JP4501006B2 - Rhizome rot control agent - Google Patents

Description

  The present invention relates to a rhizome rot control agent and a rhizome rot control method using the same.

  Rhizome rot caused by rhizome rot (Pythium zingiberum Takahashi) is known as a disease causing great damage to ginger crops.

  Myouga is highly convertible and can be said to be one of the promising varieties in Okinawa because it can be harvested even in the winter when it is not cultivated in Okinawa, and it can be harvested in the summer when vegetable production is insufficient.

  Before 1987, myoga had a large production area in the northern part of the main island of Okinawa, such as Nago City, and the cultivation area expanded and the yield increased. However, as a result of continuous cropping, myoga rhizome rot occurred, and as a result of the enormous damage caused by its spread, its cultivation was forced to shrink, and now the shipment in this prefecture has decreased to 1 / 100th of its peak. ing.

  Traditionally, soil sterilization and metalaxyl granules have been used to control rhizome rot, but the environmental burden has been pointed out, and it is desirable to establish a control system that does not depend on chemical pesticides as much as possible. Yes. Even in this disease, attempts have been made to control using antagonistic bacteria such as Trichoderma and actinomycetes, and cellulose-degrading bacteria (Non-Patent Document 1), but the fixability to soil is unstable and still Not established.

In recent years, cultivation methods using coconut husks have been carried out, and it has been demonstrated that yields are increased and work efficiency is good. Furthermore, although this cultivation method is known to have a rhizome rot inhibitory effect, the mechanism of its suppression has not yet been clarified.
Hironori Ogura and Hitoshi Yoshimoto (1984). Drugs and microbial treatment for myoga rhizome rot. Shikoku Plantation Prevention 19: p15-23.

  Accordingly, an object of the present invention is to provide means for controlling rhizome rot that occurs in ginger family plants such as ginger without using chemical pesticides.

  In order to solve the above problems, the present inventors focused on the effect of suppressing rhizome rot by the cultivation method using coconut husk, and as a result of investigating the reason, the microorganisms inhabiting coconut husk antagonized with rhizome rot fungus. I found out that the growth of rhizome rot fungus is suppressed. As a result of further research, a microorganism that antagonizes rhizome rot fungus was isolated, and it was found that this can be used as an active ingredient of a rhizome rot fungus control agent, thereby completing the present invention.

  That is, the present invention provides a rhizome rot control agent comprising a rhizome rot fungus antagonistic microorganism belonging to the genus Aspergillus or Penicillium as an active ingredient.

  Moreover, this invention provides the rhizome rot control composition which combines the said microorganisms and coconut husk.

  Furthermore, the present invention provides a method for controlling rhizome rot in ginger crops, characterized in that a rhizome rot fungus antagonistic microorganism belonging to the genus Aspergillus or Penicillium is present in the soil of the ginger family crop growing field. .

  By utilizing the rhizome rot control agent or rhizome rot control composition of the present invention, it is possible to protect ginger family crops from rhizobacteriaceae without using chemical pesticides such as soil disinfection and metalaxyl granules. Become.

  The microorganism which is an active ingredient of the rhizome rot control agent of the present invention belongs to the genus Aspergillus or Penicillium and has an antagonistic activity against rhizome rot fungi.

  Such microorganisms can be obtained separately from, for example, growing soil of ginger family crops such as ginger or coconut shells used here. More specifically, after isolating filamentous fungi from the above soil or coconut shell using a rose bengal medium or the like by a conventional method, the antagonistic activity of each rhizome rot fungus is examined by anti-culturing etc., and the one having a high activity is selected. Thus, a target rhizobia rot-antagonizing microorganism (hereinafter referred to as “antagonizing microorganism”) belonging to the genus Aspergillus or Penicillium can be obtained.

  Among the antagonistic microorganisms thus obtained, a microorganism belonging to Aspergillus terreus is preferable, and an Aspergillus terreus S-78 (Aspergillus terreus S-78) strain having high antagonistic activity against rhizobia is particularly preferable. This was deposited as FERM AP-21087 on November 13, 2006 at the National Institute of Advanced Industrial Science and Technology Patent Biological Depositary Center (1st, 1st East, 1-chome, Tsukuba City, Ibaraki 305-8566). .

  The rhizome rot control agent of this invention can be manufactured in accordance with the general method of a biopesticide except using the above-mentioned antagonistic microorganism as an active ingredient. That is, the microorganism can be produced by adsorbing or adhering to a suitable solid carrier or suspending it in a suitable liquid carrier.

There are no particular restrictions on the amount of the rhizome rot control agent sprayed in ginger and other ginger crop growing fields, but generally about 10 ³ to 10 ⁵ antagonistic microorganisms per 1 m ² of the field. Preferably, the number is about 10 ⁸ to 10 ¹⁰ .

  The antagonistic activity of the above-mentioned antagonistic microorganisms can provide an excellent effect particularly when coconut husk is selected as a solid carrier and combined with this. Coconut husk used as a solid carrier is an organic medium composed of fibers outside the coconut palm, and it is considered that excellent effects can be obtained depending on the pH of coconut husk itself and the condition that antagonistic microorganisms adhere and grow easily. .

  Such a rhizome rot control composition (hereinafter referred to as “composition”) combining coconut husks and antagonistic microorganisms is produced, for example, by adding antagonistic microorganisms cultured in 10 ml of PDA agar medium to 100 g of coconut husks for 3 days. can do.

  In addition, the amount of the obtained composition to be applied on the ginger crop growing field may be such that the amount of antagonistic microorganisms is in the above-mentioned range.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by these Examples.

Example 1
Microbial isolation and acquisition:
Zingiber mioga (Thunb. Rosc.) Grown at the Okinawa Prefectural Agricultural Experiment Station Horticulture Branch was used as a test plant. In addition, as soils to be tested, (1) soil collected from Nishiga-cho, Myouga cultivation field in Okinawa Prefecture (jagal mother rock: peat rock (kucha) pH: 6.2 or less, referred to as “field soil zone”), (2) An undisturbed Kunigami merger (pH: 4.5 or less, referred to as “Kunigami merge ward”) collected from the forest of Ogimi Village in Okinawa Prefecture was used.

Myouga was planted in the cultivation field using the test soil, and a commercial coconut shell with an amount of about 10 kg / m ² was laid on the surface and grown in this state. After growing the myoga for 10 months, used coconut husks were collected from the field of cultivating myoga and divided into a part where the rhizobacteria rot occurred (affected area) and a part where it did not occur (healthy area). Subsequently, the microbial flora of the coconut husks in this healthy area and diseased area was examined as follows.

1) Separation of cellulose-degrading bacteria 50 g of coconut shells (healthy area, diseased area) was added to 450 ml of sterilized water containing a small amount of Tween 20 and stirred for 5 minutes. 50 ml of this primary dilution (dilution ratio 10 times) was taken with a sterilized pipette and placed in 450 ml of sterile water. In the same manner, preparation up to the sixth dilution was performed, and 1 ml of each stage of the diluted solution was put into a sterilized petri dish, and 0.5 g of cellulose medium ((NH ₄ ) ₂ SO ₄ , KH ₂ PO ₄ 1. 0 g, 0.2 g of MgSO ₄ · 7H ₂ O, 0.5 g of KCl, 0.1 g of CaCl ₂ , 0.5 g of yeast extract, 20.0 g of agar, 10.0 g of cellulose powder, 1,000 ml of distilled water) Then, after the medium was solidified, it was placed in a sealed container with a beaker containing water in order to prevent the medium from drying, and cultured at room temperature for 4 weeks. Cellulolytic bacteria were judged by the clear zone around the colony and counted. Furthermore, streak culture was performed on the WA plate medium to obtain a single strain.

2) Separation of coconut husk microorganisms other than cellulose-decomposing bacteria General microorganisms other than cellulose-degrading bacteria were also separated by the dilution plate method in the same manner as in Experiment 1). As a selective medium, rose bengal medium (peptone 5 g, KH ₂ PO ₄ 1 g, MgSO ₄ .7H ₂ O 0.5 g, glucose 10 g, rose bengal 0.033 g, agar 20 g, streptomycin 1 ml, distilled water 1, 000 ml), albumin medium (egg albumin 0.25 g, glucose 1 g, K ₂ HPO ₄ 0.5 g, MgSO ₄ .7H ₂ O 0.2 g, Fe ₂ (SO ₄ ) ₃ small amount for bacteria and actinomycetes , Agar 15 g, distilled water 1,000 ml).

3) Identification of filamentous fungi From experiment 2), 100 colonies were randomly punched out of the colonies formed on the rose bengal medium, transplanted onto the PDA medium, and allowed to stand at room temperature for 1 to 2 weeks. Then, the end of the bacterial flora in which sporulation was observed was scraped with a platinum wire together with the medium, placed on a slide glass, examined under the morphological characteristics, and identified at the genus level of the filamentous fungus.

4) Identification of bacteria Gram stainability with potassium hydroxide (KOH) solution 100 fungi were randomly picked from the colonies formed on the albumin medium in Experiment 2), and PSA slant medium for bacteria (potato boiled juice 1 2,000 ml, Ca (NO ₃ ) ₂ · 4H ₂ O 0.5 g, Na ₂ HPO ₄ · 4H ₂ O 2 g, peptone 5 g, sucrose 15 g, agar 10 g) and colony formation with 3% KOH solution Simple identification of sex was performed. One drop of a 3% KOH solution was placed on a slide glass, and an amount of 1 platinum loop of slant culture cells was taken and mixed well. At this time, Gram-negative bacteria aggregate and become viscous, and when they are lifted with platinum ears, the thread is pulled. On the other hand, Gram-positive bacteria are uniformly dispersed and have no viscosity. Gram negative and positive were simply judged from this difference in properties.

Example 2
Selection of microorganisms having antagonistic properties against rhizome rot fungi Using the filamentous fungi, bacteria and actinomycetes isolated by the dilution plate method, simple counter-culture with pathogenic bacteria was performed on PDA medium, and the antagonistic properties were examined. About the microorganisms which have antagonistic property, the strain which shows stronger antagonisticity was selected by the counterculture, and the inhibition rate was investigated. Simple counter culture and counter culture were performed as follows.

A) Simplified antipodal culture A coconut husk isolate was placed at a position 1 cm away from both ends of the petri dish, and the pathogen was left in the center, and the antagonisticity was examined from the degree of inhibition of the hyphal elongation of the pathogen. Strains that showed relatively strong antagonistic properties in simple counter-culture were selected and counter-culture was performed. In the counter culture, 3 days after the test bacteria were allowed to stand, the pathogens were allowed to stand at a distance of 5 cm, and the width of the inhibition zone was measured after 4 days. The strength of antagonisticity was judged by the length of the inhibition zone. Those having no blocking band were defined as-, less than 2 mm +, 2-4 mm +, 5-7 mm ++, and 8 mm or more +++. The results are shown in Table 1.

  As is clear from this result, 28 types of antagonistic microorganisms were obtained, and in particular, 5 types of strong antagonists with a band width of 8 mm or more were found.

B) Antibiotic culture Strains with clearly different antagonistic results as a result of simple antimicrobial culture were selected and their hyphae inhibition rates were examined. Three days after the test bacteria were allowed to stand, the pathogens were allowed to stand at a distance of 5 cm, and the pathogenic mycelium elongation of the control and antipodal areas was measured the next day, and the hyphal elongation inhibition rate was calculated by the following formula. The results are shown in Table 2.

Mycelial elongation inhibition rate = [(A−B) / B] × 100
A: Mycelial elongation in the control group
B: Mycelial elongation in antipodal ward

In addition, the myoga rhizome rot fungus (Pythium zingiberum) was acquired as follows.
30 g of coconut moth (healthy and diseased areas) or diseased roots during cultivation of myoga were placed in 60 ml of sterilized water and allowed to stand overnight at room temperature. The supernatant of the suspension was sterilized with 0.5% Hiter (active ingredient: sodium hypochlorite) and washed with water for 5 minutes. Thereafter, young pineapple leaves that were air-dried for 10 minutes were put into this, and after 2 to 3 days, the base was confirmed to be water-immersed, and was taken out and cut into 5 × 5 mm. This section was sterilized with 1% hyter for 2 minutes, washed with sterilized water for 3 minutes, placed in a glass petri dish with sterile filter paper, air-dried, and placed on an agar medium (10 g agar, 1,000 ml distilled water). And static culture at room temperature.

The next day, the mycelium extended into the medium from the pineapple tissue section was observed under a microscope, and the mycelium lacking a septum and further having spores and vegetative hyphaly body (VHB) was selected, and the tip of the mycelium was V8 juice agar. It was transplanted to a culture medium (200 ml of V8 juice, ₃ g of CaCO ₃ , 10 g of agar, 1,000 ml of distilled water), and statically cultured at room temperature. Further, the formed flora is punched out with a cork borer with a diameter of 3 mm, injured or innocuously inoculated on the flowers of myoga, left in an airtight insole-sealed container, and caused by the presence or absence of disease. The sex was confirmed.

Example 3
Disease control effect test in culture pots Four strains (Aspergillus sp. S-78, Aspergillus sp. S-82, Aspergillus sp. S-100 and Penicillium sp. S-70) that showed high antagonistic properties in antipodal culture The disease-inhibiting effect test was conducted in a culture pot. A total of 8 treatment zones were set up as follows. The drug was coconut husk mixed in 15 kg / 10a conversion (agricultural chemical registration amount), and the microorganism was 100 g / kg coconut husk culture cultured for 3 days in 10 ml of PDA agar medium.

(1) Field Soil (Jagar, pH 6.2)
(2) Kunigami merger zone (pH 4.5)
(3) Coconut husk only (control) group (4) Coconut husk + drug group (trade name: Ridomil granule 2, ingredient: metalaxyl,
Syngenta Japan Co., Ltd.)
(5) Yashigara + Aspergillus sp. S-78 (6) Yashigara + Aspergillus sp. S-82 (7) Yashigara + Aspergillus sp. S-100 (8) Yashigara + Penicillium sp S-70

  In the experimental method, 10 ml of PDA was dispensed into a culture pot, and this was autoclaved at 120 ° C. for 20 minutes in an autoclave, and the cultivated rot fungus was cultivated for 3 days to cover the entire mycelium. In the antagonistic treatment group, the bacterial agar containing 4 types of antagonistic bacteria pre-cultured in 10 ml of PDA plate medium was added to coconut husk adjusted to a water content of 75% and stirred well. It was laid down to the height. Further, Myouga flower sterilized with 2% hypochlorous acid was placed on the upper part, and then the elongation to the upper part of the mycelium and the incidence of flower buds were examined. The same was done for the field soil (jargar), Kunigami merger, drug and coconut shell only (control). The results are shown in Table 3.

  As is apparent from this result, when Aspergillus sp. S-78 strain and coconut husk were used, the effect of controlling Myogya rhizome rot was similar to that using metalaxyl and coconut husk. When the species of this Aspergillus sp. S-78 strain was identified, it was identified as a species belonging to the Aspergillus terreus group from the morphological characteristics.

  According to the present invention, rhizome rot fungus can be controlled without using a chemical agent.

  Therefore, the present invention can be widely used as a biocontrol agent, a soil improvement material, and the like in cultivation of ginger family plants such as ginger.

Claims (4)

A rhizome rot control agent comprising Aspergillus tereus S-78 strain (FERM AP-21087) as an active ingredient. A composition for controlling rhizome rot by combining Aspergillus tereus S-78 strain (FERM AP-21087) and coconut shells . A method for controlling rhizome rot of ginger family crops, characterized in that Aspergillus terreus strain S-78 (FERM AP-21087) is present in the soil of the field for growing ginger family crops.   Aspergillus tereus S-78 strain (FERM AP-21087).