JP2598208B2 - Control method of bacterial blight of rice seedling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling bacterial blight of rice seedlings by spraying or dusting bacteria belonging to the scientific name Erwinia carotovora on rice paddy and nursery soil while alive. It is.

[0002]

2. Description of the Related Art Pseudomonas plantarii bacteria (Pseudomonas plantarii)
As a method for controlling rice seedling bacterial wilt caused by i), few pesticides are currently applied, and the development of pesticides that can be effectively controlled is desired.

[0003]

[Means for Solving the Problems] As a result of intensive studies, the present inventors have sprayed or sprayed a microbial pesticide preparation containing a non-pathogenic soft rot fungus effective for controlling soft rot on rice paddy or nursery soil. The inventors have found that by spraying, it is possible to effectively control rice seedling blight bacterial disease, and arrived at the present invention.

[0004] That is, the present invention is to control rice seedling blight disease characterized by immersing rice paddy in a suspension containing Erwinia carotobola bacteria having a pathogenic deficiency, and then planting it in soil. A method for controlling rice seedling blight disease, which is characterized by applying a powder containing Erwinia carotobola bacterium with pathogenicity to rice paddy and then planting it in soil. After irrigating or mixing a suspension, a powder or a granule containing the Erwinia carotobola bacterium, and then planting rice paddy, a method for controlling rice seedling blight bacterial disease, and a nursery soil planted with rice paddy A method for controlling bacterial blight of rice seedlings, which comprises spraying a suspension containing Erwinia carotobola bacteria having a pathogenicity on the rice. In addition, Erwinia carotobola bacterium that has lost pathogenicity is
The present invention relates to a method for controlling bacterial blight of rice seedlings, which is also characterized by being Carotebola CGE234M403 strain.

[0005] Erwinia carotobola is a bacterium that causes so-called soft rot, which softens and rots storage tissues of many plants, and is reported to be present in the soil in an unbiased manner. Occasionally, the occurrence of soft rot may be observed even in a field where a crop serving as a host of this fungus has not been produced for more than 5 years. The ecology of this fungus is considered as follows (Hiroyuki Tsuyama, Plant Protection, 34: 294-298, 1980). For example, in the case of Chinese cabbage, 40
From the daytime, the bacteria grow around the roots, and their presence is found in almost all places such as rhizosphere soil and leaves. If typhoons, insects, or daily work damages the Chinese cabbage, bacteria will invade from it, and if the climatic conditions are met, the concentration of pathogenic bacteria will rise overnight and lesions will be observed. In order to prevent these diseases, if it becomes possible to grow non-pathogenic Erwinia carotobola bacteria in place of the pathogenic strains in the rhizosphere soil and leaves in place of the pathogenic bacteria, Can be expected to control soft rot by suppressing the growth of toxic bacteria.
From among the mutant strains of Calotobora, strains that grow well in competition with virulent strains of the same strain and that have no virulence are selected and Ervinia that lacks these virulences.・ We found that inoculation of live roots or leaves of plants affected by soft rot bacteria with live bacteria of Carotobola can effectively control soft rot, and filed patent applications (JP-A-3-101606, JP-A-4-179475).
No.).

[0006] Next, Ervinia
A method for producing Carotobola bacteria is described. The present inventors have collected a large number of Erwinia bacteria from soft rot or healthy vegetables. Erwinia carotobola bacteria, which have lost pathogenicity, were created by mutating these soft-rot fungi. As the mutation method, commonly used mutation reagents, for example, a method using ethylmethanesulfonyl, nitrosoguanidine or the like or an ultraviolet ray (Microbiological Experiment Method, Microbial Research Method Council, pp. 288-306, Kodansha 1982, Genetic Experiments, edited by Tatsuo Ishikawa, pp. 3-32, Kyoritsu Shuppan (1982)), and processing may be performed according to these methods.

[0007] By the way, it is considered that the main factor of the pathogenicity of Erwinia carotobola is the pectinase secreted by this bacterium, particularly pectate lyase (Matsuo Goto, New Plant Bacteriology, p. 166, Soft Science). (1981). Therefore, screening for pathogenic deletion strains was carried out by picking up strains with reduced pectinase secretion ability and conducting pathogenicity tests using Chinese cabbage slices. The pathogenicity test was performed by scratching the leaf section of Chinese cabbage, applying a high-concentration test bacterial solution, and leaving it in a constant temperature bath at 28 ° C. for 24 hours in the presence of water, and then measuring the lesion length. .

When the pathogenic deletion strain of the Erwinia carotobora bacterium thus obtained is mixed with the pathogenic strain and inoculated on wounded Chinese cabbage slices, the growth of the pathogenic strain is suppressed and a lesion is formed. A strain was obtained that did not allow or significantly reduced the rate of lesion formation. Then, strains having particularly high lesion inhibition ability are selected from these pathogenic deletion strains and deposited with the Research Institute of Microbial Industry and Technology, and given the following deposit numbers.

[0009] Erwinia carotobola subspiro carotobola CGE6M14 Microtechnical Laboratory Bacteria No. 10998 (FERM P-1099)
8) Elvinia Carotobola Subspi Carotobola
CGE6M16 Microbiological Research Laboratories No. 10999 (FERM P-1099
9) Elvinia Carotobola Subspi Carotobola
CGE10M2 Microtechnical Research Laboratories No. 11000 (FERM P-1100
0) Elvinia Carotobola Subspi Carotobola
CGE11M5 Microbiological Research Laboratories No. 11001 (FERM P-1100
1) Elvinia Carotobola Subspi Carotobola
CGE234M403 Microtechnological Laboratory No. 11792 (FERM P-1179)
2) The present invention uses the Erwinia carotobola bacterium lacking these virulences, and more preferably the CGE234M403 strain (FERM P-1179).
2).

Next, a method for preparing the microbial pesticide of the present invention will be described. First, Erwinia carotobola bacterium which has been deleted from pathogenicity is cultured in an appropriate medium. The medium used here is not particularly limited as long as the bacteria can proliferate, and a commonly used medium may be used.
After culturing and growing at -35 ° C for 10-35 hours, the cells are collected by centrifugation to remove the medium components. By such an operation, the bacterial density is usually 2 × 10 ^{11 to} 3 × 10 ¹¹ cfu / g.
It is concentrated to a degree.

[0011] Then, the wet cells are treated with an inorganic substance such as alumina, silica gel, molecular sieve, perlite, activated carbon, sand or red earth, a saccharide solution comprising one or more of saccharose, glucose, fructose, sorbitol and the like, or glutamic acid. sodium,
It is placed in a fixing agent such as a sodium phosphate buffer, suspended by stirring, and freeze-dried.

The dried cells thus obtained are mixed with a diluent, an auxiliary agent and the like, if necessary, to prepare a formulation. The dosage form at this time may be a commonly used dosage form such as a powder, granule, wettable powder, suspension and the like, and may be appropriately selected depending on the purpose and the like.

The diluents include diatomaceous earth, talc,
Specific examples include clay, acid clay, bentonite, kaolin, wood flour, tub flour, cake flour, calcium carbonate, water, and the like.
More than one type can be used in combination.

Specific examples of the adjuvant include surfactants, stabilizers, and other powerful agents for increasing the efficacy of the active ingredient. One of these may be used alone, or two or more may be used. Can be used in combination.

The microbial pesticide of the present invention is prepared as described above. At this time, the bacterial density in the preparation is about 1 × 10 ⁶ to 1 × 10 ¹¹ cfu / g in the case of powders and granules, and
In the case of a suspension, it is preferable to prepare the suspension to be about 1 × 10 ⁶ to 1 × 10 ⁹ cfu / ml.

Next, a method for using the microbial pesticide of the present invention will be described. Generally, when raising rice, various pesticides are used to disinfect seed-borne pathogens, such as to control various plant diseases that occur during seedling, for example, to control rice seed blight bacterial disease (seedling rot) and take-all disease. Is used. There are several methods for its use, such as immersing the paddy in the pesticide solution, dressing the pesticide powder on the paddy, irrigating the seedbed soil with the pesticide solution, or mixing the pesticide powder, grains, There is a method of spraying a pesticide solution on the soil in which paddy is planted. These methods can be used as they are for the microbial pesticide of the present invention containing an Erwinia carotobola bacterium having a pathogenicity as an active ingredient.

[0017] That is, as a method of using the microbial pesticide of the present invention, a method of immersing rice paddy in a suspension containing Erwinia carotobola bacterium lacking pathogenicity and then planting it in soil, Sprinkling with powder containing Erwinia carotobola bacteria with pathogenic deficiency, then planting it in soil, and irrigating nurseries with suspensions, powders or granules containing pathogenic deficient Erwinia carotobola bacteria Alternatively, a method of planting rice paddy after mixing, or a method of spraying a suspension containing Erwinia carotobola bacteria having pathogenicity deletion on a nursery soil in which rice paddy has been planted can be used.

Of these methods, in the method of immersing rice paddy in a suspension containing pathogenic deficient Erwinia carotobola bacteria and then planting the same in soil, the time of immersion in the suspension is particularly long. There is no limitation, and it may be about 10 minutes to several days required for immersion. In addition, it may be used by mixing with a seed disinfectant at the time of soaking or seed disinfection, or before or after soaking.

In the case of a method in which rice paddy is dusted with a powder containing Erwinia carotobola bacterium having no pathogenicity and then planted in soil, the time for dusting the powder is not particularly limited, and is about 10 minutes to several minutes. It can be for days. Also, it may be performed before or after soaking.

Further, a method of irrigating or mixing a suspension, a powder or a granule containing Erwinia carotobora bacteria having a pathogenic deficiency in a nursery, and then planting rice hulls, and a method of planting rice husks in a nursery soil in which rice husks are planted. In the case of a method of spraying a suspension containing Erwinia carotobola bacteria with pathogenicity deficiency, the amount of the drug to be irrigated, mixed or sprayed is about 1 g to 100 g per 1 L of soil in the case of powder or granules, In addition, in the case of a suspension, 10 ml per liter of soil is used.
Preferably, the volume is about 1000 ml.

[0021]

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

The composition of the medium used in the examples is shown below. 802 medium: polypeptone 10 g, yeast extract 2
_{g, MgSO 4 · 7H 2 O} 1g, water 1L, PH7.
0 (including 15 g of agar in the case of a plate) Example 1 Erwinia carotobola CGE234M in 802 medium
403 strains [Microtechnical Laboratory No. 11792 (FERMP)
-11792) and 30
C. for 15 hours. The culture solution is collected using a centrifugal separator, and the cell concentrate (cell count 3.0 × 10 ¹¹ cfu /
ml). Then, a fixing agent [40% (w / w) saccharose, 2% (w / w) sodium glutamate,
A solution containing 0.1 M sodium phosphate buffer Ph7.0] was dried and frozen, and dissolved in water to give a bacterial density of 1 × 10 ^8.
A suspension adjusted to be cfu / ml was prepared.

Rice seedlings infected with the bacterial wilt of rice seedlings were immersed in the above suspension for 3 days, replaced with a new bacterial suspension, immersed for another 3 days, and then sown. In the control group, the same operation was performed using water instead of the bacterial suspension. All of the above operations were performed at a liquid temperature of 15 ° C., and then the temperature was raised to 30 ° C. for one day for germination. One month after planting, the occurrence of bacterial wilt of rice seedlings was investigated, and the results shown in Table 1 were obtained. The control value was 100%.

[0024]

[Table 1] Example 2 Erwinia carotobora CGE234M403 strain prepared in the same manner as in Example 1 [Microcosms Deposit No. 1179
No. 2 (FERM P-11792)] (cell density of 1 × 10 ⁸ cfu / ml) was sprayed onto seedbed soil at 100 ml per liter of soil. Then, the rice seedlings infected with the bacterial wilt of rice seedlings were immediately sown. In the control group, the same operation was performed using water instead of the bacterial suspension. All of the above operations were performed at a liquid temperature of 15 ° C., and then the temperature was raised to 30 ° C. for one day for germination. After 15 days from the seeding, the occurrence of bacterial wilt of rice seedlings was investigated. The results shown in Table 2 were obtained. The control value was 96.3%.

[0025]

[Table 2]

[0026]

Industrial Applicability According to the present invention, it has become possible to effectively control rice seedling bacterial wilt, which is one of the major plant bacterial diseases that have been conventionally difficult to control. The present invention is a method of using living bacteria as a so-called biological control measure,
Moreover, the present invention provides a method for controlling rice seedling blight disease without chemical injury.

Claims (5)

(57) [Claims] The present invention relates to a rice paddy comprising Erbinia elegans having a pathogenic deficiency.
A method for controlling bacterial blight of rice seedlings, comprising immersing in a suspension containing carotobora bacteria and then planting in soil. 2. An Erbinia rice plant having pathogenicity deleted in rice paddy.
A method for controlling bacterial blight of rice seedlings, comprising spraying a powder containing carotobora bacteria and then planting it in soil. 3. A rice seedling wilt disease, characterized by irrigating or mixing a suspension, powder or granules containing Erwinia carotobola bacteria having a pathogenicity deficiency in a nursery, and then planting rice seed. How to control. 4. A method for controlling bacterial seedling blight of a rice plant, which comprises spraying a suspension containing pathogenic deletions of Erwinia carotobola bacteria on a seedbed soil in which rice paddy has been planted. 5. The bacterium of the present invention, wherein the bacterium of the genus Erwinia carotobola lacking pathogenicity is CGE234M4.
The method for controlling bacterial blight of rice seedling according to any one of claims 1 to 4, wherein the bacterial strain is 03 strain.