Plant disease control agents

Abstract

To identify a substance having a control effect on plant disease and provide a plant disease control agent and method employing the substance.SOLUTION: It has been found out that a combinational use of proanthocyanidin and a metal compound can have an improved control effect on plant disease in comparison with the case these substances are used separately.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a plant disease control agent containing as active ingredients proanthocyanidin and a metal or a compound containing the metal (metal chelate, metal oxide, etc.), and a method for controlling plant diseases comprising applying the control agent to plants. [Background technology]

[0002] Humanity depends on plants for much of its food and useful substance production. In global agricultural production, plant diseases caused by plant pathogens (fungi such as filamentous fungi, bacteria, viruses, etc.) cause a loss of 15% of the world's food production, and it is estimated that plant diseases cause economic damage of approximately 220 billion dollars per year worldwide. Plant diseases are one of the main factors that greatly reduce plant productivity, and it is predicted that crop yields would decrease by 70% if crops were cultivated without protection against plant diseases. In this way, reducing crop yield losses by controlling plant diseases has an effect comparable to increasing production through mass cultivation of crops.

[0003] For this reason, various control agents have been developed to protect crops from plant diseases. For example, control agents containing the antibiotics kasugamycin and streptomycin as their main ingredients, strobilurin fungicides (QoI agents), succinate dehydrogenase inhibitors (SDHI agents), and other control agents are used against plant diseases caused by infection with plant pathogens such as fungal and bacterial diseases. However, it has been pointed out that these control agents have the problem that resistance develops within a few years, making disease control difficult.

[0004] On the other hand, although Lentemin is registered in Japan as a pesticide for controlling plant diseases caused by infection with plant viruses, there is still no chemical pesticide that can act as a specific cure (Lentemin is a registered trademark of Noda Shokukin Kogyo Co., Ltd. Agricultural Chemical Registration Nos. 15584, 17774, 19439, and 19440).

[0005] Under these circumstances, the present inventors have found that proanthocyanidins, metal chelates, or metal oxides have a control effect against plant diseases, and have proposed using them as control agents against plant diseases (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-178838 A [Patent Document 2] JP 2020-002016 A [Patent Document 3] JP 2020-132552 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to identify a substance having an excellent control effect against plant diseases, and to provide a control agent and a control method for plant diseases utilizing said substance. [Means for solving the problem]

[0008] As a result of intensive research conducted by the present inventors to achieve the above object, it was found that a mixture of proanthocyanidin and a metal compound (a mixture of shell ginger-derived proanthocyanidin and zinc sulfate, zinc gluconate, or copper gluconate) exhibits a stronger control effect against plant viruses than when proanthocyanidin or these metal compounds are applied alone. Furthermore, it was also found that the control effect is exerted not only on the site directly treated with these agents, but also on the surrounding area. Similarly, the present inventors also found that a mixture of proanthocyanidin and a metal compound exhibits a stronger control effect against plant pathogenic bacteria and plant pathogenic fungi than when applied alone. Furthermore, it was found that no phytotoxicity occurs in the mixture of proanthocyanidin and a metal compound, and the present invention was completed.

[0009] That is, the present invention relates to a plant disease control agent containing a mixture of proanthocyanidin and a metal or a compound containing the metal as an active ingredient, and a method for controlling plant diseases which comprises applying the control agent to a plant, and more specifically, provides the following inventions. <1> A plant disease control agent comprising, as active ingredients, proanthocyanidin and a metal or a compound containing said metal. <2> The metal is at least one metal selected from the group consisting of zinc and copper; <1> The control agent described above. <3> The compound containing a metal is at least one compound selected from the group consisting of a metal chelate and a metal oxide. <1> or <2> The control agent described above. <4> The compound containing a metal is at least one compound selected from the group consisting of zinc gluconate, copper gluconate, and zinc sulfate. <1> ~ <3> The control agent according to any one of the above. <5> The plant disease is at least one disease selected from the group consisting of a plant virus disease, a plant fungal disease, and a plant bacterial disease. <1> ~ <4> The control agent according to any one of the above. <6> <1> ~ <5> A method for controlling a plant disease, comprising applying the control agent according to any one of the above to a plant. Effect of the Invention

[0010] According to the present invention, it is possible to control plant diseases. Furthermore, according to the present invention, it is possible to control plant diseases safely without causing phytotoxicity such as leaf atrophy or spotting. Furthermore, the control effect of the present invention was observed not only on the leaves directly sprayed with the agent, but also on the upper leaves, which is considered to cause an improvement in the immunity of the plant (resistance to pathogens). Therefore, according to the present invention, it is possible to bring about a very effective control effect. [Brief description of the drawings]

[0011] [Figure 1] 1 is a graph showing the synergistic effect of combined use of shell ginger proanthocyanidin (PAC) and various metal chelates in suppressing plant viral infection. [Diagram 2] 1 is a graph showing the synergistic effect of combined use of shell ginger proanthocyanidins and zinc sulfate or zinc gluconate in suppressing plant viral infection. [Diagram 3] 1 is a graph showing the synergistic effect of combined use of shell ginger proanthocyanidin and copper gluconate in suppressing infection by bacterial black spot pathogen. [Figure 4] 1 is a graph showing the synergistic effect of combined use of shell ginger proanthocyanidin and copper gluconate in suppressing infection by anthracnose bacteria. [Diagram 5] 1 is a graph showing the synergistic effect of combined use of shell ginger proanthocyanidin and copper gluconate in suppressing infection by brown spot fungus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Pest control agent> As shown in the examples below, it has been revealed that a mixture of proanthocyanidin and a metal chelate or metal oxide has a control effect against plant diseases. Therefore, the present invention provides a plant disease control agent containing proanthocyanidin and a metal or a compound containing the metal as active ingredients.

[0013] (About proanthocyanidins) In the control agent of the present invention, proanthocyanidins contained as one of its active ingredients can be used in combination with a metal or a compound containing said metal (hereinafter also referred to as a "metal compound, etc.") to more significantly control plant diseases than when used alone, as shown in the Examples described later.

[0014] In the present invention, "proanthocyanidin" refers to a compound in which multiple flavan-3-ols such as catechin and epicatechin are bonded. The proanthocyanidin used in the present invention is not particularly limited as long as it has a plant disease control effect, and may be an artificially synthesized compound, but the preferred form of proanthocyanidin in the present invention is a naturally derived purified product (plant purified product) extracted and purified from shell ginger of the genus Alpinia (genus Alpinia) of the Zingiberaceae family.

[0015] Examples of plants in the genus Alpinia include shell ginger, Alpinia zerumbet (Pers.) BL Burtt & R.M. Sm., such as the Shima shell ginger of Okinawa Prefecture and the Shima shell ginger of Amami Oshima, the Thai Lin shell ginger (Hanasoka) of Kitadaito Island and Miyako Island, the Tachibana shell ginger, the Taiwanese Thai Lin shell ginger, the Urai shell ginger, and the Tonka shell ginger, and hybrids thereof. Examples of shell ginger include Alpinia formosana, Alpinia boninensis, Alpinia flabellata, and hybrids thereof. Among these, shell ginger is more preferred.

[0016] In the present invention, the purified product may be a completely purified product or a crude purified product. The purified product contains proanthocyanidins after removing impurities by dialysis or the like, and may be a liquid or a dried product containing the proanthocyanidins.

[0017] The purification of the "proanthocyanidin" according to the present invention can be performed by a person skilled in the art with reference to the methods described in International Publication No. 2017 / 125993, Patent Document 2, etc. For example, the plant can be physically crushed by using a crusher to extract the proanthocyanidin. Furthermore, the plant juice thus obtained may be purified by applying it to a reverse phase carrier. The elution solvent in this case is not particularly limited, and may be, for example, acetonitrile. When elution is performed with acetonitrile, the acetonitrile concentration is usually 5% or more, preferably 5% to 30%, and more preferably 5% to 20%. Acetonitrile with a concentration of 40% or more may be used, but it is considered that the proportion of inactive components in the extract will increase.

[0018] Proanthocyanidins can also be extracted with alcohol. The form of the plant to be extracted is not particularly limited, but is preferably the stem and leaf part, and is desirably divided as finely as possible. The plant thus prepared can be immersed in, for example, an aqueous alcohol solution to extract proanthocyanidins. The alcohol used for extraction is not particularly limited, but examples thereof include ethanol. The alcohol concentration in this case is usually 40% to 80%, preferably 60% to 80%. The immersion time is 24 hours, preferably 8 to 16 hours, and more preferably 12 hours.

[0019] Furthermore, when further purification is required, the organic solvent (acetonitrile, alcohol such as ethanol) is removed from the fraction thus obtained (for example, by distillation using an evaporator (for example, at 50°C for 15 minutes)), and the remaining solution can be purified using a dialysis membrane with a molecular weight cutoff of 3500 or more (preferably 8500 or more, more preferably 9000 or more, and even more preferably 10000 or more). Furthermore, the dialysis internal solution thus obtained can be freeze-dried to obtain a proanthocyanidin purified product (dried product).

[0020] The concentration of proanthocyanidin contained in the purified product (extract) thus obtained is usually 0.1mg / ml or more, preferably 0.3mg / ml or more, more preferably 0.5mg / ml or more (e.g., 1mg / ml or more, 5mg / ml or more, 10mg / ml or more, 20mg / ml or more). On the other hand, in order to prevent negative effects such as phytotoxicity, it is considered that the concentration of proanthocyanidin contained in the purified product is usually 50mg / ml or less. In addition, the purified product of proanthocyanidin usually contains proanthocyanidin in a dry weight ratio of 1% or more, preferably 5% or more, more preferably 10% (e.g., 20% or more, 30% or more, 50% or more).

[0021] The molecular weight of the "proanthocyanidin" according to the present invention is not particularly limited as long as it can exert plant disease control activity, but for example, it is 3500 (4000 or more, 5000 or more, 6000 or more, 7000 or more, 8000 or more, etc.), preferably 8500 or more, more preferably 9000 or more, even more preferably 10000 or more, more preferably 11000 or more, even more preferably 12000 or more, more preferably 13000 or more. The molecular weight of proanthocyanidin is usually 25000 or less. In addition, the molecular weight of proanthocyanidin can be determined by a known method such as high performance liquid chromatography (HPLC) using polystyrene or the like as a standard.

[0022] The "proanthocyanidin" according to the present invention preferably has a terminal structure that is substantially epicatechin. Here, "substantially" means that the ratio of epicatechin to the total ratio of epicatechin and catechin in the terminal structure is at least 95% or more (for example, 96% or more, 97% or more, 98% or more, 99% or more). An example of a proanthocyanidin having such a terminal structure is a proanthocyanidin derived from Shima shell ginger. The structure of proanthocyanidin can be identified by a known analysis method such as NMR.

[0023] In the present invention, proanthocyanidins can be used alone or in combination of two or more.

[0024] (Metal compounds, etc.) In the control agent of the present invention, the "metal compound, etc. (metal or a compound containing said metal)" contained as one of its active ingredients can be used in combination with proanthocyanidins to more significantly control plant diseases than when the metal compound is used alone, as shown in the Examples described later.

[0025] The "metal" that can be contained in the control agent of the present invention is not particularly limited as long as the control agent of the present invention can exert its effect, and also includes metalloids. Examples of the "metal" according to the present invention include zinc, copper, iron, potassium, manganese, molybdenum, magnesium, silicon, boron, calcium, cobalt, and nickel. Among these, zinc and copper are preferable because they are essential elements for plant growth and have low toxicity to plants.

[0026] The "compound containing a metal" is not particularly limited as long as the control agent of the present invention can exert its effect, and examples thereof include oxides, hydroxides, halides (chlorides, etc.), acid halides, and alkoxides of the metals, such as sulfates, nitrates, organic acid salts, perhalogenates, hypohalites, phosphates, acetates, and carbonates. Among these, metal oxides are preferred, metal sulfates are more preferred, and zinc sulfate is even more preferred, since they combine excellent control effects with low toxicity.

[0027] Furthermore, when metal ions are applied to soil as they are (as inorganic), the metal ions may combine with phosphoric acid and the like in the soil to form insoluble precipitates, and the desired effect may not be fully obtained. Therefore, by preparing a chelate by combining with a chelating agent in advance and applying the chelate, it is possible to prevent the chelate from combining with other components and to exert the original fertilizer effect. Furthermore, metal chelates have the property of being easily absorbed by plants. From this viewpoint, in the present invention, chelated metals can also be suitably used as the metal-containing compound according to the present invention. In the present invention, the metal chelate compound or chelate salt is also referred to as a metal chelate, a metal complex, or a metal chelate complex.

[0028] Examples of metal chelating agents include gluconic acid, EDTA (ethylenediaminetetraacetic acid), DTPA (diethylenetriamine pentaacetic acid), NTA (nitrilotriacetic acid), EDDS (ethylenediamine-N,N'-disuccinic acid), DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), citric acid, formic acid, phytic acid, ethylenediamine, bipyridine, and phenanthroline. Among these, gluconic acid is preferred because of its low toxicity to plants. Zinc gluconate and copper gluconate combine excellent control effects with low toxicity, and therefore can be most suitably used as the active ingredient of the control agent of the present invention. From the viewpoint of versatility, EDTA-based chelating agents can be preferably used, and from the viewpoint of natural decomposition, EDDS and the like can be preferably used.

[0029] In the present invention, the metal compounds and the like can be used alone or in combination of two or more.

[0030] (Other ingredients) The formulation of the control agent of the present invention can take various forms depending on the application method described below. For example, liquid formulations such as emulsions, oils, aerosols, and flowables, as well as wettable powders, water-soluble powders, powders, granules, tablets, etc. When applied to plants by spraying, etc., liquid formulations or formulations that can be made into a liquid form at the time of application are preferred.

[0031] Depending on the formulation type, shape, etc., the control agent of the present invention may contain other optional components as long as the control effect against plant diseases is not impaired. Examples of other optional components include carriers, spreading agents, emulsifiers, dispersants, fillers, extenders, binders, wetting agents, disintegrants, lubricants, diluents, and excipients.

[0032] Examples of the liquid carrier include a solvent for dissolving or dispersing the proanthocyanidin and the metal compound, etc., such as water, alcohols such as 1-propanol and butanol, polyhydric alcohols such as ethylene glycol and propylene glycol, and hydrocarbons such as xylene, etc. Examples of the solid carrier include kaolin, attapulgite, bentonite, calcium carbonate, talc, and zeolite.

[0033] A surfactant is usually used as the spreading agent, emulsifier and dispersant. Examples of the "surfactant" include nonionic surfactants (e.g., polyalkylene glycol alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyoxyalkylene fatty acid ester, polyoxyethylene hexitane fatty acid ester, sorbitan fatty acid ester, polyoxyethylene resin acid ester, polyoxyethylene fatty acid ester), anionic surfactants (e.g., sodium higher alcohol sulfate, sodium polynaphthylmethanesulfonate, sodium dioctyl sulfosuccinate, sodium alkylbenzenesulfonate, calcium ligninsulfonate, etc.), cationic surfactants (e.g., dialkyldimethylammonium polynaphthylmethanesulfonate, stearyltrimethylammonium chloride), silicon-based surfactants (e.g., polyoxyalkyleneoxypropylheptamethyltrisiloxane, polyoxyethylenemethylpolysiloxane), amphoteric surfactants, etc. The nonionic surfactants can also be used in combination with anionic surfactants or cationic surfactants.

[0034] In the control agent of the present invention, other active ingredients may be contained in addition to the proanthocyanidins and metal compounds, etc., as long as the control effect against plant diseases is not inhibited. For example, in order to further enhance the control effect against plant diseases or to widen the range of plant diseases to which the agent is applied, the agent may be used in combination with known drugs such as lentemin. In addition, since there are cases where plant viruses are transmitted by insects, the agent may be used in combination with known insecticides, miticides, antibacterial agents, etc. In addition, in order to further enhance the control effect against plant fungal diseases or plant bacterial diseases or to widen the range of plant diseases to which the agent is applied, the agent may be used in combination with known bactericidal pesticides. It is preferable that the control agent of the present invention does not contain glycine.

[0035] <Control method> The present invention also provides a method for controlling plant diseases, which comprises applying the above-mentioned control agent to a plant.

[0036] In the present invention, "plant disease" refers to a disease of a plant caused by a pathogen (virus, bacteria, fungus, etc.), and includes, without particular limitation, examples thereof, such as a plant viral disease caused by a virus that infects a plant, a plant bacterial disease caused by a bacterium that infects a plant, and a plant fungal disease caused by a fungus that infects a plant.

[0037] The control effect of the control agent of the present invention against plant pathogens includes the effect of suppressing or inhibiting infection of the pathogen, the effect of suppressing or inhibiting the proliferation, spread or movement of the pathogen, and the effect of killing the pathogen.

[0038] Examples of "plant viral diseases" to which the control agent of the present invention is applicable include diseases caused by infection with viruses of the genus Tobamovirus, Potexvirus, Carlavirus, Cucumovirus, Carmovirus, Potyvirus, or Begomovirus.

[0039] Examples of "Tobamovirus viruses" include tomato mosaic virus (ToMV), tobacco mosaic virus (TMV), cucumber green mottle mosaic virus (KGMMV), pepper mild mottle virus (PMMoV), and watermelon green mottle mosaic virus (CGMMV). Examples of "Potexvirus viruses" include plantain mosaic virus (PlAMV) and potato X virus (PVX), and examples of "Carlavirus viruses" include potato M virus (PVM). Examples of "Cucumovirus viruses" include cucumber mosaic virus (CMV), and examples of "Carmovirus viruses" include melon necrotic spot virus (MNSV). Examples of "Potyvirus viruses" include potato Y virus (PVY) and plum ring virus (PPV), and examples of "Begomovirus viruses" include, but are not limited to, tomato yellow leaf curl virus (TYLCV).

[0040] The plant viral disease targeted by the control agent of the present invention is preferably a mosaic disease caused by infection with various mosaic viruses, potato virus X, or the like.

[0041] The plant to which the control agent of the present invention is applied is not particularly limited as long as it is infected with the above-mentioned plant viruses. For example, the plant may be a solanaceous plant (tobacco, tomato, eggplant, potato, green pepper, red pepper, petunia, etc.), a cucurbitaceous plant (cucumber, gourd, pumpkin, melon, watermelon, etc.), a grass family plant (rice, barley, wheat, corn, sugarcane, sorghum, sorghum, lawn grass, etc.), a cruciferous plant (Chinese cabbage, cabbage, radish, bok choy, komatsuna, broccoli, rapeseed, etc.), a corn family plant (corn, corn, cornstarch ... Examples of such plants include Gramineae plants (soybeans, peanuts, peas, kidney beans, broad beans, etc.), Rosaceae plants (strawberries, apples, pears, peaches, plums, roses, cherry blossoms, etc.), Convolvulaceae plants (sweet potatoes, etc.), Liliaceae plants (leeks, onions, lilies, tulips, etc.), Asteraceae plants (lettuce, chrysanthemums, gerberas, etc.), Vitaceae plants (grapes, etc.), Caryophyllaceae plants (carnations, etc.), Orchidaceae plants (cattleyas, cymbidiums, etc.), Gentianaceae plants (lisianthus, etc.), and Plumaceae plants (static, etc.).

[0042] In this way, the control agent of the present invention can be widely applied to plants of the family Solanaceae, Cucurbitaceae, Gramineae, Cruciferae, Legumes, Rosaceae, Convolvulaceae, Liliaceae, Asteraceae, Vitaceae, Caryophyllaceae, Orchidaceae, Gentianaceae, Plumageae, etc. For the relationship between plant viruses and host plants, see the Japan Plant Disease Name Database (Agricultural Biological Resources Genebank).

[0043] Examples of "plant pathogenic bacteria" to which the control agent of the present invention is applied include, but are not limited to, bacteria of the genera Pseudomonas, Erwinia, Xanthomonas, Ralstonia, Streptomyces, Clavibacter, Agrobacterium, Curtobacterium, Acidovorax, and Burkholderia.

[0044] Specific examples of "plant pathogenic bacteria" include black spot bacteria of cruciferous plants (Pseudomonas syringae pv. maculicola, Pseudomonas cannabina pv. alisalensis), tomato leaf spot bacteria (Pseudomonas syringae pv. tomato), tomato spot bacteria (Xanthomonas campestris pv. vesicatoria), rot bacteria of lettuce and Chinese cabbage, etc. (Pseudomonas cichorii, Pseudomonas marginalis, Pseudomonas viridiflava), peach hole bacteria (Xanthomonas arboricola pv. pruni, Pseudomonas syringae pv. syringae, Brenneria nigrifluens, Erwinia nigrifluens), red clover spot bacteria, adzuki bean brown spot bacteria, citrus brown spot bacteria, etc. (Pseudomonas syringae pv.syringae), soybean bacterial spot (Pseudomonas savastanoi pv.glycinea), cucumber bacterial spot (Pseudomonas syringae pv.lachrymans), tobacco wildfire blight (Pseudomonas syringae pv.tabaci), pea vine blight (Pseudomonas syringae pv.pisi), kiwi fruit canker (Pseudomonas syringae pv.actinidiae), Chinese cabbage, cabbage, radish, lettuce, etc. soft rot bacterium (Erwinia carotovora), rice bacterial leaf blight (Xanthomonas oryzae pv.oryzae), soybean leaf burn bacterium (Xanthomonas campestris pv.glycinea, Xanthomonas axonopodis pv.glycinea), the cabbage, broccoli and other cruciferous plants black rot fungus (Xanthomonas campestris pv.campestris), lettuce spot pathogen (Xanthomonas axonopodis pv.vitians), citrus canker pathogen (Xanthomonas citri subsp.citri), Ralstonia solanacearum, the pathogen of bacterial wilt of tomatoes, eggplants, peppers, strawberries, and ginger, Streptomyces spp., Clavibacter michiganensis subsp. michiganensis, Agrobacterium tumefaciens, the pathogen of crown gall of plants of the Asteraceae and Rosaceae families, Agrobacterium rhizogenes, Agrobacterium vitis, Rhizobium radiobacter, Curtobacterium flaccumfaciens pv. flaccumfaciens, Curtobacterium flaccumfaciens pv. oortii, Acidovorax avenae, the pathogen of bacterial fruit spot of watermelon subsp.citrulli), Acidovorax avenae subsp.avenae, Burkholderia glumae, Burkholderia plantarii, Pectobacterium carotovorum, Pectobacterium atrosepticum, and other fungi are not limited to these.

[0045] The plant bacterial disease targeted by the control agent of the present invention is preferably black spot bacterial disease caused by infection with cruciferous plants (Pseudomonas cannabina pv. alisalensis, Pseudomonas syringae pv. maculicola).

[0046] In addition, examples of the "plant pathogenic fungi" to which the control agent of the present invention is applied include, for example, the genera Colletotrichum, Phytophthora, Podosphaera, Sphaerotheca, Leveillula, Oidium, Oidiopsis, Erysiphe, Uncinula, Botrytis, Fusarium, Pyricularia, Fulvia, Pseudocercospora, Gibberella, Monilia, and the like. These include, but are not limited to, the genera Graphella, Pestalotiopsis, Corynespora, Puccinia, Alternaria, Plasmopara, Bremia, Peronospora, Cochliobolus, Rhizoctonia, Sclerotinia, Verticillium, Venturia, Monilinia, Cercospora, and Leptosphaeria.

[0047] Specific examples of "plant pathogenic fungi" include Colletotrichum higginsianum, Colletotrichum orbiculare, Colletotrichum acutatum, Colletotrichum gloeosporioides species complex (C. aenigma, C. fructicola, C. siamense), Colletotrichum incanum, Colletotrichum dematium, Glomerella cingulata, Colletotrichum fioriniae, Colletotrichum graminicola ... spp.), tomato brown spot fungus, cucumber brown spot fungus, pepper black blight fungus, perilla leaf spot fungus, salvia spot fungus (Corynespora cassiicola), potato and tomato phytophthora blight fungus (Phytophthora infestans), strawberry phytophthora blight fungus (Phytophthora nicotianae, Phytophthora cactorum, Phytophthora sp.), taro phytophthora blight fungus (Phytophthora colocasiae), vegetable, ornamental, tobacco and other host plant phytophthora blight fungus (Phytophthora spp.), strawberry powdery mildew fungus (Podosphaera aphanis, Sphaerotheca aphanis, Sphaerotheca humuli), tomato powdery mildew fungus (Leveillula taurica, Oidium sp., Oidium lycopersici, Oidium neolycopersici), cucumber powdery mildew (Sphaerotheca fuliginea, Sphaerotheca cucurbitae, Oidiopsis sicula, Erysiphe polygoni, Oidium sp.), powdery mildew of barley and wheat (Erysiphe graminis), powdery mildew of grapes (Erysiphe necator, Uncinula necator), powdery mildew of peas (Erysiphe pisi), powdery mildew of pumpkin (Sphaerotheca cucurbitae, Oidium citrulli), powdery mildew of eggplant (Erysiphe cichoracearum, Sphaerotheca fuliginea, Oidiopsis sicula), powdery mildew of vegetables, ornamentals and other host plants, gray mold of tomato, strawberry, cucumber, vegetables, grapes and other host plants (Botrytis cinerea), strawberry yellows (Fusarium oxysporum f.sp.fragariae), rice blast (Pyricularia grisea (P.oryzae), tomato leaf mold (Fulvia fulva), tomato leaf mold (Pseudocercospora fuligena), wheat head blight (Gibberella zeae, Fusarium avenaceum, Fusarium culmorum, Fusarium crookwellense, Monographella nivalis), tea ring spot (Pestalotiopsis longiseta, Pestalotiopsis theae), soybean acute wilt (Fusarium tucumaniae, Fusarium virguliforme), barley and wheat black rust (Puccinia graminis), barley and wheat stripe rust (Puccinia striiformis Westendorp var.striiformis, barley rust (Puccinia hordei Otth), wheat leaf rust (Puccinia recondita Roberge ex Desmazieres), onion rust (Puccinia allii), chrysanthemum white rust (Puccinia horiana Hennings), rusts of coffee, pear, apple, peanut, vegetables, ornamental plants and other host plants, pear black spot (Alternaria alternata), cabbage black spot (Alternaria brassicicola), Chinese cabbage black spot (Alternaria brassicae, Alternaria brassicicola, Alternaria japonica), other vegetables (e.g. cucumber, cruciferous vegetables), apple, tomato and other host plants (Alternaria spp.), grape downy mildew (Plasmopara viticola, lettuce downy mildew (Bremia lactucae), cucumber downy mildew (Pseudoperonospora cubensis), Chinese cabbage downy mildew (Peronospora parasitica), downy mildews of soybean, tobacco, onion and other host plants (Peronospora spp.), rice leaf spot (Cochliobolus miyabeanus), cucumber fusarium wilt (Fusarium oxysporum f.sp. cucumerinum), tomato wilt (Fusarium oxysporum f.sp.lycopersici, Gibberella fujikuroi, Rhizoctonia solani, Sclerotinia minor, Verticillium albo-atrum, Verticillium dahliae, Verticillium nigrescens, Verticillium tricorpus, Alternaria solani, Sclerotinia sclerotiorum, Venturia inaequalis, Monilinia fructicola, Cercospora kikuchii, Cercospora beticola, Leptosphaeria nodorum, but are not limited to these. .

[0048] Examples of plant fungal diseases that are targeted by the control agent of the present invention include anthracnose, which is caused by infection with fungi belonging to the genus Colletotrichum, and tomato brown spot fungus, cucumber brown spot fungus, bell pepper black rot fungus, perilla leaf spot fungus, and salvia leaf spot fungus, which are caused by infection with Corynespora cassiicola.

[0049] Representative plants for which phytopathogenic bacteria or phytopathogenic fungi (collectively referred to as "phytopathogenic fungi") are to be controlled include, for example, solanaceae plants such as tomato, eggplant, bell pepper, chili pepper, tobacco, potato, etc.; cucurbitaceae plants such as cucumber, pumpkin, melon, watermelon, etc.; roseaceae plants such as strawberry, apple, pear, plum, peach, etc.; cruciferae plants such as Chinese cabbage, radish, bok choy, cabbage, komatsuna, Arabidopsis, etc.; legumes such as soybean, pea, kidney bean, etc.; gramineae plants such as rice, wheat, barley, etc.; Araceae plants such as taro, etc.; lily plants such as leek, onion, lily, tulip, etc.; Asteraceae plants such as lettuce, chrysanthemum, gerbera, etc.; and grapes, etc.; but the present invention can also be widely applied to many other plants that are infected with the above-mentioned phytopathogenic fungi. For the relationship between plant pathogens and host plants, please refer to the Japanese Plant Disease Name Database (Agricultural Biological Resources Genebank).

[0050] The method of applying the control agent of the present invention to plants is not particularly limited, and examples thereof include spraying, coating, immersion, etc. In addition, it is also possible to add the agent to the soil if the target plant is cultivated in soil, or to the hydroponic solution if the target plant is cultivated hydroponically. In the case of plant tissue culture, it is also possible to add the agent to the medium. Since a very high control effect is observed in the area where the control agent of the present invention is applied, the application method is preferably application to the whole plant body or leaves by spraying or coating, or immersion in seeds, bulbs, etc. The control agent of the present invention is advantageous in that it can also show a control effect against plant diseases in the surrounding area of ​​the applied area.

[0051] The application time of the control agent of the present invention to plants is not particularly limited, but preventive control is the most effective. Specifically, application from the seedling stage to before harvest is effective. In addition, there is no particular limit to the number of times the control agent is applied.

[0052] The concentration of each active ingredient at the time of application is not particularly limited as long as it is an amount that has a control effect against plant diseases, and a person skilled in the art can adjust it appropriately taking into consideration the chemical damage to the plant body, etc.

[0053] In the case of proanthocyanidin, the amount is preferably 10 to 5000 ppm, more preferably 100 to 2000 ppm, and even more preferably 300 to 1000 ppm. In addition, in the control agent of the present invention, the amount of metal compound or the like when mixed with proanthocyanidin is preferably 0.05 to 50 mM, more preferably 0.1 to 10 mM, and even more preferably 0.1 to 5 mM. For example, in the case of zinc sulfate, the amount is preferably 0.1 to 50 mM, more preferably 0.5 to 10 mM, and even more preferably 0.5 to 5 mM. In the case of metal chelate, the amount is preferably 0.05 to 50 mM. More specifically, in the case of zinc gluconate, the amount is preferably 0.05 to 40 mM, more preferably 0.1 to 10 mM, and even more preferably 1 to 10 mM. In the case of copper gluconate, the amount is preferably 0.05 to 10 mM, more preferably 0.1 to 10 mM, and even more preferably 0.3 to 5 mM. EXAMPLES

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0055] (Preparation of purified proanthocyanidins derived from shell ginger) The juice (120 ml) of Shima shell ginger from Kunigami County, Okinawa Prefecture was applied to a reverse phase carrier (Sep-Pak C18 (35 cc) manufactured by Nippon Waters Co., Ltd.), washed with ultrapure water (100 ml), and then eluted with 20% acetonitrile (100 ml) to obtain a fraction. The acetonitrile contained in the obtained fraction was distilled off with an evaporator (50 ° C, 15 minutes), and the remaining solution was placed in a dialysis membrane (manufactured by Spectrum Co., Ltd.) with a molecular weight cutoff of 10,000, and dialyzed against distilled water (4 L x 4 times). The obtained dialysis liquid was freeze-dried (4 days) to obtain a shell ginger-derived proanthocyanidin purified product (492.7 mg). In the following examples, this shell ginger-derived proanthocyanidin purified product (hereinafter also referred to as "shell ginger proanthocyanidin") was used.

[0056] [Example 1] Synergistic effect of combined use of shell ginger proanthocyanidin and metal chelate in suppressing plant virus infection We evaluated whether a combination of shell ginger proanthocyanidin and chelate metals could have a synergistic effect on plant virus disease control using a Tomato mosaic virus (ToMV)-Nicolas benthamiana evaluation system.

[0057] First, as the plant material, Nicotiana benthamiana was used by sowing one seed per pot in a 2:1:1 ratio of peat moss (Super Mix A, Sakata Seed Co., Ltd.):white vermiculite (A-2, Asahi Kogyo Co., Ltd.):obsidian perlite (Fuyolite No. 3, Fuyo Perlite Co., Ltd.) and cultivating it at 24°C under a 24-hour light / dark cycle (16 hours light and 8 hours dark).

[0058] A solution of shell ginger proanthocyanidin (PAC) at a final concentration of 500 ppm, metal chelate (final concentration 1 mM zinc gluconate (ZnGluc) or final concentration 1 mM copper gluconate (CuGluc)), a mixed solution of shell ginger proanthocyanidin at a final concentration of 500 ppm and zinc gluconate at a final concentration of 1 mM, or a mixed solution of shell ginger proanthocyanidin at a final concentration of 500 ppm and copper gluconate at a final concentration of 1 mM was added with 0.01% Mylino (Nihon Nohyaku Co., Ltd., polyalkylene glycol alkyl ether-containing spreader, diluted with water (DDW) for use) to prepare the test drug. In addition, an aqueous solution containing only Mylino at a final concentration of 0.01% was used as a control.

[0059] Then, 21 days after sowing, each of the thus prepared agents was sprayed onto the stems and leaves of all Nicotiana benthamiana plants in which three true leaves had developed but the third leaf was still small, and the plants were left standing at 24°C under a 24-hour light / dark cycle (16 hours light and 8 hours dark). Three days later, the mature third leaf was inoculated with ToMV and left standing at 24°C under a 24-hour light / dark cycle (16 hours light and 8 hours dark).

[0060] ToMV was prepared by transcription synthesis using 2 μg of a plasmid (pTLBN.G3, see Kubota K. et al., J Virol. 2003 Oct;77(20):11016-26) encoding ToMV-GFP (a virus with green fluorescent protein GFP added) as a template, and an RNA in vitro transcription synthesis kit (product name: AmpliCap-Max T7 High Yield Message Maker Kits, CellScript). The RNA transcript was then diluted 40-fold, and 10 μl of the solution was applied to two locations on the third leaf of Nicotiana benthamiana using carborundum (600 mesh, Nacalai Tesque, Inc.), to inoculate the virus.

[0061] Three days after inoculation, the number of GFP fluorescent spots corresponding to the sites of ToMV infection and proliferation was counted, and the infection inhibition rate of each drug was assayed. The infection inhibition rate (control titer) was calculated using the following formula. Infection inhibition rate (control value) % = 100 - {(average number of fluorescent spots on treated plants) / (average number of fluorescent spots on control-treated plants)} x 100.

[0062] As a result, as shown in Figure 1, a virus control effect was observed when using shell ginger proanthocyanidin, zinc gluconate, or copper gluconate alone. Furthermore, it was found that a stronger virus control effect was achieved by using shell ginger proanthocyanidin and zinc gluconate in combination, or by using shell ginger proanthocyanidin and copper gluconate in combination.

[0063] As shown in Patent Documents 1 to 3, the present inventors have clarified that shell ginger proanthocyanidin, zinc gluconate, and copper gluconate each have a strong plant disease control effect by themselves. However, it has also been revealed that the combined use of these has an even better effect.

[0064] Although not shown in the figure, at 6 days after virus infection, the virus infection usually spreads to the upper leaves, and virus-derived GFP fluorescence can be detected in the fourth and subsequent leaves. However, in the Nicotiana benthamiana plants sprayed with the above-mentioned drug, the GFP fluorescence in these upper leaves was suppressed. Thus, the virus control effect of the mixture of shell ginger proanthocyanidin and metal chelate was observed not only in the leaves directly sprayed with the mixture, but also in the upper leaves, so it is considered that these drugs cause an improvement in the immunity (resistance to pathogens) of the plant.

[0065] Furthermore, although not shown in the figure, no phytotoxicity (white spots on leaves, wilting, etc.) was observed due to the combined use of shell ginger proanthocyanidin and metal chelate.

[0066] [Example 2] Synergistic effect of shell ginger proanthocyanidin in combination with zinc sulfate or zinc gluconate in suppressing plant virus infection Final concentration 333 ppm or final concentration 500 ppm shell ginger proanthocyanidin, final concentration 1 mM zinc sulfate (ZnSO 4 ), a mixed solution of shell ginger proanthocyanidin at a final concentration of 333 ppm and zinc sulfate at a final concentration of 1 mM, a mixed solution of shell ginger proanthocyanidin at a final concentration of 333 ppm and zinc gluconate at a final concentration of 1 mM, or a mixed solution of shell ginger proanthocyanidin at a final concentration of 500 ppm and zinc gluconate at a final concentration of 5 mM, to prepare each test drug by adding Mylino to a final concentration of 0.01%.

[0067] The plant viral disease control effects of these drugs were evaluated using the ToMV-Nicolas benthamiana evaluation system described in Example 1. In addition, an aqueous solution containing only Myrinow at a final concentration of 0.01% was used as a control.

[0068] As a result, as shown in Figure 2, a virus control effect was observed by treating shell ginger proanthocyanidin, zinc sulfate, or zinc gluconate alone. Furthermore, it was found that a stronger virus control effect was achieved by using shell ginger proanthocyanidin and zinc sulfate in combination, or by using shell ginger proanthocyanidin and zinc gluconate in combination. In addition, although not shown in the figure, these mixed agents also suppressed virus infection in upper leaves. Furthermore, no phytotoxicity was observed when zinc sulfate and shell ginger proanthocyanidin were used in combination, as in the case of using copper gluconate or zinc gluconate in combination as shown in Example 1.

[0069] [Example 3] Synergistic effect of combined use of shell ginger proanthocyanidin and copper gluconate in suppressing infection by plant pathogenic bacteria First, Chinese cabbage (variety: Kigokoro 85, Takii Seed Co., Ltd.) was used as the plant material by sowing three seeds per pot in a 2:1:1 ratio of peat moss (Super Mix A, Sakata Seed Co., Ltd.):white vermiculite (A-2, Asahi Kogyo Co., Ltd.):obsidian perlite (Fuyolite No. 3, Fuyo Perlite Co., Ltd.) and cultivating them at 24°C under a 24-hour light / dark cycle (16 hours light and 8 hours dark).

[0070] A solution of shell ginger proanthocyanidin with a final concentration of 1000 ppm, a solution of copper gluconate with a final concentration of 0.3 mM, or a mixed solution of shell ginger proanthocyanidin with a final concentration of 1000 ppm and copper gluconate with a final concentration of 0.3 mM was added with Mylino, a spreading agent, to a final concentration of 0.01%, to prepare each test drug. In addition, an aqueous solution containing only Mylino at a final concentration of 0.01% was used as a control.

[0071] Each of the thus prepared agents was sprayed on the Chinese cabbage 14 days after sowing. 6The plants were inoculated by spraying with Pseudomonas cannabina pv. alisalensis, the bacterial black spot pathogen of cruciferous plants, adjusted to cfu / ml, and left to stand in a moist room at 24°C with a 24-hour light / dark cycle (16 hours light and 8 hours dark). Five days after inoculation, symptoms were examined (disease survey). The infection inhibition rate (control value) relative to the control was calculated.

[0072] The severity of the disease based on the results of disease investigation is expressed by the following formula. Severity = {(1n 1 +2n 2 +3n 3 +4n 4 +5n 5 ) / (5 × number of surveys) × 100 The disease survey was conducted by classifying the severity of the disease into the following five categories. 0: no symptoms, 1: minute spots, 2: lesions observed on less than 25% of the leaf area, 3: lesions observed on 25% to less than 50% of the leaf area, 4: lesions observed on 50% or more of the leaf area, 5: death n 1 From 5 indicates the number of individuals showing the degree of disease.

[0073] The control value is expressed by the following formula. Control value = {1 - disease severity in treated area / disease severity in untreated area)} x 100.

[0074] As a result, as shown in Figure 3, a stronger control effect was observed against black spot bacterial disease in the areas treated with a mixture of shell ginger proanthocyanidin and copper gluconate compared to areas treated with shell ginger proanthocyanidin or copper gluconate alone.

[0075] Although not shown in the figure, similarly to Nicotiana benthamiana, no phytotoxicity was observed in Chinese cabbage treated with a mixture of shell ginger proanthocyanidin and copper gluconate.

[0076] [Example 4] Synergistic effect of shell ginger proanthocyanidin and copper gluconate in suppressing infection by plant pathogenic fungi In the method described in Example 3, 5 × 10 6 cfu / ml of the Brassica plant black spot pathogen instead of 5.3 × 10 5 Two days after the above-mentioned spray treatment, the plants were inoculated by spraying with Colletotrichum higginsianum, a pathogenic fungus for anthracnose of cruciferous vegetables, adjusted to a concentration of 1 / ml, and the control value of each agent was calculated.

[0077] As a result, as shown in Figure 4, a stronger control effect was observed against anthracnose in the area treated with a mixture of shell ginger proanthocyanidin and copper gluconate compared to the area treated with shell ginger proanthocyanidin or copper gluconate alone. In addition, no phytotoxicity (such as white spots on Chinese cabbage leaves) was observed in the area treated with the mixture.

[0078] [Example 5] Synergistic effect of combined use of shell ginger proanthocyanidin and copper gluconate in suppressing infection by plant pathogenic fungi First, as the plant material, tomatoes (variety: Regina, Sakata Seed) were sown at 3 seeds per pot in a 2:1:1 ratio of peat moss (Super Mix A, Sakata Seed):white vermiculite (A-2, Asahi Kogyo Co., Ltd.):obsidian perlite (Fuyolite No. 3, Fuyo Perlite Co., Ltd.) and cultivated at 24°C under a 24-hour light / dark cycle (16 hours light and 8 hours dark).

[0079] A solution of shell ginger proanthocyanidin with a final concentration of 1000 ppm, a solution of copper gluconate with a final concentration of 0.3 mM, or a mixed solution of shell ginger proanthocyanidin with a final concentration of 1000 ppm and copper gluconate with a final concentration of 0.3 mM was added with Mylino, a spreading agent, to a final concentration of 0.01%, to prepare each test drug. In addition, an aqueous solution containing only Mylino at a final concentration of 0.01% was used as a control.

[0080] Each of the thus prepared drugs was sprayed onto tomatoes that had been thinned out to two plants per pot 10 days after sowing and then cultivated for another nine days under the above conditions. 4The tomato brown spot pathogen (Corynespora cassiicola) was sprayed and inoculated at a concentration of 1 / ml, and symptoms were examined (disease survey) 8 days later. The infection inhibition rate (control value) against the control was calculated.

[0081] The severity of the disease based on the results of disease investigation is expressed by the following formula. Severity = {(1n 1 +2n 2 +3n 3 +4n 4 +5n 5 ) / (5 × number of surveys) × 100 The disease incidence survey was conducted by classifying the severity of the disease into the following five categories. 0: no symptoms, 1: minute spots, 2: lesions observed on less than 25% of the leaf area, 3: lesions observed on 25% to less than 50% of the leaf area, 4: lesions observed on 50% or more of the leaf area, 5: dead or defoliated n 1 From 5 indicates the number of individuals showing the degree of disease.

[0082] The control value is expressed by the following formula. Control value = {1 - disease severity in treated area / disease severity in untreated area)} x 100.

[0083] As a result, as shown in Figure 5, a stronger control effect was observed against brown ring spot in the areas treated with a mixture of shell ginger proanthocyanidin and copper gluconate compared to areas treated with shell ginger proanthocyanidin or copper gluconate alone. [Industrial Applicability]

[0084] As described above, according to the present invention, it is possible to exert an excellent control effect against plant diseases. The control effect is superior to that when proanthocyanidin or metal compound is used alone, and extends not only to the application site but also to the surrounding area. Furthermore, the present invention is also unlikely to cause phytotoxicity. Therefore, the present invention can make a great contribution to the agricultural field as a pesticide that combines safety and effectiveness.

Claims

1. The present invention uses proanthocyanidin and a compound containing a metal as active ingredients, A plant disease control agent, wherein the metal-containing compound is at least one compound selected from the group consisting of zinc gluconate, copper gluconate, and zinc sulfate.

2. The control agent according to claim 1, wherein the plant disease is at least one disease selected from the group consisting of a plant viral disease, a plant bacterial disease, and a plant fungal disease.

3. A method for controlling plant diseases, which comprises applying the control agent according to claim 1 or 2 to a plant.

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