JPS5924126B2 - Method for controlling soil diseases of Solanaceae plants - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a scientific name: Pseudomonas solanacearum (Pse).
The present invention relates to a method for controlling soil diseases of plants belonging to the Solanaceae family by heat-sterilizing a strain of bacteria belonging to the genus Udomonas solaqacearum and then applying the same to soil.

Tobacco damping-off, late blight, bacterial wilt, and tomato wilt are known as soil-borne diseases of Solanaceae plants, but these are generally recognized as difficult-to-control diseases.

The occurrence of soil diseases occurs when the crops cultivated under the name of forming main production areas are unified, and the pathogenic bacteria that survived in the infected plants in the previous planting survive at high density in the soil. Cultivation of pathogens is thought to be a major cause, and even soil disinfection cannot completely eliminate pathogenic bacteria.

Soil disinfectants such as chloropicrin and methyl bromide kill microorganisms living in the soil indiscriminately, and are not selective in killing unrelated or beneficial microorganisms in addition to pathogenic microorganisms. There is a risk that pollution may occur.

In addition, because there are limits to the use of resistant varieties, effective control methods have not yet been established [Chemistry and Biology Vol. 7, p. 323 (1979) and vol. 18, p.
619 (1980), l.

Pseudomonas solanacearum bacterium is a bacterium also known as tobacco damping-off bacterium or solanaceae plant blight bacterium, and this bacterium is heat-treated (hereinafter referred to as heated bacterium).

) is injected into tobacco leaves with a syringe, it is known that the injection site becomes less susceptible to diseases [Nature, Vol. 205, p. 823 (1965).
)).

However, this method of controlling plant diseases has many drawbacks as follows.

First, the method of injecting heated bacteria with a syringe takes 15 to 20 minutes per tobacco leaf, even for an experienced person.

In the case of humans and higher animals, it is worth the effort and effort to vaccinate each individual, but in the case of agricultural products, it is almost impossible from a practical standpoint to vaccinate each individual with a syringe.

Second, unlike vaccination of humans and higher animals, the area where heated bacterial bodies are treated to make them less susceptible to disease is limited to the treated area.

Therefore, even if a lot of effort is taken to treat leaves with heated bacterial cells using a syringe, no control effect will be exerted on untreated leaves or newly emerging leaves or roots.

However, the present inventors have discovered that an excellent control effect can be obtained by irrigating the soil at the base of a target plant with a strain of heated bacteria belonging to the tobacco damping-off fungus, and have thus completed the present invention.

That is, the present invention aims to provide a method for effectively controlling soil-borne diseases of plants of the Solanaceae family.
The gist is to apply 23R to soil.

The present invention will be explained in detail below. First, the bacteria used in the present invention has the scientific name Pseudomonas solanacearum (Pse
Pseudomonas solanacearum M23R (Ps.

solanaoearum M 23 R), which has been deposited with the National Institute of Microbial Technology as Microbiological Research Institute No. 6352, FEBM P-6352.

This bacterium can be cultured using known methods, such as known liquid media [Phytopathology].
gy) Vol. 44, p. 693] and inoculated at 28°C to 3
It is sufficient to culture with shaking at 0°C for about 48 hours.

It may also be cultured in a slant medium or plate medium containing agar.

Next, the cultured bacteria are treated as follows to prepare a heated bacterial suspension.

In the case of a liquid medium, centrifugation is performed after culturing, e.g.
0 rpm, 30 minutes) The precipitate is suspended in distilled water.

The bacterial concentration in the suspension is 108-10 per ml of suspension.
'.

number, preferably 109 to 1010.

This suspension is heated to 50-120°C, preferably 80-100°C.
Heat at ℃ for 20 to 10 minutes to kill bacteria, then allow to cool.

In the case of a flat plate or slant culture medium, the bacterial bodies may be scraped into sterilized water and sterilized by heating and cooling in the same manner.

The heated bacterial suspension prepared in this way is sprinkled onto the soil near the roots of the plants to be controlled.

If it is difficult for the suspension to reach the tip of the roots, drill into the soil through a suitable support and irrigate.

Select an appropriate time for irrigation before the time when soil diseases are expected to occur.

The processing amount is 10 ml to 113. Desirably, the volume is from 3 oml to 200 ml.

Crops targeted for disease control by the present invention include tobacco, eggplant, tomatoes, green peppers, potatoes, and other solanaceous plants. Includes soil-borne diseases such as blight and tomato wilt.

Although the mechanism of action of the present invention is not clear, the heated bacterial cells of Pseudomonas solanacearum mentioned above are considered to be a lumber because the plant's own defense reaction occurs when it is fed from the roots.

The content of the present invention will be explained in detail with reference to Examples below.
The present invention has the following advantages over other methods.

(1) Heated bacterial bodies are not toxic by themselves;
It works only on the crops that need it, and it is thought that the crops recognize the heated bacteria and mount a defensive response, so it does not harm the environment.

(2) It is extremely practical because soil-borne diseases that are considered difficult to control can be effectively controlled with simple treatments.

Example 1 Twenty seedlings of tobacco (variety: Mito No. 3) grown in flower pots with a diameter of 15 CrIL were tested.

Prepare an aqueous suspension containing 109 cells/ml of Pseudomonas solanacearum M23R (Feikoken Bacteria No. 6352), sterilize it by heating it at 100°C for 10 minutes, and then leave it to room temperature. After cooling, the solution was irrigated at the base of 10 tobacco seedlings at a rate of 30 ml per seedling.

As a control, sterile distilled water was poured at the base of 10 other tobacco seedlings at a rate of 30 TL per seedling.

After 4 days, 106 pathogenic tobacco damping-off bacteria/ml
Immediately after preparing an aqueous suspension with a concentration of
This water suspension was then irrigated.

After 21 days, the disease state was observed.

The degree of disease onset was graded into six levels from 0 to 5 as shown below, and the average morbidity index was determined using the following formula, from which the control rate was calculated.

OXn+IXn +2X n +3Xn +4X
n -4-5
Average disease index control rate of population treatment plots belonging to -(1-)X100 The average disease index experimental results of the control plots are shown in Table-1.

Although the attack rate was the same, the average morbidity index, which indicates the severity of the disease, was statistically significantly lower in the treatment area (risk rate 5%).
), the control rate was 30%.

Example 2 Tobacco seedlings grown in the same manner as Example 1 (variety: BY4)
I tried 20 bottles.

A suspension of Pseudomonas solanacearum M23R bacteria prepared in the same manner as in Example 1 (bacteria concentration: 2 x 109 cells/
ml) was applied to 10 cigarettes at 100 ml each.

As a control, the same amount of sterile distilled water was given to the other 10 cigarettes.

After 4 days, an aqueous suspension whose concentration was adjusted to contain 107 pathogenic damping-off bacteria/ml was added to 10 mL of water in the same manner as in Example 1.
One inoculation was given.

The disease onset state after 14 days was observed, and the disease attack rate, average morbidity index, and control rate were determined in the same manner.

The experimental results are shown in Table-2.

The disease incidence rate is lower in the treated plots, the average morbidity index is also statistically significantly lower in the treated plots (risk rate 1%), and the control rate is 7.
It was 9%.

Example 3 Twenty eggplant seedlings (variety: Group Kou No. 2 eggplant) grown in the same manner as in Example 1 and 7 weeks after sowing were tested.

A suspension of Pseudomonas solanacearum M23R prepared in the same manner as in Example 1 (bacteria concentration: 101 cells/ml) was given to 10 seedlings at 100 ml per seedling.

As a control, the same amount of sterilized distilled water was given to other 10 seedlings.

Four days later, a suspension of pathogenic bacterial wilt was given in the same manner as in Example 1.

The disease onset state after 12 days was observed, and the disease onset rate, average morbidity index, and control rate were determined in the same manner as in Example 1.

The experimental results are shown in Table-3.

The disease incidence rate is lower in the treated area, the average morbidity index is statistically significantly lower in the treated area (risk rate 1%), and the control rate is 8.
It was 4%.

Example 4 Tomato seedlings (variety:
Fukuju No. 100) was tested.

A suspension of Pseudomonas solanacearum M23R (bacteria concentration: 109 cells/ml) prepared in the same manner as in Example 1 was added to
It was applied to 10 seedlings at a rate of 100m1 each.

As a control, the same amount of sterilized distilled water was given to other 10 seedlings.

After 5 days, tomato wilt fungus Fusarium oxyspora A
A suspension was prepared to contain 104/7711 conidia of (Fusarium oxysporum), and 10 ml of the suspension was inoculated onto each tomato.

Furthermore, after 20 days, an investigation on the onset of disease was conducted, and the degree of onset of disease was divided into 6 levels as shown in the table below, and the average morbidity index and control rate were determined using the formula described in Example 1.

The results are shown in Table-4.

The disease attack rate was low in the treated area, the average morbidity index was statistically significantly lower ((risk rate 5%), and the control rate was 76%) than in the control area.
%Met.

Example 5 A suspension of the tobacco damping-off bacterium Pseudomonas solanacearum M23R prepared in the same manner as in Example 1 (bacterial concentration: 101
0 pieces/ml) to tobacco seedlings that had grown to a total of 7 leaves (
Breed: Inu Daruma) 10ml each was applied to the roots of 10 plants.

After treatment, Phytophthora parasitic bacteria (Phytophthora parasitic)
The above tobacco seedlings were transplanted into a vat filled with soil artificially inoculated with a).

As a control, 10 other tobacco seedlings were given the same amount of sterilized distilled water and transplanted in the same manner.

After 20 days, a disease onset investigation was conducted, and the control rate was calculated using the following formula.

Incidence rate in treated area Defense 11 rate = (“Paired construction area.

Table 5 shows the 100 disease rate results.

The disease incidence rate in the treated area was only 20%, and the control rate was 80%.
%.

Claims (1)

[Claims] 1. A method for controlling soil diseases of plants of the Solanaceae family, which comprises applying heat-sterilized bacteria Pseudomonas solanacearum M23R to soil.