JPH01299207A - Plant blight-controlling fungus and control of plant blight using said fungus - Google Patents

Abstract

PURPOSE:To provide a controlling fungus composed of a non-pathogenic fusarium fungus and useful for the control of plant blight caused by Verticillium dahliae. CONSTITUTION:F-4 strain (FERM P-9976) which is a mold belonging to genus Fusarium is cultured in a medium for conventional mold (e.g., potato soup medium added with sucrose) at 25-30 deg.C. The obtained cells of F-4 strain are suspended in water. The root of a plant seedling grown for a prescribed period is immersed in the suspension for a specific period and the plant is planted on soil to control the plant blight caused by Verticillium dahliae. The control fungus is especially effective for the control of verticillium wilt of soybean, verticillium wilt of green pepper, verticillium wilt of eggplant, etc.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a control bacterium that is effective in controlling plant diseases;
A method of controlling plant diseases using this control bacterium, specifically, a non-pathogenic control bacterium effective for controlling Verticillium dahliae, which has been known as a harmful bacterium to plants, and a control method using the same. It is.

[Conventional technology]

Verticilliu
adahlias) is a filamentous fungus that causes diseases in various plants.

Verticillium dahliae is distributed worldwide.

In Japan, edamame, tomatoes, eggplants, and green peppers are also popular.

Diseases caused by the Verticillium dahliae bacterium occur in various crops such as Udo and Chinese cabbage, and this has become a major factor hindering agricultural production.

To eliminate the damage caused by Particillium disease, it has been common practice to disinfect the soil with chloropicrin, but on the other hand, treatments such as crop rotation with non-host crops have been used to eliminate the damage caused by Particillium disease. Efforts are being made to keep this to a minimum.

[Problem to be solved by the invention]

Disinfecting soil with chemicals such as the chloropicrin agent has major problems in that it increases processing costs due to the use of large quantities of these chemicals, requires a great deal of labor for disinfection work, and is toxic to humans and animals. As a result, the use of disinfectants is being restricted, especially in areas surrounding residential areas.

On the other hand, treatment by single crop rotation also has many problems in terms of agricultural management, such as the difficulty of selecting a single alternative crop, and there is a long-awaited development of a safe and easy-to-implement control method to replace these.

The inventors of this invention under the present circumstances.

As an alternative to the above-mentioned chemical disinfection, soybean plants &
We isolated various microorganisms from L1va and searched for microorganisms effective in controlling this disease, and as a result, we discovered that a specific strain belonging to the genus Fusarium was highly effective.
This led to the establishment of a pest control method.

[Means to solve the problem]

The invention of claim 1 of this invention is a plant disease control bacterium characterized by comprising a non-pathogenic Fusarium fungus that has properties effective against plant diseases caused by Verticillium dahliae.

A second aspect of the invention is a method for controlling plant diseases, which comprises immersing the roots of a plant in a culture solution of the non-pathogenic Fusarium fungus according to the first aspect of the invention and then planting the plant in soil.

The control bacterium consisting of non-pathogenic Fusarium fungi (hereinafter referred to as F-4 bacterium) of the present invention is sterilized from the internal tissue of edamame stems randomly collected from an edamame field in Tone Village, Tone District, Gunma Prefecture. It was obtained by removing tissue pieces and separating the various microorganisms present in the two tissues.

This F-4 bacterium is a filamentous fungus that belongs to the genus Fusarium and has the mycological properties described in the following ■～■. 9th
No. 976/FERM P-9976).

■ Morphological properties Oval or ovoid small conidia are formed pseudocephalically at the tip of the short basidiophore (no septum).

Small conidia have 0 septa and a size of 2.5-3゜Ox5.
．． O~10.0 μm (average 2.8×7.5 μm).

The size of macroconidia is 3.0 - 4.0° for a spore with one septum.
5 x 13.8~22.5 pm (average 3.5 x
17.3μm), 2-septate spores are 3.0-4.5X1
8°8~35.0μm (average 4.OX 25.3μm
), 3 septate spores are 3.0-4.5 x 32.5-4
7.5 μm (average 4.3 x 40.0 μm), 4 septate spores are 4°0-4.8 x 38.8-50.0 μm (average 4
．． 5 x 44.5 μm) and is mainly composed of 3-septate spores.

■ Properties in various media PSA medium (decoction of 200 g of potatoes).

1.000ml of water! , 10g of white sugar, 15g of agar)
The growth on the top is good, the hyphae elongate quickly, the aerial hyphae are fluffy, and the cultured fawns are soft and produce a pale bluish-purple pigment.

Czapek medium (NaNOs 2g, MgSO4.7H
zO0,5g, KCj! 0.5g, KzHPOa 1
g, F e S・o4・7 H2OI Omg, shi!
! 1!30 g, PCN875mg, water 1.000m
l.

Growth on 15 g of agar) was good, hyphae elongated quickly,
Aerial hyphae are fluff-like and extend radially.

Cultured fawns are soft and do not produce 9 pigments.

■ Physiological properties F-4 bacteria are aerobic, and the conditions under which they can grow are
, o~8.0. More preferably pH 6.5.

The temperature is 5-35°C, with the optimum temperature being around 28°C.

■ Controllable plant diseases Particularly effective in controlling edamame wilt, green pepper wilt, and eggplant wilt caused by Verticillium dahliae.

From the mycological properties described above, it is clear that this fungus belongs to the genus Fusarium among filamentous fungi.

This F-4 bacterium can be cultured in a medium containing nutrients that can be used by ordinary filamentous fungi. ! It can be easily cultured in a potato broth medium containing added sugar, and the suitable temperature for culturing is 25 to 30°C.

Further, the culture method may be shaking culture, plate culture, etc. In shaking culture, the bacterial concentration reaches its maximum in about 7 days.

The F-4 bacterium of the present invention cultured in this manner can be used to control various plant diseases caused by Verticillium dahliae.

For example, by suspending cultured F-4 bacteria in water, immersing the roots of plant seedlings grown for a certain period of time in this suspension for a certain period of time, and then planting the plants in soil, an excellent control effect can be obtained. It is something that demonstrates the.

The amount of F-4 bacteria used depends on the type of target plant,
It varies depending on whether or not the soil is sterilized, how long the roots of the plant seedlings are immersed, whether additives other than F-4 bacteria are used, etc.
Although it is difficult to define generally, 1 in suspension? The appropriate number of spores (spores/m1) of -4 bacteria is approximately in the range of 107 to 10''/m1.

This F-4 bacterium can be applied to a wide variety of diseased plants affected by Verticillium dahliae, including edamame wilt, green pepper wilt, and eggplant wilt. It can be found to be highly effective against hemi-body wilt disease, etc.

[For production]

Cross-protection is a phenomenon in which when a plant is infected with another microorganism prior to being infected with a pathogen, the plant's resistance to the disease increases.
) or induced resistance
ty), and attempts to control plant diseases using this are also being considered.

However, all of these methods are limited to indoor-scale experiments, and there are few examples of application in the field, and there are almost no examples of successful practical application.

The control bacteria of this invention also utilizes cross protection or induced resistance.・It is capable of effectively controlling plant diseases caused by Darrier.

Regarding the effect of the F-4 bacterium on expressing the disease control effect, it is probably that resistance to Verticillium dahliae is induced in the plant body by pre-inoculating the roots of the plant with this F-4 bacterium. As a result, it is presumed that the invasion of pathogenic bacteria through the roots is prevented.

〔Example〕

Hereinafter, this invention will be described in more detail with reference to Examples.

Example 1 Tissue pieces were aseptically removed from the internal tissues of edamame stems arbitrarily collected in an edamame field in Tone Village, Tone District, Gunma Prefecture, and various microorganisms present in the 9 tissues were isolated.

For isolation of microorganisms, modified ethanol Czapek medium (
NaNO32g, Mg5Oa ・7H2OO, 5g,
KCj! 0.5g, KzHPO41g, Fe5o4 ・
7 Hzo 10mg, Shilli 7.5g, PC
N875mg, streptomycin 100g, polyoxin AL50mg, chloramphenicol 250mg,
Ethanol 5g, plasticidin 30.25mj! ,
After culturing at a temperature of 25°C for 10 to 14 days using a medium consisting of 1.000 ml of water and 15 g of agar, the colonies that appeared on the medium were cultured on a PSA medium (a decoction of 200 g of potatoes and 1.000 ml of water).

The bacteria were transplanted into a test tube containing a medium (medium consisting of 10 g of sucrose and 15 g of agar).

The various microorganisms isolated were grown in PS medium (decoction of 200 g of potatoes, 1.000 m m of water, Sea I
The cells were cultured with shaking in a medium (medium containing 10 g of sugar).

The thus obtained culture was examined for morphological properties, growth conditions in various media, physiological properties, etc., and the results as described above were obtained. Due to this.

The main bacteria of this culture is Fusarium (Fusarium).
A non-pathogenic Fusarium fungus belonging to the genus
ri-ua+ oxysporum).

Example 2 A potato decoction liquid medium containing 1.7% sucrose was used, and this medium was used at 100 mJ! After sterilizing a 500 ml shaking culture flask at a temperature of 120°C for 30 minutes,
- Inoculate 1 platinum loop of slant culture of 4 bacteria at 25°C.
Cultured with shaking for 1 day.

This culture solution with a spore count of 10''/m12 is used as a stock solution, and this stock solution and this are mixed with water 10 times (spore count 10'/mfi>, 100 times (spore count 106/m1)
and 1,000 times (10' spores/ml) to prepare a bacterial solution for control.

The roots of edamame (Yukimusume) seedlings, which have been sown for 10 days, are immersed in these fungal solutions for 1 hour, and then the roots are infected with Verticillium dahliae (Edamame wilt disease fungus), which has a strong pathogenicity specific to edamame. ) was planted in soil containing

Approximately two months after the planting, the edamame was examined for disease development and its effectiveness in controlling the F-4 bacteria was determined.

The results are shown in Table 1.

According to this Table 1, the number of spores in the shaking and shaking culture of F-4 bacteria is 10''/mj! (undiluted solution) and 10'/nu (1
The 0x diluted solution) was found to have a particularly high control effect on edamame wilt, and as a result, a significant increase in the number of seeds and pod weight per plant was observed.

In addition, nine individual plants per 1-treated light were used in the test.

[Margin below]

Table 1 (Note) The disease severity in Table 1 was calculated using the formula below. (The same applies hereinafter) Class values are based on the following evaluation.

0: A healthy plant with no wilt at all 1: A plant where only the lower leaves are withered 2: A plant whose middle leaves are withered 3: A plant whose upper leaves are withered or dead A stock solution of F-4 bacteria (10" spores/ml) cultured in the same manner was used as a bacterial solution for control.

The roots of eggplant and green pepper seedlings that had been sown for 35 days were immersed in this control fungus for 1 hour to infect Verticillium dahliae (an eggplant wilt disease fungus that is highly pathogenic specifically to eggplants and green peppers). and green pepper half-leaf wilt fungus).

Thereafter, after about two months had elapsed, the planted eggplants and green peppers were investigated for disease onset, and the effectiveness of controlling the F-4 bacteria was determined.

The results are shown in Table 2.

In this Table 2, in the untreated area caused by F-4 bacteria, eggplant half-body wilt disease was 9, and pepper half-body wilt was 10.
The disease rate has reached 0%, but in the area treated with F-4 bacteria, the rate of disease in eggplants is almost 1/2. Approximately 1/7 to 1/2 green pepper
The disease rate was suppressed to 8, and the disease severity was 173 in eggplant. It was about 177 to 1/8 for green peppers.

In addition, 15 individual plants were used for each treatment in the test.

Table 2 [Effects of the Invention] The invention of claim 1 of this invention is a plant disease control method consisting of a non-pathogenic Fusarium fungus having specific mycological properties for plant diseases caused by Verticillium dahliae. These fungicidal bacteria can be easily isolated and obtained from the internal tissues of edamame stems in a sterile manner.
It can be produced in large quantities at low cost in a short period of time using conventional culture methods.

The invention as claimed in claim 2 is a method of controlling a plant disease by immersing the root part of a plant in the bacterial solution of the plant disease controlling bacteria obtained in the invention as claimed in claim 1 for a certain period of time and transplanting it into soil. It has an excellent effect of suppressing the onset of psyllium disease, thereby achieving significant labor savings compared to treatment with conventional soil fungicides such as chloropicrin.
s1 It is possible to control harmful pathogens at an extremely low cost.

In addition, this method eliminates the need to avoid plant diseases through single crop rotation, and enables efficient cropping, so the impact on agricultural management is:

It is unfathomable.

Patent applicant group Ma prefecture Representative Patent Attorney Yuki 1) Hiroshi Zen

Claims (2)

[Claims] (1) A fungicide for controlling plant diseases, characterized by comprising a non-pathogenic Fusarium fungus that is effective against plant diseases caused by Verticillium dahliae. (2) A method for controlling plant diseases, which comprises immersing the roots of plants in a culture solution of the non-pathogenic Fusarium fungus according to claim 1 and planting them in soil.