JPH09104606A - Plant disease controlling agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plant disease controlling agent capable of suppressing occurrence of powdery mildew and growth of gray mold, etc., which is other important plant disease by using a microorganism of the genus Alcaligenes as an active ingredient. SOLUTION: This plant disease controlling agent contains Alkaligenese faecalis belonging the genus Alkaligenese and separated from soil in Kanagawa prefecture or cultured product of its genetic variant as an active ingredient. Alkaligenese faecalis No.4 (FERM P-15229) is preferably used as Alkaligenese faecalis. The genetic variant is obtained by subjecting the Alkaligenese faecalis No.4 as an original strain to natural or induced mutation. The variant is improved in performance, compared with No.4 strain. The cultured microorganism cell can also directly used without separating from the cultured products. The cell can also be used as water dispersible powder, etc. A microbial suspension obtained by controlling the microbial concentration to >=1×10<7> /ml concentration is preferably used as the spraying concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to biological control of plant diseases. More specifically, it relates to a plant disease control agent containing a microorganism of the genus Alcaligenes.

[0002]

2. Description of the Related Art Diseases of agricultural and horticultural crops are often controlled by chemically synthesized pesticides (so-called chemical pesticides), cultivating methods such as rotation, and breeding methods using disease-resistant varieties. There is. However, since chemical pesticides act on organisms other than the target organisms, it is pointed out that there are concerns about safety and environmental pollution such as destruction of the ecosystem.
Furthermore, it has been pointed out that pesticide-resistant pathogens have emerged, making it difficult for pesticides to work effectively. Rotation is an effective control method experimentally, but under the current intensive agricultural production system, it is the actual situation that an effective rotation system cannot be taken due to the difficulty of selecting crops that are economically viable. Further, it is not an effective control method for diseases with a wide range of hosts.

Breeding resistant varieties requires a great deal of labor and a long time, and is effective only for controlling a specific disease.
It has the drawback that resistance to new pathogens that enter from outside the region cannot be guaranteed. For the above reasons, effective control methods alternative to these means are demanded, and as a control method having high safety and not polluting the environment, a biocontrol method using a specific naturally occurring antagonistic microorganism has been studied. ing. That is, a biological control method has been developed in which a microorganism having an antagonistic action against a pathogenic bacterium is applied to plants and soil to suppress the growth of the pathogenic bacterium and the infection of the plant body.

Various antagonistic microorganisms have been developed for soil diseases caused by pathogenic filamentous fungi and pathogenic bacteria present in soil. For example, Trichoderma (Trichoderma), Bacillus (Bacillus), nonpathogenic Fusarium (Fusarium), non-pathogenic Pseudomonas (Pseu
domonas), a non-pathogenic Eruvinia (Erwinia), such as Fusarium (Fusarium), Pseudomonas (Rseudomona
s ), Rhizoctonia ( Rhizoctonia ), Erwinia ( Er )
It is known to control various soil diseases caused by winia ). However, Bacillus subtilis ( Ba
control method using cillus subtilis (Japanese Patent Laid-Open No. 2-209803)
No.), Anperomisesu-Kisukarisu (Ampelomyces quis
Qualis) by controlling method (JP-A-2-113883), Chirechiopushinu sp. (Tilletiopsis sp.) by the control method (Phyto
pathology (1994) Vol.84, No4, 341-351), control method by Verticillium lecanii (Netherlands Journal of Plant Pathology (1993) V
ol.99, No2, 101-103) is only disclosed, a microorganism belonging to Alcaligenes faecalis has a plant disease,
There is no report that it is particularly effective against powdery mildew.

[0005]

DISCLOSURE OF THE INVENTION Under the present circumstances, the inventors of the present invention have eagerly searched for a novel antagonistic bacterium having a controlling activity against powdery mildew. Suppressing a result, certain bacteria belonging to been Alcaligenes (Alcaligenes) genus isolated from Kanagawa soil suppressing the occurrence of powdery mildew, and also the growth of Botrytis cinerea, etc. is another important plant pathogens Therefore, they have completed a plant disease controlling agent based on this.

[0006]

The present invention is a plant disease controlling agent containing Alcaligenes faecalis cells or a culture thereof as an active ingredient. Hereinafter, the present invention will be described in detail. The microorganisms isolated from the soil of Kanagawa prefecture, which are used as the active ingredients of the plant disease controlling agent of the present invention, have the mycological properties shown in Table 1. Alcaligenes faecal
is a microorganism belonging to Alcaligenes faecalis No4 (hereinafter, A. faecalis
Abbreviated as No4. ), And has been deposited at the Institute of Biotechnology, Institute of Industrial Science and Technology with a deposit number of 15229 (FERM P-15229).

[0007]

[Table 1]

[0008]

[Table 2]

The microorganism used in the present invention is A. faeca described above.
Not limited to the lis No4 strain, all microorganisms belonging to Alcaligenes faecalis capable of controlling plant diseases can be used in the present invention. Further, by using the above A. faecalis No4 strain as the original strain by natural or induced mutation, a genetic mutant with improved plant disease control performance of the strain can be obtained and used as a plant disease control agent according to the present invention. . As a method for preparing these mutant strains, a conventionally known conventional method, for example, artificial mutation by irradiating the original strain with ultraviolet rays or a drug such as N-methyl-N'-nitro-N-nitrosoguanidine (NTG) is used. After treatment, spread on agar medium coated with a suspension of phytopathogenic bacteria, clear zone formed around the colony from the growing strains,
A method can be used in which larger colonies are selected and a strain having an excellent activity of suppressing the growth of phytopathogenic bacteria is selected. In addition, a gene having the property of controlling plant diseases of the present invention is ligated to an appropriate self-replicating DNA, and an appropriate host cell is transformed with this gene to improve the activity of suppressing the growth of phytopathogenic bacteria by the gene amplification effect. You can also let it.

Any medium can be used in the present invention for culturing the strain as long as the strain can grow, but a medium using an ammonium salt as a nitrogen source is preferable. Gives good results. The culture in the present invention can be carried out under aerobic conditions by, for example, aeration and agitation culture method, shaking culture method or solid culture method. Can be cultured. The culture conditions are not particularly limited, but the temperature is 20 to 40 ° C and the pH is 6.0.
.About.8.0, and the culturing time is suitably in the range of 15 to 72 hours.

The cultured microbial cells can be used as a plant disease control agent without being separated from the culture.
Furthermore, the culture can be dried and used,
Further, it is also possible to use a formulation such as a wettable powder together with various additives according to a conventional method for pesticide formulation. The thus-prepared culture of microorganisms or separated bacterial cells is suspended in water and then sprayed on plants. The spraying concentration varies depending on the disease to be controlled, but in general, a method of spraying a bacterial suspension in which the bacterial concentration is adjusted to 1 × 10 ⁷ / ml or more before the disease occurs is desirable. According to the method of the present invention, the development of powdery mildew can be effectively controlled.

[0012]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

Example 1: Antagonism against various plant pathogens Twelve species of plant pathogens [ Alternaria m. ( Alternaria m.
ali ), Botrytis cinerea ,
Cercospora kikuchi ( Cercospora kikuchi ), Cochliobolus miyabeanus,
Fusarium oxysporum J1
J1), Fusarium oxysporum J2 (Fusarium ox
ysporum J2), Fusarium oxysporum J3 ( Fusa
rium oxysporum J3), Phomopsis sp. 4-2 ( Pho
mopsis sp.4-2), Rhizoctonia solani AG-4 ( Rhi
zoctonia solani AG-4), Rhizoctonia solani rm3 50
A spore suspension of 03 ( Rhizoctonia solani rm3 5003), Verticillium dahliae , and Xanthomonas oryzae ] was applied to each petri dish in an amount of 100 μl, and A. faecalis No4
Was inoculated. After culturing in a dark place kept at 25 ° C. for about 1 week, the activity of A. faecalis No4 to suppress the growth of various plant pathogens was measured by the area of the inhibition circle formed around the A. faecalis No4 colony. In the case of Xanthomonas oryzae, the same procedure was performed using PYM medium. Table 2 shows the results. A. faecalis
No4 had an activity to suppress the growth of all the test plant pathogens.

[0014]

[Table 3]

Example 2 Culture of Microorganisms A medium (pH 7.0) containing the components shown in Table 3 was prepared and sterilized under high pressure under heat. 100 ml of the medium was placed in a 500 ml flask, 1 ml of A. faecalis No4 bacterial solution was inoculated, and then cultured at 30 ° C. and 120 spm for 48 hours.
A. faecalis No4 culture was obtained.

[0016]

[Table 4]

Example 3: Control of cucumber powdery mildew ( Sphaerotheca fuliginea ) Three cucumber plants were cultivated per pot in a pot having a diameter of about 15 cm, and obtained in Example 2 when the second true leaf was developed. A. faecali
5 ml of a suspension prepared by diluting the s No4 culture solution 100 times with water was sprayed per strain. After the sprayed leaves have been dried, the cucumber udon powder pathogen ( Sphaerot frisini ( Sphaerot
heca fuliginea )) spores were inoculated and the disease was caused to occur in the greenhouse. 14 days after the inoculation, the lesion area of cucumber powdery mildew was measured and the control value was calculated from the following formula.

[0018]

[Equation 1] Control value (%) = (1-lesion area ratio of test plot / lesion area ratio of untreated plot) × 100

The results are shown in Table 4. By spraying the culture of A. faecalis No4 on the plants, the severity of the powdery mildew of cucumber was significantly reduced compared to the untreated plots, and a high control effect was obtained.

[0020]

[Table 5]

[0021]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to control diseases caused by a wide range of plant pathogenic fungi including cucumber powdery mildew, which is highly safe and provides a plant disease controlling agent which does not pollute the environment at low cost. it can.

Claims (2)

[Claims] 1. Alcaligenes faecalis
Genes faecalis) or plant disease controlling agent containing a culture of the genetic variant as an active ingredient. 2. Alcali faecalis
genes faecalis ) is Alcaligenes faecalis ( Al
caligenes faecalis ) No4 (Contract No. 15229 (FERM P-15229), Institute of Biotechnology, Institute of Biotechnology, Industrial Technology Institute)), The plant disease controlling agent according to claim 1.