JP5223132B2 - Plant pathogen infection inhibitor and method for suppressing pathogen infection - Google Patents

Description

  The present invention relates to a plant pathogen infection inhibitor and a pathogen infection suppression method capable of suppressing the infection of a plant pathogen that causes a significant decrease in the yield of agricultural crops.

  In recent years, crop shortages due to global population growth and climate change have become a problem. Most of the yield reduction in crop production is damage caused by pests and weeds. Among them, disease control is also important for stable crop production and stable supply to consumers. Conventionally, chemically synthesized pesticides are generally used for such disease control.

  Many chemically synthesized pesticides directly affect phytopathogenic fungi that cause disease by sterilization or antibacterial action to prevent the spread of phytopathogenic fungi. Rice blast and cucumber brown spots are also controlled with chemically synthesized pesticides. An insecticide composition comprising a chlorophyll biosynthesis modulator and δ-aminolevulinic acid is also a method for inducing the accumulation of tetrapyrrole in a living insect and directly killing the insect (Patent Document 1).

  However, chemical synthetic pesticides that prevent the spread of infection by sterilizing or antibacterial action against phytopathogenic fungi may cause resistant bacteria to appear by using the same type continuously. The emergence of resistant bacteria can cause serious damage to crop production, and the emergence of resistant bacteria is also a problem in rice blast disease and brown spot disease of cucumber.

In addition, because of consideration for the environment and heightened awareness of food safety, the production of crops with reduced or no use of chemically synthesized pesticides, and the prevention of crop damage caused by infection with pathogens by effectively utilizing the plant's own control mechanism against plant pathogens It is demanded.
5-Aminolevulinic acid, which is one of the active ingredients of the plant pathogen infection inhibitor of the present invention, is a chlorophyll precursor, and most plants can synthesize themselves, but when given an appropriate amount from the outside It is known to enhance photosynthetic activity (Patent Document 2).
Special table hei 6-500989 JP-A-4-338305

  The problem to be solved by the present invention is to suppress plant pathogen infections in plants such as rice and cucumber, which can effectively prevent plant damage caused by pathogen infection by effectively utilizing the suppression mechanism against plant pathogens possessed by the plant itself. Providing an agent and method thereof.

  The present inventor considered that chemically synthesized pesticides that prevent the spread of infection by sterilizing or antibacterial action against plant pathogens may cause the emergence of resistant bacteria, and photosynthesis, which is the center of life activity of plants, is considered. We thought that the infection of phytopathogenic fungi could be suppressed if 5-aminolevulinic acid contained in the plants to be enhanced could enhance the suppression mechanism for the phytopathogenic fungi of the plants themselves. On the other hand, the exogenous application of 5-aminolevulinic acid is also known to have a tendency to open pores, and there was a concern that the release of pores might enhance one of the infection routes of pathogenic bacteria.

  Therefore, the present inventors have conducted intensive research in view of the present situation, and have completed the present invention by using 5-aminolevulinic acid and a metal together.

That is, the present invention is as follows.
(1) General formula (1)
R ² R ¹ NCH ₂ COCH ₂ CH ₂ COR ³ (1)
[In the formula, ^{R 1} and ^{R 2} is a water MotoHara child; ^{R 3} represents a hydroxy group, an alkoxy group having 1 to 12 carbon atoms. ]
As an active ingredient, 5-aminolevulinic acid, a derivative thereof or a salt thereof represented by the formula (I) and at least one metal selected from K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B, and Mo are used. Plant pathogen infection inhibitor.
(2) 5-aminolevulinic acid represented by the general formula (1) and derivatives thereof are 5-aminolevulinic acid, 5-aminolevulinic acid methyl ester, 5-aminolevulinic acid ethyl ester, 5-aminolevulinic acid propyl ester, 5-aminolevulin The plant pathogen infection inhibitor according to the above (1), which is acid butyl ester, 5-aminolevulinic acid pentyl ester or 5-aminolevulinic acid hexyl ester.
(3) At least one metal selected from K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B, and Mo is K, Ca, Mg, Na, Fe, Mn, Cu, Zn, and Mo. The plant pathogen infection inhibitor as described in (1) or (2) above, which is a metal of the above.
(4) The plant pathogen infection inhibitor according to any one of (1) to (3) , wherein the plant is a cereal and the plant pathogen is a blast fungus.
(5) The plant pathogen infection inhibitor according to any one of (1) to (3) , wherein the plant is a vegetable and the plant pathogen is a brown spot fungus.
(6) before 24 to 100 hours for planting plants, (1) to (5) pathogen infection suppression method of the plant, characterized in that the pathogen infection inhibitor according to foliar application to any one of the.

One of the active ingredients of the plant pathogen infection inhibitor of the present invention is 5-aminolevulinic acid of the general formula (1), a derivative thereof or a salt thereof (5-aminolevulinic acid of the general formula (1), its Derivatives are referred to as “ALA”, their salts as “ALA salts”, and the two as “ALAs”).
The groups represented by R ¹ and R ² in the general formula (1) will be described.
The alkyl group is preferably a linear or branched alkyl group having 1 to 24 carbon atoms, more preferably an alkyl group having 1 to 18 carbon atoms, and particularly preferably an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a sec-butyl group. As the acyl group, a linear or branched alkanoyl group, alkenylcarbonyl group or aroyl group having 1 to 12 carbon atoms is preferable, and an alkanoyl group having 1 to 6 carbon atoms is particularly preferable. Examples of the acyl group include formyl group, acetyl group, propionyl group, butyryl group and the like. As the alkoxycarbonyl group, an alkoxycarbonyl group having 2 to 13 carbon atoms is preferable, and an alkoxycarbonyl group having 2 to 7 carbon atoms is particularly preferable. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, and an isopropoxycarbonyl group. As an aryl group, a C6-C16 aryl group is preferable, for example, a phenyl group, a naphthyl group, etc. are mentioned. The aralkyl group is preferably a group consisting of an aryl group having 6 to 16 carbon atoms and the alkyl group having 1 to 6 carbon atoms, and examples thereof include a benzyl group.

The group represented by R ³ in the general formula (1) will be described.
The alkoxy group is preferably a linear or branched alkoxy group having 1 to 24 carbon atoms, more preferably an alkoxy group having 1 to 16 carbon atoms, and particularly preferably an alkoxy group having 1 to 12 carbon atoms. Examples of the alkoxy group include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, pentyloxy group, hexyloxy group, octyloxy group, decyloxy group, dodecyloxy group and the like. As the acyloxy group, a linear or branched alkanoyloxy group having 1 to 12 carbon atoms is preferable, and an alkanoyloxy group having 1 to 6 carbon atoms is particularly preferable. Examples of the acyloxy group include an acetoxy group, a propionyloxy group, and a butyryloxy group. As the alkoxycarbonyloxy group, an alkoxycarbonyloxy group having 2 to 13 carbon atoms is preferable, and an alkoxycarbonyloxy group having 2 to 7 carbon atoms is particularly preferable. Examples of the alkoxycarbonyloxy group include a methoxycarbonyloxy group, an ethoxycarbonyloxy group, an n-propoxycarbonyloxy group, an isopropoxycarbonyloxy group, and the like. The aryloxy group is preferably an aryloxy group having 6 to 16 carbon atoms, and examples thereof include a phenoxy group and a naphthyloxy group. As the aralkyloxy group, those having the aralkyl group are preferable, and examples thereof include a benzyloxy group.

In general formula (1), R ¹ and R ² are preferably hydrogen atoms. R ³ is preferably a hydroxy group, an alkoxy group or an aralkyloxy group, more preferably a hydroxy group or an alkoxy group having 1 to 12 carbon atoms, particularly a methoxy group or a hexyloxy group.

  As ALA, 5-aminolevulinic acid, 5-aminolevulinic acid methyl ester, 5-aminolevulinic acid ethyl ester, 5-aminolevulinic acid propyl ester, 5-aminolevulinic acid butyl ester, 5-aminolevulinic acid pentyl ester, 5-aminolevulinic acid hexyl ester , 5-aminolevulinic acid benzyl ester and the like, and 5-aminolevulinic acid is particularly preferable.

  Examples of ALA salts include hydrochloride, phosphate, nitrate, sulfate, sulfonate, acetate, propionate, butyrate, valerate, citrate, fumarate, maleate, malic acid Examples include acid addition salts such as salts, and metal salts such as sodium salts, potassium salts, and calcium salts.

ALAs can be produced by any of chemical synthesis and methods using microorganisms or enzymes. For example, methods described in JP-A-4-9360, JP-A-11-501914, Japanese Patent Application No. 2004-99670, Japanese Patent Application No. 2004-99671, and Japanese Patent Application No. 2004-99672 are mentioned. It is done. The product can be used as it is without separation and purification as long as it does not contain substances harmful to rice. Moreover, when a harmful substance is contained, it can be used after removing the harmful substance to a level not harmful.
In the present invention, these ALAs may be used alone or in combination of two or more thereof.

The metal that is one of the active ingredients in the plant pathogen infection inhibitor of the present invention is, for example, K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B, and Mo, and preferably Mg. Fe and Mn. These may contain at least one or more kinds, but preferably contain Mg, Fe and Mn, and include K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B and Mo. It is particularly preferred that
The compounding ratio of ALAs and metals may be 0.0001 to 1 mol, preferably 0.0005 to 0.1 mol, particularly preferably 0.001 to 0.01 mol, relative to 1 mol of total metals. .
The plant pathogen infection inhibitor of the present invention is used as an aqueous solution at least at the time of use. Therefore, although the said metal is used as forms, such as a salt which can be cationized in aqueous solution, it may be a free cation in the state of aqueous solution, or may be a form of ALA salt.

  The plant to be applied in the pathogen infection inhibitor of the plant of the present invention is not particularly limited, and includes plants widely cultivated in the agricultural field, such as rice, barley, wheat, millet, maize, millet, etc. Cereals; Vegetables such as pumpkin, turnip, cabbage, Japanese radish, Chinese cabbage, spinach, Komatsuna, honeybee, asparagus, broccoli, leek, celery, lettuce, garlic, kyouna, chinsai, green pepper, tomato, eggplant, cucumber, okra; Fruits such as oranges, apples, oysters, ume, pears, grapes, peaches, strawberries, watermelons, melons, etc .; Trees such as beech; adzuki beans, green beans, soybeans, peanuts, broad beans, peas, etc. Beans; lawn grasses such as potato moth, bentgrass, wild buckwheat; potatoes such as potato, sweet potato, taro, yam, taro, etc .; Cereals and vegetables are preferred, and rice and cucumber are more preferred.

  The plant pathogenic fungi to be applied in the plant pathogen infection inhibitor of the present invention include rice blast, standing seedling disease, stupid disease for cereals; mycorrhizal disease, gray for vegetables. Mold, leaf mold, powdery mildew, brown spot, gray mold, downy mildew, yellow rot; for fruits, scab, rot, moniliosis; Rot disease; for trees, Pestalothia disease, branch blight, rice blast; for beans, legume anthracnose, mycorrhizal disease, anthracnose; Disease, mycosis, crown rust, dollar spot disease, brown spot disease; for potatoes, fungal disease, plague, summer plague; for green onions, gray mold disease, white plague; root vegetables On the other hand, black stripe disease, black root disease and root rot are mentioned, and rice blast disease and brown spot disease are preferable.

The plant pathogen infection inhibitor of the present invention can be treated with a foliage to a plant in which no disease has occurred, and is preferably subjected to a foliar treatment. In that case, the pathogen infection inhibitor of the plant of the present invention is 0.01 to 10 ppm, preferably 0.01 to 1 ppm, more preferably 0.05 to 1 ppm in terms of an aqueous solution concentration on the basis of mass of 5-aminolevulinic acid hydrochloride. It is preferably contained and used. The application time may be sprayed 24 to 100 hours before planting, preferably 48 to 72 hours before planting. In addition, it is better to irradiate enough sunlight after a process.
Moreover, the metal concentration used together is calculated from the blending ratio with the ALA.

The reason why the disease caused by plant pathogens can be suppressed by the plant pathogen infection inhibitor of the present invention is considered as follows.
That is, when the plant pathogen infection inhibitor of the present invention is pre-treated on plants such as rice and cucumber, photosynthesis is increased and plant substance production increases, and the plant recognizes these substances as foreign substances that are plant pathogens. It is considered that the substances produced in the plant body can be used to enhance the defense function of the plant itself, to suppress the infection of the phytopathogenic fungus, and to efficiently suppress the spread of the infection damage caused by the phytopathogenic fungus. On the other hand, the reason why the effect is further improved by using a metal in combination has not been clarified, but it is assumed that some effect is exerted on the release of pores by exogenous application of ALAs. However, it was further surprising that it became clear that the timing of treating the plant pathogen infection inhibitor of the present invention with plants was important in order to efficiently control infection. This is because, for example, the plant pathogen infection inhibitor of the present invention is treated in consideration of the timing of transplanting from seedling cultivation to a field like rice, that is, the timing of exposure to an environment where the presence of pathogenic bacteria is highly likely. Means that it is effective.
In addition, since there are treatment periods with low inhibitory effects, it is not only more effective to treat a small amount of chemically synthesized pesticides at a timing with low inhibitory effects, but the use time of chemically synthesized pesticides can be limited to short periods of time. It is expected that the treatment amount of synthetic pesticides can be reduced and infection control effects can be obtained.

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

Example 1
3 g of 5-aminolevulinic acid hydrochloride was dissolved in 1 L of a modified medium adjusted so that each ionic component of the ionic composition of the Naaldwijk cucumber medium listed in Table 1 was 1000 times, and used as a plant pathogen infection inhibitor of the present invention. A mixed solution (hereinafter referred to as a mixed solution) was prepared. The rice cultivar used in the test was “Asahi”, and the rice blast fungus used “Race 007”, which is pathogenic to the rice cultivar “Asahi”.
Details of the Naaldwijk cucumber medium can be found, for example, in `` COMPARISON OF THE MINERAL COMPOSITION OF 12 STANDARD NUTRIENT SOLUTIONS De Rijck G. and Schrevens E. Faculty of Agricultural and Applied Biological Sciences Department of Applied Plant Sciences KULeuven Wilem de Croylaan 42, B- 3001 Heverlee (Belgium) ".

  Rice is immersed in distilled water, and after germination, it is put into a case (5 x 8 x 5 cm) with paddy rice growing granular soil green soil (nitrogen 0.9 g, phosphoric acid 1.1 g, potassium 1.0 g / 3.3 kg). It was seeded, grown to the third leaf stage, and used for the experiment.

(2) Cultivation of Blast Fungus Blast fungus (Race 007) was prepared in a 20 ml potato broth agar (PSA) medium (potato 200 g, sucrose 20 g, agar 20 g, distilled) in a test tube (diameter 1.8 × 18 cm). What was planted in water (1000 ml) and cultured at 26 ° C. was used. The above blast was transplanted to a rice bran agar medium (50 g of rice bran, 20 g of agar, 1000 ml of distilled water) dispensed in a plastic petri dish having a diameter of 9 cm and cultured for 14 days. Thereafter, the aerial hyphae in the flora were removed, and spores were formed by maintaining for 2 days under irradiation with a BLB fluorescent lamp set at 26 ° C.

(3) Preparation of spore suspension Pour distilled water onto the spore-formed microflora, filter with quadruple gauze, remove mycelium fragments, etc., then centrifuge (2000 xg, 5 minutes), Collected spores. The collected spores were adjusted to 1 × 10 ⁵ spores / ml using a hemocytometer.

(4) Treatment of the mixed solution to rice leaves and inoculation of blast disease Prepare the mixed solution diluted 500 times, 1000 times and 5000 times with distilled water and distilled water, and spray 20 ml of one case onto the above rice leaves Then, after sufficient irradiation, 48 hours later, a spore suspension of blast fungus was spray-inoculated. After inoculation, it was kept in a damp room / darkness for 24 hours, and after 5 days, the incidence rate of each case and the number of lesions per leaf were confirmed.

As a result, in the distilled water section 5 days after the inoculation, the disease strain rate was 80.0 ± 9.4%, indicating a high disease individual rate. However, in the dilution factor group of 500 times, 1000 times and 5000 times of the mixed solution, the disease individual rate becomes 23.3 ± 14.1%, 30.0 ± 14.1%, 26.6 ± 9.4%, respectively. A high disease inhibitory effect was confirmed (FIG. 1). The disease individual rate indicates the rate at which one or more diseased lesions were observed per individual (strain having several leaves).
Furthermore, as a result of investigating the number of blast spots on a rice leaf, it was 6.8 ± 3.7 in the distilled water section, whereas the dilution ratio was 500 times, 1000 times and 5000 times that of the mixed solution. In each ward, the number of lesions was 1.4 ± 1.9, 1.5 ± 2.9, and 1.5 ± 3.0, confirming high suppression of lesion formation (FIGS. 2 and 3). ). In addition, a disease spot point means a typical disease state spot having a dark brown point in the center having a diameter of about 0.5 mm or more and a slightly light brown area around it.

  As shown in FIG. 1, FIG. 2, and FIG. 3, it was confirmed that the pretreatment of the mixed solution to rice leaves reduces the incidence of blast and the number of lesions per leaf, thereby suppressing infection. It was.

Example 2
The spore suspension of the mixed solution, rice and blast fungus was the same as in Example 1.
Prepare 500-fold diluted solution and distilled water, spray 20ml of rice case into one case, and irradiate with enough light. After 0 hours, 12 hours, 24 hours, 48 hours, 72 hours, blast fungus Sprayed with a spore suspension of After inoculation, it was kept in a damp room / darkness for 24 hours, and after 5 days, the incidence rate of each case and the number of lesions per leaf were confirmed.

  As a result, 5 days after the inoculation, the number of lesions per leaf was 7.4 ± 2.7 in the distilled water section. On the other hand, in the 0-hour, 12-hour, 24-hour, 48-hour, and 72-hour pretreatment sections, the number of lesions was 0.9 ± 2.1, 8.4 ± 2.0, and 2.0 ± 3.0, respectively. The number was 1.9 ± 2.4, 2.6 ± 1.4, and the lesion formation inhibitory effect was confirmed after 24 hours (FIGS. 4 and 5).

  As shown in FIGS. 4 and 5, it was confirmed that the number of lesions per leaf of blast decreased after 24 hours after the pretreatment of the mixed solution on rice leaves, and the infection was suppressed. Moreover, in the mixed inoculation at 0 hours, since the number of lesion spots per leaf of blast was reduced, it was confirmed that the mixed solution has an action to directly inhibit the infection behavior of the fungus.

Example 3
The spore suspension of the mixed solution, rice and blast fungus was the same as in Example 1. However, rice is soaked in distilled water, and after sprouting, a paddy rice-growing granular soil green soil (nitrogen 0.9 g, phosphoric acid 1.1 g, potassium 1.0 g / 3.3 kg) is added (15 × 6 × 10 cm) ) And grown to the 5th leaf stage and used for the experiment.
Diluted water and distilled water were prepared 500 times, and the mixed liquid or distilled water was treated with a syringe on the back skin of the rice leaf sheath. Then, light was sufficiently irradiated, and after 24 hours, the mixed solution or distilled water was sufficiently washed away with distilled water, and a rice leaf sheath was inoculated with a spore suspension of blast fungus. After inoculation, the inoculated rice leaf sheath was placed in a wet plastic chamber and kept in a 26 ° C. meteorological device. 48 hours after inoculation, a razor was used to prepare a slice of the back of the leaf sheath, the invading hyphae in the cells were observed under an optical microscope, and the invading hyphae formation rate and hyphae extension were calculated by the method of Takahashi et al. (1958).

  As a result, the invading mycelia formation rate of blast disease 48 hours after inoculation was 73.0 ± 20.1% in the distilled water pretreatment section. On the other hand, it was 21.9 ± 20.8% in the mixed solution pretreatment section. Furthermore, when the mycelial extension was investigated, it was 2.5 ± 1.3 (maximum extension 13.0) in the distilled water pretreatment section, whereas 0.4 ± 0.5 in the mixed solution pretreatment section. (Maximum extensibility 4.0). These results confirmed that the suppression mechanism against the rice blast fungus on the rice side worked and the invasion was suppressed by the mixed solution pretreatment (Table 2, FIG. 6).

Example 4
The spore suspension of the mixed solution, rice and blast fungus was the same as in Example 1. However, rice is soaked in distilled water, and after sprouting, a paddy rice-growing granular soil green soil (nitrogen 0.9 g, phosphoric acid 1.1 g, potassium 1.0 g / 3.3 kg) is added (15 × 6 × 10 cm) ), And grown to 4-5 leaf stage and used for the experiment.
Diluted water and 500-fold and 1000-fold diluted metal solutions were prepared. Suspensions of blast fungus were suspended in each, and then 20 ml of one case was sprayed onto the rice leaves. . After inoculation, it was kept in a wet room / darkness for 24 hours, and the number of lesions per leaf in each case was confirmed 7 days later.

  As a result, in the blast disease inoculation 7 days after the inoculation, the number of lesions was 0.95 ± 2.1 and 2.5 ± 2.8, respectively, in the mixed solution and the 500-fold diluted solution containing only trace metals. In the 1000-fold diluted solution containing only trace metals, the number of lesions was 1.8 ± 2.8 and 2.5 ± 3.7, respectively. A higher lesion formation inhibitory effect was confirmed with the liquid (FIGS. 7 and 8).

Example 5
The mixed solution was the same as in Example 1, the cucumber variety was “Kitashin”, and the cucumber brown spot fungus was a strain that was pathogenic to the cucumber variety “Kokushin”.

(1) Cucumber cultivation method Cucumber seeds are sown in a plastic pot (diameter 9 x height 8 cm) with Sakata Supermix A (nitrogen 180 mg, phosphoric acid 120 mg, potash 220 mg / 1 L) and grown until the second leaf stage. And used in the experiment.

(2) Cultivation of brown spot fungus and preparation of spore suspension In the culture of blast fungus of Example 1, except that cucumber brown spot fungus was used, spores were formed in the same manner as in Example 1. A spore suspension was prepared.

(3) Treatment of mixed solution on cucumber leaves and inoculation of cucumber with brown spot disease Prepare a 100-fold diluted mixed solution and distilled water, spray 2 ml per leaf on the above cucumber leaves, and light enough 48 hours later, a spore suspension of cucumber brown spot fungus was spray-inoculated. Five days after the inoculation, the number of lesions per leaf was confirmed.

  As a result, 5 days after inoculation, the number of lesions was 31.0 ± 17.0 in the distilled water pretreatment group, and many lesions were formed. However, the number of lesions was 7.6 ± 9.6 in the pretreatment group at a dilution ratio of 100 times that of the mixed solution, and a high inhibitory effect on lesion formation was confirmed (FIGS. 9 and 10).

  As shown in FIG. 9 and FIG. 10, it was confirmed that the number of lesions per leaf was reduced and infection was suppressed in the inoculation of the cucumber leaves after the pretreatment of the mixed solution to the cucumber leaves.

  According to the plant pathogen infection inhibitor of the present invention, it is possible to effectively suppress the infection of plant pathogens such as rice blast fungus and cucumber brown spot fungus that cause plant diseases.

  Therefore, the mixture of 5-aminolevulinic acid and trace metals of the present invention has the possibility of being widely used in many crops such as rice and cucumber.

2 is a graph showing the incidence rate of rice disease in Example 1. 2 is a graph showing the number of lesions per leaf of rice in Example 1. It is a photograph which shows the lesion of rice used for graph preparation of FIG. Distilled water or 500 times, 1000 times, and 5000 times in the figure correspond to each dilution rate of the distilled water or mixed solution of FIG. In Example 2, it is a graph which shows the number of the lesion spots per rice leaf with respect to the processing time to the rice of a liquid mixture. It is the photograph which shows the lesion of rice used for graph preparation of FIG. Distilled water in the figure, or 0 hours, 12 hours, 24 hours, 48 hours, and 72 hours correspond to the treatment times of the distilled water or mixed liquid in FIG. It is an optical microscope photograph of the rice leaf sheath back surface epidermal section used for preparation of Table 2. The distilled water or mixed solution in the figure corresponds to the distilled water or mixed solution in Table 2. It is a graph which shows the number of lesions per rice leaf in Example 4. It is the photograph which shows the lesion of rice used for preparation of the graph of FIG. In the figure, ALA + / 500 times, ALA− / 500 times, ALA + / 1000 times, and ALA− / 1000 times respectively correspond to those shown in FIG. 7. 10 is a graph showing the number of lesions per cucumber leaf in Example 5. It is the photograph which shows the lesion of a cucumber used for graph preparation of FIG. The distilled water or mixed solution in the figure corresponds to the distilled water or mixed solution in FIG.

Claims (6)

General formula (1)
R ² R ¹ NCH ₂ COCH ₂ CH ₂ COR ³ (1)
[In the formula, ^{R 1} and ^{R 2} is a water MotoHara child; ^{R 3} represents a hydroxy group, an alkoxy group having 1 to 12 carbon atoms. ]
As an active ingredient, 5-aminolevulinic acid, a derivative thereof or a salt thereof represented by the formula (I) and at least one metal selected from K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B, and Mo are used. Plant pathogen infection inhibitor. 5-aminolevulinic acid represented by the general formula (1) and derivatives thereof are 5-aminolevulinic acid, 5-aminolevulinic acid methyl ester, 5-aminolevulinic acid ethyl ester, 5-aminolevulinic acid propyl ester, and 5-aminolevulinic acid butyl ester. The plant pathogen infection inhibitor of claim 1, which is 5-aminolevulinic acid pentyl ester or 5-aminolevulinic acid hexyl ester. At least one metal selected from K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B and Mo is a metal of K, Ca, Mg, Na, Fe, Mn, Cu, Zn and Mo. The plant pathogen infection inhibitor according to claim 1 or 2. The plant pathogen infection inhibitor according to any one of claims 1 to 3 , wherein the plant is a cereal and the plant pathogen is a blast fungus. The plant pathogen infection inhibitor according to any one of claims 1 to 3 , wherein the plant is a vegetable and the plant pathogen is a brown spot fungus. In 24 to 100 hours prior to planting the plant, pathogen infection suppression method of the plant, characterized in that the pathogen infection inhibitor according to any one of claims 1-5 foliar application.