JP2915960B2 - How to control Fusarium disease - Google Patents

Description

The present invention relates to a method for controlling soil diseases which are difficult to control, and more particularly, to a method for controlling chitinase-producing bacteria and antagonists in the presence of chitin or a substance containing chitin in soil. The present invention relates to a method for controlling Fusarium disease, which comprises adding a bacterium (Seracia sp.).

[Prior Art] Conventionally, as a method for controlling soil diseases, there has been a method of indirectly rotating a cropping system. As direct control methods, fumigation sterilization method, steam sterilization method, and hot water sterilization method using pesticides have been mainly performed in greenhouse horticulture. Soil diseases of crops
It is a disease that is mainly caused by continuous cropping of a single crop, and is extremely difficult to control. Conventionally, soil crops have been avoided by rotating the cropping system. Recently, continuous cropping of single crops has been promoted due to the expansion of the acreage and the designation of production areas.

[Problems to be solved by the invention]

Fumigation with pesticides has problems such as danger in handling, necessity of covering material such as vinyl, gas damage to the surrounding area, etc. Recently, environmental pollution by pesticides and adverse effects on humans and livestock are problems. It has become. In addition, the steam sterilization method and the hot water sterilization method are partially performed in facility horticulture in terms of equipment.
Furthermore, there is a method of applying a chitin-containing substance such as crab, krill, and shrimp shell to soil to control them, but it has been reported that the effect may not be stable and may be promoted.

Furthermore, recently, a biological control method in which an antagonistic bacterium is inoculated has been attempted, but it has been difficult to stably inhabit the soil and sufficient effects have not been achieved.

Then, the present inventors conducted intensive studies and completed the present invention.

[Means to solve the problem]

The present invention is a method for controlling Fusarium disease, which comprises adding a chitinase-producing bacterium and an antagonistic Serratia spp. Microorganism that inhabits the plant root surface and has antibacterial activity to soil containing chitin or a chitin-containing substance. In this method, an antagonistic bacterium assimilate a chitin-decomposing substance produced by a chitinase-producing bacterium so that the antagonistic bacterium can stably inhabit the soil, and an antibacterial substance produced by the antagonistic bacterium can cause roots of Fusarium disease. Access can be prevented and Fusarium disease can be controlled.

Chitinase-producing bacteria include microorganisms belonging to the genus Streptomyces, and antagonistic bacteria that inhabit the plant root surface and exhibit antibacterial activity include microorganisms belonging to the genus Serratia.

In the present invention, as the target Fusarium disease,
Watermelon vine, cucumber vine, melon vine,
Tomato wilt, tomato root wilt, eggplant semi-wilt, kidney bean root rot, cabbage yellow wilt, radish yellow wilt, strawberry yellow wilt, green onion wilt, onion dry rot, potato brown rot, asparagus dead Fusarium disease such as burdock disease, burdock wilt, spinach wilt and lettuce root rot.

The chitin applied to the soil may be any of flaky chitin and powdered chitin, which is obtained by decalcifying crab shells and shrimp shells by acid treatment and deproteinizing by alkali treatment. The chitin-containing substance is preferably powdered with crab shell, shrimp shell, krill, or the like.

The application rate of these chitin or chitin-containing substances to soil is
It is in the range of 0.1 to 3% by weight, preferably 0.5 to 1% by weight. In addition, if chitin is applied in an amount of 3% or more, the growth of the crop is impaired.

As the chitinase-producing bacterium used in the present invention, for example, Streptomyces sp CK-A (Microtechnical Laboratory No. 11413) is used.

The actinomycetes are isolated from the chitin-added soil and secrete several chitinases having high chitin-decomposing activity. This chitinase is an endo- and exo-type enzyme that efficiently degrades high-molecular-weight chitin and mainly produces a mixture of chitopentose from chitotriose. This actinomycete can be cultured and propagated by an ordinary method.

Examples of the antagonistic bacteria that inhabit the plant root surface and exhibit antibacterial activity used in the present invention include microorganisms belonging to the genus Serratia, and specifically, Serratia marcescens CK-B (Microtechnical Laboratories No. 11414). No.

This bacterium is isolated from root-dwelling bacteria such as tomato and strawberry. That is, the roots of tomato or strawberry are sufficiently washed with tap water and sterilized water to completely remove the surface soil, and then the washed roots are ground and the low-speed centrifuged supernatant is spread on a plain agar plate. After the agar surface has dried, the seedlings that have been previously aseptically grown are placed on a plate and cultured for several days. Bacteria grown on the root contact surface are isolated in a single colony.
The isolated bacteria were cultured and grown on Tupec agar medium.

Regarding the treatment of soil with chitinase-producing bacteria and antagonistic bacteria, a method of treating the soil with chitinase-producing bacteria followed by antagonistic bacteria, a method of simultaneously treating the soil with chitinase-producing bacteria and antagonistic bacteria, and further containing chitin or chitin-containing bacteria Any method of simultaneously treating the substance, the chitinase-producing bacterium, and the antagonistic bacterium is used.

The amount of chitinase-producing bacteria added was 10 ⁵ c per 1.0 g of soil.
fu or more, and the amount of antagonistic bacteria is preferably 10 ⁵ cfu or more per 1.0 g of soil.

〔The invention's effect〕

In the present invention, in the presence of chitin, the antagonistic bacteria can be stably inhabited in soil by using a chitinase-producing bacterium and an antagonistic bacterium having antibacterial properties in combination,
Fusarium disease was effectively controlled. Also,
The present invention is also a great advantage in that it does not cause a problem of environmental pollution due to the conventional spraying of chemicals.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Streptomyces sp CK-A (Microbial Laboratories No. 11413)
No.) in a chitin medium (4.01 g of inorganic salt of Czapek / chitin 12
g / added medium) and cultured, and the chitinase accumulated in the culture filtrate was examined.

The chitinase in the culture was confirmed by the chitin-azur method (Mackman, RHand Goldberg, M. Anal. Biochem.,
8 397 (1964)) and ethylene glycol chitin assay reducing sugars chitinase activity as a substrate (Imoto, T., K.Yag
ishita Agric., Biol. Chem., 35 , 1154 (1971)).

As a result, endo-type chitinase and exo-type chitinase were confirmed. When 100 ml of this chitinase-containing solution was allowed to act on 1.0 g of high-molecular-weight chitin, the chitin was efficiently decomposed from chitotriose to a mixture of chitopentose,
Finally, it was decomposed into N-acetylglucosamine to obtain 0.9 g of N-acetylglucosamine.

Example 2 The possibility of growth of Serratia marcescens isolated from the root surface of strawberries with chitin and a chitin hydrolyzate and the presence or absence of antibacterial activity against Fusarium disease were examined.

Serratia marcescens CK-B
No. 4) was added to a minimal agar medium containing 0.2% of chitin or a chitin-decomposed product (monomer, dimer and pentamer), and cultured at 26 ° C. for 3 days to examine the viability of the growth. As a control test, the same test was performed using Pseudomonas putida.
The results are shown in Table 1.

Next, Serratia Marcescens and Pseudomonas
The antibacterial activity of Putida against Fusarium disease in the presence of chitin and chitin hydrolyzate was examined. The results are shown in Table 2.

Example 3 The degree of growth of Streptomyces sp. And Serratia marcescens in the chitin medium used in Example 1 was examined daily. 5.0 × 10 ⁵ cfu / ml of medium and Streptomyces sp.
6.0 × 10 ⁵ cfu was inoculated and cultured with shaking at 26 ° C. for 5 days. After the start of the culture, sampling was performed every 24 hours, and the numbers of the two microorganisms in the medium were measured.

As shown in Table 3, the results were Streptomyces sp.
And Serratia Marcescens grew together.

Example 4 The antibacterial activity of Serratia spp. Against Fusarium bacilli was examined.

As various Fusarium wilts, tomato wilt, cucumber vine wilt, strawberry wilt, spinach wilt,
And cabbage wilt fungus were used.

Serratia marcescens and Fusarium bacterium were inoculated on a potato decoction agar medium for sucrose addition, and cultured at 26 ° C. for 5 days. After the culture, the antibacterial activity was measured from the length of the growth inhibition zone of the Fusarium bacterium.

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Claims (2)

(57) [Claims] 1. A method for controlling Fusarium disease, comprising adding a chitinase-producing bacterium and an antagonistic Serratia spp. Microorganism that inhabits the root surface of a plant and has an antibacterial activity to soil containing chitin or a chitin-containing substance. 2. The chitinase-producing bacterium is Streptomyces sp.
2. The control method according to claim 1, wherein the control method is CK-A (Microbial Laboratories No. 11413).