JP5212936B2 - Control method of scab in tuber plants - Google Patents

Description

  The present invention relates to a method for controlling scab in tuber plants without using chemical pesticides.

  Potatoes are one of the important crops produced in Japan, but potato scabs are becoming more common due to continuous cropping, causing great damage. Potato scab is a soil-borne disease caused by Streptomyces sp., A member of the actinomycete family of bacteria. In the damaged tuber, a scab-like lesion is generated on the surface of the tuber and the appearance is remarkably impaired, so that the commercial value is greatly reduced. This disease occurs when a large amount of immature organic matter is applied to the field or in soils where the pH of the soil is neutral to weakly alkaline.Therefore, the amount of compost is reduced or the amount of calcareous materials is reduced in the occurrence area. The disease is avoided by keeping the soil pH low. It is known that pathogens are transmitted by soil as well as contaminated seeds, and countermeasures are required to clean up contaminated fields by soil disinfection and prevent pathogens from being brought into the field. It is. Soil fumigants such as chloropicrin are used for soil disinfection, but in the field where soil disinfection is carried out, the microflora in the soil is poor. It is known to cause an outbreak. For this reason, it is indispensable to disinfect seeds in the field after soil disinfection and in virgin virgin areas.

  Registered pesticides used for disinfecting potato scab seeds include oxytetracycline / streptomycin wettable powder (trade name: agrimycin 100 wettable powder), oxytetracycline / streptomycin / copper wettable powder (tradename: bacteside) Wettable powder), Streptomycin solution (trade name: Agret solution), Streptomycin wettable powder (trade name: Agrepto wettable powder, etc.), Streptomycin / thiophanate methyl wettable powder (trade name: Atackin wettable powder), Copper / Streptomycin water Japanese hydrating agent (trade name: Stomai wettable powder), cupric hydroxide wettable powder (trade name: Kosaido Bordeaux), tolcrofosmethyl / flusulfamide wettable powder (trade name: knot ban wettable powder), fluazinam wettable powder (Product name: Frontside wettable powder), Fursulfamide wettable powder (Product) : Scan block SC) and the like. Thus, a method for disinfecting potato scab seed using chemical pesticides has been known.

  As a control measure that does not use chemical pesticides, it is envisaged that healthy potatoes grown in fields that do not cause scab disease may be used as seeds. It is a normal bacterium that normally exists in the soil, and the density of bacteria in the soil increases by cultivating potato, so it is practically impossible to cultivate disease-free species.

On the other hand, Patent Document 1 discloses a soil improving material for controlling potato scab disease containing an extract of Sozonohana. However, Patent Document 1 does not disclose any disinfection method.
JP 2004-238308 A

  Seed disinfection with chemical pesticides is indispensable to prevent the introduction of pathogenic bacteria to the field, but since it is practically impossible to produce disease-free seeds cultivated in the field, conventionally, seeds that replace chemical pesticides are also available. There was no disinfection method. However, it is an alternative in developing low-environmentally friendly disease control technology that is far from the use of chemical pesticides in organic farming, especially consumer demand for safe and secure agricultural cultivation with reduced use of chemical pesticides. There is a great demand for the establishment of technology.

  Then, an object of this invention is to provide the method of controlling the common scab in tuber plants, such as a potato, without using a chemical pesticide.

By immersing the tuber plant seeds in a methanol extract of the seaweed (Red algae) Sozonohana (Laurencia brunnatiii) inhabiting the Amami Islands, the transmission of scab disease seeds is also controlled. As a result, the present invention has been completed. The present invention includes the following inventions.
(1) A method for controlling scab in a tuber plant serving as a host of a scab that belongs to the genus Streptomyces, the tuber used as a seed for cultivating the tuber plant is selected from Sozonohana The said method including the process of immersing in an extract.
(2) The method according to (1), wherein the extract of Sozonohana is an extract of Sozonohana with methanol or ethanol.
(3) The method according to (1) or (2), wherein the tuber plant serving as a host for scab is potato.

  According to the method of the present invention, a control effect equivalent to that of a common scab control method using a chemical pesticide is achieved without using a chemical pesticide.

1. Plants to be Controlled The plant to which morbidity of scab is controlled according to the present invention is not particularly limited as long as it is a tuber plant that is a host of scab pathogen belonging to the genus Streptomyces, but more specifically, potato. Varieties are not particularly limited as long as they are potatoes, but in the case of Hokkaido varieties, the present invention is used for main varieties such as baron candy, make-in, aseiro, toyoshiro, scallops, etc. Can be used.

2. Sozonohana extract As an extraction solvent for obtaining an extract of the red alga Laurencia brogniiarti (hereinafter referred to as Sozonohana), ethanol, methanol, isopropanol, isobutanol, n-hexane, methyl amyl alcohol, 2-ethylbutanol, n- Alcohols such as octyl alcohol, polyhydric alcohols such as glycerin, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, triethylene glycol, 1,3-butylene glycol, hexylene glycol or the like Derivatives, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl-n-propyl ketone, ethyl acetate, isopropyl acetate Esters such as Le, ethyl ether, isopropyl ether, one or more mixed solvents selected from polar solvents such as ethers such as n- butyl ether can be preferably used. Also, phosphate buffered saline can be used. Alternatively, it is selected from hydrocarbons such as petroleum ether, n-hexane, n-pentane, n-butane, n-octane and cyclohexane, and low polar solvents such as carbon tetrachloride, chloroform, dichloromethane, trichloroethylene, benzene and toluene. One kind or two or more kinds of mixed solvents can also be suitably used.

  For the purpose of the present invention, as the extraction solvent, among organic solvents, low alkyl alcohols (straight and branched ones having 1 to 6 carbon atoms) are preferable, and alkyl alcohols having 1 to 3 carbon atoms are more preferable. For example, it is preferable to use methanol, ethanol or isopropanol, or shochu shochu and / or brown sugar liquor to which water is added, and further re-distilled to have ethanol as a main component, alone or in combination and used as an extraction solvent. .

  As the Sozonohana used in the present invention, the collected one can be used as it is or dried. Also, the use site is not particularly limited, and the whole Sozonohana may be used, or only a part such as a body part, a branch part, or a root part may be used.

  The ratio of Sozonohana to the solvent during the extraction is such that the extraction solvent is added 3 to 6 times by volume, preferably 4 times the volume of Sozonohana wet weight, and pulverized with a stirrer such as a mixer. Extract soluble components into Although extraction temperature is not specifically limited, Room temperature under normal pressure is preferable. The stirring time may be a time required for extraction, and is preferably as short as possible. Although it depends on the treatment amount, it can be extracted within one hour, preferably 3 to 15 minutes, more preferably 5 to 8 minutes.

  The Sozonohana extract mixture obtained by the above method is filtered with gauze or the like, and the filtrate is further solid-liquid separated using a centrifuge or the like. The extraction stock solution thus obtained may be used as it is as an “Sozonohana extract” as it is, or a solution obtained by appropriately concentrating or diluting the extraction stock solution. When the extraction solvent contained in the extract affects potato itself and inhibits growth such as budding, it is preferable to use a solution obtained by removing the extraction solvent and further diluting with an appropriate solvent.

3. Immersion One of the features of the present invention is the step of immersing a tuber used as a seed for cultivating a tuber plant as a host of scab pathogen belonging to the genus Streptomyces in an extract of Sozonohana.

  Varieties to be used: Available seed varieties vary depending on the area where they are cultivated (Hokkaido: summer cultivation, south-west warm season: spring / autumn two-phase cultivation, Nansei Islands to Okinawa: winter cultivation) Seed is prepared according to the known method. It is desirable to disinfect as much seed as possible. However, seeds are often in a dormant state at the end of storage, except for those that have been stored in a temperature-controlled storage. For this reason, seeds with Sozonohana extract may be sterilized for seeds that are normally germinated, except for cases where germination has progressed too much and seeds are inappropriate. The size of the seed used at this time is preferably about S to L.

  Immersion conditions: The immersion treatment is basically the same as the immersion method using chemical pesticides. That is, it is preferable to soak the seeds in a sufficient amount of Sozonohana extract for 5 to 10 seconds. The treatment temperature is preferably about room temperature.

4). Cultivation By cultivating a tuber plant using the tuber after the immersion step as a seed, it is possible to control the occurrence of common scab during the cultivation of the tuber plant.

1. Test conditions <br/> Field: Using the field (Kuroboku soil) in the Central Agricultural Research Center, the test area was pre-disinfected with chlorpicrin (30L / 10a) (dotted March 26, degassing: April 4, 6, 9).
Variety: Nishitaka. Planted on April 11, 2007 and moated on July 12. Spring cropping cultivation.
Fertilizer application: March 5, 2007, wheat straw compost (600kg / 10a), chemical fertilizer (all agricultural products made with kurea urea organic organic potato only 10-16-14, 120kg / 10a).
Ward system and area: Ward 6m ² (Head width 60cm x Stock 25cm, 30 shares / ward), 3 iterations.

2. Test method (1) Preparation of methanol extract from Sozonohana Sozonohana was collected in December 2006 from the sea near Tokunoshima and used for testing.
The collected Sozonohana was subdivided by 10 kg and stored frozen at −20 ° C. to −30 ° C. until used in the test. Preparation of methanol extract from Sozonohana was carried out by Kamei method. That is, after thawed sozonohana well with tap water, wash off shellfish and sand particles on the surface of seaweed, drain water, add 400 ml of methanol to 100 g of sozonohana, and homogenize for 5 minutes with a mixer (Toshiba MX-W 10GM). Filtration with gauze gave a methanol extract.

(2) Seed disinfection with Sozonohana methanol extract Using a 1L beaker, put Sozonohana methanol extract in about 6 minutes, submerge 2 to 3 seeds at a time, soak for 5-10 seconds, then pull up. Air dried.

  For comparison, methanol was treated in the same manner using methanol instead of Sozonohana extract as a methanol treatment section.

  As a control, spraying treatment or soaking treatment with agrimycin 100 wettable powder was performed. In the case of spraying treatment of agrimycin 100 wettable powder, 40-fold diluted solution was sprayed on seeds with a small sprayer at a rate of 2.5 L per 100 kg. Also, in the soaking treatment of agrimycin 100 wettable powder, a 100-fold diluted solution was put in a 1 L beaker for about 6 minutes, 2 to 3 seeds were submerged at a time, soaked for 5 to 10 seconds, then pulled up and air-dried. .

  After each treatment, the seeds were spread indoors so that they would not overlap with the shallow bats and allowed to air dry sufficiently.

  Various treated seeds were planted 2 days after the treatment. The soil pH at the time of planting was 6.7-7.0.

3. Survey method After harvesting tubers on July 12, 2007, they were placed in a net room and dried, and on July 19, the diseased tuber rate and yield were investigated. Moreover, the disease severity was calculated | required by following Formula. The phytotoxicity was examined with the naked eye at any time after emergence.
Disease severity = 100 x Σ (morbidity index x number of tubers) / (5 x number of surveys)
Disease index = 1-5
Disease index 0: No lesion disease index 1: Disease area is less than 1% of tuber surface area Disease index 2: Disease area is less than 1% to 10% of tuber area Disease index 3: Disease area is 10 of tuber area % To less than 25% Disease index 4: Disease area is 25% to less than 50% of tuber area Disease index 5: Disease area is 50% or more of tuber area

The control value (morbidity) was determined by the following formula.
Control value (morbidity) = 100 × (morbidity of untreated area−morbidity of treated area) / (morbidity of untreated area)

The control value (the diseased tuber rate) was determined by the following formula.
Control value (rate of diseased tuber) = 100 × (rate of diseased tuber in untreated group−rate of diseased tuber in treated group) / (rate of diseased tuber in untreated group)

4). The test result is shown in Table 1. It has been clarified that soaking seeds with a methanol extract of Sozonohana shows the same control effect as spraying or soaking with agrimycin 100 wettant, a conventional control agent.

  FIG. 1 shows the state of the sozonohana methanol extract treatment, FIG. 2 shows the state of the agrimycin 100 wettable powder treatment, and FIG. 3 shows the state of the untreated treatment. . Thus, the occurrence of common scab was significantly suppressed in the Sozonohana treated with methanol extract compared to the untreated group.

FIG. 1 is a photograph showing a state of a sozonohana methanol extract treatment section. FIG. 2 is a photograph showing the state of the soaking treatment section of agrimycin 100 wettable powder. FIG. 3 is a photograph showing the condition of the untreated area.

Claims (2)

A method for controlling scab in potatoes , comprising the step of immersing potato seeds in an extract of Laurencia brogniiati.   The method according to claim 1, wherein the extract of Sozonohana is an extract of Sozonohana with methanol or ethanol.

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