shellac solution is sprayed on the mixture of clay granules and diatomaceous earth, while simultaneously introducing a stream of air into the lumen of the blender. After the spraying of the solution is completed, the blending is continued. The air flow into the lumen of the blender is maintained until the granules are dry and free-flowing.

The agro-minerals clay (India) employed above analyses as follows: Analysis Percent Silica 39.15 Ferric oxide 5.01 Titanium dioxide 6.84 Alumina 29.22 Manganous oxide 0.02 Calcium oxide 1.88 Magnesium oxide 1.08 Potassium oxide 0.03 Sulfur trioxide 0.20 Loss on ignition 16.45 Sp. gravity at 30/300C = 2.86 pH (106F aq. suspension) = 7.2 Oil absorption 29.91 By employing the above procedure, but substituting O,O-diethyl S-[(1, 1-dimethylethylthio) methyl]phosphorodithioate for O,O-diethyl S-[(ethylthio) methyl]phosphorodithioate, a coated granular insecticidal composition, containing said O,O-diethyl S-[(1,1,-dimethylethylthio) methyl]phosphorodithioate is prepared.

Example 2 The procedure of Example 1 is followed in every detail except that composition is prepared from the following components: Example 2 Component Percent by weight O,O-diethyl S- [(ethylthio)methyl)j phosphorodithioate, 88.5% real 12.43 Propylene glycol 4.0 PEG 6000* 1.0 Shellac 5.0 Calcium Silicate 1.0 Agro-Minerals Clay (India)** 20/40 mesh, q.s. ad 100.0 * = Polyethylene glycol, av. mol. wt. 6000 ** = Composition given in Example 1.

By the above procedure, but substituting O,O-diethyl S-[(1,1-dimethylethylthio) methyl]phosphorodithioate for the above-named toxicant, a coated granular insecticidal composition, containing 11.0% by weight of said O,O-diethyl S-[(1,1-dimethylethylthio) methyl]-phosphordithioate can be prepared, respectively.

Example 3 Components Percent by weight O,O-diethyl S-(ethylthio)methyl phosphorodithioate (technical, 88.5% real) 12.43 Propylene glycol 2.00 PEG 6000 3.33 Shellac 5.50 Attapulgite * 24/48 mesh (U.S. standard), q.s. ad 100.0 *Analysis appended to Example Procedure to make 100 grams Shellac (5.50 g) is dissolved in methanol (25 ml) at 450C to 50"C with stirring. To the above solution O,O-diethyl S- [(1,1 -dimethylethylthio) methyl] phosphorodithioate (88.5% real, 12.43 g), propylene glycol (2.0 g) and PEG 6000 (3.33 g) are added and the mixture stirred until a homogeneous solution is obtained.

Next, the clay granules (q.s. ad 100So) are charged to a rotary blender. With the blender in operation, the above prepared methanolic solution is sprayed on the mixture of clay granules while simultaneously a stream of air is directed into the lumen of the blender. After the spraying of the solution is completed, the blending is continued, and the air flow into the lumen of the blender is maintained until the granules are dry and free flowing.

By the above procedure, but substituting O,O-diethyl S-p(ethylthio)methyl] phosphordithioate for the above toxicant, a coated granular insecticidal composition. containing 11.0%, by weight. of said O,O-diethyl S-[(ethylthio) methyl]phosphorodithioate can be prepared.

Analysis of Attapulgite (Attaclay A LVM) dried at at 1050C is: Component Percent Silica 64.37 Alumina 12.46 Ferric oxide 5.93 Magnesium oxide 5.28 Calcium oxide 0.99 Sodium oxide 0.05 Potassium oxide 1.58 Titanium dioxide 0.73 Loss on ignition 8.21 Example 4 Components Percent w/w O.O-diethyl S-(ethylthio)methyl phosphorodithioate (technical.

88.5cm real) 12.43 Propylene glycol 4.00 PEG 6000 1.00 Shellac 5.00 Calcium silicate (200 mesh) 1.00 Agro-Minerals Clay (India)* 20/40 mesh a.s. ad. 100.0 *Analysis given in Example 1.

Propylene glycol 40 parts) and O,O-diethyl S-[ethylthio]methyl phosphorodithioate 88.5%real, 122 parts) are mixed and stirred until a homogeneous solution forms, hereinafter termed solution A. Powdered shellac (50 parts) is dissolved in methanol (125 parts by volume) with stirring, and solution is next diluted to 250 parts by volume with methylene chloride and filtered. The filtered solution is hereinafter termed solution B. Thereafter, PEG 6000 (10 parts) and methylene chloride (50 parts by volume are mixed and stirred until a homogeneous solution forms hereinafter termed solution C.

Agro-Minerals Clay granules are then charged to a tumbling type blender. With the blender in operation, the tumbling granules are sprayed with solution A and the granules are blended for at least five minutes after the addition of solution A is completed. Immediately thereafter, the contents of the blender are heated to 50"C to 550C with hot air and the shellac solution B is sprayed on the cascading granules in portions sufficient to slightly wet the surface of the granules, while maintaining the temperature of the granules at 50"C to 550C.

After a few applications of portions os solution B, the granules may start forming aggregates.

Calcium silicate is then added in small portions between the applications of solution B to keep the granules free-flowing. When all of the solution B is sprayed on the granules, blending and tumbling of the same is continued and the PEG 6000/methylene chloride solution C is sprayed on the granules in small portions alternating with the addition of small amounts of calcium silicate to keep the granules free-flowing.

After the addition of solution C, is completed, blending is continued and additional calcium silicate added if necessary to keep the granules free-flowing. The granules are then screened on 10 and 100 mesh screens to remove aggregates and fines. There is obtained approximately 1000 g of granular, coated insecticidal composition, containing 12,43%, by weight, of the technical grade O,O-diethyl S-(ethylthio)methyl phosphordithioate.

Example 5 to 13 By the procedures of Example 4, coated granular insecticidal compositons can be prepared, as summarized in Table I below.

Table I Component Composition of Formulations in Percent by Weight 5 6 7 8 9 10 11 12 13 O,O-diethyl S-[(ethylthio)methyl]phosphorodithioate; real 5.0 7.5 10.0 15.0 20.0 - - - O,O-diethyl S-[1,1-dimethylethylthio)methyl]phosphorodithioate; real - - - - - 5.0 7.5 10.0 15.0 Propylene glycol 4.0 3.0 2.5 3.0 4.0 4.0 3.0 2.5 3.0 PEG 6000 - 1.0 2.5 2.0 2.0 - 1.0 2.5 3.0 Shellac 1.66 3.0 5.0 5.0 7.5 1.66 3.0 5.0 5.0 Diatomaceous earth 4.0 3.0 2.0 - - 4.0 3.0 - Calcium silicate 1.5 2.0 2.0 - - 1.5 2.0 - Agro-Minerals Clay (India) Attapulgite Q.S. Q.S.

100 100 Montmorillonite Q.S. Q.S.

100 100 Sand Q.S. Q.S.

100 100 Brick Chips Q.S. Q.S.

100 100 Corncob grits Q.S.

100 Example 14 Components Parts by weight O,O-diethyl S-(ethylthio)methyl phosphorodithioate (technical, 90% real) 122 Propylene glycol 40 Shellac 100 Diatomaceous earth 42 Agro-Minerals Clay (India)* 20/40 mesh (U. S. standard), q.s. ad. 1000 *Analysis as in Example 1.

Shellac (100 parts) is dissolved in methanol (250 parts by volume) with stirring at 450C. to 50"C. and to this solution is added O,O-diethyl S-(ethylthio)-methyl phosphorodithioate (90No real, 122 parts) and propylene glycol (40 parts) and the mixture is stirred well until a homogeneous solution results.

Clay granules (q.s. ad 1000) and diactomaceous earth (42 parts) are next charged to a rotary blender. With the blender in operation, the above prepared homogeneous methanolic shellac solution is sprayed on the mixture of clay granules and diatomaceous earth, while simultaneously introducing a stream of air into the lumen of the blender. After the spraying of the solution is completed, the blending is continued. The air flow into the lumen of the blender is maintained until the granules are dry and free-flowing.

By employing the above procedure, but substituting O,O-diethyl S-[(1 ,1dimethylethylthio)methyl] -phosphorodithioate for O,O-diethyl S-[(ethylthio)methyl2 -phosphorodithioate, a coated granular insecticidal composition, containing said O,O-diethyl S-[(l,l -dimethylethylthio) methyl] phosphorodithioate is prepared.

Example 15 The procedure of Example 14 is followed in every detail except that composition is prepared from the following: Component Parts by weight O,O-diethyl S-[(ethylthio)- methyl]phosphorodithioate 90% real 122 Propylene glycol 40 PEG 6000* 10 Shellac 100 Calcium Silicate 10 Agro-Minerals Clay (India)** 20/40 mesh (U. S. standard), q.s. ad. 1000 * = Polyethylene glycol, av. mol. wt. 6000 ** = Composition given in Example 1.

By the above procedure, but substituting O,O-diethyl S-[(1,1-dimethylethylthio) methyl]phosphorodithioate for the above-named toxicant, a coated granular insecticidal composition, containing 11.0% by weight of said O,O-diethyl S-[(1,1-dimethylethylthio) methyl]phosphorodithioate can be prepared, respectively.

Example 16 Components Parts by weight O,O-diethyl S-[(1,1-dimethyl ethylthio)methyl] phosphoro dithioate (90% real) 122 Propylene glycol 20 Shellac 100 PEG 6000 30 Attapulgite * 24/48 mesh, q.s. ad 1000 * Analysis appended to Example 3.

Shellac (100 parts) is dissolved in methanol (250 ml.) at 450C to 50"C. with stirring. To the above solution O,O-diethyl S- [(1, 1-dimethylethylthio) methyl]phosphorodithioate (90% real, 122 parts), propylene glycol (20 parts) and PEG 6000 (30 parts are added and the mixture stirred until a homogeneous solution is obtained.

Next, the clay granules (q.w. ad 100 No) are charged to a rotary blender. With the blender in operation, the above prepared methanolic solution is sprayed on the mixture of clay granules while simultaneously a stream of air is directed into the lumen of the blender. After the spraying of the solution is completed, the blending is continued, and the air flow into the lumen of the blender is maintained unitl the granules are dry and free-flowing.

By the above procedure, but substituting O,O-diethyl S-[(ethylthio) methyl]phosphorodithioate for the above toxicant, a coated granular insecticidal composition, containing 11.0%, by weight of said OO-diethyl S-[(ethylthio) methyl]phosphorodithioate can be prepared.

Example 17 Componel2ts Percent w/w O,O-diethyl S-[(ethylthio)methyl] phosphorodithioate (Technical, 90 % real) 12.23 Propylene Glycol 4.00 PEG 6000 (Polyethylene glycol 6000) 1.00 Shellac 10.00 Talc (200 mesh) 10.00 Agro-Minerals Clay (India)* 20/40 mesh, q.s. ad. 100.00 *Analysis as given in Example 1.

Propylene glycol (40 parts) and O,O-diethyl S-[(ethylthio) methyl]phosphorodithioate (90% real, 122 parts) are mixed and stirred until a homogeneous solution forms, hereinafter termed solution A. Powdered shellac (100 parts) is dissolved in methanol (250 parts by volume) with stirring. and solution is next diluted to 500 parts by volume with methylene chloride and filtered. The filtered solution is hereinafter termed solution B. Thereafter, PEG 6000 (10 parts) and methylene chloride (50 parts by volume) are mixed and stirred until a homogeneous solution forms, hereinafter termed Solution C.

The clay granules (100 parts) are then charged to a tumbling type blender. With the blender in operation. the tumbling granules are sprayed with solution A and the granules are blended for at least five minutes after the addition of solution A is completed. Immediately thereafter, the contents of the blender are heated to 50 C. to 55"C. with hot air and the shellac solution B is sprayed on the cascading granules in portions sufficient to slightly wet the surface of the granules, while maintaining the temperature of the granules at 50"C. to 55"C.

After a few applications of portions of solution B, the granules may start forming aggregates.

Talc is then added in small portions between the applications of solution B to keep the granules free-flowing. When all of solution B is sprayed on the granules, blending and tumbling of the same is continued and the PEG 6000/methylene chloride solution C is sprayed on the granules in small portions alternating with the addition of small amounts of talc to keep the granules free-flowing.

After the addition of solution C is completed, blending is continued and additional talc added, if necessary, to keep the granules free-flowing. The granules are then screened on 10 and 100 mesh screens to remove aggregates and fines. There is obtained approximately 100 g. of granular, coated insecticidal composition, containing 12.23%by weight of O,O-diethyl S-[(ethylthio) methyl]phosphorodithioate.

Example 18 The same procedure as in Example 17 is followed excepting that 80 parts of powdered shellac is dissolved in 200 parts by volume of methanol.

Example 19 Determination ofthe dry dermal LDso of experimental coated granular formulations containing 11 %by weight of O, O-diethyl S-(ethylthio) methylphosphorodithioate, using albino rats as the test animal Test Animal Charles Foster albino rats, 150 to 224 g body weight, randomly distributed in groups of five.

Test formulations The formulations for the first 2 groups are prepared by the procedure of Example 4 and for the last 3 groups according to Example 14 and have the following composition in Table II.

Table II Percent by Weight Compound Control I II III IV V O,O-diethyl S-(ethylthio)methyl phosphorodithioate real or 100% 11.0 11.0 11.0 11.0 11.0 11.0 Propylgene glycol 4.0 4.0 4.0 4.0 4.0 4.0 PEG 6000 1.0 1.0 1.0 1.0 1.0 Shellac - - 5.0 5.0 10.0 10.0 10.0 Calcium silicate 1.0 1.0 1.0 10.0 10.0 10.0 Agro-Minerals Clay (India) 20/40 mesh, q.s. ad. 100.0 100.0 100.0 100.0 100.0 100.0 The above formulations are evaluated at the following dosage rates: Control: 250, 200, 150, 100 and 75 mg/kg body weight.

Formulae land II: 1710, 1135, 760, 505, and 340 mg/kg body weight.

Formulae III & IV: 3875, 2583, 1722, 1148, 765 and 510 mg/kg body weight.

Formulae V: 5812, 3875, 2583, 1722, 1148, 776 and 510 mg/kg body weight.

For each dosage rate, five (5) animals are use.

Method The hair is shorn from the back and flanks of each animla. The selected dosages of the above formulae are then spread evenly on the animals skin and covered with aluminum foil.

The trunk of the rats is then encircled with a 3" x 9" adhesive tape to fasten the formulation and its aluminum cover securely to the skin of the rat, the elastic tape is tightened sufficiently to prevent the animal from wiggling free and is wrapped around to form a double layer.

The rats are caged along for a contact period of 24 hours. The tape is then removed and the animals skin and surrounding hair are sponged thoroughly with solvent free detergent and warm water, rinsed and dried with a towel.

The animals are then caged and observed for seven days or until affected individuals are clinically recovered. From the mortality data obtained, the LD50 values are calculated and are summarised as follows: Formulation LDso mg/kg Body Weight Control 148 1 931 II 803 III 2400 IV 2160 V 2280 It can be clearly seen from the data above that the coated granular formulations of the present invention are markedly dermally safer than the conventional granular formulations containing O,O-diethyl S-(ethylthio)methyl phosphorodithioate.

Example 20 Evaluation of the bio-efficacy of a coated granular insecticidal formulation for the control of soil insects and mites For these tests, a coated granular formulation containing O,O-diethyl S-(ethylthio)methyl phosphorodithioate and a standard granular composition, containing the same pesticide, are prepared by the procedure of Example 4. The composition of the samples is as follows in Table III.

Table III Percent by Weight Component A (Uncoated, B (coated) standard O,O-diethyl S-(ethylthio)methyl phosphorodithioate: real 11.0 11.0 Propylene glycol 4.0 4.0 PEG 6000 - 1.0 Shellac 5.0 Calcium silicate - 1.0 Angro-Minerals Clay (India) 20/40 mesh q.s. ad. 100 q.s. ad. 100 Systemic Test The test formulations are compared for activity on Western Potato Leafhoppers Empoasca abrupta DeLong, and organophosphate susceptible two-spotted spider mites Tetranychus urticae Koch, at rates of 7.5, 15 and 30 mg active ingredient per 10 cm plastic pot of soil. The treatments and untreated controls are replicated three times.

Method The granules are evenly distributed on top of approximately 2.5 cm of soil in the pots.

Cotton plants with 2-3 true leaves are transplanted on the treated soil surface and the pots are topped with untreated soil. The transplanted cotton plants are placed in the greenhouse and thoroughly watered until the soil is soaked.

Three days post-treatment both cotyledons of each cotton plant are excised and placed in petri dishes for bioassay with Western Potato Leafhoppers. The true leaves are left intact on the plants and infested with two-spotted spider mites.

The mortality of both species is recorded three days after infestation (six days after soil treatment). The data obtained are averaged and summarized in Table IV below.

Table IV Efficacy of a Coated Granular Composition for the Systemic Control of Leafhoppers and Two-Spotted Spider Mites Rate Percent Mortality, Average of 3 Replicates Formulations mg, a.i./pot Leafhopper Two-Spotted Spider Mite A (Uncoated 7.5 100 100 standard) 15.00 100 100 30.00 100 100 B (Coated) 7.5 100 100 15.00 100 100 30.00 100 100 Control - 0 0 One hundred percent control of western potato leafhoppers and two-spotted spider mites is observed at all rates with both formulations. Thus, the results clearly show that the experimental coated formulation (B) releases O,O-diethyl S-(ethylthio)methyl phosphorodithioate properly and the active ingredient is taken up by the cotton plants as effectively as it is taken up from the standard uncoated formulation (A).

Soil Test for the Control of Southern Corn Rootworm This test compares the efficacy of the above-described formulations (A and B) against a soil insect, the Southern Corn Rootworm Diabrotica undecipunctata howardi Barber.

The test method involves treatments of 1, 5 and 10 mg of active ingredient/quart of soil.

The granules are added to moist soil and mechanically mixed for two minutes to achieve uniformity throughout the soil. Five one-ounce samples of each treatment rate are placed in glass jars with 1 ml of millet seed. Each jar is agitated and then infested with 10 Southern Corn Rootworm larvae. Mortality counts are made six days post-treatment. The data are averaged and summarized in Table V below.

Table V Bio-Efficacy of a Coated Granular Formulation for the Control of Southern Corn Rootworm Percent Mortality Rate Average of 5 Replicates Formulation a.i./Quart Soil Southern Corn Rootworms A (Uncoated 1 100 standard) 5 100 10 100 B (Coated) 1 100 5 100 10 100 Control O One hundred percent (100%) control of the southern corn rootworm larvae is observed at all rates with both formulations. This test supports the results obtained in the above systemic test. i.e.

Claims (17)

WHAT WE CLAIM IS:

1. A granular pesticidal composition, comprising a sorptive or non-sorptive granular carrier material coated or impregnated with (1) a pesticide of the formula:

wherein R is the radical -C2H5 or -C(CH3)2, said pesticide being present in an amount of from 5% to 20%, by weight. based on the total weight of the composition; (2) shellac, in a pesticide-to-shellac ratio of 1:1 to 3: 1, by weight; and (3) a glycol type deactivator selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol and mixtures thereof. said deactivator being present in an amount of from 4% to 6%, by weight, based on the total weight of the composition; and either (a) said composition comprising also from 1% to 10%, by weight, based on the total weight of the composition. of a finely divided sorptive substrate when the granular carrier is non-sorptive, or (b) said composition optionally comprising also from 1% to 10%, by weight, based on the total weight of the composition. of a finely divided sorptive substrate when the granular carrier is sorptive.

2. A pesticidal composition according to Claim 1, wherein said pesticide is O,O-diethyl S-[(ethylthio) methyl] phosphorodithioate.

3. A pesticidal composition according to Claim 1, wherein said pesticide is O,O-diethyl S-[(l,t-dimetbylethylthio) methyl]phosphorodithioate.

4. A pesticidal composition according to any preceding claim, wherein said pesticide is present in an amount of from 10% to 15% by weight, based on the total weight of the composition.

5. A pesticidal composition according to any preceding claim, wherein the pesticide-toshellac ratio is 2:1 by weight.

6. A pesticidal composition according to any preceding claim, wherein said deactivator is propylene glycol or polyethylene glycol with an average molecular weight of 6000, or a mixture thereof.

7. A pesticidal composition according to any preceding claim, wherein there is used a sorptive granular carrier selected from clays, pumice, brick chips, talc, volcanic cinders and corncob grits.

8. A pesticidal composition according to Claim 7, wherein said carrier is attapulgite or montmorillonite clay.

9. A pesticidal composition according to any one of Claims 1-6, wherein there is used a non-sorptive granular carrier selected from sand and limestone chips.

10. A pesticidal composition according to any preceding claim, wherein the sorptive substrate is selected from calcium silicate, diatomaceous earth and fumed silica.

11. A pesticidal composition according to any preceding claim, wherein the composition comprises from 1% to 6% by weight, based on the total weight of the composition, of a sorptive substrate.

12. A method for the preparation of a granular pesticidal composition as defined in any one of Claims 1-11, comprising the steps of: (a) preparing a 20W30% w/v solution of shellac in an inert solvent; (b) dissolving the pesticide and glycol type deactivator in the shellac solution thus obtained; (c) spraying the solution obtained in step (b) onto the surface of the granular carrier, the sorptive substrate, if necessary or desired, being admixed with said carrier prior to said spraying or being added during said spraying; and (d) evaporating the solvent until the composition is free-flowing and dry.

13. A method according to Claim 12, wherein said inert solvent is methanol, ethanol, acetone or methyl ethyl before, alone or in combination with methylene chloride.

14. A method for the preparation of a granular pesticidal composition as defined in any one of Claims 1-11, comprising the steps of: (a) spraying a mixture of the pesticide and glycol type deactivator onto the surface of the granular carrier; (b) heating the thus sprayed granules at from 50 to 55"C; (c) further spraying the granules with a 20%-30% w/v solution of shellac in an inert solvent whilst the granules are agitated and maintained at from 50-55"C; (d) if necessary or desired, adding the sorbtive substrate incrementally during step (c); and (e) if desired, further spraying the granules obtained in step (c) with a solution of a polyethylene glycol in methylene chloride.

15. A granular pesticidal composition, according to Claim 1 and substantially as described in any one of the Examples herein.

16. A method for the preparation of a granular pesticide composition according to Claim 1, substantially as described in any one of the Examples herein.

17. A granular pesticide composition according to Claim 1, whenever prepared by a method according to any one of Claims 12-14 or Claim 16.

TREGEAR THIEMANN & @I EACH