JPH0448762B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for controlling soil diseases of Solanaceae plants caused by parasitism of Pseudomonas solanacearum bacteria. [Prior Art] Tobacco damping-off and bacterial wilt of solanaceous plants other than tobacco, such as eggplants, tomatoes, green peppers, and potatoes, are caused by parasitism of pathogenic Cydomonas solanacearum bacteria. When plants are infected with these diseases, they wither and become unharvestable, causing great damage. As a means to control tobacco damping-off and bacterial wilt of plants in the Solanaceae family other than tobacco (in this specification, these diseases are collectively referred to as soil diseases of plants in the Solanaceae family), based on the Patent Cooperation Treaty, International application published in (International publication number WO85/
03519), Cydomonas solanacearum
A method is disclosed in which live bacteria of the M4S (Feikoken Jokyo No. 700) strain is inoculated into the roots of a Solanaceae plant. [Problems to be Solved by the Invention] The effect of suppressing the onset of soil diseases by the above method has been confirmed in this field, but in order to use it as a soil disease control method in this field, it is necessary to further enhance the control effect. is desired. [Means for solving the problem] In this invention, Cydomonas solanacearum
In order to further enhance the effect of M4S live bacteria on controlling soil diseases of Solanaceae plants, we inoculated live Cydomonas solanacearum M4S bacteria into the roots of Solanaceae plants.
Within 7 days after this inoculation, a bacteriophage growth solution that lyses both the viable bacteria and the pathogenic Pseudomonas solanacearum is sprayed onto the soil at the roots. By the way, attempts have been made for a long time to use bacteriophages (hereinafter simply referred to as phages) that lyse pathogenic bacteria in plants to control plant diseases caused by parasitism of pathogenic bacteria. However, at present, these attempts have not reached the level of practical use. The reason is thought to be as follows. In other words, pathogenic bacteria that have grown inside the plant form clumps and are surrounded by a large amount of mucilage such as sugars, so that all bacterial cells are not infected by phages and the distribution of phages is extremely localized. This is because they are being realized. In other words, it is thought that a major cause of this is that phage is distributed in large numbers in old diseased spots on plants, and is rare in healthy parts. Since the control effect of phage cannot be expected due to such reasons, in this invention, phage is introduced into the plant body and allowed to proliferate before the pathogenic bacteria proliferate within the plant body. More specifically, Sydomonas solanacearum M4S, a non-pathogenic strain of Sydomonas solanacearum that is a soil pathogen of solanaceous plants, is inoculated into the roots of the solanaceous plants to allow the bacteria to invade the plant body, and the phage By spraying phage, the phages multiply within the plant before the pathogenic bacterium Sydomonas solanacearum invades the plant, thereby increasing the soil disease control effect. As mentioned above, the Sydomonas solanacearum M4S strain used in the method of this invention (hereinafter simply referred to as the M4S bacterium) has been deposited at the Institute of Fine Technology (Deposit number: Article No. 700 of the Institute of Fine Arts and Technology). issue),
The acquisition method, culture method, mycological properties, etc. are as described in detail in the above-mentioned International Publication WO85/03519. Phages used in this invention can be isolated by applying the method described in Microbiological Experimental Methods (edited by the Microbial Research Methods Council, published by Kodansha Scientific Books, December 1975). Specifically, tobacco stems grown at Japan Tobacco Inc.'s Utsunomiya Experiment Station and infected with tobacco damping-off were cut into strips of 1 cm or less on each side, and 10 g of the stems were suspended in 100 ml of sterilized water for 1 hour. Shake. The supernatant was centrifuged at 10,000 rpm for 10 minutes, and the supernatant was filtered through a Millipore filter (0.45 μm). 0.2 ml of the filtrate was added to a well-known strain containing pathogenic tobacco blight bacteria.
CPG medium (ingredients: 1 g of casamino acids, 10 g of glucose)
g, peptone 10 g, water 1 liter), 48
Cultured with shaking for hours. After filtering the supernatant of the culture filtrate with a Millipore filter, it was serially diluted, 0.1 ml of the filtrate was suspended in 3 ml of CPG agar medium containing pathogenic damping-off bacteria, and this was
The mixture was poured into a 1.5 cm Shear dish and cultured at 30°C for 24 hours. Phages were isolated from the formed lytic plaques. Cultivation of phages is similar to that of M4S bacteria. That is, a liquid medium inoculated with Phage and M4S bacteria is cultured at 28 to 30°C for 36 to 72 hours, preferably 48 hours. Transfer the culture medium at high speed (e.g.
Centrifuge at 10,000 revolutions/min) and use the supernatant as the fur growth solution. When actually spraying on soil, the number of phages per ml should be 10 to ⁶ or more, preferably 10 ^{to 8.}
Adjust it to more than one. According to the present invention, in order to control soil diseases of Solanaceae plants, first, live M4S bacteria are preferably suspended in sterile water (bacterial concentration: 10 ⁶ -
10 ¹⁰ cells/ml, preferably 10 ⁷ to ^{10 9} cells/ml), and inoculate the roots of the plants 3 weeks before transplanting, including the day of main field planting, as described in the International Publication No. do. The timing of this inoculation is preferably 1 to 4 days before transplantation. Note that the root part refers to the part that exists in the soil and absorbs water and nutrients when cultivated using soil, and also includes tubers of potatoes. Inoculation to the roots is
This can be easily done by immersing the roots in a suspension of M4S bacteria. The immersion time is usually 30 minutes to 3 hours, preferably about 1 hour. One hour to 7 days after inoculation with M4S bacteria, apply the above Phage propagation solution with adjusted number of Phage to the root soil of the inoculated seedlings at 100% per solid.
Spray more than ml. When transplanting seedlings to the main field (planting), spray Phage propagation solution and leave for 1 to 7 hours.
It is preferable to carry out the treatment after 1 day, preferably from 1 to 4 days. [Operations and Effects of the Invention] The mechanism by which soil diseases of Solanaceae plants, that is, tobacco damping-off and bacterial wilt of Solanaceae plants other than tobacco, are controlled by the method of the present invention is thought to be as follows. . That is, first, a Solanaceae plant was inoculated in advance.
M4S bacteria invade the plant body. Phage added later moves into the plant body while lysing this M4S bacterium (it has been experimentally confirmed that Phage moves into the plant body). This fuage is
It inhibits the growth of pathogenic Sydomonas solanacearum that invaded later and suppresses the onset of disease. In addition,
The action of M4S fungi induces the plant's own control response. Thus, according to the present invention, soil diseases of Solanaceae plants are effectively controlled. [Example] Example 1 Tobacco seedlings with 9 true leaves (variety: Hakuenshū No. 1) grown in vinyl chloride resin pots (25 plants) with a side of 28.5 cm and grown to a size that can be transplanted to the main field. Each of these 20 seedlings was treated as follows: (1) Treatment area with M4S bacteria and Phage solution (invention): Live M4S bacteria were added to a concentration of 10 ^{to 10} cells/ml. A suspension was prepared in sterilized water so that tobacco seedlings were immersed in this for 1 hour, and then planted in flower pots with a diameter of 15 cm.After 4 days, the phage solution (number of phages: ¹⁰⁸ /ml sterile water) was added. 100 ml of each pot was added. (2) M4S bacteria treatment group: The same procedure as treatment group (1) was carried out except that Phage was not added. (3) Phage solution treatment group: Treatment with M4S bacteria The same treatment as treatment group (1) was carried out, except that the treatment was not carried out. (4) Control group: Tobacco seedlings were immersed in distilled water only and then potted in the same flower pots. 4 days after each treatment. Later, an aqueous suspension containing pathogenic Sydomonas solanacearum at a concentration of ¹⁰⁷ cells/ml was prepared, and the roots of the 80 seedlings were inserted with a knife to injure them. The bacterial suspension was injected in 10 ml portions.The disease state was observed after 10 days.The disease severity was graded into 6 levels from 0 to 5 as shown in Table 1 below, and the average morbidity index was calculated using the following formula to control the disease. The results are shown in Table 2.

【table】

[Table] 4 Whole leaf wilt
5 Withering and death

Claims (1)

[Claims] 1. Live bacteria of Pseudomonas solanacearum M4S are inoculated into the roots of plants of the Solanaceae family, and within 7 days of this inoculation, a growth solution of bacteriophage that can lyse both the live bacteria and pathogenic Pseudomonas solanacearum is applied. A method for controlling soil diseases of Solanaceae plants, which comprises spraying the soil at the roots.