Strain belonging to Exserohilum monoceras, and uses thereof

Details Strain belonging to Exserohilum monoceras, and uses thereof Strain belonging to Exserohilum monoceras, and uses thereof

1997-07-17

2001-11-06

Scheiner, Laurie (Department: 1641)

Plant protecting and regulating compositions

Plant growth regulating compositions

Micro-organisms or from micro-organisms

C504S116100, C504S118000, C435S254100, C424S274100

Reexamination Certificate

active

06313069

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a novel strain belonging to
Exserohilum monoceras
, a weed-controlling agent containing the same and a weed-controlling method using the same.
BACKGROUND ART
The use of agrochemicals is essential in farms for stable food production. However, a large amount of synthesized agrochemicals containing substances not found in nature are applied to land for a long period of time, thus bringing about harm. The most serious problem is their direct influences on human and domestic animals and their destruction of the ecological system. In recent years, the harmful influences on human and domestic animals have been reduced owing to drastic improvements in the specificity of agrochemicals for weeds, harmful insects and disease germs, but one should still pay adequate attention when coming into contact with a high concentration of agrochemicals in applying thereof. Further, the selectivity of agrochemicals for weeds, harmful insects and disease germs is not necessarily high, resulting often in disturbance of the ecological system.
To solve the problem, there is a need for development of pesticides not adversely affecting other species than the target species to protect the environment. One example of such pesticides is herbicides using weed pathogens. Certain weed pathogens are ubiquitous in weeds, and it is known that such pathogens can be used in a herbicide with little or no damage to humans, domestic animals, and small creatures including fishes, insects etc. and with less phytotoxicity on plants. Further, the specificity of such herbicides using pathogens for the target weed is so high that their selectivity is considered high and the ecological system is hardly disturbed. Examples of herbicides using weed pathogens commercially available at present are a herbicide DeVine using
Phytophthora palmivora
for Stranglervine, a herbicide Collego using
Colletotrichum gloeosporioides
f. sp.
aeschynomene
for Northern jointvetch, and a herbicide BioMal using
Colletotrichum gloeosporioides
f. sp.
malvae
for round-leaved mallow.
Examples of herbicides using weed pathogens for controlling Echinochloa spp. as the most serious weed in paddy fields are
Cochliobolus lunatus
(Anamorph:
Curvularia lunata
) [Weed Research, 27, 43-47, (1987) and Japanese Patent Application Laid-Open Publication No. 284,963/93],
Ustilago trichophora
[w093/05656], and
Drechslera monoceras
(synonym of
Exserohilum monoceras
) [Japanese Patent Application Laid-Open Publication Nos. 219,883/91, 226,905/92, 360,678/92, 370,090/92, 277,042/94, 329,513/94, and 247,822/94].
However, these conventional herbicides are disadvantageous:
for example,
Cochliobolus lunatus
needs dew period for more than 18 hours to demonstrate its sufficient effect;
Ustilago trichophora
needs 4 to 5 weeks after spraying until its sufficient effect appears; and
Drechslera monoceras
produces a small amount of spores. Therefore, herbicides using these fungi still have not come into practical use.
Problem for Solution by the Invention
The object of the present invention is to provide microorganisms having both a sufficient herbicidal effect and a high ability to produce spores.
DISCLOSURE OF THE INVENTION
The inventors screened strains pathogenic to Echinochloa spp. for a strain having a strong herbicidal effect, and found a group of strains having both a strong herbicidal effect and a high ability to produce spores. Further, the inventors examined these strains for their esterase zymogram pattern, and found that said group showed a similar esterase zymogram pattern not resembling any esterase zymogram patterns of known strains. On the basis of these findings, the inventors completed the following invention:
The present invention is a strain belonging to
Exserhilum monoceras
showing the esterase zymogram pattern shown in FIG.
1
.
In addition, the present invention is a weed-controlling agent comprising said strain as the active ingredient.
Further, the present invention is a method of controlling weeds comprising use of said weed-controlling agent.
Hereinafter, the present invention is described in detail.
The strains of the present invention were isolated from diseased Echinochloa spp., and the fungal properties are as follows:
They are aerobic which form dark gray or black colonies on a potato sucrose agar medium plate. White or gray aerial mycelium may be observed. They bear a large number of dark conidia, each having about 2 to 8 septa and being spindle-shaped and widest in the middle and thin towards the ends. A hilum protrudes at the basal terminal. The conidium is about 40-150×10-25 &mgr;m in size.
From the above results, particularly the form and shape of their colonies and the morphology of their conidia, the inventors identified said strains as
Exserohilum monoceras
by referring to A. Sivanesan: “Graminicolous Species of Bipolaris, Curvularia, Drechslera, Exserohilum and Their Teleomorphs” (mycological Papers, No. 158, p. 261, Nov. 1987) pp. 201 to 237.
The genus designation “Exserohilum” follows the classification of A, Sivanesan. Luttrell (Revue de Mycologie,41, 271-279, (1977)) and Alcorn (Mycotaxon, 8, 411-414, (1978)) have also supported this classification. On the other hand, Ellis (Dematioceous Hyphomycetes, CMI, Kew, 608 (1971)) has classified the genera Exserohilum and Bipolaris as the genus Drechslera and he uses only the genus Drechslera. In recent years, however, there is no researcher other than Ellis who does not approve the genera Exserohilum and Bipolaris, so the adoption of the genus Exserohilum is considered appropriate. Because the teleomorph state of the genus Exserohilum is known to be the genus Setosphaeria, those microorganisms which are classified as the genus Setosphaeria can also be encompassed with in the scope of the present invention.
The strains of the present invention are specifically JTB-012, JTB-013, JTB-799, JTB-803, and JTB-808. JTB-012 has been deposited as FERM BP-5271, JTB-013 as FERM BP-5272, JTB-799 as FERM BP-5273, JTB-803 as FERM BP-5274, and JTB-808 as FERM BP-5275, all of which were deposited on Oct. 27, 1995 with the National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology (1-3, Higashi 1-chome, Tsukuba-shi, Ibaraki-ken, Japan).
As shown in
FIG. 2
, these strains show an esterase zymogram pattern which is different from those of IF09800, IMI125854, IMI125855, ATCC24641, and ATCC58346 as known strains belonging to
Exserohilum monoceras.
The culture of the present strains can be effected in the same manner as for known strains belonging to
Exserohilum monoceras
without requiring any special method. The medium may be any synthetic or natural medium insofar as it suitably contains assimilative carbon and nitrogen sources and inorganic matter as well as a necessary growth promoter. Examples are oatmeal sucrose agar medium, oatmeal agar medium, potato sucrose agar medium, V-8 juice agar medium, Czapek-Dox agar medium, etc. During culture, the medium is maintained at a temperature of 15 to 30° C. , preferably 20 to 25° C., and at pH 3 to 9, preferably pH 5 to 8. After 7 to 14 days in culture under the above conditions, spores have been formed in a sufficient amount on the surface of the medium plate.
The weed-controlling agent of the present invention is prepared by adding surfactant etc. to said spores as the active ingredient. The density of spores can be arbitrarily determined within the range in which they demonstrate a herbicidal effect, where 10
2
to 10
6
spores/ml, preferably 10
3
to 10
5
spores/ml, can be suitably used.
For applying the weed-controlling agent of the present invention over an actual field, it is preferred to apply 10
9
to 10
10
spores/1000 m
2
.
The weeds subject to the weed-controlling agent of the present invention include, but are not limited to, Echinochloa spp.


REFERENCES:
patent: 3661935 (1972-05-01), Aldridge et al.
patent: 4775405 (1988-10-01), Caulder et al.
patent: 4808207 (1989-02-01), Gotlieb et al.
patent: 53

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