JPS6350323B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to kasugamycin or its salts (referred to as KSM), methyl 1-(n-butylcarbamoyl)benzimidazol-2-yl-carbamate (referred to as benomyl), and bis(dimethylthiocarbamoyl) disulfide (referred to as TMTD).
This invention relates to a seed disinfectant characterized by containing a mixture of three types of as an active ingredient. The aim is to provide a new seed disinfectant that has a broad disinfection spectrum against rice blast, sesame leaf blight, baka-nae disease, and seedling rot caused by rice blight bacteria. It is in. Conventionally, as seed disinfectants, benomyl, a mixture of benomyl and TMTD, 1,2-bis(3-methoxycarbonyl-2-thioureido)benzene (thiophanate methyl), 1,2-bis(3-ethoxycarbonyl- Many drugs have been put into practical use, such as a mixture of 2-thioureido)benzene (thiophanate) and TMTD. Until now, when these were used as rice seed disinfectants, pathogenic bacteria such as rice blast, sesame leaf blight, and bakanae blight were the main targets of disinfection. However, in the method of raising rice seedlings in rice seedling boxes for mechanical transplantation, which has become widespread in recent years from the viewpoint of labor saving in rice farming and improvement of cultivation techniques, seedlings are raised in rice seedling boxes at a constant temperature of 28 to 35 degrees Celsius in order to ensure uniform germination.
The seeds are left in the sun and then cultivated under hot and humid conditions. Along with this, bacterial rice blight disease (scientific name: Pseudomonas glumae)
Rice seedling rot disease occurs frequently due to this disease, but existing drugs have little control effect. Particularly in early cultivation areas and cold regions, rice seedlings are cultivated in plastic greenhouses or plastic tunnels during the early and middle stages of growth, so rice blast disease and rice seedling rot disease tend to occur frequently. However, the reality is that there is no seed disinfectant that is particularly effective against rice seedling rot, which is viewed as a particular problem. The present inventors have conducted intensive research to develop a new seed disinfectant that compensates for the drawbacks of conventional chemicals. As a result, it has been widely used as a foliar spray for controlling rice blast disease.
By using a mixture of KSM, benomyl, and TMTD, which have already been put into practical use as seed disinfectants, we successfully solved the above problems. In other words, the seed disinfectant of the present invention exhibits an outstanding control effect on rice seedling rot as well as rice baka-seed disease and sesame leaf blight, and is also used during the standard cultivation period in the box seedling method.
It has an ideal seed disinfection effect that can prevent seedling blast infection for several days. As is clear from the test examples described below, the seed disinfection effect was demonstrated when KSM, Benomyl, and TMTD were applied alone or when two of them were used for controlling rice seedling rot and rice blast. It has been found that there is a synergistic disease control effect enhancement effect that even those skilled in the art would not have expected from the effects when used in combination. In other words, for the first time, a practically excellent seed disinfection effect was observed by using three types of chemicals together against diseases for which the effect was weak when using each agent alone or as a mixture of the two. It has a much wider range of effects than existing drugs and has a more powerful effect. The present invention has been made based on such new findings, and is something that even those skilled in the art could not have imagined. Furthermore, the seed disinfectant according to the present invention can exhibit superior effects compared to existing chemicals, and is therefore highly practical. When carrying out the present invention, the active ingredient is diluted with a carrier and formulated into a commonly used form, such as a wettable powder, emulsion, tablet, granule, powder, powder coating, etc., and then prepared according to a known method. can be used. These formulations may generally contain between 10 and 70%, preferably between 20 and 50%, by weight of the seed disinfectant of the invention. At this time, the blending ratio of benomyl and TMTD to KSM in the preparation is preferably 1:2 to 20:2 to 30 parts by weight, but they can be further blended in an appropriate ratio if necessary. Next, some examples of the seed disinfectant according to the present invention will be given, but the present invention is not limited to the following examples. In addition, all parts in the following examples indicate parts by weight. KSM also used hydrochloride. Example 1 Wettable powder A wettable powder is obtained by uniformly mixing and pulverizing 2.3 parts of KSM, 20 parts of benomyl, 20 parts of TMTD, 3 parts of lauryl sulfate, 2 parts of white carbon, and 52.7 parts of sucrose. Example 2 Wettable powder 2.3 parts of KSM, 20 parts of benomyl, 20 parts of TMTD, sodium naphthalene sulfonate-formalin condensate 4
1 part, 7 parts of sodium dodecylbenzenesulfonate, and 46.7 parts of clay are uniformly mixed to obtain a wettable powder. Next, the usefulness of the seed disinfectant according to the present invention will be specifically explained using test examples. Test Example 1 Seed disinfection effect test on paddy affected by rice bacterium blight Sample rice: Rice blight bacterium suspension (bacterial concentration: 1
Seed rice of the variety "Sasanishiki" obtained by spray inoculation with ¹⁰⁸ seeds per ml. Test drug: KSM hydrochloride (KSM
2% hydration powder prepared from (purity 86.1%),
For single use of Benomyl and TMTD, 20% hydrating powder prepared from each pure product was used and diluted with water to the specified concentration. The two-drug mixed area was prepared by diluting each drug with water to a concentration twice the predetermined concentration, and then thoroughly mixing and stirring equal amounts of each drug. The three-drug mixed area was prepared by diluting each drug with water to a concentration three times the prescribed concentration to be tested, and then thoroughly mixing and stirring equal amounts of each drug. Test method: 15 times the diseased paddy was placed in a sarannet bag.
I sent it to g. Seed disinfection with the test chemical was carried out at 48°C at 15°C in a chemical solution with a 1:1 ratio of the amount of diseased rice to the amount of disinfectant.
Disinfect by soaking for an hour. After disinfection, the rice seeds were soaked in stagnant water for 3 days. After soaking, the seed rice is kept at 30℃.
After 24-hour germination treatment, the seeds were densely sown on Pearl Mart soil (trade name) according to the mechanical planting box seedling method, kept in a thermostat at 32℃ for 2 days for germination treatment, and then cultivated in a plastic greenhouse. Managed. To investigate the onset of seedling rot, 10 days after sowing,
The number of rotten and dead seedlings and the number of leaf sheath browning seedlings were examined for 1/2 of the plot, and the disease severity was calculated using the following formula, and the seedling rot control value (%) was calculated from the comparison with the disease severity in the untreated area. Incidence of disease = Number of rotting and dead seedlings x 10 + Number of seedlings with browned leaf sheaths x 3 / Total number of surveyed seedlings x 10 x 100 The test was conducted in triplicate per section, and the average control value was determined. The results are shown in Table 1.

[Table] As a control drug, a commercially available hydrating agent containing 2% streptomycin was used. Test Example 2 Rice Blast Control Efficacy Test Chemical treatment and cultivation management were carried out in almost the same manner as in Test Example 1, except that the rice sample was uninoculated rice of the variety "Asahi". However, 20 days after sowing (2.8 leaf stage), 15 ml of rice blast fungus spore suspension (spore concentration: 150 spores per field of view under a 150x optical microscope) was sprayed and inoculated per seedling box, and kept in a moist room at 24°C for 20 hours. I kept it. After inoculation, the seedlings were transferred to the plastic greenhouse again, and 5 days after inoculation, the number of spreading lesions of blast disease on the third leaves of the 300 seedlings per box was investigated.
The rice blast control value (%) was calculated using the following formula. Control value = 1-A/B x 100 However, A is the 300 leaves surveyed in the treatment area (3rd leaf)
B shows the average number of blast-expanding lesions per leaf, and B indicates the number of blast-expanding lesions in the untreated plot. The results are shown in Table 2.

[Table] As a control drug, a commercially available thiram and thiophanate methyl hydrating agent containing 30% each of thiophanate methyl and TMTD was used. Test Example 3 Seed disinfection effect test on rice bakanae disease-affected paddy and rice sesame leaf blight-affected paddy (1) Rice bakanae disease Test paddy: Rice bakanae disease fungus (Fusarium monylform) was applied during the flowering period of the variety Kuebsa. Artificially inoculated rice grains obtained by spray inoculating a concentrated spore suspension twice with water and then air-dried. Test drug: Prepared according to Test Example 1. Test method: 15 g of the air-dried diseased paddy was placed in a Saranette bag. Seed disinfection is carried out by adding 15% of the amount of diseased rice to the sample disinfectant in a chemical solution with a ratio of 1:1.
It was sterilized by soaking at ℃ for 24 hours. After disinfection, the rice seeds were pre-soaked for 6 days at 15°C after washing with water. After pre-soaking, the rice seeds were germinated at 30℃ for 24 hours, then densely sown on Pearlmart medium (trade name) according to the mechanical planting box seedling method, stored in a thermostat at 32℃ for 2 days, and then Cultivation was managed by placing them side by side in a vinyl greenhouse. The disease onset was investigated by visual observation 32 days after sowing (5-leaf stage) to determine the number of seedlings affected by rice baka-nae disease (elongated length and diseased and dead seedlings), and the seed disinfection rate (%) was calculated using the following formula. Seed disinfection rate = 1 - number of diseased seedlings in treated area / number of diseased seedlings in untreated area x 100 (2) Rice sesame leaf blight Test paddy: Naturally infected paddy from 1972 (variety: Kinki)
No. 33) was washed with water and air-dried. Test drug: Prepared according to Test Example 1. Test method: 10g of the air-dried rice packed in a sarannet bag was immersed in a test chemical solution at a ratio of 1:2 of the rice to the chemical solution at 15°C for 5 days.
Seed sterilization was performed on paddy affected by rice sesame leaf blight.
After disinfection, the rice seeds were germinated for 20 hours at a temperature of 30°C, then densely sown on Kumiai synthetic potting soil (trade name) according to seedling cultivation, and stored in a thermostat at 32°C for 2 days before being placed in a glass room. I left it there. Disease onset was investigated 20 days after sowing (2.8 leaf stage) by examining the number of diseased seedlings according to disease severity using the following investigation criteria.
Then, the control value (%) was determined from the seedling incidence (%) of the sum of the disease severity (severe) and disease severity (medium). The test was conducted in two consecutive sessions in one area, and the average control value was calculated. Severity of disease (light): The lesions (browning disease) on rice seedlings are limited to only a small portion of the primary leaves or the coleoptile leaves (those whose growth status is almost the same as healthy seedlings without disease). Disease severity (medium): Most of the primary leaves turn brown and die.
Parts of the first or second leaves also have brown lesions (leaf age is comparable to that of healthy seedlings, but plant height is clearly inferior to healthy seedlings). Disease severity (severe): Growth is extremely poor and curved, and the entire plant is browning and dying (growth only reaches almost the first leaves or the entire plant appears in a clustered manner). The results are shown in Table 3.

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Claims (1)

[Claims] 1 Kasugamycin or its salts and methyl 1-
A seed disinfectant characterized by containing a mixture of three types of (n-butylcarbamoyl)benzimidazol-2-yl-carbamate and bis(dimethylthiocarbamoyl)disulfide as an active ingredient.