Plant disease control agent and plant disease control method

Abstract

To provide plant disease control means that can be used at a site of agricultural production immediately and at low cost.SOLUTION: The present invention pertains to a plant disease control agent for root immersion containing acetic acid, and a plant disease control method including a step of immersing the roots of a plant in aqueous solution of acetic acid.SELECTED DRAWING: None

Description

[Technical field]

[0001] TECHNICAL FIELD The present invention relates to a plant disease control agent and a plant disease control method TECHNICAL FIELD The plant disease control agent and the plant disease control method of the present invention have the advantages of being low cost and highly safe. [Background technology]

[0002] Once soil-borne plant diseases occur, they are difficult to eradicate, and they may spread not only to the area around the initial field, but to the entire production area and surrounding areas. In general, measures to prevent soil-borne diseases are taken to reduce damage by using resistant varieties, disinfecting the soil, and improving the physicochemical and biological properties of the soil, but sometimes it is necessary to change the cropping season, switch to crops that have less impact, or leave the land fallow.

[0003] Chemically synthesized fumigants have mainly been used to disinfect soil to prevent continuous crop damage caused by soil diseases, but there is a demand for the development of new countermeasure technologies that do not rely on existing soil fumigants due to the impact on the target fields and surrounding environment, the burden on workers, and product image strategies.

[0004] However, the development of new synthetic chemical pesticides and microbial pesticides requires a large amount of research and development costs, and it is said that it takes more than 10 years from searching for new compounds and useful microorganisms to safety evaluation, residual and efficacy tests, registration of the pesticide, and launching it on the market, so there is a demand for the development of lower-cost countermeasure technologies. On the other hand, specified pesticides (specified control materials) such as vinegar are defined in Article 2, Paragraph 1 of the revised Agricultural Chemicals Control Act as "pesticides designated by the Minister of Agriculture, Forestry and Fisheries and the Minister of the Environment as pesticides that are clearly not likely to cause harm to agricultural crops, human livestock, and aquatic animals and plants in light of their raw materials," and it is expected that they will be further utilized for pest control as low-cost agents that can be used immediately in agricultural production sites.

[0005] As measures against soil-related diseases, the use of resistant varieties and rootstocks and various soil disinfection methods have been introduced as core technologies, and the development of control agents for some soil-related diseases is also underway. Regarding tomato bacterial wilt (pathogen: Ralstonia solanacearum), one of the important soil diseases, prior patents relating to treatment agents for plants include "Microorganisms and methods for controlling diseases in solanaceae crops" (Patent Document 1) and "Bacterial wilt resistance inducer and method for controlling bacterial wilt" (Patent Document 2).

[0006] Meanwhile, in the case of plant disease control using vinegar, "Control of rice seedling diseases using vinegar" (Non-Patent Document 1) and a method of using vinegar to dilute German Bordeaux A for vegetable seed disinfection (Non-Patent Document 2) have been developed. In addition, pure brown rice black vinegar (manufactured by Kewpie Brewing Co., Ltd.) is sold for general agricultural horticulture use, and the usage method is described as "For tomato bacterial wilt, root rot, etc., a 50-fold diluted solution is irrigated into the soil to control diseases." In addition, prior patents related to disease control using vinegar include "Post-harvest disease control agent and post-harvest disease control method" (Patent Document 3), "Rice disease control method" (Patent Document 4), "Plant vitalizer and crop cultivation method using the plant vitalizer" (Patent Documents 5 and 6), and "Seaweed disease control agent and seaweed disease control method" (Patent Document 7). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 01-090107 [Patent Document 2] Patent No. 6007360 [Patent Document 3] JP 2017-165654 A [Patent Document 4] Patent No. 3990691 [Patent Document 5] JP 2001-061344 A [Patent Document 6] JP 2001-064112 A [Patent Document 7] Patent No. 3629049 [Non-patent literature]

[0008] [Non-Patent Document 1] Junko Sekihara, Toshiyuki Morikawa, "Control of rice seedling diseases using vinegar", Plant Protection, Vol. 63, No. 11 (2009), pp. 690-694 [Non-Patent Document 2] National Agriculture and Food Research Organization, Vegetable and Tea Research Institute, "Manual for the Control of Bacterial Fruit Spot Disease of Cucurbitaceae Vegetables (for Seed Production and Inspection)" (2009), p.1-22. http: / / www.naro.affrc.go.jp / publicity_report / publication / files / uri-2.pdf Summary of the Invention [Problem to be solved by the invention]

[0009] In general, the development and introduction of resistant varieties and rootstocks is being promoted as a measure against soil-borne diseases, but the types of diseases for which varieties and rootstocks with strong resistance can be developed are limited. In addition, there are cases where new races emerge, and multiple races or types of soil-borne diseases occur in the same field, and responses to these are also required. Furthermore, there are problems such as recontamination of pathogens from deep soil layers or around the field after soil disinfection, and there is a need to develop a control method that can be applied after planting in the field.

[0010] Regarding tomato bacterial wilt, new grafting methods and soil reduction disinfection methods (Nakayasu et al., 2019) have been developed, but there is a demand for simpler and lower-cost techniques than conventional techniques. Among these, methods such as immersing tomato seedlings in a solution of non-pathogenic Fusarium bacteria (JP Patent Publication No. 01-090107) and histidine, a type of amino acid (Patent Publication No. 6007360, Seo et al., 2016) have been developed and are considered promising, but there is a need to develop even lower-cost control techniques in order to expand user options.

[0011] The present invention has been made against such a technical background, and has as its object to provide a means for controlling plant diseases which is low-cost and can be immediately used in agricultural production sites. [Means for solving the problem]

[0012] As a result of intensive research to solve the above problems, the present inventors have found that tomato bacterial wilt can be controlled by immersing the roots of tomato seedlings in a diluted vinegar solution. The present inventors have also found that tomato bacterial wilt can be controlled even at a low concentration of vinegar that does not exhibit antibacterial activity against bacterial wilt bacteria. Furthermore, the present inventors have also found that by immersing the roots of tomato seedlings in a diluted vinegar solution and irrigating the seedlings at the base of the potted plants with the diluted vinegar solution, the control effect is significantly improved compared to the case where only the roots are immersed. Furthermore, the present inventors have found that immersing the roots of komatsuna seedlings in a diluted vinegar solution can also control komatsuna downy mildew. The present invention has been completed based on the above findings.

[0013] That is, the present invention provides the following (1) to (13). (1) A plant disease control agent for root dipping, characterized by containing acetic acid.

[0014] (2) The plant disease control agent for root dipping according to (1), characterized in that the plant disease is bacterial wilt.

[0015] (3) The plant disease control agent for root dipping according to (1), wherein the plant is tomato and the plant disease is tomato bacterial wilt.

[0016] (4) The plant disease control agent for root dipping according to (1), characterized in that the plant disease is downy mildew.

[0017] (5) The plant disease control agent for root dipping according to (1), characterized in that the plant is komatsuna and the plant disease is komatsuna downy mildew.

[0018] (6) The plant disease control agent for root dipping according to any one of (1) to (5), wherein the concentration of acetic acid is 0.004 to 0.4 v / v %.

[0019] (7) A method for controlling plant diseases, comprising the step of immersing roots of a plant in an aqueous acetic acid solution.

[0020] (8) The method for controlling a plant disease according to (7), wherein the plant disease is bacterial wilt.

[0021] (9) The method for controlling a plant disease according to (7), wherein the plant is a tomato and the plant disease is tomato bacterial wilt.

[0022] (10) The method for controlling a plant disease according to (7), wherein the plant disease is downy mildew.

[0023] (11) The method for controlling a plant disease according to (7), wherein the plant is komatsuna and the plant disease is komatsuna downy mildew.

[0024] (12) The method for controlling plant diseases according to any one of (7) to (11), wherein the concentration of acetic acid is 0.004 to 0.4 v / v %.

[0025] (13) The method for controlling plant diseases according to any one of (7) to (12), further comprising the step of irrigating soil in which the plant, the roots of which have been immersed in the aqueous acetic acid solution, is grown. Effect of the Invention

[0026] The present invention provides a novel plant disease control agent and a novel method for controlling a plant disease. The plant disease control agent and the method for controlling a plant disease of the present invention have the advantages of being low cost and highly safe. [Brief description of the drawings]

[0027] [Figure 1]A graph showing the disease-reducing effect of tomato bacterial wilt caused by root soaking and irrigation with a diluted grain vinegar solution. In the graph, - indicates the distilled water treatment area, and + indicates the grain vinegar diluted solution (×1 / 100) treatment area. [Diagram 2] FIG. 1 is a graph showing the disease-reducing effect of tomato bacterial wilt caused by root immersion in a mixed solution of acetic acid and amino acids. Only root immersion was performed. [Diagram 3] A graph showing the effect of various vinegar treatments in reducing the incidence of bacterial wilt in tomatoes. Root soaking and irrigation were used in combination. [Figure 4] Graph showing the disease-reducing effect of root immersion treatment with a diluted grain vinegar solution. Only root immersion treatment was performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The present invention will be described in detail below. (1) Plant disease control agent for root dipping The plant disease control agent for root dipping according to the present invention is characterized in that it contains acetic acid.

[0029] In the present invention, the term "plant disease control agent for root dipping" means a plant disease control agent used for dipping the roots of a plant that is the target of disease control.

[0030] The plant disease control agent of the present invention for root dipping can be used, for example, to drench the roots of a plant seedling before the seedling is transplanted into a farm field or the like.

[0031] The acetic acid used may be that sold as a reagent, or may be that contained in foods such as vinegar (grain vinegar, rice vinegar, fruit vinegar, etc.).

[0032] The concentration of acetic acid is not particularly limited as long as it provides a control effect and does not adversely affect the roots of the plant. The specific concentration may be determined depending on the type of plant or disease, the immersion time, etc., and is preferably 0.004 to 0.4 v / v%, more preferably 0.01 to 0.1 v / v%, and even more preferably 0.02 to 0.08 v / v%.

[0033] The plant disease control agent for root immersion of the present invention may contain components other than acetic acid. Since the plant disease control agent for root immersion of the present invention can be prepared from vinegar, it may contain components other than acetic acid in vinegar (e.g., various amino acids, organic acids other than acetic acid). In addition, the plant disease control agent for root immersion of the present invention may contain components generally contained in plant disease control agents, such as fertilizer components, plant activators, growth promoters, pH adjusters, surfactants, antifoaming agents, suspending agents, and stabilizers.

[0034] The plant disease to be controlled is not particularly limited, and for example, soil-borne diseases can be controlled. Specific examples include bacterial wilt and downy mildew. Examples of bacterial wilt include tomato bacterial wilt, eggplant bacterial wilt, potato bacterial wilt, and pepper bacterial wilt, and examples of downy mildew include komatsuna downy mildew, cabbage downy mildew, cucumber downy mildew, onion downy mildew, and grape downy mildew. As shown in the examples described below, the plant disease control agent for root immersion of the present invention is effective not only against bacterial wilt but also against downy mildew, which is a disease completely different from bacterial wilt (bacterial wilt is a disease caused by bacteria, and downy mildew is a disease caused by oomycetes). From this, it is considered that the plant disease control agent for root immersion of the present invention is effective not only against specific diseases but also against a wide range of diseases.

[0035] There are no particular limitations on the plants to be controlled, and examples thereof include tomato, wolfberry, cornstarch, ground cherry, eggplant, potato, chili pepper, tobacco, Datura stramonium, and Tsukubaneagao, and other Solanaceae plants; komatsuna, Arabidopsis, rapeseed, cabbage, broccoli, Chinese cabbage, and wasabi, and other Brassicaceae plants; banana, musa, and Heliconia, and other Musaceae plants; mint, such as perilla, basil, and salvia; ginger, myoga, and cucumber. Examples of the plant disease control agent include plants of the Zingiberaceae family such as lucuma, Asteraceae family such as chrysanthemum, dahlia, sycamore, and sunflower, Rosaceae family such as strawberry, Fabaceae family such as peanut and kidney bean, Myrtaceae family such as clove, Pedunaceae family such as sesame, Mulberry family such as mulberry, Strelitzia recutita, Euphorbiaceae family such as cassava, Plumeriaceae family such as statice, Gentianaceae family such as lisianthus, and Cucurbitaceae family such as cucumber. As shown in the examples described below, the plant disease control agent for root immersion of the present invention is effective not only against tomatoes but also against Japanese mustard spinach, which is not closely related to tomatoes (tomatoes belong to the Solanaceae family, and Japanese mustard spinach belongs to the Brassicaceae family). From this, it is considered that the plant disease control agent for root immersion of the present invention is effective not only against specific plants but also against a wide range of plants.

[0036] (2) Plant disease control methods The method for controlling plant diseases of the present invention is characterized by comprising a step of immersing roots of a plant in an aqueous acetic acid solution.

[0037] The acetic acid used may be that sold as a reagent, or may be that contained in foods such as vinegar (grain vinegar, rice vinegar, fruit vinegar, etc.).

[0038] The concentration of acetic acid in the aqueous acetic acid solution is not particularly limited as long as it is within a range in which a control effect is obtained and the roots of the plant are not adversely affected. The specific concentration may be determined depending on the type of plant or disease, the immersion time, etc., and is preferably 0.004 to 0.4 v / v%, more preferably 0.01 to 0.1 v / v%, and even more preferably 0.02 to 0.08 v / v%.

[0039] The aqueous acetic acid solution may contain components other than acetic acid. Since the aqueous acetic acid solution can be prepared from vinegar, it may contain components other than acetic acid in vinegar (e.g., various amino acids, organic acids other than acetic acid). In addition, the aqueous acetic acid solution may contain components generally contained in plant disease control agents, such as fertilizer components, plant activators, growth promoters, pH adjusters, surfactants, antifoaming agents, suspending agents, and stabilizers.

[0040] The time for immersion in the acetic acid aqueous solution is not particularly limited as long as the control effect is obtained and the roots of the plant are not adversely affected. The specific time may be determined depending on the type of plant or disease, the acetic acid concentration, etc., but is preferably 10 to 120 hours, more preferably 20 to 100 hours, and even more preferably 30 to 80 hours.

[0041] The plant disease to be controlled is not particularly limited, and for example, soil-borne diseases can be controlled. Specific examples include bacterial wilt and downy mildew. Examples of bacterial wilt include tomato bacterial wilt, eggplant bacterial wilt, potato bacterial wilt, and pepper bacterial wilt, while examples of downy mildew include komatsuna downy mildew, cabbage downy mildew, cucumber downy mildew, onion downy mildew, and grape downy mildew. As with the plant disease control agent for root immersion of the present invention, the plant disease control method of the present invention is effective not only against specific diseases but also against a wide range of diseases.

[0042] There are no particular limitations on the plants to be controlled, and examples thereof include tomato, wolfberry, cornstarch, ground cherry, eggplant, potato, chili pepper, tobacco, Datura stramonium, and Tsukubaneagao, and other Solanaceae plants; komatsuna, Arabidopsis, rapeseed, cabbage, broccoli, Chinese cabbage, and wasabi, and other Brassicaceae plants; banana, musa, and Heliconia, and other Musaceae plants; mint, such as perilla, basil, and salvia; ginger, myoga, and cucumber. Examples of suitable plants include plants of the Zingiberaceae family, such as lucuma, Asteraceae family, such as chrysanthemum, dahlia, sycamore, and sunflower, Rosaceae family, such as strawberry, Fabaceae family, such as peanut and kidney bean, Myrtaceae family, such as clove, Pedunaceae family, such as sesame, Mulberry family, such as mulberry, Strelitzia recutita, Euphorbiaceae family, such as cassava, Plumeriaceae family, such as statice, Gentianaceae family, such as lisianthus, and Cucurbitaceae family, such as cucumber. As with the plant disease control agent for root immersion of the present invention, the plant disease control method of the present invention is effective not only for specific plants but also for a wide range of plants.

[0043] The plant disease control method of the present invention may further comprise the step of irrigating the soil in which the plant, the roots of which have been immersed in the aqueous acetic acid solution, is grown with the aqueous acetic acid solution.

[0044] The acetic acid aqueous solution to be irrigated may be the same as the acetic acid aqueous solution used for soaking the roots.

[0045] The amount of irrigation is not particularly limited as long as it is within a range in which a control effect can be obtained and no adverse effects are caused on the plant. The specific amount may be determined depending on the type of plant or disease, the size of the plant body, the acetic acid concentration, etc., but is preferably 1 to 100 ml, more preferably 10 to 80 ml, and even more preferably 20 to 50 ml per plant. EXAMPLES

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0047] Example 1: Effect of root soaking and irrigation with diluted grain vinegar on the occurrence of bacterial wilt in tomatoes A seedling cell tray (cell size 25 mm square x depth 45 mm, Yanmar Holdings) was filled with seedling soil (organic horticultural soil, Kanto Nosan), tomato "Momotaro" (Takii Seed) was sown, and the seedlings were grown in a greenhouse. From two weeks after sowing, a 500-fold diluted solution of Hyponex concentrate (Hyponex Japan) was applied once a week instead of irrigation, and after the seedlings had grown to about two true leaves, they were cultivated by bottom watering. The tomato was grown to about three true leaves, and the roots that had grown from the bottom of the cell tray were cut with scissors. With the seedlings still in the cell tray, 5 x 5 cells (total of 25 cells) were transferred to a polypropylene tray (320 x 230 x 52 mm, As One), and 1 L of distilled water or grain vinegar (Mizkan Holdings) diluted 100 times (v / v) with distilled water was poured into the tray to start the root immersion treatment. After the root immersion treatment of the seedlings was performed for a specified period, the roots of the seedlings were immersed in a suspension of the tomato bacterial wilt pathogen (strain 8107R) of a specified concentration for 1 minute, and each seedling was potted in a 7.5 cm diameter pot filled with culture soil (Nippi Engei Baido No. 1, Nippon Hyogo). The day after the inoculation with the pathogen, 30 ml of distilled water or grain vinegar diluted 100 times (v / v) with distilled water was irrigated at the base of the tomato. After that, the plants were cultivated with bottom watering, and 21 days after the inoculation with the pathogen, the presence or absence of disease (wilting symptoms) in the above-ground parts of the tomatoes was investigated. The test was performed three times, and the average rate of diseased plants in each treatment group was calculated. The results are shown in Figure 1. Twelve tomato plants were used for each treatment group. The root immersion treatment period of the seedlings was 2 days (first test) or 3 days (second and third tests), and the concentration of the tomato bacterial wilt pathogen was 1.5 × 10 7 cfu / ml (first test), 1.3 x 10 7 cfu / ml (test 2), or 1.7 × 10 7 The average temperatures in the greenhouse after inoculation were 20.9°C (test 1), 19.9°C (test 2), and 20.2°C (test 3).

[0048] As shown in Figure 1, the onset of bacterial wilt was suppressed by immersing the roots of tomato seedlings in a diluted grain vinegar solution. In addition, the control effect was further enhanced by irrigating the base of the seedlings with a diluted grain vinegar solution after potting.

[0049] [Example 2] pH of grain vinegar and antibacterial activity against bacterial wilt disease The pH of the original grain vinegar solution or a solution diluted 10 to 10,000 times (v / v) with distilled water was measured with a pH meter (B-712, Horiba, Ltd.). In addition, the tomato wilt bacterium was cultured on a Yeast Pepton Agar (YPA, yeast extract 5g / L, peptone 10g / L, Na2HPO4·12H2O 4g / L, KH2PO4 0.5g / L, agar 15g / L, distilled water 1L) slant medium for 3 days and suspended in a small amount of sterile distilled water to obtain a pathogen solution. After heating and dissolving, the pathogen solution was added in 1 / 100 volume (v / v) to the YPA medium cooled to about 50°C, stirred, and poured into a sterile petri dish with a diameter of 9 cm, solidified, and prepared a plate. Sterilized paper disks (diameter 8 mm, thin, ADVANTEC) were placed on plates, and 20 μl of undiluted grain vinegar or a solution diluted 10 and 100 times (v / v) with sterile distilled water was dropped onto the paper disks, and the plates were incubated at 30°C in the dark for 2 days. If a growth inhibition zone was visually observed around the paper disk, it was judged that there was antibacterial activity against the pathogen, and if not, there was no antibacterial activity. The results are shown in Table 1. [Table 1]

[0050] As shown in Table 1, the 100-fold diluted grain vinegar, which was confirmed to have a preventive effect against tomato bacterial wilt by root immersion treatment, did not show any antibacterial activity. From this, it is speculated that the reason for the preventive effect is due to factors other than direct antibacterial activity.

[0051] [Example 3] Effect of acetic acid and amino acid solution treatment on the occurrence of bacterial wilt in tomatoes As in Example 1, tomato "Momotaro" seedlings were grown in a cell tray until they had about three true leaves, and the roots that had grown from the bottom of the cell tray were cut off with scissors. 15 seedlings were transferred to a new cell tray (5 x 5 cells) and placed in a polypropylene tray (320 x 230 x 52 mm, AS ONE). After that, the seedlings were soaked in a mixture of distilled water or grain vinegar diluted 100 times (v / v) with distilled water, 0.042 v / v% acetic acid※, amino acid mixture solution※※ (0.87 mg / L L-leucine, 0.86 mg / L (+)-arginine, 0.37 mg / L L-alanine, 0.36 mg / L L-serine, 0.37 mg / L L-valine), acetic acid / amino acid mixture solution (0.042 v / v% acetic acid, 0.87 mg / L L-leucine, 0.86 mg / L (+)-arginine, 0.37 mg / L The root immersion treatment was started by pouring 1.5 L of 1×10 L-alanine, 0.36 mg / L L-serine, and 0.37 mg / L L-valine into the seedlings. After 3 days of root immersion treatment, each seedling was potted in a 7.5 cm diameter pot filled with culture soil and was diluted with 1×10 L-alanine, 0.36 mg / L L-serine, and 0.37 mg / L L-valine. 8 The tomato plants were inoculated with 30 ml of a suspension of bacterial wilt pathogen (cfu / ml) by irrigation at the base of each plant. After that, the plants were managed by bottom watering, and the presence or absence of disease (wilting symptoms) in the above-ground parts of the tomatoes was examined after a specified period of time had passed since the inoculation.

[0052] *We requested Tsukuba Food Evaluation Center to analyze the organic acids contained in the grain vinegar (undiluted solution), and found that the main organic acid was acetic acid at 4.23g / 100g. Since the specific gravity of vinegar and acetic acid is about 1.0g / ml, we adjusted acetic acid (special grade reagent, Fujifilm Wako Pure Chemical) with distilled water to 0.042v / v%, which is the concentration contained in the grain vinegar (100 times diluted solution), and used it for the test.

[0053] ※※ When the free amino acids contained in the grain vinegar (undiluted solution) were analyzed by Tsukuba Food Evaluation Center Co., Ltd., the top amino acids in terms of molar concentration were 0.66 mM leucine, 0.49 mM arginine, 0.42 mM alanine, 0.34 mM serine, and 0.32 mM valine. For these five amino acids, an amino acid mixture solution containing 0.87 mg / L L-leucine, 0.37 mg / L L-alanine, 0.36 mg / L L-serine, 0.37 mg / L L-valine (the above four amino acids are special grade reagents, Fujifilm Wako Pure Chemical Industries), and 0.86 mg / L (+)-arginine (Wako special grade, Fujifilm Wako Pure Chemical Industries), which are equivalent to the concentrations contained in the grain vinegar (100 times diluted solution), was prepared with distilled water and used for the test.

[0054] The test was carried out three times, and the average rate of diseased plants in each treatment was calculated. The results are shown in Figure 2. Twelve tomato plants were used for each treatment. The presence or absence of disease was investigated 14 days (first test) or 21 days (second and third tests) after inoculation of the pathogen. The average temperatures in the greenhouse after inoculation of the pathogen were 22.8°C (first test), 19.6°C (second test), and 21.5°C (third test).

[0055] As shown in Figure 2, the onset of tomato bacterial wilt was suppressed by immersing the roots of tomato seedlings in a 0.042% acetic acid solution, which is the same concentration as the acetic acid contained in the grain vinegar (100 times diluted solution). From this, it is believed that acetic acid is involved in the control effect of root immersion in the diluted grain vinegar solution.

[0056] [Example 4] Effect of various vinegar treatments on reducing the incidence of bacterial wilt in tomatoes As in Example 1, tomato "Momotaro" seedlings were grown in cell trays until they had about 3 to 4 true leaves, and the roots were pruned. They were then placed in a tray and 1L of distilled water or grain vinegar diluted 100 times (v / v) with distilled water, rice vinegar* (Mizkan Holdings) diluted 107 times (v / v), or apple cider vinegar* (Mizkan Holdings) diluted 119 times (v / v) was poured in to start the root immersion treatment. After the root immersion treatment of the seedlings was performed for 3 days, the roots were immersed in a suspension of tomato bacterial wilt bacteria of a predetermined concentration as in Example 1, and the seedlings were potted up one by one in a 7.5 cm diameter pot filled with culture soil. The day after the inoculation of the pathogen, 30 ml each of distilled water or grain vinegar, rice vinegar, and apple cider vinegar diluted to the same concentration as above were irrigated at the base of the tomato. Thereafter, the plants were cultivated and managed with bottom watering, and 14 days after the inoculation of the pathogen, the presence or absence of disease (wilting symptoms) in the above-ground parts of the tomatoes was investigated.

[0057] *We requested Tsukuba Food Evaluation Center to analyze the organic acids contained in rice vinegar and apple vinegar (both undiluted), and found that the main organic acid was acetic acid at 4.52g / 100g and 5.03g / 100g, respectively. Since the specific gravity of vinegar and acetic acid is about 1.0g / ml, rice vinegar and apple vinegar were adjusted with distilled water to the same acetic acid concentration of 0.042v / v% as the grain vinegar (100 times diluted solution) in Example 3, and then used for the test.

[0058] The test was carried out three times, and the average percentage of diseased plants in each treatment was calculated. The results are shown in Figure 3. Twelve tomato plants were used for each treatment. The concentration of the tomato wilt bacteria was 1.8 x 10 7 cfu / ml (first test), 1.5 x 10 7 cfu / ml (test 2), or 1.7 × 10 7 The average temperatures in the greenhouse after inoculation were 22.9°C (test 1), 23.6°C (test 2), and 28.8°C (test 3).

[0059] As shown in Figure 3, the onset of tomato bacterial wilt was suppressed even when tomato seedlings were dipped in a diluted solution of rice vinegar or apple cider vinegar (acetic acid concentration adjusted to 0.042%).

[0060] [Example 5] Effect of root immersion in diluted vinegar on the occurrence of komatsunabe mildew Using the same seedling cell tray and culture soil as in Figure 1, Komatsuna "Kuromisugi" (Sakata Seed) was sown and grown in a greenhouse. The seedlings were grown to the cotyledon stage, and 3 × 5 cells (total of 15 cells) were transferred to a polypropylene tray, and 1 L of distilled water or grain vinegar diluted 100 times (v / v) with distilled water was poured into the tray to begin root immersion. After 2 days of root immersion, the seedlings were transferred, still in the cell tray, to a strawberry pack (M-500A, Minechron Chemical Industry) thinly filled with tap water, and then immersed in water until a conidial concentration of 10 was reached. 3 The cotyledons were inoculated by dropping 10μl of a suspension of Komatsunabe parasitica (strain koma-tu1) adjusted to conidia / ml onto the cotyledons, and then maintained under moist conditions at 15 / 15℃, approximately 10,000 / 0 Lux (12 / 12hrs). Seven days after inoculation, the presence or absence of disease (conidia formation) on the underside of the cotyledons was examined with the naked eye. Thirty plants (60 cotyledons) were used for each treatment group per test, and the test was conducted three times.

[0061] As shown in Figure 4, the incidence of komatsuna downy mildew was reduced by immersing the roots of komatsuna seedlings in a diluted grain vinegar solution. [Industrial Applicability]

[0062] The present invention is expected to be used by tomato producers and agricultural chemical companies. The vinegar used (grain vinegar, rice vinegar, apple vinegar, Mizkan Holdings Co., Ltd.) is available at low cost at general retail stores. Since the treatment is simple and can be carried out at low cost, it is expected to be introduced and used preventively not only in fields where bacterial wilt has already occurred, but also in fields where it has not yet occurred.

[0063] In addition, bacterial wilt is distributed around the world, mainly in tropical and temperate regions, and causes damage to many crops, including tomatoes. Although it is necessary to confirm the disease control effect and the occurrence of damage for each vinegar product, vinegar is one of the major seasonings produced and used around the world, and it is thought that it is used in a wide range of agricultural situations.

[0064] In addition, a rice seed-borne bacterial disease control agent that contains acetic acid as an active ingredient (Ecofit, Kumiai Chemical) is commercially available, but there is potential for the development of a new control agent that uses acetic acid as an active ingredient not only as a seed disinfectant but also targets soil diseases.

Claims

1. A plant disease control agent containing acetic acid, characterized in that: 1) the plant disease is bacterial wilt or downy mildew, 2) the plant disease control agent is used to immerse the roots of seedlings before transplanting the seedlings into a field, and 3) the concentration of acetic acid is 0.004 to 0.4 v / v%.

2. 2. The plant disease control agent according to claim 1, wherein the plant is tomato, and the plant disease is tomato bacterial wilt.

3. 2. The plant disease control agent according to claim 1, wherein the plant is Komatsuna (Brassica napus), and the plant disease is Komatsuna downy mildew.

4. A method for controlling plant diseases, comprising the step of immersing roots of a plant seedling in an aqueous solution of acetic acid prior to transplanting into a field, wherein the method is characterized in that 1) the plant disease is bacterial wilt or downy mildew, and 2) the concentration of the acetic acid is 0.004 to 0.4 v / v%.

5. 5. The method for controlling a plant disease according to claim 4, wherein the plant is a tomato, and the plant disease is tomato bacterial wilt.

6. 5. The method for controlling a plant disease according to claim 4, wherein the plant is Komatsuna (rapeseed), and the plant disease is Komatsuna downy mildew.

7. 7. The method for controlling plant diseases according to claim 4, further comprising the step of irrigating soil in which seedlings of a plant having roots immersed in the aqueous acetic acid solution are grown with the aqueous acetic acid solution.

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