JPH06253823A - Soil nematode-parasitic mould and method for controlling noxious nematode - Google Patents

Abstract

PURPOSE:To control plant-parasitic nematode causing plant damages by using a natural enemy, newly discovered mould belonging to Hirsutella. CONSTITUTION:Noxious soil nematode can be controlled by applying (A) the cultured microbes and spores obtained from soil nematodeparasitic mould belonging to Hirsutella, a kind of newly discovered bacteria parasitic onto the body, nits or cocoons of plant-parasitic noxious nematode and suppressing nematode proliferation on (B) soil before planting and/or during raising crops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filamentous fungus (mold) that suppresses the growth of plant parasitic harmful nematodes and a method for controlling plant parasitic harmful nematodes using this fungus.

[0002]

BACKGROUND OF THE INVENTION Plant parasitic harmful nematodes are widely distributed from boreal regions to tropical regions, and have long been one of the important factors causing continuous crop failure of field crops, vegetables and flowers. Even in Japan, soybeans from Hokkaido to the Kanto region are particularly damaged by the outbreak of soybean cyst nematodes among harmful nematodes, and after 1973,
Establishing nematode control measures has become more important as potato cyst nematodes, which had not occurred in the past, have occurred in Hokkaido crops, and more recently, the nematodes have invaded a part of the Kyushu area. ing.

[0003] In various regions south of the Kanto region, sweet potatoes, potatoes, and various vegetables such as cucumbers and tomatoes cause sweet potato root-knot nematodes and Japanese root-knot nematodes to cause serious damage. In addition to this, Negusaaresenchu are widely distributed from Hokkaido to Okinawa,
It is an important factor that inhibits the production of agricultural products, not less than root-knot nematodes.

As a method for controlling these harmful nematodes, fumigants such as chloropicrin and DD agents have been widely used, and a considerable controlling effect has been achieved.

In addition to the above, use of nematode-resistant varieties or rootstocks (grafting), introduction of counter-plants, rotation with non-host crops, application of organic matter, soil waterlogging, field rotation, solar heat treatment, etc. A method of controlling nematode density by an agronomical method has been attempted.

[0006]

[Problems to be Solved by the Invention] The fumigant has a strong toxicity and odor to humans and animals, is difficult to use in the vicinity of a house, is feared to have an adverse effect on groundwater, cannot be treated while standing, and is soil. There are many problems that the density recovery of nematodes is abnormally fast because it also kills the beneficial natural enemy microorganisms at the same time, and that the application of each crop is forced, and that the drug cost is high and the cost is high. Have,
The alternative solution is eagerly awaited.

On the other hand, the cultivated method is not necessarily applicable to resistant varieties, crops without rootstocks, highly concentrated institutional horticulture or cropping systems where introduction of counter plants and rotation are impossible, and upland fields lacking irrigation facilities. The problem is that the use of solar heat is also subject to the weather. The present invention aims to solve the above problems.

[0008]

Means for Solving the Problems To solve the above-mentioned problems, the present inventor has conducted extensive studies and has been found to infect eggs, larvae, and adults of plant parasitic harmful nematodes (cyst nematodes, root-knot nematodes, etc.). The present invention has been completed by finding out filamentous fungi of the genus Hirsutella that kill these and suppress the growth of these nematodes. By applying this filamentous fungus to the soil, damage by plant parasitic harmful nematodes in the soil was prevented.

That is, the present invention relates to a filamentous fungus of the genus Hirsutella (NG-) which has an effect of suppressing the growth of nematodes by parasitizing the parasites of harmful plant-parasitic nematodes and eggs or oocysts. 306 shares, Micro Engineering Lab. No. 12622)
Also, the present invention is characterized in that the cultivated cells and spores of the filamentous fungus are applied to the soil before planting and / or during cultivation of the crop to control harmful soil nematodes.

The morphological characteristics of the strain of the present invention are as follows. Almost spherical conidia are 0-4 branched and length 13-
It is formed on the tip of a conidial stalk of 15 μm. Conidia lack a septum and are about 5 μm in size, and the outside is 1-2 μm thick.
m covered with mucilage.

The properties of the strain of the present invention in various media are as follows. This strain NG-306 was used in a medium such as potato decoction agar (PDA) for glucose addition for 20-28.
It grows well under the temperature condition of ℃, but the optimum temperature condition is 25
It is around ℃. The average diameter of the colonies 45 days after culturing using the vegetable juice agar medium (V8) was 9.6 ± 1.6 cm at 15 ° C. and 18.3 ± 2.3 at 20 ° C.
cm, 24.2 ± 4.5 cm (n = 12) at 25 ° C
Met.

[0012]

When the NG-306 strain mycelium cultivated on the medium is applied to a soil with a high organic matter content such as black volcanic ash soil (black soil), the mycelium grows using the organic matter in the soil and eventually conidia. To form.

When these conidia contact the worms of the plant parasitic harmful nematodes that live in the soil, they adhere to the worms due to the stickiness of the spore surface and eventually germinate to give hyphae of the nematodes. It penetrates the skin (cuticle) and invades into the worm body, killing the host nematode, and the worm body is almost filled with hyphae that have grown and branched.

The dead worm body characteristically shows a mummy-like atrophy or curved shape. Conidia are formed on the body surface of these dead nematodes. In addition, N cultured on the medium
The G-306 strain forms many conidiospores with the growth of hyphae, but when these conidiospores were applied to the soil, they were contacted with harmful nematodes in the soil and formed in the soil. Like conidia, they adhere to nematodes and germinate and parasitize, causing the parasites to die.

The NG-306 strain can parasitize nematode eggs. Hirsutella (H
No filamentous fungus of the genus irsutella) was known to parasitize nematode eggs or oocysts. The mycelia of this strain parasitize eggs and egg vesicles such as cyst nematodes and root-knot nematodes in the soil, causing many eggs to die. Thus, the NG-306 strain exerts an action of remarkably suppressing the growth of these nematodes.

[0016]

The present invention will be described in more detail with reference to the following examples. 2.5 kg of sterilized black volcanic ash soil (black soil)
After adding 0.6 g of urea, 2.9 g of lime superphosphate, 0.4 g of potassium chloride and 1.3 g of magnesia lime, the area is 1/50
A pot of 00a was filled with 50 cysts per pot in the case of cyst nematode, and 5000 second stage larvae in the case of Meloidogyne incognita were inoculated.

The NG-306 bacterium was shake-cultured in a vegetable juice liquid medium (V8) at 25 ° C. for 10 days. The cultured bacterial cells were treated with a homogenizer for several seconds to be crushed, filtered and thoroughly washed with sterile distilled water. 4 g of crushed viable cells was suspended in 5 ml of water, added to a Wagner pot containing nematodes, and mixed well.

Four soybean seeds (cultivar Fukuyutaka) were sown in a soybean cyst nematode (hereinafter abbreviated as HG) inoculation pot. One potato (cultivar Mayhou) tuber was planted in a potato cyst nematode (hereinafter abbreviated as GR) inoculation pot. One tomato (cultivar Plitz) five-leaf seedling was planted in an inoculation pot of Sweet potato Nematoda (hereinafter abbreviated as MI).

Cultivation was carried out in a glass greenhouse from March 23 to July 18, 1992, and the degree of cyst infestation, the degree of root-knot infestation, and the nematode density in soil were examined on July 18.
The test was repeated 3 times in each section.

The evaluation criteria for the cyst parasitic degree and the Necob parasitic degree were as follows. 0 ... (no parasitic), 1 ... (less parasitic), 2
‥‥ (parasitic medium) 3 ‥ (parasitic often), 4 ‥‥
(Parasitic)

The nematode density was determined by the two-layer centrifugation method in soil 1.
The number was set to 0 g, and each pot was repeated twice. The results are shown in Table 1 as an average value and standard deviation.

[0022]

[Table 1] Cyst parasitism, cats parasitism, nematode density [Nematode] [Presence or absence of bacterial inoculation] [Parasiticity] [Nematode density] H. G. None 2.92 ± 0.79 697 ± 295 G. Yes 1.00 ± 0.74 157 ± 67 G. R. None 2.67 ± 0.58 296 ± 88 G.I. R. Available 1.33 ± 0.58 87 ± 18 M.I. I. None 3.67 ± 0.58 170 ± 50 M.I. I. Yes 3.00 ± 0.00 110 ± 43

As shown in Table 1, it is understood that by applying natural enemy filamentous fungi to the soil, the density of cyst nematodes and root-knot nematodes in the soil is reduced and plant infestation is suppressed.

[0024]

As described above, according to the method for controlling soil nematode-parasitic filamentous fungi and harmful nematodes of the present invention, parasites of harmful plant-parasitic nematodes and eggs or egg capsules are parasitic. , Found a filamentous fungus, a new genus that suppresses the growth of nematodes. In addition, the cultured cells and spores of this natural enemy filamentous fungus,
By applying the crop to the soil before planting and / or during cultivation, the density of plant parasitic nematodes in the soil can be reduced, and damage to the crop can be reduced.

Claims (2)

[Claims] 1. Hirsutella, a new genus Microorganism Research Institute No. 12622, which inhibits the growth of nematodes by parasitizing the parasites of phytoparasitic harmful nematodes and eggs or oocysts.
) Soil nematode parasitic filamentous fungi of the genus. 2. The filamentous fungus micro-engineering laboratory No. 126 according to claim 1.
A method for controlling harmful nematodes, which comprises applying the cultured bacterial cells and spores of No. 22 to soil before planting and / or cultivating a crop to control harmful soil nematodes.