JPH0247961B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a fungicide for controlling plant diseases that has an excellent control effect on plant diseases derived from fungi of the genus Botrytis, Fusarium, Helminthosporium, and Alternaria. Regarding drugs. Many organic synthetic compounds and antibiotics with antibacterial properties have been discovered and developed as agricultural fungicides, contributing to the stable supply of agricultural products.However, in recent years, so-called drug resistance of plant pathogens has actually increased. This issue has come to be viewed as important. The current effective method for preventing the emergence of resistant bacteria is the alternating or mixed application of agents with different antibacterial operations against pathogenic bacteria. Therefore, there is a need to develop a fungicide different from conventional fungicides. As a result of examining the plant disease control effects of various antibiotics, the present inventors found that the formula () We have discovered that frenolicin B, represented by the following formula, exhibits an excellent control effect on plant diseases of agricultural and horticultural crops originating from Botrytis, Fusarium, Helminthosporium, and Alternaria, and have completed the present invention. . The frenolicin B of the present invention represented by the formula () is
J. Antibiotics 31 , 959 (1978), and is said to have some activity against the rice blast fungus (Piricularia) in vitro. They tested it in vivo against the blast fungus and found no activity. However, frenolicin B of the present invention has no known control effect on plant diseases of fruit trees and vegetables, and has a high control effect on fungi of the genus Botrytis, Fusarium, Helminthosporium, and Alternaria. What we have shown is something that was discovered for the first time by the present inventors. Diseases to be controlled that the frenolicin B of the present invention exhibits a practically excellent control effect include
Examples include gray mold on vegetables such as eggplant and strawberries, black spot on pears, tomato wilt, and leaf blight on rice and sesame, and it also shows a control effect on sclerotium on cucumbers. Diseases caused by bacteria of the genus Alternaria include black spot of pears and leaf spot leaf blight of apples, and diseases caused by bacteria of the genus Botrytis include gray mold of vegetables such as cucumbers, eggplants, and strawberries, and Fusarium. Diseases caused by bacteria of the genus Helmintosporium include seedling blight of rice, vine splitting of Japanese cucumbers, and wilt of tomatoes. Examples include nuclear disease. As described above, it has excellent properties, and its use as a fungicide for agriculture and horticulture is agriculturally beneficial. Regarding the method for producing frenolicin B of the present invention,
J. Antibiotics, 31 , 959 (1978) and JP-A-1978-
It is described in Japanese Patent No. 110395 and can be obtained by this method. When applying frenolicin B of the present invention,
It can be used in a conventional manner, for example, in the form of powder, wettable powder, oil, emulsion, granule, etc. The application concentration varies depending on the application situation, application time, application method, crop, etc., but generally it is 10~
1000 ppm, preferably 100-500 ppm is suitable. Furthermore, it can be used without any problems even when mixed with other fungicides and insecticides. Next, the present invention will be explained with reference to examples and formulation examples, but the present invention is not limited to the scope of these examples. Example 1 Gray mold prevention test Kiyu cucumber seedlings (variety Sagami Hanshiro) grown for about 3 weeks
1 of a predetermined concentration of a chemical solution of a hydrating agent of the compound of the present invention.
After spraying 30ml per pot and air drying, inoculate with Botrytio cinerea mycelia and leave for 4 days.
After keeping it in a humid room at 20°C, the degree of disease onset was investigated, and the control value was calculated using the following formula based on the degree of disease onset in the untreated control plot. The results are shown in Table 1. Control value = (Incidence in untreated area) - (Incidence in treated area) / Incidence in untreated area

[Table] Example 2 Pear black spot prevention test A 3-year-old pear seedling (variety: 20th century) was used as a test plant, and each seedling was allowed to produce 3 to 4 new shoots.
When 10 to 20 new leaves had developed, a chemical solution prepared by diluting an emulsion of the compound of the present invention with water to a predetermined concentration was sprayed onto each leaf in an amount of 50 ml. After spraying and air-drying, conidia of pear black spot fungus (Alternaria kikuchiana) obtained by culturing on PSA medium for 10 days were suspended in water and inoculated onto the top 3 to 5 cut leaves of each branch. I immediately put it in a humid room. Two days after inoculation, the degree of disease onset was investigated using the disease index of 0, 1, 2, 3, 4, and 5 as shown below. The results are shown in Table 2. Disease state index No lesions observed 0 Less than 10% lesions observed on the leaf surface 1 ″ 10-20% ″ 2 ″ 20-40% ″ 3 ″ 40-60% ″ 4 ″ 60% or more ″ 5

[Table] Example 3 Control test against tomato wilt Tomato seedlings grown in pots (variety: Fukuju No. 2,
Gently pull out the first node leaf development) without damaging the roots and culture with shaking in Richard's medium for 2 days (25℃)
Fusarium oxysporum (Fusarium oxysporum)
oxysporum) for a few seconds and immediately put it in another pot (8 cm in diameter and 200 g of soil).
(containing). This tomato seedling has a soil temperature of 28
Placed in a greenhouse maintained at ~35°C. One day after inoculation, frenolicin B was adjusted to a predetermined concentration and treated (irrigated) into the soil at a rate of 10 ml per pot. The investigation was conducted by cutting tomato stems with a razor two weeks after inoculation.
The degree of browning of the conduit was observed. The results are shown in Table 3 according to the following criteria. 0: No browning at all 1: Browning only underground 2: Up to the ground level 3: Futaba 4: First node leaves 5: Wilting and withering

[Table] Example 4 Control effect test against rice sesame leaf blight Rice grown in pots (variety: Nipponbare, 5-leaf stage)
20ml of drug solution adjusted to the specified concentration per pot.
It was abolished at a rate of One day after withdrawal of vaccination, PSA
A spore suspension of rice and sesame leaf blight fungus (Helminthosporium oryzae) formed on a medium (cultivated at 28°C for 10 days) was sprayed and kept in a room at 28°C and 100% humidity overnight. It was then placed in a greenhouse. In the investigation, the number of lesions formed on rice leaves was counted 5 days after inoculation, and the control value was calculated according to the formula below. The results are shown in Table 4. Control value = (Number of lesions in untreated area) - (Number of lesions in treated area) / Number of lesions in untreated area

[Table] Formulation Example 1 Emulsion By mixing 10 parts of the compound of the present invention, 50 parts of xylene, 30 parts of dimethyl sulfoxide, and 10 parts of an emulsifier (polyoxyethylene phenyl phenol ether), an emulsion with a base concentration of 10% is obtained. . Formulation Example 2 Wettable powder A wettable powder having a base ingredient content of 50% is obtained by thoroughly pulverizing and mixing 50 parts of the compound of the present invention, 5 parts of a wetting agent (calcium salt of alkylbenzenesulfonate), and 45 parts of diatomaceous earth.

Claims (1)

[Claims] 1 Formula () A fungicide for controlling plant diseases derived from bacteria of the genus Botrytis, Fusarium, Helminthosporium, and Alternaria, which contains frenolicin B shown by the following as an active ingredient.