JPH0213367A - Novel pathogenic microorganisms, herbicides containing the microorganisms, and weed control methods using them - Google Patents

Abstract

NEW MATERIAL:Fusarium oxysporum MH-0008 (FERM 10056). USE:A herbicide selectively killing barnyard millet which is harmful weed in rice field. PREPARATION:Barnyard millet exhibiting disease symptom is collected, sterilized at the surface, placed on an agar medium and cultured at 25 deg.C for 48-72hr to obtain the objective microorganism.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a pathogenic microorganism that is effective for controlling weeds, particularly barnyard grass, which is a harmful weed in the cultivation of important crops of the Poaceae family, such as rice and wheat, and a method containing the microorganism. This invention relates to herbicides and methods for controlling weeds using them.

[Prior art]

Weed outbreaks cost farmers a large amount of money due to damage to crops and the cost of weed control. The damage caused by harmful weeds to such crops is thought to be mainly due to reduced yields, deterioration in crop quality, and damage to crops caused by insects and diseases living in weeds. Currently, chemical herbicides are mainly used to reduce the damage caused by these weeds. However, recently humans have become concerned about the effects of chemical herbicides on the food they eat, the land they live on, and the groundwater they use. As a major countermeasure to this problem, there is currently a trend toward many crops being grown without pesticides. However, this manual method causes problems such as an increase in working hours and workability. On the other hand, it is also recognized that there are difficult-to-control weeds that are always difficult to eliminate with chemical herbicides. Recently, microbial herbicides have been attracting attention as a herbicide that improves the shortcomings of these chemical herbicides.This method uses naturally occurring microorganisms (pathogens for weeds) and is effective against pollution and crops. It is thought that the effect on the human body through the chemical herbicides is much lower than that of chemical herbicides, and it is becoming increasingly important as an alternative to chemical herbicides. Considering the importance of this, research is currently being conducted in many laboratories, and research and practical trials have been particularly active in the United States over the past few years. Examples of these can be found in U.S. Patent No. 3,849,104 [Colletotrichum gloeos volioides penzuaescynomene].
porioi-des Peoz, aes-chyn
No. 3,999.973 (Colletotrichum walva-
rum); No. 4,263.036 [Fusarfum roseum Cu1
4, No. 390.360 (Control of Sicklebod and other Weeds by Alternaria casiea)]. The microbial herbicides used are DsVine (trade name of Abbott) and Collego.

Upjiten Co., Ltd. (trade name), each of which has shown herbicidal effects against specific harmful weeds. However, nothing has been found to be effective against the genus Echinochloa, which is a harmful weed in the cultivation of rice, wheat, etc., which are important crops of the Poaceae family.

[Problem to be solved by the invention]

The present invention provides a more effective means for solving the problems of current agricultural crop production as described above. That is, an object of the present invention is to provide a pathogenic microorganism that controls weeds harmful to grass crops, a herbicide containing the pathogenic microorganism, and a weed control method. .

[Means for Solving the Problems] The present inventors have developed Echino-chl.
Focusing on pathogenic bacteria for the genus A. oa and barnyard grass, we searched for and isolated many strains, evaluated their weed control effects, and investigated whether they are pathogenic to other crops, especially rice and wheat. We have discovered a new pathogenic microorganism that can control barnyard grass in wheat cultivation.

That is, pathogenic microorganisms were purified and isolated from barnyard grass growing in rice fields and exhibiting disease symptoms using the usual method used to isolate plant pathogenic microorganisms. Among these many isolated microorganisms, we searched for pathogenic microorganisms that have a herbicidal effect on barnyard grass and are not disease-causing or parasitic on rice, and by discovering the pathogenic microorganism of the present invention, we have completed the present invention.

The present invention relates to Fusarium oxysporum (Fusarju).
+moxysporum) M H-0008 (Feikoken Bokujo No. 10056) relates to a novel pathogenic microorganism, a weed control agent characterized by containing the microorganism, and a weed control method using the same.

The pathogenic microorganisms according to the present invention can be easily isolated from naturally occurring diseased barnyard grass, can be easily cultured in large quantities, and can efficiently obtain spores in large quantities. The pathogenic microorganism is an aerobic bacterium, and the pH at which it can grow is 4 to 8, preferably 5 to 6,
The growth temperature is 15 to 30°C, preferably 23 to 28°C.6 The pathogenic microorganism according to the present invention exhibits pathogenicity and control effects on barnyard grass, and is suitable for rice, edible wheat, grass crops such as wheat, and eggplant. For solanaceous crops such as tomatoes, cruciferous crops such as radish, and cucurbitaceous crops such as kapocha,
It exhibits no colonization or pathogenicity, and exhibits high selective control activity against barnyard grass.

〔Example〕

The pathogenic microorganisms according to the present invention will be specifically explained below using Examples.

Example 1 1) Method for isolating pathogenic microorganisms Barnyard grass naturally occurring in paddy fields and exhibiting disease symptoms were collected.

Cut a section of 2 to 3 c'Il centered around the symptomatic area, and cut 70
% ethanol solution for 2 to 3 seconds, and then immersed in a 2% sodium hypochlorite solution for 10 minutes to kill the surface of the barnyard grass. After washing several times with sterile water, prepare an oligotrophic plate medium [115 potato dextrose agar medium (hereinafter referred to as PDA).
abbreviated as culture medium), placed on 115 Chabekku agar medium],
The microorganisms were cultured in a thermostat at 25° C. for 48 to 72 hours, and the grown microorganisms were separated into single hyphae under a stereomicroscope to isolate pure pathogenic microorganisms. The obtained pathogenic microorganisms were tested for pathogenicity, colonization, and herbicidal effect on barnyard grass, and were further tested for pathogenicity and colonization on rice. Microorganism MH-0008, which does not exhibit pathogenicity or colonization in the mouth, was isolated.

2) Identification of the isolated microorganisms The isolated microorganisms were identified by culturing them in PDA medium and checking the spore morphology and pigment production. (
white) to pale red-purple (pale redν1o
or duel light red violet
and macroconidia (macrocoa ld)
ia ) and microconidia (a+1croconid
ia) and form large numbers of chlamydospores.

Based on the thickness of the macroconidia and its crescent-shaped shape with septa, and the size and shape of the microconidia, Fusarium oxysporum (Fusari
um oxy-sporum).

3) Growth status on each medium Growth on PDA plate medium, potato shakerose agar medium, and Chavek agar medium is very good in all mediums. When cultured for 5 days in a 25°C incubator, it spreads over the entire Petri dish (9 cm) and takes on a light purple color.

4) Physiological properties It is an aerobic bacterium, and the pH at which it can grow is 4 to 8, and the temperature is 1.
5-30'C. Optimal growth conditions are pH 5-6 and temperature 23-28°C.

Example 2 Large-scale cultivation method The pathogenic microorganism of the present invention was grown on potatoes in jar fermenta.
By culturing at 25°C for 48 hours using dextrose Saichi (PD medium), 2 to 3 and 101 spores/d were obtained.
becomes.

As described above, the pathogenic microorganism of the present invention can be used as a microorganism weed killer because spores can be obtained efficiently and in large quantities by mass culturing.

Next, according to test examples, the pathogenic microorganism MH-0008 of the present invention
The excellent effects of this will be explained in detail.

Test Example 1 Japanese barnyard grass was cultivated in a commercially available pot, and a test for fixation was conducted using leaf pieces at approximately the 3rd to 4th leaf stage by the following method.

The leaf pieces were immersed in a 2% sodium hypochlorite solution for 10 minutes, and then thoroughly washed with sterile water. The leaf pieces were placed in a plastic petri dish lined with filter paper soaked with sterile water.

On the other hand, pathogenic microorganism MH-0008 isolated from diseased leaves
Plate culture was performed in PDA medium. Agar is extracted from the cultured plate medium using a sterilized cork polar plate, and this disk is placed on top of a leaf piece of barnyard grass in a petri dish aseptically. After culturing for 72 hours in a thermostat at 25°C, microorganisms colonize the barnyard grass. The sex was determined. For comparison,
A pathogenic microorganism (MH
-0007 and M H-0010) were used. The results are shown in Table 1.

Table 1 Pathogenic microorganisms that colonize barnyard grass
Colonization MH-0008 (pathogenic microorganism of the present invention) ++10MH-
0007 (Other pathogenic microorganisms) -MH-001
0 (Other pathogenic microorganisms) - (Note) +++i Significant growth on the leaf surface ++; Growth on the leaf surface 10; Slight growth on the leaf surface -; No growth Test results showed that the pathogenic microorganism of the present invention M H- 0008 significantly proliferated on the surface of barnyard grass and exhibited excellent fixation properties.

Test Example 2 Aseptically growing barnyard grass in a test tube (up to the 1.5 leaf stage),
It was used as a test material. That is, the seeds were immersed in a 2% sodium hypochlorite solution for 10 minutes, and then thoroughly washed with sterilized water. The seeds were transplanted into test tubes containing previously prepared and sterilized B5 medium.

On the other hand, the isolated pathogenic microorganism MH-0008 of the present invention was plate cultured on a PDA medium. Agar was extracted from the cultured plate using a sterilized cork polar plate, and the disk was placed in a test tube aseptically and incubated in a thermostat at 25°C for 120 hours, after which the pathogenicity of the pathogenic microorganism to barnyard grass was determined. . The results are shown in Table 2.

Table 2 Pathogenic microorganisms pathogenic to barnyard grass
Pathogenic MH-0008C Pathogenic microorganisms of the present invention) ++10MM-
0007 (Other pathogenic microorganisms) -MH-0010
(Other pathogenic microorganisms) - (Note) +++; Death of barnyard grass ++; Significant growth inhibition + ; Slight growth inhibition -; No effect As a result of the test, the pathogenic microorganism MH-0008 of the present invention was superior to barnyard grass. It showed pathogenicity.

Test Example 3 Growing barnyard grass in a commercially available vinyl pot (1st and 5th leaf stage)
, the pathogenic microorganism of the present invention M H-000 was used as a test material.
No. 8 was subjected to liquid culture in a potato dextrose liquid medium (PD medium). After culturing, only spores were obtained from the culture solution.

The obtained spores were mixed with 0.05% Tween-80 (Theen-80).
-80) was suspended in an aqueous solution and sprayed on barnyard grass grown in pots, and the mixture was grown in a greenhouse at 25 to 30°C to observe changes in the barnyard grass. The inoculation amount is 1.5 x 10', 1.
It was inoculated at 5 x 10 h and 1.5 x 10' spores/Id, and the herbicidal activity was examined by the percentage of death of barnyard grass two weeks later. The results are shown in Table 3.

Table 3 Inoculum amount (spores/d) with control activity against barnyard grass Control rate (%) 1.5X10
'85 i,s x 1o'' to.

As a result of the 1.5 x 10' 100 test, MH-0008 of the present invention showed an excellent herbicidal effect on barnyard grass.

Next, we investigated the pathogenicity and colonization of the pathogenic microorganism MH-0008 of the present invention on crops, and confirmed that the pathogenic microorganism MH-0008 of the present invention is a pathogenic microorganism that does not cause disease on crops. .

Test Example 4 Pathogenicity was tested in the same manner as in Test Example 3, and fixation was tested in accordance with the method in Test Example 1. Plants other than barnyard grass include rice (Nipponbare, Sasanishiki)
, edible beetles (Panicum spp.), wheat, eggplant, tomatoes, radish, and kapocha. The results are shown in Table 4.
It was shown to.

As a result of the test, the pathogenic microorganism MH-0008 of the present invention was found to be effective in rice (Nipponbare, Sasanishiki), edible rice (Banicum sp.),
For wheat, eggplant, tomato, radish, kapocha,
It showed no pathogenicity or colonization.

Table 4 Reactivity of the pathogenic microorganism of the present invention to crops
Pathogenicity Fixed rice Nipponbare −− Sasanishiki −− Edible barnyard grass −− Wheat − −Eggplant
-- Tomato -- Radish -- Kapocha -- [Effects of the Invention] The pathogenic microorganism Fusarium oxysporum (Fu
sarium oxysporum) M H-000
8 (Feikoken Bacteria No. 10056) exhibits selective pathogenicity and colonization properties for barnyard grass, and when the spores of this microorganism are used, they can be used to chemically control plants without affecting other crops or plants. Unlike synthetic pesticides, there are fewer restrictions on the timing of application, and it can control barnyard grass, which is a harmful weed to rice.

Furthermore, the pathogenic microorganism MH-0008 of the present invention is selected from naturally occurring microorganisms and can be used safely without the environmental pollution concerns associated with chemically synthesized pesticides.

Claims (3)

[Claims] (1) Fusarium oxysporum (Fusarium oxysporum)
xysporum) MH-0008 (Microtechnical Laboratory No. 10
No. 056) Novel pathogenic microorganism. (2) Fusarium oxysporum
xysporum) MH-0008 (Microtechnical Laboratory No. 10
No. 056) A weed control agent characterized by containing a novel pathogenic microorganism. (3) Fusarium oxysporum
xysporum) MH-0008 (Microtechnical Laboratory No. 10
No. 056) Weed control method using novel pathogenic microorganisms.