JPH10273405A - Aqueous suspension formulation for direct application in flooded sewage fields - Google Patents

Abstract

(57) [Summary] (Solution) [Solution] A sulfonylurea-based herbicidal active ingredient and / or a herbicidal active ingredient having a suicidal activity as an agricultural chemical active ingredient, an average degree of polymerization of 2000 or less, and a saponification degree of 69 to 9
An aqueous suspension formulation for direct application in flooded sewers, comprising 0 mol% of polyvinyl alcohol and water. First, the herbicidal active ingredient, particularly a sulfonylurea herbicide, has good stability. Secondly, since the medicine does not adhere to the rice body at the time of spraying, there is little phytotoxicity to the rice and a high herbicidal effect is exhibited. Third, the herbicidal active ingredient has good diffusibility in paddy water. Fourth, since the preparation is a dispersion using water as a dispersion medium, there is little danger such as ignitability and flammability, and there is no problem on environmental health due to irritation and odor to the human body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a flooded sewage paddy which can be sprayed by directly dropping a preparation from a container into a paddy field without diluting it with water, and capable of pre-treatment, simultaneous transplantation and post-transplantation of rice. And an aqueous suspension formulation for direct application.

[0002]

2. Description of the Related Art Heretofore, some aqueous suspension preparations in which a herbicidal active ingredient is suspended and dispersed in water are known. For example, an aqueous suspension formulation in which a herbicide base material having a water solubility of 100 ppm (25 ° C.) or less is suspended and dispersed in water using a surfactant (Japanese Patent Publication No. 7-47521).
The following finely water-insoluble herbicidal active ingredient is suspended in water to have a viscosity of 180 to 500 centipoise (20 ° C), an initial water surface spreading speed of 4.0 cm / sec (20 ° C) or more, and a surface tension of 25.0. Water-suspended paddy field herbicide having physical properties of 31.0 dyne / cm (25 ° C.) (JP-A-62-875).
No. 01), a herbicidal compound having an average particle size of 0.5 to 5.0 μm and a water solubility of 100 ppm (25 ° C.) or less is suspended in water using a surfactant, and the surface tension is 36 to 6 μm.
Aqueous suspension formulation for herbicide having physical properties of 5 dyne / cm (25 ° C.) (JP-B-7-47522), a herbicidally active compound, a surfactant and water, having a surface tension of 35 to 65.
Aqueous suspension formulation for herbicide having physical properties of dyne / cm (25 ° C.) (Japanese Patent Application Laid-Open No. 62-289502), hydrophobic herbicide (butamiphos) and polyvinyl alcohol or gum arabic, and a thickener, water Oil-in-water suspension herbicidal composition (JP-A-55-124708), comprising a paste-like or solid water-insoluble biocide having a melting point of 38 to 110 ° C, polyvinyl alcohol, a water-soluble thickener and water. Aqueous Suspended Insecticide Composition (JP-A-61-12)
No. 6001).

[0003] However, it has been known that attempts to use these conventional techniques in aqueous suspension preparations containing a sulfonylurea-based herbicidal active ingredient are extremely difficult. One of the causes
Finally, sulfonylurea-based herbicidal compounds are very susceptible to hydrolysis, and the decomposition of the active ingredient is particularly promoted in aqueous suspension preparations. A method in which a specific carboxylate or inorganic acid salt is blended for the purpose of preventing the decomposition of the active ingredient (Japanese Patent Publication No. 5-8164), the pH of an aqueous suspension preparation is adjusted to 6 or less, or a sulfonylurea herbicidal active ingredient (JP-A-5-105606) and a method of blending a polyacrylic acid derivative (JP-A-6-219913) have been proposed. However, these methods are not enough to keep the sulfonylurea-based herbicidally active compound stable in an aqueous suspension formulation, and cannot prevent phytotoxicity to rice due to the high activity of the sulfonylurea-based herbicidal active ingredient.

[0004]

The aqueous suspension formulation for direct spraying of submerged paddy fields using water as a dispersing medium can be safely dropped on a paddy water from a container without being diluted with water when spraying a drug. It is an excellent dosage form in terms of properties, economy and labor saving. However, the aqueous suspension formulation for direct spraying of flooded submerged rice fields containing the conventional sulfonylurea herbicidal active ingredient has remarkable degradation of the sulfonylurea herbicidal active ingredient,
Since the formulation contains surfactants such as nonionic surfactants, anionic surfactants, and cationic surfactants, it is easy for the drug to adhere to the rice body when spraying, and the surfactant alone or a sulfonylurea-based herbicide The herbicidal effect is liable to occur due to the synergistic action with the active ingredient and / or herbicidal active ingredient having a herbicidal activity, and the herbicidal active ingredient is not sufficiently exhibited in the paddy water due to insufficient diffusion. There was such a problem.

[0005] Therefore, the herbicidal active ingredient has high stability in place of the conventional aqueous suspension for direct application to flooded sewage paddy fields, and the herbicidal active ingredient has excellent diffusibility in water during application to rice plants. It has been desired to develop an aqueous suspension formulation which is free from phytotoxicity, and an object of the present invention is to provide an aqueous suspension formulation for direct spraying of a flooded submerged paddy field which meets these needs.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies for the purpose of improving the stability of the preparation, improving the diffusibility in water, preventing the adhesion of the drug to the rice body and preventing phytotoxicity. An aqueous suspension preparation comprising a sulfonylurea-based herbicidal active ingredient and / or a herbicidal active ingredient having an anti-hypercidal activity as an active ingredient, polyvinyl alcohol having an average degree of polymerization of 2,000 or less and a saponification degree of 69 to 90 mol%, and water is used for these purposes. Have been found to exhibit excellent effects, and have completed the present invention.

The polyvinyl alcohol used in the present invention is
When the degree of polymerization exceeds 2,000, the viscosity of the preparation becomes too high, and there are problems such as poor diffusibility in water. When the saponification degree is less than 69 mol%, precipitation of polyvinyl alcohol becomes remarkable at a high temperature, and when it exceeds 90 mol%, there is a problem that the solubility in water is poor and the diffusibility in water during spraying is poor. Therefore, the polymerization degree is 2000 or less, and the saponification degree is 69 to 90.
It can be said that mol% is the most suitable polyvinyl alcohol.

The sulfonylurea herbicidal active ingredient which can be used in the present invention includes, for example, methyl = α-
(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl) -o-toluate (bensulfuronmethyl), ethyl = 5- (4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl) -1-methyl Pyrazole-4-carboxylate (pyrazosulfuronethyl), 1- (2-chloroimidazo [1,2-a]
Pyridin-3-ylsulfonyl) -3- (4,6-dimethoxypyrimidin-2-yl) urea (imazosulfuron), 1H-pyrazol-5-sulfonamide, N
-(((4,6-dimethoxypyrimidin-2-yl) aminocarbonyl))-1-methyl-4- (2-methyl-
2H-tetrazol-5-yl) (azimsulfuron), 1-{[0- (cyclopropylcarbonyl) phenyl] sulfamoyl} -3- (4,6-dimethoxy-
2-pyrimidinyl) urea (AC-140), N- (2-
Chloroimidazole [1,2-a] pyridin-3-yl-sulfonyl) -N '-(4,6-dimethoxy-2-
Pyrimidyl) urea (TH-913), 3- (4,6-
Dimethoxy-1,3,5 triazin-2-yl) -1-
[2- (2-methoxyethoxy) phenylsulfonyl]
-Urea (cinosulfuron), 3- (4,6-dimethoxypyrimidin-2-yl) -1- (2-ethoxyphenoxysulfonyl) urea (ethoxysulfuron) and the like, but are not limited thereto. There is no problem even if one or two or more of these are used in combination.

The herbicidal active ingredient having a fungicidal activity which can be used in the present invention includes, for example, phenothiol, CNP, clomethoxynil, bifenox, benthiocarb, esprocarb, dimepiperate, butachlor, pretilachlor, thenylchlor, mefenacet, dimuron, dimethmethrin, oxadiazon, Pyrazolate, pyrazoxifene, dithiopyr, piperophos, AC
N, cinmethylin, pyributicarb, 3- [4-chloro-5- (cyclobentyloxy) -2-fluorophenyl] -5-isopropylidene-oxazolidine-2,4
-Dione (KPP-314), [R-(+)-n-butyl-2- (4- (2-fluoro-4-cyanophenoxy) phenoxy) propionate (cyhalofop butyl), N, N- Diethyl-3-mesitylsulfonyl-1
H-1,2,4-triazol-1-carboxamide (CH-900), S- (N (4-chlorophenyl)-
N-isopropylcarbamoylmethyl) -O, O-dimethyldithiophosphate (anilophos), methyl = 2
-[(4,6-dimethoxypyrimidin-2-yl) oxy] -6- [1- (methoxyimino) ethyl] benzoate (KUH-920), 2- [2- (3-chlorophenyl) -2, 3-epoxypropyl] -2-ethylindan-1,3-dione (MK-243), 4- (2-chlorophenyl) -N-cyclohexyl-4,5-dihydro-N-ethyl-5-oxo-1H- Tetrazol-1
-Carboxamide (NBA-061), 3- [1-
(3,5-dichlorophenyl) -1-methylethyl]-
2,3-dihydro-6-methyl-5-phenyl-4H-
1,3-oxazin-4-one (MY-100), 3-
[2,4-Dichloro-5- (2-proponyloxy) phenyl] -5-1,1-dimethylethyl) -1,3,4
-Oxadiazol-2 (3H) -one (oxadialgyl), but is not limited thereto, and there is no problem even if one or two or more of these are used in combination.

The names of these compounds are the common names described in "Agrochemical Handbook 1994 Edition" (published by the Japan Plant Protection Association).

The content of these herbicidally active ingredients in the preparation can be arbitrarily changed depending on the kind of the herbicidal active ingredient, but may be added in the range of 0.1 to 60% by weight in the preparation.

The polyvinyl alcohol which can be used in the present invention includes an average degree of polymerization of 2,000 or less and a degree of saponification of 69 to 90.
Mol%, for example, Kuraray Povar P
VA-405 (manufactured by Kuraray Co., Ltd., average degree of polymerization 500,
Saponification degree 80.0 to 83.0 mol%, Kuraray Povar PVA-210 (manufactured by Kuraray Co., Ltd., average polymerization degree 100)
0, saponification degree 87.0-89.0 mol%), Kuraray Povar PVA-420 (manufactured by Kuraray Co., Ltd., average degree of polymerization 2)
000, saponification degree 78.0 to 81.0 mol%), Kuraray Povar L-8 (manufactured by Kuraray Co., Ltd., average polymerization degree 100)
0 or less, a saponification degree of 69.5 to 72.5 mol%), and the like, but is not limited thereto.
There is no problem even if one or more of these are used in combination. The content of polyvinyl alcohol in the preparation is 0.1
-20% by weight, preferably 0.5-15% by weight.

If necessary, for example, thickeners, antifoaming agents, antifreezing agents, antiseptic and antibacterial agents, and stabilizers for herbicidally active ingredients can be used as auxiliaries.

As the thickener, those generally used may be used, for example, xanthan gum, tragacanth gum, casein, dextrin, colloidal hydrous aluminum silicate, colloidal hydrous magnesium silicate, colloidal hydrous aluminum magnesium silicate And water-containing amorphous silicon dioxide. However, the present invention is not limited thereto, and there is no problem even if one or more of these are used in combination.

Examples of the antifoaming agent include silicone-based and fatty acid-based substances; antifreezing agents such as ethylene glycol, propylene glycol and glycerin; and antiseptic and antibiotic agents such as potassium sorbate and p-chloro-metaxylenol. As a stabilizer for the herbicidally active ingredient such as butyl p-hydroxybenzoate, an antioxidant, an ultraviolet ray inhibitor, a crystal precipitation inhibitor and the like may be added, but it is limited to the auxiliary agents exemplified here. Not something.

The aqueous suspension preparation of the present invention can be used irrespective of the water depth, as long as the paddy field after the substituting operation is flooded. In other words, from the state where a slight water layer exists on the soil surface such as when planting rice, the water depth of 3
Until the soil surface is not completely dry, it can be sprayed up to a state where the water is spread to about 5 cm, and it can be used even when irrigation water is supplied. It may be under low water conditions at the time of rice planting such as dropping treatment at the same time as rice planting,
When treated, the herbicidal active ingredient diffuses to some extent, and becomes even more uniform by the subsequent water input, so that a sufficient herbicidal effect can be exhibited.

In addition, it can be sprayed at any time before, during, or after transplanting the rice. Furthermore, it can be applied to directly sowed rice.

The aqueous suspension formulation of the present invention can be sprayed by using the stock solution without diluting it as it is, or by using a small amount of water to prepare a 2 to 5-fold high-concentration diluent and dropping it into a paddy field. However, it is not necessary to apply the ink uniformly over the entire paddy field as in the case of granules. Spraying may be carried out by shaking the stock solution or high-concentration diluent in a container or by spraying or spraying using a pressurized sprayer. In addition, airborne spraying or dripping from RC helicopters, which has become popular in recent years, is also possible. Further, when the irrigation water flows, the inflow water may be dropped at the water intake (water mouth) of the paddy field, and may be poured into the paddy field together with the inflow water.

The application rate per unit area of the aqueous suspension formulation of the present invention is not particularly limited, but in the case of undiluted solution spraying, it is in the range of 0.05 to 2 liters per 10 ares in view of labor and economic efficiency of spraying. And preferably 0.1
It ranges from liters to 1.5 liters. In the case of spraying with a high-concentration diluent (2 to 5 times), 0.1 to 6 liters, preferably 0.2 to 10 liters per 10 ares.
It is from 5 liters to 5 liters.

[0020]

EXAMPLES Next, examples of the aqueous suspension formulation for direct application to flooded sewage paddy fields according to the present invention will be described, but the present invention is not limited thereto.

In the examples, all parts are by weight.

Example 1 77.6 parts of water had an average degree of polymerization of 500 and a degree of saponification of 80.0 to
83.0 mol% of polyvinyl alcohol (trade name "Kuraray Povar PVA-405" manufactured by Kuraray Co., Ltd.) (1 part) was dissolved, and 1.4 parts of a benzulfuron-methyl raw material, 5 parts of a tenylchlor raw material, and 5 parts of propylene glycol were added. In addition,
Dynomill KDL type (Willy A. Bachofe
n AG) so that the average particle diameter of the pulverized liquid was 3 μm. Hard glass beads having a diameter of 0.7 to 1.2 mm were used as the grinding media. 10 parts of a 2% aqueous xanthan gum solution was added to the pulverized liquid, and the mixture was uniformly mixed using a three-one motor (manufactured by HEIDON) to obtain an aqueous suspension preparation.

Example 2 An average degree of polymerization of 1,000 and a degree of saponification of 87.0 in 64.7 parts of water.
Dissolve 3 parts of ポ リ ビ ニ ル 89.0 mol% of polyvinyl alcohol (trade name “Kuraray Povar PVA-210” manufactured by Kuraray Co., Ltd.) and use Jet-O-mizer (manufactured by Seishin Enterprise Co., Ltd.) in advance to obtain an average particle diameter of 3 μm. Then, 0.3 parts of a pulverized pyrazosulfuron ethyl substance, 27 parts of a CNP substance and 5 parts of a 2% xanthan gum aqueous solution are added and mixed using a three-one motor. 5000r
Stirring at pm for 20 minutes gave a homogeneous aqueous suspension formulation.

Example 3 An average degree of polymerization of 1700 and a degree of saponification of 87.0 in 75.8 parts of water.
~ 89.0 mol% of polyvinyl alcohol (trade name "Kuraray Poval PVA-217EE" manufactured by Kuraray Co., Ltd.)
2 parts were dissolved, and 1.4 parts of a benzmeflon methyl base substance, 4.2 parts of a tenylchlor base substance, and cyhalofop butyl 3.6 were prepared.
Parts, propylene glycol 5 parts, Dynomill K
The pulverized liquid was finely pulverized using a DL type so that the average particle diameter of the pulverized liquid was 4 μm. At this time, the pulverization was performed while cooling so that the temperature of the pulverization liquid did not exceed 20 ° C. Hard glass beads having a diameter of 0.7 to 1.2 mm were used as the grinding media. A 2% xanthan gum aqueous solution 8
Was added and mixed uniformly using a three-one motor to obtain an aqueous suspension formulation.

Example 4 76.2 parts of water had an average polymerization degree of 500 and a saponification degree of 72.5 to
4 parts of 74.5 mol% of polyvinyl alcohol (trade name "Kuraray Poval PVA-505" manufactured by Kuraray Co., Ltd.) is dissolved, and 1.8 parts of an imazosulfuron bulk material, 12 parts of a butachlor raw material, and 3 parts of ethylene glycol are added. Using a four-cylinder sand grinder (manufactured by Imex Co., Ltd.), the pulverized liquid was finely pulverized so that the average particle diameter became 3 μm.
In addition, 0.7-1.2 mm in diameter as a grinding medium
Hard glass beads were used. 3 parts of a 2% aqueous xanthan gum solution was added to the pulverized liquid, and mixed uniformly using a three-one motor to obtain an aqueous suspension preparation.

Example 5 An average degree of polymerization of 500 and a degree of saponification of 80.0 to 8 in 91 parts of water.
Dissolve 2 parts of 3.0 mol% of polyvinyl alcohol (trade name "Kuraray Poval PVA-405" manufactured by Kuraray Co., Ltd.), 3.5 parts of a benzulfuron methyl base material, colloidal hydrous aluminum silicate (trade name "Kunipia") G "Kunimine Industries Co., Ltd.) 0.5 parts, propylene glycol 3
Then, the mixture was finely pulverized using a four-cylinder sand grinder so that the average particle diameter of the pulverized liquid became 3 μm to obtain a uniform aqueous suspension preparation. Hard glass beads having a diameter of 0.7 to 1.2 mm were used as the grinding media.

Example 6 An average degree of polymerization of 2,000 and a degree of saponification of 87.0 to 8 in 82 parts of water.
0.5 mol% of polyvinyl alcohol (trade name "Kuraray Poval PVA-220" manufactured by Kuraray Co., Ltd.) is dissolved in 0.5 part, and 12.5 parts of a raw material of tenylchlor and a water-containing amorphous silicon dioxide (trade name "Carplex") are dissolved. # 80 "(Shionogi Pharmaceutical Co., Ltd.) 1.0 part, propylene glycol 3
And pulverized using a four-cylinder sand grinder so that the average particle diameter of the pulverized liquid becomes 3 μm. Hard glass beads having a diameter of 0.7 to 1.2 mm were used as the grinding media. One part of a 2% aqueous xanthan gum solution was added to the pulverized liquid, and the mixture was uniformly mixed using a three-one motor to obtain an aqueous suspension formulation.

Comparative Example 1 In 75.6 parts of water, 2 parts of polyoxyethylene nonylphenyl ether and 1 part of sodium salt of dialkyl sulfosuccinate were dissolved as surfactants, and 1.4 parts of a benzulfuron methyl base substance and a tenyl chlor base substance were dissolved. 5 parts and 5 parts of propylene glycol were added, and pulverized using a Dynomill KDL type so that the average particle diameter of the pulverized liquid was 3 μm. Hard glass beads having a diameter of 0.7 to 1.2 mm were used as the grinding media. 10 parts of a 2% aqueous xanthan gum solution was added to the pulverized liquid, and the mixture was treated with a three-one motor (HEI).
(DON) to obtain an aqueous suspension formulation.

Comparative Example 2 The average degree of polymerization of Example 2 was 1,000 and the degree of saponification was 87.0-8.
A uniform aqueous suspension preparation was obtained by the same composition and operation as in Example 2 except that 3 parts of a polyoxyethylene polyoxypropylene block polymer was used as a surfactant instead of 9.0 mol% of polyvinyl alcohol.

Comparative Example 3 The average polymerization degree of Example 3 was 1700 and the saponification degree was 87.0 to 8
Polyoxyethylene tristyryl phenyl ether (trade name “SOPROPHOR BSU” Rhone) is used as a surfactant instead of 9.0 mol% of polyvinyl alcohol.
A homogeneous aqueous suspension preparation was obtained by the same composition and operation as in Example 3 except that 2 parts (made by Poulin Co.) were used.

Comparative Example 4 The average degree of polymerization of Example 4 was 500 and the degree of saponification was 72.5 to 7.
Polyoxyethylene nonyl phenyl ether 3 as a surfactant instead of 4.5 mol% of polyvinyl alcohol
Parts, and 1 part of sodium dodecylbenzenesulfonate, to obtain a uniform aqueous suspension preparation by the same composition and operation as in Example 4.

Comparative Example 5 Polyoxyethylene alkyl aryl ether sulfate (trade name “SOLPOL 9838P” manufactured by Toho Chemical Industry Co., Ltd.) was used as a surfactant instead of polyvinyl alcohol having a saponification degree of 80.0 to 83.0 mol% in Example 5. 2)
A uniform aqueous suspension preparation was obtained by the same composition and operation as in Example 5, except that parts were used.

Comparative Example 6 Polyoxyethylene styrenated phenol ether phosphate (trade name "SOPROPHOR FL", Rhone-Poulenc) was used as a surfactant instead of polyvinyl alcohol having a saponification degree of 87.0 to 89.0 mol% in Example 6. A uniform aqueous suspension preparation was obtained by the same composition and operation as in Example 6, except that 0.5 part of the product was used.

[0034]

[Effects of the Invention] By carrying out the aqueous suspension formulation for direct application of flooded sewage paddy fields of the present invention, the following effects can be obtained. First, the herbicidal active ingredient, particularly a sulfonylurea herbicide, has good stability. Secondly, since the medicine does not adhere to the rice body at the time of spraying, there is little phytotoxicity to the rice and a high herbicidal effect is exhibited. Third, the herbicidal active ingredient has good diffusibility in paddy water. Fourth, since the preparation is a dispersion using water as a dispersion medium, there is little danger such as ignitability and flammability, and there is no problem on environmental health due to irritation and odor to the human body. Fifth
It can be sprayed at any time after the pudding work,
It is only necessary to drop the medicine from the ridge without being diluted with water while keeping it in the container, or simply drop it into the water mouth at the time of entering the water and pour it together with the inflowing water, which can save the labor of spraying the medicine.

Next, the usefulness of the aqueous suspension preparation of the present invention is shown by test examples.

Test Example 1 Herbicidal active ingredient stability test An aqueous suspension prepared according to the examples was sealed in a glass bottle and stored at 40 ° C. for 90 days. It calculated by the formula of. Each herbicidal active ingredient was analyzed by high performance liquid chromatography (HPL).
C) or by gas chromatography (GC). The results are shown in Tables 1 and 2.

[0037]

(Equation 1)

Test Example 2 Paddy Rice Adhesion and Chemical Damage Test Paddy field soil was filled into a 1/5000 are Wagner pot, and water was added thereto to form a chemical fertilizer (N: P: K = 17: 17: 1).
7) Two g of rice seedlings (variety: Nipponbare) at the 2.5 leaf stage were transplanted per pot after 2 g was mixed and shaved. The test was carried out in three pots in one treatment area (total of six pots),
A day later, 50 μl of the aqueous suspension preparation prepared according to the example was dropped on the center of the leaf blade of the second leaf of rice from a height of 1 cm from the leaf surface with a microsyringe, and the number of strains to which the drug was attached to the leaf blade was investigated. did. Five days after the chemical treatment, the degree of phytotoxicity of rice was investigated according to the following criteria (the degree of phytotoxicity in Tables 1 and 2 is the average value of six strains). The results are shown in Tables 1 and 2.

Investigation criteria 0: No chemical damage 1: A drug mark remains on the adhered part 2: 1/4 or less of the adhered leaf is browned 3: 1/4 to 1/2 of the adhered leaf is browned 4: 1 / of the adhered leaf 2-3: Browning occurs 5: 3/4 or more of the adhered leaves brown 6: Adhered leaves die 7: Adhered leaves die, and 1/2 or less of new leaves (fourth leaf) brown 8: Adhered Leaves die and more than half of new leaves (fourth leaf) brown 9: Adhered leaves and new leaves die 10: Whole rice die

Test Example 3 Diffusion test A test section having an area of one section of 9 (3 m × 3 m) (inundation depth 5c)
m) was prepared, and a sample prepared in accordance with the example was dropped directly from the water surface at a distance of 1 m from the center (point A) with a pipette. Three hours after the treatment, the center (point A) and four corners (BE of the test plot)
(Each point) was collected at a depth of 5 cm to the water surface in an amount of 20 ml each, and the herbicidal active ingredient concentration in the water was analyzed by HPLC.

The water was collected at an inner diameter of 1 cm and a length of 8 cm.
Using a glass tube, gently insert the glass tube into the surface water to a depth of 5 cm, put a rubber stopper on the upper part of the glass tube, gently pull out, collect about 4 ml of the surface water, and perform this operation at the same point.
The method was repeated twice to collect a total of 20 ml of water per point. Then, the diffusivity was represented by the ratio to the theoretical water concentration when the herbicidal active ingredient was uniformly dispersed in the water in the test plot by the following formula.

[0042]

(Equation 2)

The results are shown in Tables 1 and 2.

[0044]

[Table 1]

[0045]

[Table 2]

Claims (2)

[Claims] 1. An aqueous suspension formulation for direct spraying in flooded sewage fields, comprising a sulfonylurea-based herbicidal active ingredient and / or a herbicidal active ingredient having a herbicidal activity as agricultural chemical active ingredients, and polyvinyl alcohol and water. 2. An aqueous suspension preparation for directly spraying a submerged paddy field, wherein the polyvinyl alcohol according to claim 1 has an average degree of polymerization of 2,000 or less and a degree of saponification of 69 to 90 mol%.