JPH0912418A - Blight controlling agent for useful plant of family gramineae using weed pathogen and controlling method - Google Patents

Abstract

PURPOSE: To obtain a blight controlling agent free from environmental pollution problem and applicable without giving adverse effect on useful plants by using a specific microorganism having blight controlling activity on useful plants of the family Gramineae. CONSTITUTION: This blight controlling agent contains microorganism belonging to Exserohilum rostratum known as a pathogen of weed and having blight controlling action on useful plants of the family Gramineae. The especially preferable microorganisms are Exserohilum rostratum Ku-1 (FERM BP-5131) and/or Exserohilum rostratum Ku-2 (FERM BP-5131). Rice blight and other blights are controlled by scattering the blight controlling agent to the useful plant of the family Gramineae. The microorganism is usually used in the form of conidiospore and its concentration is 10<3> to 10<7> /mL in the case of solution. The agent is applied to a field at a rate of 10<8> to 10<12> conidiospores per 10 are of the field. The blight to be controlled by the agent is rice blast, helminthosporium leaf spot, bacterial leaf blight, sheath blight, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel strain having a disease controlling ability against useful plants of the family Gramineae, and a disease controlling agent and a disease controlling method using the same.

[0002]

2. Description of the Related Art Rice blast is the most common disease in rice cultivation and causes a decrease in yield.
It is necessary to apply the germicide twice. However, in recent years, due to the problem of environmental pollution caused by chemical pesticides, development of a crop disease control agent that does not rely on chemical pesticides and the use thereof have been desired.

Therefore, a method of controlling crop diseases using microorganisms has been considered, but the means can be roughly divided into two. One is a method of inducing disease resistance of rice and controlling the blast by inoculating the rice blast fungus, which is incompatible with a certain rice cultivar. As such a method, for example, Tohoku Agricultural Experiment Station Research Report No. 75
No. 27-39 (1987), and Japanese Society for Plant Pathology Vol. 56 No. 2 273-275 (1990).
In addition, there is also a method of inducing disease resistance of rice and controlling blast by inoculating rice isolates showing weak pathogenicity to rice by the same method. For example, there is a method described in Kita-Japan Pest Research Bulletin No. 30, pp. 53-55 (1979).

The other one is a method of controlling by using a microorganism having an antagonistic action against rice blast fungus. Examples of such a method include the method described in Japanese Society for Plant Pathology, Vol. 58, No. 3, 380-385 (1992), and JP-A-2-
The method described in JP-A No. 35076/1993 and the method described in JP-A-5-65209 are available.

[0005]

However, the method utilizing the above-mentioned incompatible blast fungus has the following problems. In other words, the property of non-affinity is a relative property between the race of the pathogenic fungus and the cultivar of the crop. May be indicated. For this reason, the method of spraying the rice blast fungus itself on the rice cultivated land may cause blast to varieties showing affinity. In particular, in regions where various different varieties are cultivated, there is a high possibility that blast will occur if there is an affinity rice cultivar. Further, since the non-affinity may be mutated to the affinity, there is a risk that the bacteria exhibiting the affinity may be mixed with the bacteria exhibiting the non-affinity to be sprayed.

[0006] In the method utilizing the fungus isolated from the above-mentioned rice, Helminthospori oryzae is used.
um oryzae < Bipolaris oryzae >) has a very high control effect against blast, but since this bacterium is a pathogen of rice sesame leaf blight, it cannot be applied to rice cultivated land.
The above-mentioned method using a microorganism having an antagonistic action against blast fungus generally has a low control effect in many cases. For example, according to the method described in the Japanese Society for Plant Pathology Vol. 58, No. 3, the control effect on blast is only about 50%. In addition, the microorganism used in this method is often a pathogenic fungus of a useful plant, and has a risk of harming other useful crops. For example, in the method described in JP-A-2-35076, a gladiolus soft-rot bacterial bacterium is used, and in the method described in JP-A-5-65209, a rice idiot disease bacterium is used.

For the reasons described above, at present, methods for controlling crop diseases using microorganisms are hardly used despite the high social demands. The present invention has been made in view of the above circumstances, and has as its object to provide means for controlling crop diseases such as blast without affecting the growth of useful plants.

[0008]

[Means for Solving the Problems] As a result of repeated studies on weed pathogens that do not affect the growth of useful plants, the inventors of the present invention have found that the pathogens of weeds, excellorium rostratum, have a high control effect against blast. The present invention has been completed by discovering what is shown. That is, the present invention is a disease control agent for a useful plant of the family Gramineae, which comprises, as an active ingredient, a microorganism belonging to Excellorium rostratum and having a disease controlling ability for the useful plant of the family Gramineae.

The present invention also provides a method for controlling diseases of useful plants of the family Gramineae, which comprises applying the disease controlling agent for useful plants of the family Gramineae to the useful plants of the family Gramineae. Further, the present invention is a Exelohirum rostratum KU-1 strain and an Exelohilum.
It is Rostratum KU-2 strain. Hereinafter, the present invention will be described in detail.

The microorganism used in the present invention is not particularly limited as long as it is a microorganism belonging to Excellohirum rostratum which has the ability to control diseases against useful plants of the family Gramineae, but a preferred strain is Excellohirum rostratum KU.
-1 strain and Excellohirum rostratum KU-2 strain. These strains have been deposited with the numbers shown below at the Institute of Biotechnology, Institute of Biotechnology, AIST. The deposit number of EXCELLOHILM LOSTRATUM KU-1 strain is
FERM BP-5131 (original deposit date June 12, 1995) and Exerohilum Rostratum KU-2 strain are FERM BP-5132 (original deposit date June 12, 1995).

These strains were isolated from diseased weeds, and their mycological properties are as follows. It is an aerobic bacterium and the colonies are dark green or black on potato sucrose agar medium. Also, white or gray aerial hyphae may be seen. Conidia (conidia) are dark, multivesicular with 2-16 inner and outer septa, beak-shaped with the widest central part, narrowing toward both sides, but one is longer and thinner. Also, a hilum is protruding at the base end. The size of conidia is 15-200 × 7-29 μm.

[0012] The above results are shown in "GRAMINICOLO" by A.SIVANESAN.
US SPECIES OF BIPOLARIS, CURVULARIA, DRECHSLERA, E
XSEROHILUM AND THEIR TELEO MORPHS '' (Mycological Pap
ers, No.158, p-211, Nov.1987.), the shape of the community and the morphology of conidia are the same.
Exserohilus rostratum ( Exserohilu
m rostratum ).

For culturing the KU-1 strain and the KU-2 strain, it is not necessary to use a special method, and the same method as a known strain belonging to the genus Exerohirum can be used. As the medium, any synthetic medium or natural medium can be used as long as the medium appropriately contains assimilable carbon sources, nitrogen sources, inorganic substances, and necessary growth promoting substances. Specific examples of the medium include an oatmeal sucrose agar medium, an oatmeal agar medium, a potato sucrose agar medium, a V-8 juice agar medium, a Tupec-Docs agar medium, and the like. In culturing, the temperature is 15 to 28 ° C, preferably
It is desirable to maintain the pH at 20 to 25 ° C and 3 to 9, preferably 5 to 8. When culturing is performed for about 7 to 14 days under the above conditions, a sufficient amount of conidia is formed on the surface of the medium.

When the strain of the present invention is used in a control method, microbial cells (conidia, ascospores, hyphae, etc.) are used, and preferably conidia produced by the strain are used.
Conidia can be collected by pouring sterile water onto the microbiota and scraping the surface of the medium with a brush. By this method, 10 ⁷ to 10 ⁸ conidia can be obtained from one petri dish having a diameter of 9 cm.

In the disease controlling agent of the present invention, microorganisms may be directly used as they are, but in general, they are mixed with a solid carrier or a liquid carrier which can be used for agricultural chemicals to prepare a liquid, wettable powder, powder, granule, It is used by preparing it in the form of emulsion, oil, capsule and the like. As a microorganism, conidia are usually used.
The concentration of conidia is 10 ³ to 10 ⁷ pieces / ml, preferably 10 ⁴ to 10 ⁶ pieces / ml in the case of a liquid preparation.

When the disease control agent of the present invention is actually used in a field, 10 ⁸ conidia of microorganisms are used per 10 ares of the field.
It is sprayed so as to be about 10 ¹² pieces, preferably 10 ⁹ to 10 ¹¹ . In the present invention, the leaf stage of the Gramineae plant at the time of treatment is not particularly limited. The diseases to be controlled by the present invention include rice blast, rice sesame leaf blight, rice white leaf blight, rice crest blight, corn sesame blight blight, corn smut, corn soot blight, various wheat species. Examples include smut disease.

[0017]

【Example】

(Example 1) Selection of KU-1 strain and KU-2 strain Diseased weeds were collected from all over Japan, pathogenic bacteria were separated from the lesions, and the control effect against rice blast was examined by the following method. Healthy rice (cultivar Koshihikari) was inoculated with the weed pathogen, left for a given period in a greenhouse, and then inoculated with the rice blast fungus having an affinity for this rice. Approximately one month later, the disease index of blast was evaluated objectively and the most effective weed pathogens (KU-1 strain, KU-2 strain) were selected. (Example 2) Controlling effect of rice blast disease by Excelohirum rostratum Rice (variety Koshihikari) in a pot of 1 / 10,000 are
Seeds were sown and grown in a greenhouse for about 3 weeks, and then a 1% ammonium sulfate aqueous solution was given as a fertilizer. The rice was allowed to stand still in a greenhouse for about one week, and the rice at the 4th and 5th leaf stages was used in the control effect test.

Each strain shown in Table 1 was cultured in oatmeal sucrose agar medium at 25 ° C. for 2 weeks to form conidia. The conidia were suspended in a 0.02% Tween 20 aqueous solution, and then a suspension of 5 × 10 ⁴ or 5 × 10 ⁵ conidia / ml was prepared to obtain a treatment liquid. This conidial suspension was spray-treated on rice with 2 ml per pot using a sprayer, and then placed in an inoculation box kept at 25 ° C. and 100% humidity for 20 hours. Each treatment group was subjected to a three-pot test.

After being left in the greenhouse for 1 day, the rice blast fungus ( Pyricularia oryzae) showing an affinity for Koshihikari
race 007) conidial suspension (5 × 10 ⁵ conidia / ml ・ 0.02
% Tween20 aqueous solution) was spray inoculated (2 ml per pot) and then placed in an inoculation box kept at 25 ° C. and 100% humidity for 24 hours. One week after the inoculation, the average number of lesions per leaf of the fifth leaf was investigated, and the control value was calculated by the following formula.

[0020]

[Table 1] Table 1 Control effect of Excellohirum rostratam on rice blast disease

Control rate (%) = (1-average number of lesions in treated group / average number of lesions in untreated group) × 100 (Example 3) Period after inoculation of KU-1 strain and control effect against rice blast Rice in a pot of 1 / 10,000 are (rice cultivar Koshihikari)
Seeds were sowed and grown in a greenhouse for about 3 weeks, and then fed with a 1% aqueous ammonium sulfate solution as a fertilizer. The rice was allowed to stand still in a greenhouse for about one week, and the rice at the 4th and 5th leaf stages was used in the control effect test.

KU-1 strain of weed pathogen was cultured on oatmeal sucrose agar medium for 2 weeks to form conidia. The conidia were suspended in sterile water containing 0.02% Tween 20, and then a suspension of 5 × 10 ⁴ or 5 × 10 ⁵ conidia / ml was prepared and used as an inoculum. This conidial suspension was spray-inoculated onto rice with 2 ml of conidia suspension using an airbrush, and then placed in an inoculation box kept at 25 ° C. and 100% humidity for 20 hours. Two-pot test was performed for each treatment section.

A rice blast fungus having an affinity for Koshihikari after standing in a greenhouse for 2, 3 or 9 days
( Pyricularia oryzae race 007) conidial suspension (5 × 10
^After spray inoculation (2 ml per pot) with ⁵ conidia / ml · 0.02% Tween20 aqueous solution), the mixture was placed in an inoculation box kept at 25 ° C and 100% humidity for 24 hours. Approximately one month after the inoculation, the disease index of blast was evaluated objectively (the soundness was set to 0, complete death was set to 100, and the degree of plant growth and blast lesion were evaluated).

[0024]

[Table 2] Table 2 Period after inoculation of KU-1 strain and control effect against rice blast ───────────────────────────── ─────── Conidia concentration (pieces / ml) Rice blast control value (%) ─────────────────────── After inoculation of weed pathogens Period (days) 2 3 9 ─────────────────────────────────── Untreated − − − 5 × 10 ⁴ ++ ＋ ＋ ＋ 5 × 10 ⁵ ＋＋＋ ＋＋＋ ＋＋＋ ──────────────────────────────────── Rice blast disease Control rate (%) = (1-treatment plot disease index / non-treatment plot disease index) x 100 As shown in Table 2, a high control effect against rice blast was recognized in the test plots inoculated at any concentration or regardless of the period after the inoculation of weed pathogens. (Example 4) Control effect of rice sesame leaf blight The rice (variety Koshihikari) is put in a pot of 1 / 10,000 are.
The seeds were sown and grown, and rice at the 4th and 5th leaf stages was used for the control effect test.

Conidia of KU-1 strain and KU-2 strain were 0.02
After being suspended in an aqueous solution of 10% Tween20, a suspension of 5 × 10 ⁵ conidia / ml was prepared and used as a treatment liquid. This conidial suspension was sprayed onto rice using a sprayer at 2 ml per pot.
After spraying, they were placed in an inoculation box kept at 25 ° C and 100% humidity for 20 hours. Each treatment group was subjected to a three-pot test.

After standing in a greenhouse for 1 day, a conidial suspension of rice sesame leaf blight fungus ( Bipolaris oryzae ) was sprayed and inoculated, and then placed in an inoculation box kept at 25 ° C. and 100% humidity for 24 hours. It was One week after the inoculation, the average number of lesions per leaf of the fifth leaf was investigated, and the control value was calculated from the calculation formula shown in Example 2.
As shown in Table 3, in all the strains, a high control effect against rice sesame leaf blight was recognized.

[0027]

[Table 3] Table 3 Rice sesame leaf blight control value

Control value (%) = (1-average number of lesions in treated group / average number of lesions in untreated group) × 100

[0029]

【Example of use】

Formulation Example 1 (solution) Conidia of Exerohirum rostratum KU-1 strain (2 x 1
⁰⁹ pieces), Tween 20 was added to 20 L of sterilized water and mixed,
A liquid preparation was prepared as 0.02% Tween20. Formulation Example 2 (Wettable powder) 10 ⁷ conidia (KU-1 strain) were suspended per 1 ml of a mixed solution of maltose 9%, clay 1% and water 90%. After air-drying, the dried product was mixed and pulverized to prepare a wettable powder.

Formulation Example 3 (Wettable powder) 1% of a mixed solution of lactose 9%, zeolite 1% and water 90%
10 ⁷ conidia (KU-1 strain) were suspended per ml. After air-drying, the dried product was mixed and pulverized to prepare a wettable powder. Formulation Example 4 (Wettable Powder) 10 ⁷ conidia (KU-2 strain) were suspended per 1 g of a mixed solution of diatomaceous earth 15%, kaolin 77% and polyoxyethylene alkylphenyl ether 8%. After air-drying, the dried product was mixed and pulverized to prepare a wettable powder.

Formulation Example 5 (powder) hydroxypropyl-β-cyclodextrin 14%,
10 ⁷ conidia (KU-2 strain) were mixed with 1 g of a mixture of 12% white carbon and 74% clay. After drying, the powder was uniformly ground to prepare a powder. Formulation Example 6 (Granule) 10 ⁷ conidia (KU-2 strain) per 1 g of a mixture of β-cyclodextrin 15%, starch 2%, bentonite 18%, calcium carbonate 36%, and water 29% was kneaded. Then, the granules were prepared by granulating with a granulator and drying.

Formulation Example 7 (Emulsion) Polyoxyethylene nonyl phenyl ether Ammonium phosphate 18%, polyoxyethylene nonyl phenyl ether 6%, triethyl phosphate 29%, tributyl phosphate 47% Per 1 g of a conidium (KU-) 2 strain) 10 ⁷ were uniformly suspended by adding, to prepare an emulsion.

Formulation Example 8 (Oil agent) 10 ⁷ conidia (KU-1 strain) were suspended in 1 ml of a mixed solution of spindle oil 95%, castor oil 4% and silicone oil 1% to prepare an oil agent. Formulation Example 9 (Dry flowable agent) A dry flowable agent was prepared by suspending 10 ⁷ conidia (KU-2 strain) in 1 ml of a composition containing 12% sodium alkylbenzenesulfonate and 88% polyethylene glycol ether.

Formulation Example 10 (Capsule) Conidia (KU) were added to 1 ml of a mixed solution of sodium alginate 0.7%, kaolin 5%, glycerin 15% and water 79.3%.
-1 strain) was obtained capsular product was added dropwise to 10 ^seven were suspended 0.2 molar calcium acetate solution. This was air dried to prepare a capsule.

[0035]

INDUSTRIAL APPLICABILITY The present invention provides a novel disease controlling agent and a method for controlling useful plants of the family Gramineae. INDUSTRIAL APPLICABILITY Since the control agent and control method of the present invention uses pathogens of weeds, there is no concern about environmental pollution, and there is no adverse effect on useful plants unlike conventional microbial control agents. Therefore, it is extremely useful industrially.

Front page continuation (72) Hiroshi Tsukamoto Inventor Hiroshi Tsukamoto 6-2 Umegaoka, Aoba-ku, Yokohama-shi, Kanagawa Japan Tobacco Inc. Plant Development Laboratory, Yokohama Center Of 3

Claims (5)

[Claims] Claim: 1. Exsero
hilum rostratum ), which contains as an active ingredient a microorganism having a disease controlling ability against useful plants of the family Gramineae, which is a disease controlling agent of useful plants of the family Gramineae. 2. A member of Excellohirum rostratum,
Microorganisms having disease control ability against useful plants of the grass family,
The disease control agent for useful plants of the family Gramineae according to claim 1, which is an Execrohirum rostratum KU-1 strain and / or an Execrohirum rostratum KU-2 strain. 3. A method for controlling a disease of a useful plant of the family Gramineae, which comprises applying the disease controlling agent for a useful plant of the family Gramineae according to claim 1 or 2 to a useful plant of the grass family. 4. The Exerohilum rostratum KU-1 strain having a disease control ability on useful plants of the family Gramineae. 5. The Exerohilum rostratum KU-2 strain having a disease control ability on useful plants of the family Gramineae.