JPH034521B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a harmful nematode control agent. Traditionally, perennial crops such as fruit trees and tea trees, side dishes, etc.
Damage caused by harmful soil nematodes to annual crops such as root vegetables has been considered a problem, but in recent years, as the intensive use of farmland, facility cultivation, and special production areas have progressed, continuous cropping or short-term crop rotation cultivation is no longer necessary. As a result, the damage caused by harmful nematodes is becoming even more serious. In other words, in a country like Japan, where the area of cultivated land is small and the distribution market for field crops is fully equipped, it is necessary to invest in equipment such as greenhouses on the limited farmland in order to achieve highly profitable agricultural management.
Since cultivation methods that produce high yields and high quality in a small area cannot be easily relocated, efforts are being made to avoid damage from harmful soil nematodes through crop rotation, which has long been considered the ideal cultivation method. In reality, it has become impossible. Damage caused by harmful soil nematodes manifests itself in a variety of ways, but the most common ones are suppression of early growth or death, and an accompanying reduction in yield. In addition, root vegetables may become deformed or have scratches on their surfaces, severely reducing their commercial value. Furthermore, if continuous cropping is carried out without taking any control measures, the density of nematodes in the soil, where damage occurs, will become extremely high, making it impossible to grow. Against the above background, there is a strong demand for a control agent for harmful soil nematodes that is easy and rational to apply, safe, inexpensive, and exhibits an appropriate control effect. In general, nematocides come in the form of emulsions, oils, and granules because they are applied at the site of damage, ie, in soil. The first two require special injection equipment due to spot injection or irrigation methods. The latter is generally applied by hand or by using a granulator. In addition, powders can be considered, but they are rarely used because of problems such as scattering of the chemicals during use. Among these dosage forms, those in the form of granules can be processed manually as described above in the pre-planting treatment, or can be processed using a granulator for large areas. It also has the advantage of being able to be treated by mixing it with fertilizer. Furthermore, the powder does not scatter during application and does not stain the sprayer's clothes, which is very desirable in terms of safety and health, and it is simple and rational as it does not require time or hard labor or special machinery. be. In addition, the usual method for mid-piling treatment is furrow or interplant treatment, but if it is in granule form,
Chemical processing work is easy. As described above, the ideal dosage form for the control agent for harmful nematodes is in the form of granules. Conventionally, the main agents known as harmful nematode control agents are halogenohydrocarbon-based fumigants, such as chloropicrin (trichloronitromethane),
There are methyl bromide, DD (1,3-dichloropropene), EDB (ethylene dipromide),
Due to their physicochemical properties, these drugs are used in the form of oils or emulsions, or the active ingredients themselves are placed in special containers such as cylinders. In addition, it has safety problems for humans and animals such as mucous membrane irritation and odor, and is highly corrosive to metals, making it inconvenient to handle. Furthermore, special machinery is required for use, and in order to achieve the post-application effect, the surface of the soil must be sealed with water or coated with polyethylene, etc. for a certain period of time to prevent gas from escaping.
In order to prevent chemical damage, it is necessary to plow after a certain period of time to dissipate the gas into the atmosphere, which is extremely inconvenient in terms of work. In addition, halogenated hydrocarbon compounds have relatively high boiling points, so some of them can be made into granules, such as DBCP (1,2-dipromo-3-chloropropane), DCIP ( However, the former is prohibited from being manufactured because it is toxic to humans and remains in soil and river water for a long time, and the latter has the problem of low nematicidal effect. There is. Other fumigants include dazomet (tetrahydro-3,5
-dimethyl-2H-1,3,5-thiadiazine-
2-thione), but the active ingredient is 10% to achieve the effect.
A large amount of 20 to 30 kg is required per area, and watering is also required to increase the moisture content of the soil. Furthermore, it has high herbicidal activity and requires more degassing than halogeno hydrocarbon pesticides to remove methylthioisocyanate decomposed in the soil, which is very inconvenient to use. There is no generality. On the other hand, unlike fumigants, systemic harmful nematode control agents are also known, and most of them take the form of granules, but for example,
Fensulfo-thion [0,0-diethyl 0-(4-methylsulfinyl)-phenyl phosphorothioate], Ethoprop (0-ethyl s,s-dipropyl phosphorodithioate), Phenamiphos [ethyl 3-methyl-4 -(methylthio)phenyl(1-
methyl ethyl) phosphoroamidate],
Carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranylmethylcarbamate),
Aldicarb [2-methyl-2-(methylthio)propionaldehyde 0-(methylcarbamoyl)oxime]. All of these drugs are highly toxic to humans and animals, and their use is prohibited in Japan.In the United States, for safety reasons, they are only permitted to be used in granule form, and only by experts. As mentioned above, the currently used soil harmful nematode control agents have some limitations in use or storage, are not universal, and are becoming unsuitable for future crop cultivation methods. ,
At present, there is a strong desire for the emergence of a harmful soil nematode control agent that does not cause environmental pollution, is safe for humans and livestock, and is easy to use, effective, and inexpensive. As a result of extensive research to solve these problems, the present inventors have found that certain thiol carbamate esters are extremely effective compared to currently commercially available pesticides such as DD, EDB, and DCIP. It has excellent harmful nematode control effects at low dosages without causing any chemical damage to crops, and is particularly effective in the form of emulsions and oils, as well as granules, which are ideal as soil treatment agents. The present invention has been completed. The present invention is based on the general formula (In the formula, R represents a linear ethyl, propyl, or butyl group.) This agent is characterized by containing a compound represented by the following as an active ingredient. Thiol carbamate esters consisting of N,N-dialkylamines have been known as compounds with herbicidal activity in the past, but their physiological activity against harmful nematodes is completely unknown, and no examples of their practical applications are known. . Moreover, when R in the general formula () is an alkyl group having 5 or more carbon atoms, or when one alkyl group of the asymmetric amine is a group other than a methyl group, the growth of crops may be inhibited, true leaves may be rolled, or Among the thiol carbamate esters consisting of asymmetric dialkylamines, it is not useful as an active ingredient of a soil harmful nematode control agent because it causes chemical damage such as withering and its nematicidal activity is greatly reduced. Pesticides containing compounds as active ingredients are particularly useful without causing any phytotoxicity to crops. The active ingredient content of the soil harmful nematode control agent of the present invention is suitably in the range of 5 to 30% if it is in the form of granules, and 5 to 90% if it is in the form of oil or emulsion. In addition, when using, the amount of active ingredients per 10 ares is 1 to 3 kg.
Dropping can provide a sufficient pest control effect, but it is usually preferable to drop 2 kg. Furthermore, if it is in the form of granules, it can be applied by mixing the entire surface with soil in the pre-planting treatment, or mixed with fertilizer, and it can be applied between the furrows or between plants during the raising of the crop after planting. On the other hand, if it is in the form of an oil or emulsion, it can be applied by a conventional method by dripping or irrigation. The compound represented by the general formula () according to the present invention can be easily and inexpensively prepared by reacting the corresponding secondary amine with carbonyl sulfide and reacting the resulting carbamate salt with methyl chloride or dimethyl sulfate. can be manufactured. Their physical properties are as follows. When formulating the agent for controlling harmful nematodes of the present invention, it can be mixed with various carriers and made into a dosage form such as granules, oils, emulsions, etc. using ordinary agrochemical formulation techniques.
Particularly desirable are granules. The carrier used may be either liquid or solid, or a combination thereof.
Examples of solid carriers include bentonite, talc, kaolin clay and diatomaceous earth. Liquid carriers include inert organic solvents such as xylene, orthochlorotoluene, methylnaphthalene, isophorone, kerosene, and the like. Furthermore, during formulation, a surfactant or the like may be added to impart emulsifying and dispersing properties. Examples of formulations are shown below. Parts in the text are parts by weight. Example 1 (Granules) S-Methyl-N-methyl-N-ethylthiol carbamate () 10 parts Granular diatomaceous earth (10 to 16 mesh) 90 parts The active ingredient was impregnated into granular diatomaceous earth, and the granules of the present invention were prepared. did. Example 2 (Granules) Diatomaceous earth 70 parts Bentonite 25 parts Rapizol B-80 (dispersant, NOF Corporation trademark)
Water was added to 5 parts or more, mixed, and the mixture was granulated and dried using a conventional granulation method. 85 parts of this granular carrier was impregnated with 15 parts of S-methyl-N-methyl-N-propylthiol carbamate () to prepare granules of the present invention. Example 3 (Oil agent) 10 parts of S-methyl-N-methyl-N-butylthiol carbamate () and 90 parts of O-chlorotoluene were mixed and dissolved to prepare an oil agent of the present invention. Example 4 (Emulsion) S-Methyl-N-methyl-N-ethylthiol carbamate () 80 parts Xylene Sorbol 800A (emulsifier, trademark of Toho Chemical Co., Ltd.)
At least 10 parts were mixed and dissolved to form an emulsion of the present invention. Next, the pesticidal effect of the present invention will be explained using test examples. Test Example 1 Control test against sweet potato kob nematode using tomatoes as an indicator Fill pots contaminated with sweet potato kob nematode (meloidogyne incognita) grown using sweet potatoes as hosts into 1/10000a pots with a height of 14 cm, and conduct according to Example 1. A predetermined amount of the prepared granules was mixed. For comparison purposes, DCIP 30% granules, a commercially available nematicidal granule, were also treated in the same manner. After each chemical treatment, the pots were left for 7 days, and 10 tomato seeds were sown per pot. The test was conducted in a glass greenhouse (25-30°C), and one month after sowing, the degree of root gall parasitism, chemical damage, and stem and leaf weight were investigated. The test was repeated three times, and the average value of the results is shown in Table 1. The degree of root gall parasitism and chemical damage were expressed according to the following criteria. Degree of root gall parasitism Number of root galls Corresponding disease index 0...... None 0 1...... 1-8 1-25% 2...... 9-20 26-50% 3...... 21-30 51-75 % 4...30 or more 76-100% Chemical damage - No chemical damage observed at all. ±……Minor drug damage was observed. ＋……Recognize harmful symptoms. ...Recognizable signs of harm. ...No germination or withering

【table】

[Table] Test Example 2 Control test against sweet potato knot nematode using Toyato as an indicator A predetermined amount of the oil preparation prepared according to Example 3 was injected at one spot at a depth of 8 cm in the center of the pot. Furthermore, each pot was sealed with 50 ml of water. For comparative purposes, commercially available nematicides DD and EDB were also treated in the same manner, and DD and EDB were tilled on the 5th day for degassing. Eight days after each chemical treatment, tomatoes were sown according to Test Example 1, and one month after sowing, the degree of root gall parasitism and chemical damage were investigated. The test was repeated three times, and the average value of the results is shown in Table 2.

【table】

[Table] Test Example 3 Control test against Pratylenchus penetrans using burdock as an indicator A pot contaminated with Pratylenchus penetrans grown using kidney beans as a host was filled into a 1/10000a pot with a height of 14 cm, and Example 2
A predetermined amount of the granules prepared by the method was mixed. Note that a comparative drug was also treated in the same manner. Seven days after the treatment, five burdock seeds were sown per pot. The test was conducted in a glass greenhouse (25-30℃).
Fifty days after sowing, the degree of root damage, chemical damage, and total weight were investigated. The test was repeated three times, and the average value of the results is shown in Table 3. The degree of damage to the roots was determined as follows based on the number of browned parts of the roots.
Further, regarding chemical damage, the same procedure as in Test Example 1 was conducted. Degree of damage Number of browning areas Equivalent morbidity index 0...... 0...... 0 1...... 1-5... 1-25% 2...... 6-10... 26-50% 3...... 11- 15……51~75% 4……16 or more……76~100%

【table】

[Table] As shown above, the agent of the present invention exhibits a high control effect against sweet potato knot nematodes and northern red cabbage nematodes that cause severe damage to crops. Furthermore, it has the excellent feature of not causing any chemical damage to tomatoes, burdock, etc.

Claims (1)

[Claims] 1. General formula (In the formula, R represents a straight-chain ethyl, propyl, or butyl group.) An agent for controlling harmful nematodes on soil, characterized by containing a compound represented by the following as an active ingredient.