JPS58222006A - Method of combatting soil disease in solanaceae crops - Google Patents

Abstract

PURPOSE:A bacterium of Pseudomonas solanacearum M23R is killed by heat treatment and watered in the soil near roots of Solanaceae crops such as tobacco, eggplant or tomato to combat soil diseases such as tobacco bacterial wilt, tobacco black shank, eggplant bacterial wilt or tomato Fusarium wilt. CONSTITUTION:Cells of Pseudomonas solanacearum M23R are separated from the liquid culture medium and suspended in distilled water so that the concentration of cells becomes 10<9>-10<10> per 1ml. Then, the suspension is heated at 80-100 deg.C for 2-10min to kill the cells, then stood for cooling. The resultant cell suspension is watered in the soil near the roots of the crops such as tobacco, eggplant, tomato, or green pepper. The amount of the suspension to be applied to a crop is 30-200ml and holes are bored, when it is difficult for the suspension to reach the tops of the roots. The sterilized cells are nontoxic and the application to the roots is thought to cause its own protecing action without environmental pollution.

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 family Udomonas solanacearum and then applying the same to soil.

Tobacco damping-off, late blight, bacterial wilt, and tomato wilt are known as soil-borne diseases of Solanaceous plants, but rotten wilt is generally recognized as a difficult-to-control disease. 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 indiscriminately kill microorganisms living in soil.

It does not have the selectivity to kill not only pathogenic bacteria but also unrelated or beneficial microorganisms 1, and there is a risk that drug damage and pollution may occur. Furthermore, because there are limits to the use of resistant varieties, effective control methods have not yet been established. C “Chemistry and Biology” Volume 17 P323 (1979
) and Vol. 18, P619 (1980)).

Pseudomonas solanacearum bacterium is a bacterium also known as Tobacco damping-off bacterium or Solanaceae plant blight bacterium, and this bacterium is heat-treated and is hereinafter referred to as heated bacterium. ] is injected into tobacco leaves with a syringe, it is known that the injection site becomes susceptible to disease [Nature θ, Vol. 205, P823 (1965),]
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 vaccinations for 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 Tatomo takes the effort to treat the leaves with heated bacteria using a syringe, it will not have any control effect on untreated fc leaves or newly emerging leaves or roots. However, the present inventors □: 'Tfl heated a strain of bacterial cells belonging to the tobacco damping-off fungus to the soil at the base of the target plants.
The present invention has been completed under the heading 2. That is, 1. The present invention aims to provide a method for effectively controlling soil-borne diseases of plants belonging to the Solanaceae family. This is the summary. The present invention will be explained in detail below.

First of all, the bacteria used in the present invention has the scientific name Pseudcomonae solanacea.
Nyudomonas solanacearum M 23 R (Ps,
solana-cearum M 23 R), which is FEBM P-63'
It has been deposited with the Microbial Technology Research Institute as 5'2.

To culture this bacterium, there are known methods 1, such as known liquid media [Phytobathology (ph7.topa, th.
10g3') (see Vol. 44, p. 693),
Culture may be performed at 28C to 30C for 48 hours with shaking. 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 case of liquid medium (-1, centrifugation after incubation, e.g. 3000'rpm, 30 minutes)
The precipitate is suspended in distilled water. The concentration of bacteria in the suspension is 108 to 1010 per ml of suspension, with a preference of <1.
The number is 09 to 1010. This suspension was heated at 50-125C.
, preferably at 80 to 100 C for 20 to 10 minutes to kill bacteria, and then allowed to cool. Ma! In the case of a flat plate or slant culture medium, the bacterial bodies can be scraped off 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. 1. Select an appropriate time before the time when soil diseases are expected to occur. The processing amount is 10m1 to 17cm per plant? , preferably 3Qml
to 200 ml.

Crops targeted for disease control according to the present invention include plants of the Solanaceae family, such as tobacco, eggplant, tomatoes, green peppers, and potatoes.

Tobacco damping-off, tobacco late blight, bacterial wilt of solanaceous plants.

Includes soil-borne diseases such as tomato wilt.

The mechanism of action of the present invention is not clear.

It is thought that the above-mentioned heated bacterial cells of Pseudomonas solanacearum are caused by the plant's own defense reaction occurring when this 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 cells themselves are not toxic at all.

It works only on the crops that need it, and the nine crops are thought to 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 cm were tested. Pseudomonas solana/
Arum M23R bacterium (Feikoken Bacteria No. 6352) was 109
Prepare an aqueous suspension with a concentration of 1
After sterilization by heating at 0.000C for 10 minutes, the mixture was allowed to cool to room temperature, and 30ml of each seedling was irrigated at the base of 10 tobacco seedlings. As a control, 3Qml of sterile distilled water per bottle.
The mixture was poured at the base of 10 other tobacco seedlings.

After 4 days, 106 pathogenic tobacco damping-off bacteria/1
1 Prepare a 41 degree water suspension containing the above 20 '
Immediately after cutting the root of the tobacco seedling with a knife,
This water suspension was irrigated in 0 ml portions. After 21 days, the disease state was observed. The severity of the disease is 0 to 5 as shown below.
The average morbidity index was determined using the following formula, and the control rate was calculated from this.

Disease index Disease state: 0 No disease 1 Part of the leaves are withered 2 1 to 3 leaves are withered 3 For wilt except for 2 to 3 leaves near the growing point 4
Whole plant wilting 5 Average disease morbidity index of blight - Where, N is the number of specimens tested + 'O~n5 is the number of individuals belonging to the disease index 0~5 Control rate = The experimental results are shown in Table 1.The disease incidence was the same.
The average morbidity index, which indicates the severity of the disease outbreak, was statistically significantly lower in the treated area (risk rate 5), and the control rate was 3.
It was 0%.

Table-1 Treatment area 100% 28 30% Example 2 Tobacco seedlings grown in the same manner as Example 1 (variety 2 BY No. 4)
I tried 20 bottles. A suspension of Pseudomonas solanacearum M23R bacteria prepared in the same manner as in Example 1 (bacterial concentration: 2 x 10 o cells/ml) was added at a concentration of 100+++1! Each was given to 10 cigarettes. As a control, the same amount of L sterilized distilled water was applied to the other 10 cigarettes. After 4 days, an aqueous suspension whose concentration was adjusted to contain 107 pathogenic damping-off bacteria/ml was inoculated in the same manner as in Example 1, in an amount of 10 ml each. 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 area, and the average morbidity index is also statistically significantly lower in the treated area (risk rate 1 band).
The control rate was 79%.

Table 2 Treatment area 30% 03 79% Example 3 Twenty eggplant seedlings (variety: Group 2 eggplant) grown in the same manner as in Example 1 and 7 weeks after sowing were tested. Example 1
Pseudomonas solanacearum M23 prepared in the same manner as
R suspension (bacterial concentration = 101ff/ml) at 1
100 ml per plant was applied to 10 seedlings. 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 as in Example 1, the disease attack rate was statistically significantly lower in the average treatment plot (risk rate 1), and the control rate was 84.

Table 3 Disease attack rate Average morbidity index Control rate treatment area 30% 04 84 control area 80% 2.5 0% Example 4 Tomato seedlings (variety: Fukuju No. 100) grown in a flower pot with a diameter of 120 mm were tested. . A suspension of Pseudomonas solanacearum M231 (bacteria concentration: 10'' cells/ml) prepared in the same manner as in Example 1 was given to 10 seedlings at a dose of 100 me each.As a control, the same amount of sterilized distilled water was applied. was given to other 10 seedlings. 5 days later.

Tomato wilt fungus Fusarium oxysporum (Fu-s
10 conidia of arium oxvsporum
A suspension was prepared to contain 4 seeds/me, and inoculated to Awa Sore tomatoes at 10 times each.Furthermore, after 20 days, the disease onset was investigated, and the 8 disease outbreaks were divided into 6 stages as shown in the table below.

The average morbidity index and control rate were determined using the formula described in Example 1. The results are shown in Table-4.

Class Symptoms 0 Healthy 1 Lower leaves mass or drooping 2 Lower leaves withering and falling leaves 3 Upper leaves withering and falling leaves 4 Immediately before withering 5 The disease incidence is lower in the withering treatment plot, and the average disease index is also statistically significant compared to the control plot. Low (risk rate 5ch).

The control rate was also 76%.

Table = 4 Incidence rate Average morbidity index ゛Control rate treatment area 30% 04 76% ・
7 control areas 70
% 1.7 0% Example 5 A suspension of the tobacco damping-off bacterium Pseudomonas solanacearum M23R prepared in the same manner as in Example 1 (bacterial concentration: 1o
1G pieces/ml) to tobacco seedlings that have grown to a total of 7 leaves (
10 me each was applied to the roots of 10 plants (variety Futari Daruma).

On the 6th day after treatment, the Phytophthora parasitic bacterium (Phytophthora parasitic)
The above tobacco seedlings were transplanted into a vat filled with soil artificially inoculated with T. tjca ). As a control, the same amount of sterilization 1
Ten other tobacco seedlings were given distilled water and transplanted in the same manner. 2
After 0 days, the disease onset was investigated and the control rate was calculated from the linear equation.

The results are shown in Table-5. The disease attack rate in the treatment area was only 20 cases, and the control rate was 80 cases.

Table-5 Incidence rate Control rate Treatment area 20% 80chi Control area 100% 0chi

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.