JPH1029901A - Soil fumigant and soil fumigation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a soil fumigant which has high safety to workers, easy handleability during the storage and transportation and is useful as an agent for controlling soil diseases, soil insect pests and weeds by formulating a specific component. SOLUTION: This soil fumigant contains a liquid carrier of an organic solvent and/or an inorganic solvent and methyl iodide. The weight ratio of the liquid carrier to the methyl iodide is preferably 8/2-2/8. The solvent in the liquid carrier preferably boils at 80-250 deg.C and is at least one selected from among alcohols, paraffinic hydrocarbons, halogenated hydrocarbons, halogenated alkyl ether and vegetable oil, particularly refined paraffin oil, 1,3-dichloropropene and dichlorodiisopropyl ether are cited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a soil fumigant for controlling soil pests and weeds and a method for fumigating the soil.

[0002]

2. Description of the Related Art Conventionally, various materials and methods have been used to control pests that damage agricultural crops. Among them, soil disinfection (soil fumigation) is one of the effective methods for controlling pests that inhabit the soil or on the soil surface to grow crops soundly, and various chemicals are used. To some extent, there are problems. For example, pesticides used for soil disinfection include methyl bromide, chloropicrin, DD (dichloropropene), sodium N-methyldithiocarbamate, methyl isothiocyanate, dazomet, and the like. It is used for controlling soil diseases, soil pests, soil nematodes, or weeds by mixing with soil.

Some of the problems of the control method using these agents are listed below. For example, methyl bromide is widely used as a soil fumigant, which is effective in controlling pests and weeds in soil.However, since it is a colorless and odorless gas, it has a strong problem of accidental inhalation by users and destruction of the ozone layer. It is pointed out. Chlorpicrin has also been used for a long time because of its excellent pest control effect, but is a drug that is difficult to handle for users due to its lacrimation and irritation,
It has also been pointed out that improper handling may cause irritating odors and damage not only to workers but also to nearby people. DD shows an excellent effect on soil nematodes, but hardly any soil disease or weed control effects. Sodium N-methyldithiocarbamate and methyl isothiocyanate are effective against soil nematodes, but are not sufficiently effective against soil diseases and can hardly be expected to have any weed control effects. Dazomet is effective against soil nematodes and diseases, but has a weak weed control effect, and varies in medicinal efficacy and phytotoxicity due to soil moisture. In addition, all chemicals have a high boiling point except for methyl bromide, and have low vapor pressure, so they remain in the soil for a long period of time when the soil temperature is low, making it impossible to plant crops immediately after treatment. is there.

As a method for applying the above-mentioned soil fumigant,
With the exception of Dazomet, which takes the form of granules, most methods use irrigation at regular intervals in the soil, all of which are narrow due to the narrow diffusion range of the active ingredient in the soil. There is also a problem with the application method such that a sufficient control effect cannot be obtained unless an extremely large number of irrigations are performed at intervals.

[0005] On the other hand, attempts have been made to use methyl iodide as a soil fumigant, and it has been reported that it has physiological activity (Phytopatholog).
y85, p.1168 (1995), India
nJ. Entomology 49, 1987 (1989)). However, it is difficult to use the methods described in these documents as they are as a soil fumigation method because of the physicochemical properties of methyl iodide, and it is almost impossible to use them as they are in agriculture. That is, the boiling point of methyl iodide is as low as 42 ° C., and the vapor pressure at 25 ° C. is as high as 400 mmHg. Therefore, when it is applied as it is, it is extremely easy to volatilize, and when applied to the soil surface or in the soil, not only sufficient effect is not exhibited, but also toxicity to the user caused by volatilization into the air is a problem.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a safe and effective soil fumigant containing methyl iodide as a main component and a method for treating the same.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by mixing methyl iodide with a specific solvent, the volatilization of methyl iodide is temporarily stopped. We found that we could control it. Further, the present inventors have disclosed that a soil fumigant in which methyl iodide is dissolved or dispersed and suspended in an appropriate liquid carrier is a simple manual soil disinfection machine (for example, MI3A (manufactured by Maruyama Seisakusho)) or an automatic disinfection coating device. (For example, MI-205 (Maruyama Seisakusho)
It has been found that various soil pests and weeds can be controlled by irrigating the soil with the fumigant of the present invention at a predetermined interval at a predetermined dose or treating the soil surface. The present inventors have found a soil fumigant and a soil fumigation method that can control soil pests and weeds much more safely and more effectively than treating methyl iodide alone based on the above findings. Was completed.

That is, the present invention provides a soil fumigant characterized by containing a liquid carrier comprising an organic solvent and / or an inorganic solvent and methyl iodide, and a soil characterized by irrigating the soil with the agent. It is a fumigation method.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The liquid carrier used in the present invention has a boiling point of 80 ° C. or higher 2
It is liquid at room temperature below 50 ° C and can dissolve or uniformly disperse and suspend methyl iodide, facilitating its storage, transportation and handling, and when treated on or in the soil, iodide Inorganic or organic solvents that do not prevent the diffusion of methyl in the soil, and mixtures of these solvents.

As the solvent, methanol, ethanol,
Alcohols such as propanol, ethylene glycol and propylene glycol; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as toluene, cumene and solvent naphtha; paraffinic hydrocarbons such as kerosene, white kerosene and mineral oil; soybean oil And vegetable oils such as castor oil and cottonseed oil; dimethylformamide, dimethylsulfoxide, water and the like. Also, halogenated hydrocarbons such as 1,3-dichloropropene and dichlorodiisopropyl ether, halogenated alkyl ethers and the like are suitable as solvents. In addition, two or more of the above solvents can be used in combination in consideration of solubility and stability, and in some cases, an auxiliary agent such as a surfactant and a stabilizer can be used. However, the components of these liquid carriers and auxiliary agents are not limited to those described above. The weight mixing ratio between methyl iodide and the liquid carrier in the soil fumigant of the present invention is from 8: 2 to 2: 8.

When the soil fumigant of the present invention is applied, the amount of methyl iodide is usually 1 to 200 kg / 10a, preferably 5 to 50 kg / 10a.
The formulation amount is 5 to 100 l / 10a, preferably 10 to 10 l / 10a.
An application rate of 50 l / 10a is appropriate. These rates vary depending on the type of liquid carrier,
It also depends on the method, location, type of plant pest and weed, and type of soil. If necessary, it can be mixed with other soil fumigants, fungicides, insecticides, herbicides, pesticides such as plant growth regulators, soil improvers or fertilizers, or can be simultaneously applied.

Examples of pests for which the composition and method of the present invention are effective include sweet potato blight, vine wilt, purple scab, black bruise; potato scab, black bruise; Seedling wilt, vine rot, plague; melon black spot rot; eggplant half body wilt, wilt; tomato white rot,
Wilt, half body wilt, wilt; Strawberry blight, yellow wilt; Spinach wilt, wilt, root rot; Brassica root-knot disease, root constriction, wilt, yellowing;
Carrot root rot, dry rot; pea root rot; kidney bean scab; celery wilt, yellow rot; parsley wilt; tobacco wilt, plague, black root, dwarf A disease caused by a filamentous fungus or bacterium such as carnation blight or wilt; furthermore, various virus diseases, nematodes, scarab beetles, caterpillars, keratosis, etc., but are not limited thereto. Absent. Examples of weeds for which the compositions and methods of the invention are effective include, but are not limited to, various grasses, cyperaceae, and broadleaf weeds.

[0013]

Next, the present invention will be described with reference to examples and test examples, but the present invention is not limited to these examples. In the examples, “parts” represents “parts by weight”.

Example 1 Soil fumigant A 30 parts of methyl iodide, 10 parts of ethylene glycol,
White kerosene: 60 parts were uniformly mixed and dissolved to obtain a soil fumigant.

Example 2 Soil fumigant B A soil fumigant was obtained by uniformly mixing and dissolving 20 parts of methyl iodide, 10 parts of propanol, and 70 parts of white kerosene.

Example 3 Soil fumigant C Soil fumigant was obtained by uniformly mixing and dissolving 40 parts of methyl iodide and 60 parts of white kerosene.

Example 4 Soil fumigant D Methyl iodide: 30 parts, 1,3-dichloropropene: 4
0 parts and 30 parts of white kerosene were uniformly mixed and dissolved to obtain a soil fumigant.

Example 5 Soil fumigant E 10 parts of methyl iodide, 40 parts of dichlorodiisopropyl ether and 50 parts of white kerosene were uniformly mixed and dissolved to obtain a soil fumigant.

EXAMPLE 6 Soil Fumigant F Methyl iodide: 20 parts, 1,3-dichloropropene: 6
0 parts and 20 parts of white kerosene were uniformly mixed and dissolved to obtain a soil fumigant.

Test Example 1 Spinach wilt control test (soil irrigation treatment) Spinach wilt fungus (Fusarium oxysp)
orum f. sp. Example 3 or 4 after sufficiently cultivating and leveling the field contaminated with S. spinaceae)
Fumigant C or fumigant D prepared as above is put into a soil disinfecting machine (MI3A, manufactured by Maruyama Seisakusho Co., Ltd.) and the depth is 1
A predetermined amount was irrigated at 30 cm intervals or 45 cm intervals at 5 cm, and immediately covered with a polyethylene film (0.03 cm thickness). The section was tested with a width of 90 cm and a length of 5 m. 14 days after the treatment, the coating was removed, and spinach seeds (variety: Splendor) were sown. Methyl iodide drug substance and carbam sodium 30% as control drugs
Using a liquid agent (sodium N-methyldithiocarbamate, trade name: Kilper), treatment was carried out in the same manner as the above agent. 14 days after the treatment, the coating was removed, and the sodium N-methyldithiocarbamate test plot was again tilled and degassed.
Seven days later, spinach seeds (variety: Splendor) were sown. 40 days after sowing, the degree of wilt disease was observed and evaluated for any 200 strains. The results are shown in Table 1 (Table 1).

[0021]

[Table 1] In the carbam sodium treatment group, poor germination and growth suppression, which are considered to be caused by chemical damage, were observed at a rate of about 50%. There was no phytotoxicity in the other test drugs and in the methyl iodide drug substance-treated area.

Test Example 2 Test for controlling root-knot nematodes of sweet potato (soil irrigation) After sufficiently cultivating a field contaminated with root-knot nematodes of sweet potato, fumigant C or fumigant D prepared as in Example 3 or 4 was used. Soil disinfection machine (MI3A,
Maruyama Seisakusho Co., Ltd.), 30cm at 15cm depth
A predetermined amount was irrigated at m intervals or 45 cm intervals, and immediately covered with a polyethylene film (0.03 cm thickness). The section was tested with a width of 90 cm and a length of 5 m.
After 14 days from the treatment, the coating was removed, and tomato seedlings (cultivar: the world's best, 3 leaf stage) were transplanted. Methyl iodide drug substance and sodium N-methyldithiocarbamate (carbam sodium) were used as control drugs and treated in the same manner as the above drugs. 14 days after the treatment, the coating was removed, and the N-methyldithiocarbamate test plot was again tilled and degassed. After 7 days, as in the other test drug plots, tomato seedlings (variety: the world's first and third leaf stage) Was transplanted. Forty days after transplantation, arbitrary 50 strains were observed and evaluated for the degree of root knot formation by the sweet potato root-knot nematode.

[0023]

[Table 2] The phytotoxicity of growth suppression was observed in the carbam sodium treatment group. There was no phytotoxicity in the other test drugs and in the methyl iodide drug substance-treated area.

Test Example 3 Measurement of Aerial Concentration After sufficiently cultivating and leveling the field, fumigant C, fumigant D or methyl iodide prepared as in Example 3 or 4 was applied to a soil disinfecting machine (MI3A). , Manufactured by Maruyama Seisakusho Co., Ltd.) and irrigated with a predetermined amount at an interval of 30 cm at a depth of 15 cm.
l of air was sampled, and the amount of methyl iodide volatilizing from the soil to the ground surface was measured.

[0025]

[Table 3] As is evident from the results of the test examples, the amount of methyl iodide volatilized from the soil surface into the atmosphere after the treatment was significantly suppressed as compared with the case where the raw material was used as it was. This means that the safety for the worker is enhanced, and it can be seen that the soil fumigant of the present invention and the treatment method thereof are extremely useful.

[0026]

EFFECT OF THE INVENTION The soil fumigant of the present invention and the method for fumigating the soil have no phytotoxicity, show a far superior effect as compared with a commercially available soil fumigant, and are compared with the case where the methyl iodide drug substance is used as it is. It shows excellent effects and is highly safe for workers. In addition, the soil fumigant of the present invention is effective in handling because it can suppress volatilization at room temperature during storage and transportation before use.

Claims (6)

[Claims] 1. A soil fumigant comprising a liquid carrier comprising an organic solvent and / or an inorganic solvent and methyl iodide. 2. The soil fumigant according to claim 1, wherein the boiling point of the solvent in the liquid carrier is from 80 ° C. to 250 ° C. 3. The method according to claim 1, wherein the solvent is selected from at least one selected from the group consisting of alcohols, paraffinic hydrocarbons, halogenated hydrocarbons, halogenated alkyl ethers and vegetable oils. The described soil fumigant. 4. The soil fumigant according to claim 1, wherein the solvent is at least one selected from the group consisting of white kerosene, 1,3-dichloropropene, dichlorodiisopropyl ether and the like. 5. The soil fumigant according to claim 1, wherein the weight mixing ratio between methyl iodide and the liquid carrier is from 8: 2 to 2: 8. 6. A soil fumigating method comprising irrigating the soil fumigant according to claim 1 into soil.