Nematode control composition containing l-methionine and nematode control method

Abstract

The present disclosure addresses the problem of providing: a nematode control composition that exhibits high control activity even when the amount of methionine applied is small; and a control method. The present disclosure pertains to a nematode control composition containing methionine, wherein the methionine includes more than 50 wt% of L-methionine with respect to the total weight of the methionine. Moreover, the present disclosure also provides a nematode control method comprising applying 5-80 kg of methionine per 1,000 m2 of a field.

Description

L-methionine-containing composition for controlling nematodes and method for controlling nematodes

[0001] The present disclosure relates to a composition for controlling nematodes that parasitize plants and hinder their growth, more specifically to a composition for controlling nematodes containing L-methionine. Furthermore, the present disclosure relates to a method for controlling nematodes using L-methionine.

[0002] Plant-parasitic nematodes are nematodes that parasitize plants and are known to cause damage such as plant growth inhibition and plant death. For example, plant-parasitic soil nematodes such as root-knot nematodes, root-lesion nematodes, and cyst nematodes are one of the factors that inhibit agricultural crop production, and nematode damage accounts for 16% of the causes of continuous crop damage in Japan. Furthermore, the average yield loss due to nematodes in all crops worldwide is 12%. Meanwhile, damage caused by plant-parasitic nematodes is also known to occur in the production and use of useful plants such as lawns and shrubs. Therefore, it is an urgent task to provide an effective method for controlling nematodes in order to reduce plant damage caused by nematodes and increase crop productivity.

[0003] Nematode control or nematode damage suppression techniques in the agricultural sector can be divided into chemical, physical, biological, and cultural methods. Chemical methods include the use of a range of pesticides supplied in the form of fumigants and granules. Physical methods include those that use heat (solar soil disinfection, hot water soil disinfection, steam disinfection) and flooding treatments using water (run-off soil, field-field rotation). Biological methods include the use of microbial materials that parasitize or prey on nematodes. Cultural methods include crop rotation, the development and use of nematode-resistant varieties, the development and use of nematode-suppressing green manure, and the use of soil reduction disinfection.

[0004] Among these nematode control and suppression technologies, for example, control measures against root-knot nematodes that infest sweet potatoes rely heavily on synthetic pesticides, such as fumigants (e.g., D-D agents and chloropicrin fumigants) and granules (e.g., fosthiazate). In contrast, the adoption rate of agricultural methods is extremely low, and physical and biological methods are rarely used (Non-Patent Document 1). However, D-D agents are restricted by the US EPA due to issues such as their carcinogenicity, and their pesticide registration in the EU has already expired. Furthermore, chloropicrin is highly irritating to the human body, so its use in crowded environments tends to be avoided. Meanwhile, soil reduction disinfection, one of the agricultural methods, is expected to contribute to the promotion of sustainable agriculture due to its low environmental impact, but its implementation is constrained and its widespread adoption has not progressed.

[0005] Attempts have been made to develop control techniques for harmful soil nematodes using amino acids as a control method with minimal environmental impact. Non-Patent Documents 2 and 3 report that DL-amino acids, including D-amino acids, are applied to plants as metabolic inhibitors of L-amino acids, and that among various amino acids, DL-methionine exhibits the highest toxicity to the sweet potato root-knot nematode. The toxicity of DL-methionine to the sweet potato root-knot nematode is also reported in Non-Patent Documents 4, 3, and 5, and a root-knot nematode control technique using DL-methionine has also been developed (Patent Document 1). Other nematode species in which DL-methionine toxicity has been demonstrated include, for example, the nematode Echinochloa nigricans (Non-Patent Document 2), the wheat cyst nematode (Non-Patent Document 6), the peel nematode (Non-Patent Document 6), the potato cyst nematode (Non-Patent Document 7, Patent Document 2, Patent Document 3), a species of the genus Veronoraimus (Non-Patent Document 8), and a species of the genus Mesocuriconema (Non-Patent Document 8).

[0006] However, there have also been reported cases where the toxicity of DL-methionine did not affect all nematodes. Examples of such nematodes include a type of spiral nematode (Non-Patent Document 2), a false root-knot nematode (Non-Patent Document 6), a potato-lesion nematode (Non-Patent Document 6), and a type of long-horn nematode (Non-Patent Document 9). As such, it has become clear that the toxicity of DL-methionine does not affect all nematodes.

[0007] The mechanisms by which methionine exhibits toxicity to nematodes are thought to be oral toxicity and contact toxicity. For example, Non-Patent Document 7 reports that the D- and L-isomers of methionine are equally toxic to potato cyst nematodes, and the mechanism of action is considered to be oral toxicity. Furthermore, Patent Document 2 reports that the oral toxicity of D-methionine to potato cyst nematodes is lower than that of L-methionine. Meanwhile, with regard to contact toxicity, Non-Patent Document 3 cites Non-Patent Document 4, which states that the DL-methionine exhibited contact toxicity to sweet potato root-knot nematodes, but the L-methionine did not.

[0008] A major problem with using methionine to control nematodes is its phytotoxicity. Non-Patent Documents 6, 7, 3, 1, and 10 report that DL-methionine inhibits the growth of tomatoes or potatoes. However, Patent Documents 1 and 2 also reveal that DL-methionine cannot reliably control potato cyst nematodes and sweet potato root-knot nematodes at doses that do not inhibit plant growth.

[0009] JP 2000-007506 A International Publication No. 2019 / 004252 JP 2022-118806 A

[0010] Mizukubo, T. (2015) Trends in nematode control research and technology in Japan - 20th anniversary project of the Japanese Society of Nematology: Compilation of questionnaires on nematode control (1999-2011) - Journal of the Japanese Society of Nematology 45: 63-76. Overman, AJ and Woltz, SS 1962. Effects of amino acid antimetabolites upon nematodes and tomatoes. Florida Agricultural Experiment Stations Journal Series No. 1524: 166-170. Reddy, PP, Govindu, HC and Setty, KGH 1975. Studies on the effect of amino acids on the root-knot nematode Meloidogyne incognita infecting tomato. Indian Journal of Nematology 5: 36-41. Setty, KGH 1968 Studies on the biology and host-parasite relationships of root-knot nematode (Meloidogyne spp.) on tomatoes. Ph. D Thesis, univ. Lond. 293pp.Reddy, PP, Govindu, HC and Setty, KGH 1975. Studies on the action of DL-methionine on Meloidogyne incognita infecting tomato. Indian Journal of Nematology 5: 42-48.Prasad, SK, and Webster, JM 1967. The effect of amino acid antimetabolites on four nematode species and their host plants. Nematologica 13: 318-323. Evans, K. and Trudgill, DL.1971 Effects of amino acids on the reproduction of Heterodera rostochiensis. Nematologica 17: 495-500.Crow, WT, Cuda, JP, Stevens, BR 2009. Efficacy of Methionine Against Ectoparasitic Nematodes on Golf Course Turf. Journal of Nematology, 41: 217-220.Epstein, E. 1973. Effect of pretreatment with some acids amino and amino acids antimetabolites on Longidorus africanus infected and non-infected Bidens triparitita. Nematologica 18: 555-562. Talavera, M., and Mizukubo, T. 2005. Effects of DL-methionine on hatching and activity of Meloidogyne incognita eggs and juveniles. Pest Management Science 61: 413-416.

[0011] An object of the present disclosure is to provide a composition for controlling nematodes and a method for controlling nematodes that exhibit high control activity even when the application rate of methionine is small.

[0012] The inventors have found that when L-methionine is applied, a nematode control effect can be obtained even at a low concentration, and have completed the nematode control composition and control method of the present disclosure.

[0013] A first aspect of the present disclosure is a composition for controlling nematodes, comprising methionine, wherein the methionine comprises more than 50% by weight of L-methionine based on the total weight of the methionine.

[0014] A second aspect of the present disclosure is a method for controlling nematodes, comprising: 2The method comprises applying methionine in an amount of 5 to 80 kg per acre, wherein the methionine comprises more than 50% by weight of L-methionine based on the total weight of the methionine.

[0015] The nematode-controlling composition of the present disclosure contains methionine, and since the methionine contains L-methionine, it can control nematodes safely, inexpensively, and effectively. Furthermore, the nematode-controlling composition of the present disclosure has a low environmental impact and can be easily applied, thereby contributing to the promotion of sustainable agriculture.

[0016] The nematode control method of the present disclosure is carried out in a field 10a (1000 m 2 By applying 5 to 80 kg of methionine per 1000 stalks, and by including L-methionine in the methionine, nematodes can be controlled safely, inexpensively, and effectively compared to conventional control methods. Furthermore, the method of the present disclosure has the advantage that, because the amount of methionine applied is smaller than that of conventional methods, it is not toxic to plants and can be carried out during the cultivation period. Furthermore, the method of the present disclosure has a small environmental impact and is simple, and therefore can contribute to the spread of sustainable agriculture.

[0017] The results of evaluating the nematode-inhibiting effect of a methionine aqueous solution using the method described in Example 1 are shown in terms of the relationship between methionine concentration and survival rate. (A) shows the result after 1 day, and (B) shows the result after 4 days. The results of evaluating the nematode-inhibiting effect of a methionine aqueous solution using the method described in Example 1 are shown as changes over time. (A) shows the result at 2500 ppm, and (B) shows the result at 250 ppm. The results of evaluating the effect of the L-methionine to D-methionine ratio on the inhibitory effect of Meloidogyne incognita using the method described in Example 2 are shown in terms of the relationship between methionine concentration and survival rate. The results of evaluating the nematode-inhibiting effect of a methionine aqueous solution using the method described in Example 4 are shown in terms of the relationship between methionine concentration and survival rate. The results of evaluating the inhibitory effect of a methionine aqueous solution on Meloidogyne incognita using the method described in Example 5 are shown. (A) shows the results after 1 day, and (B) shows the results after 4 days. The results of evaluating the inhibitory effect of a methionine solution on the root-knot nematode, methionine concentration, and survival rate were evaluated using the method described in Example 6. (A) shows the results after 3 hours, (B) after 2 days, and (C) after 3 days. The results of comparing the control effects of optical isomers of methionine on the root-knot nematode, methionine, were compared using the method described in Example 7. These are photographs of tomato roots collected in the test described in Example 7. (A) shows two control tomato roots, (B) shows two tomato roots treated with 67 ppm D-methionine, and (C) shows, from the right, roots of tomatoes treated with 67 ppm, 133 ppm, and 200 ppm D-methionine. These are photographs of tomato roots collected in the test described in Example 7. (A) shows, from the right, tomato roots to which L-methionine was added at 67 ppm, 133 ppm, and 200 ppm. (B) shows, from the right, tomato roots to which DL-methionine was added at 67 ppm, 133 ppm, and 200 ppm. The results of evaluating the nematode-suppressing effects of powdered L-methionine and DL-methionine using the method described in Example 11 are shown. (A) shows a comparison of the number of root galls, and (B) shows a comparison of the control value.

[0018] Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments. Note that duplicated descriptions of identical components may be omitted.

[0019] 1. Composition A first aspect of the present disclosure relates to a composition for controlling nematodes containing methionine. The composition of the present disclosure may contain 20 to 100% by weight, preferably 40 to 100% by weight, and more preferably 60 to 100% by weight of methionine. The composition of the present disclosure may consist solely of methionine. Furthermore, in the composition of the present disclosure, the methionine comprises L-methionine. In one embodiment, the composition of the present disclosure contains 50 to 100% by weight, preferably 75 to 100% by weight, and more preferably 95 to 100% by weight of L-methionine, based on the total weight of the composition.

[0020] (Methionine) Methionine is one of the 20 amino acids that make up proteins and is an essential amino acid. It exists in D-form (D-methionine) and L-form (L-methionine), and when the D- and L-forms exist in equal amounts, it is called a racemic mixture (DL-methionine, DL-form). Methionine is widely used as a human medicine, veterinary medicine, food additive, and feed additive, and is a highly safe substance. Furthermore, it is less expensive than existing pesticides.

[0021] In the composition of the present disclosure, the methionine comprises L-methionine. The methionine comprises more than 50% by weight, preferably 75% by weight or more, more preferably 85% by weight or more, even more preferably 95% by weight or more, and most preferably 99% by weight or more of L-methionine, based on the total weight of methionine. In one embodiment, the methionine comprises up to 100% by weight of methionine. In one embodiment, the methionine may consist solely of L-methionine. By including L-methionine as an active ingredient, the composition of the present disclosure can provide a nematode control composition that is highly safe, inexpensive, and has a low environmental impact.

[0022] L-methionine in the present disclosure may be produced by any method. Examples of methods for producing L-methionine include synthetic methods, enzymatic methods, extraction methods, and fermentation methods. The synthetic method is a method for isolating only L-methionine from a racemic form of methionine that has been chemically synthesized by a known method. The enzymatic method is a method for converting a precursor substance into L-methionine by an enzymatic reaction. The extraction method is a method for isolating only L-methionine from a mixture of amino acids obtained by decomposing proteins. The fermentation method is a method for selectively producing only L-methionine by fermenting a raw material using a microorganism.

[0023] As described in the Examples section, it has been suggested that D-methionine may interfere with the nematode control effect of L-methionine in the compositions of the present disclosure. Therefore, in one embodiment, it is desirable that methionine does not contain D-methionine. If present, the amount of D-methionine is desirably less than 50% by weight, preferably 25% by weight or less, more preferably 15% by weight or less, even more preferably 5% by weight or less, and most preferably 1% by weight or less, based on the total weight of methionine. In one embodiment, the composition of the present disclosure does not contain D-methionine.

[0024] (Surfactant) The composition of the present disclosure can further contain a surfactant. By including a surfactant in the composition of the present disclosure, it is possible to promote the penetration of methionine into pores in the soil and to promote contact between L-methionine and the target nematodes. The composition of the present disclosure can contain the surfactant in an amount of 0.1 to 20% by weight, preferably 0.1 to 10% by weight.

[0025] Surfactants that can be used in the composition of the present disclosure include, for example, nonionic surfactants, anionic surfactants, cationic surfactants, etc. Nonionic surfactants include, but are not limited to, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, alkyl glycosides, etc. Anionic surfactants include alkyl sulfates, alkyl ether sulfates, lignin sulfonates, etc. Cationic surfactants include, for example, quaternary alkyl ammonium salts, etc.

[0026] (Additional Components) The composition of the present disclosure may further contain additional components, such as a bulking agent, a solvent, a pH adjuster, a binder, a disintegrant, a physical property improver, an antifungal agent, a stabilizer, a colorant, a fragrance, a phytotoxicity safener, etc.

[0027] Examples of fillers include, but are not limited to, talc, bentonite, diatomaceous earth, amorphous silica, clay, attapulgite, calcium carbonate, and other inorganic salts.

[0028] Examples of solvents include, but are not limited to, water, methanol, and ethanol.

[0029] Examples of pH adjusters include, but are not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, lactic acid, sodium lactate, phosphoric acid, sodium dihydrogen phosphate, citric acid, and sodium citrate.

[0030] Examples of binders include, but are not limited to, polyvinylpyrrolidone, polyvinyl alcohol, carboxymethylcellulose, sodium carboxymethylcellulose, starch, starch derivatives, sodium acrylates, oils and fats (e.g., vegetable oils such as soybean oil, palm oil, and corn oil, and animal oils such as lard, fish oil, and butter), and the like.

[0031] (Form of composition) The composition of the present disclosure can be in any form. For example, the composition of the present disclosure can be in the form of a solid or liquid that can be directly mixed or sprayed on soil, or in the form of a solid or liquid that can be dissolved in a solvent such as water before use. More specifically, the form of the composition of the present disclosure includes, but is not limited to, dusts, granules, powders, wettable powders, water-soluble powders, emulsions, liquids (including solutions), oils, aerosols, liniments, microcapsules, etc. The composition of the present disclosure is preferably in the form of a dust, granules, dust, powder, wettable powder, or water-soluble powder, and more preferably in the form of a granule, dust, powder, powder, or water-soluble powder.

[0032] (Method for Producing Composition) The composition of the present disclosure can be produced by any method known in the art. For example, in the case of a solid form, the composition of the present disclosure can be produced by using processes such as grinding, mixing, classification, and granulation, either alone or in any combination. In the case of a liquid form, the composition of the present disclosure can be obtained in the form of a solution by, for example, a dissolution process, or in the form of a suspension or emulsion by a dispersion process. Note that bulk methionine powder can also be used as the composition of the present disclosure.

[0033] The milling step involves milling bulk methionine powder to a desired particle size by methods known in the art. The milled methionine may be incorporated into the composition of the present disclosure or may be subjected to further processing.

[0034] The blending step involves blending raw or milled methionine with additional ingredients, such as bulking agents, by methods known in the art. The blend of methionine and additional ingredients may be a composition of the present disclosure, or the blend may be subjected to further processing steps.

[0035] The classification step is a step of separating methionine or a raw material containing methionine according to the particle size of the powder or particles. Classification methods are broadly classified into dry classification and wet classification, both of which are known in the art. The methionine or a composition containing methionine obtained by the classification step may be used as the composition of the present disclosure or may be further subjected to another step.

[0036] The granulation process is a process of processing methionine or a mixture of methionine and additional ingredients into a desired particle size. Granulation methods are broadly classified into wet granulation and dry granulation, and are known in the art. The obtained granules may be used as the composition of the present disclosure or may be further subjected to another process.

[0037] The dissolving step is a step of dissolving a raw material containing methionine in a solvent. The raw material dissolved in the solvent may consist of methionine alone or may contain additional components. The dissolving step can also be used in combination with the above-mentioned grinding, mixing, and granulation steps. For example, in the dissolving step, methionine bulk powder may be dissolved in a solvent, or a raw material containing methionine that has been processed by at least one of grinding, mixing, and granulation steps may be dissolved in a solvent. The resulting solution may be used as a composition of the present disclosure or may be further subjected to another step.

[0038] The dispersion step is a step in which methionine or a raw material containing methionine in a solid or liquid form is dispersed in a solvent, oil, or the like. The methionine or a raw material containing methionine may be obtained through the above-mentioned steps of grinding, mixing, classification, granulation, or the like. The dispersion step can be carried out by any method known in the art. The obtained dispersion may be used as the composition of the present disclosure or may be further subjected to another step.

[0039] The above-described production methods are merely examples, and the production method of the composition of the present disclosure is not limited to these. Additional components and solvents in each step are as described in the section (Additional Components).

[0040] (Nematodes) Nematodes are a general term for animals belonging to the phylum Nematoda, and are slender worms with body lengths of 0.1 mm to 1000 mm. Nematodes are found in large numbers in all biospheres on Earth, and are divided into free-living species and parasitic species. In the agricultural sector, a group of parasitic species known as plant-parasitic nematodes (also known as harmful nematodes or plant-pathogenic nematodes) are problematic because they cause agricultural damage.

[0041] The composition of the present disclosure can be suitably used to control plant parasitic nematodes, more specifically, plant parasitic nematodes living in soil. Nematodes that can be controlled by the composition of the present disclosure include, but are not limited to, root-knot nematodes, root-lesion nematodes, and cyst nematodes. Examples of root-knot nematodes include Meloidogyne incognita, Meloidogyne nigricans, Meloidogyne arenarinensis, and Meloidogyne javanica. Examples of root-lesion nematodes include Meloidogyne nigricans, Meloidogyne malvaceae, Meloidogyne walnuti, Meloidogyne kumamotoi, and Meloidogyne cornii. Examples of cyst nematodes include Meloidogyne gracilis, Meloidogyne leucopeniae, Meloidogyne glycerin, Meloidogyne glycerin, Meloidogyne glycerin, and Meloidogyne glycerin. Other examples include the nematode, the nematode, and the false nematode.

[0042] (Method of Use) The composition of the present disclosure can be applied to soil by any method known in the art. The composition of the present disclosure may be applied before or after planting of plants. Alternatively, the composition may be applied both before and after planting of plants. When the composition of the present disclosure is applied before planting, it is preferable to apply it within 20 days, preferably within 15 days, and more preferably within 10 days before planting of plants. Furthermore, it is more preferable that the soil to which the composition of the present disclosure has been applied is uniformly mixed. When the composition of the present disclosure is applied after planting, it is preferable to apply it 20 to 60 days, preferably 25 to 50 days, more preferably 30 to 40 days, and most preferably 30 days after planting. It is preferable that the soil to which the composition of the present disclosure has been applied is uniformly mixed. Note that, as used herein, the term "plant" includes plants grown in fields, i.e., crops, as well as useful plants other than crops, such as lawns and shrubs. As used herein, the term "useful plant" refers to plants that are useful for human life.

[0043] The composition of the present disclosure was applied to field 10a (1000 m 2 The amount of L-methionine applied per 1000 stalks of rice is preferably 5 to 40 kg, more preferably 7.5 to 30 kg, and even more preferably 10 to 20 kg per 1000 stalks of rice. This range is preferable because it does not inhibit plant growth and effectively controls nematodes. In this specification, the term "field" includes not only a place where crops are grown, but also a place where useful plants other than crops are grown.

[0044] In addition, the composition of the present disclosure may be mixed with a surfactant at the time of application, or may be dissolved or dispersed in a solvent or oil. In this case, the composition of the present disclosure may be in a solid or liquid form. The surfactant, solvent, and oil are as described in the (Additional Components) section.

[0045] The composition of the present disclosure contains L-methionine as an active ingredient, enabling nematode control with high safety, low cost, and effectiveness. Furthermore, the composition of the present disclosure requires a smaller amount of methionine than conventional compositions, and therefore has the advantage of not inhibiting plant growth and allowing application during the cultivation period. Furthermore, the composition of the present disclosure has a low environmental impact and can be easily applied, contributing to the spread of sustainable agriculture.

[0046] 2. Nematode Control Method A second aspect of the present disclosure relates to a nematode control method. 2 The method includes applying methionine in an amount of 5 to 80 kg, preferably 7.5 to 60 kg, more preferably 10 to 40 kg per 10 ...

[0047] In the methods of the present disclosure, methionine can be applied by any method known in the art. For example, methionine may be applied to soil in powdered or granular solid form, or may be applied after dissolving it in a solvent. Methionine or a solution thereof may be mixed with a surfactant at the time of application. Alternatively, methionine formulated by a method known in the art may be applied. Methods for formulating methionine are as described in the section "1. Composition" (Methionine Manufacturing Method), and surfactants are as described in the section "Additional Components."

[0048] In the methods of the present disclosure, methionine may be applied before or after planting of the plants. In one embodiment, the methods of the present disclosure involve applying methionine within 20 days, preferably within 15 days, and more preferably within 10 days before planting. In another embodiment, the methods of the present disclosure involve applying methionine 20 to 60 days, preferably 25 to 50 days, more preferably 30 to 40 days, and most preferably 30 days after planting. In yet another embodiment, the methods of the present disclosure involve applying methionine before planting and applying methionine after planting.

[0049] Nematodes primarily live at a depth of 10 to 20 cm from the soil surface. Therefore, in one embodiment, the method of the present disclosure preferably includes uniformly mixing the soil after application of methionine. The depth of the mixed soil can be 20 cm, more preferably 15 cm, from the soil surface. Mixing the soil after application of methionine can effectively reduce nematode damage to plants.

[0050] The method of the present disclosure may further include applying a surfactant. Surfactants that can be used in the method of the present disclosure are as described in the section "1. Composition" (Surfactant). In the method of the present disclosure, the surfactant may be applied before or after the methionine. Alternatively, methionine and a surfactant may be blended together and applied simultaneously.

[0051] The method of the present disclosure can control nematodes safely, inexpensively, and effectively. Furthermore, the method of the present disclosure has the advantage that it requires a lower amount of methionine than conventional methods, is not toxic to plants, and can be carried out during the cultivation period. Furthermore, the method of the present disclosure has a low environmental impact and is simple, so it can contribute to the spread of sustainable agriculture.

[0052] The present disclosure will be specifically described below with reference to examples and comparative examples, but the present disclosure is not limited to the following examples.

[0053] Example 1 Comparison of the nematode-inhibitory effect of aqueous methionine solutions using optical isomers (1) Aqueous solutions of D-, L-, and DL-methionine at various concentrations were contacted with Meloidogyne incognita, and the inhibitory effect of each optical isomer on nematodes was evaluated.

[0054] 1. Test Method: (1) Meloidogyne incognita (MAFF108258 strain) was added to tap water to prepare a nematode suspension at 250 nematodes / mL, which was stored at 10°C until use. Six days after egg collection, newly hatched larvae were collected and immediately used to prepare the suspension. (2) D-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%), L-methionine (Asuka Animal Health Co., Ltd., purity 99.6%), and DL-methionine (Asuka Animal Health Co., Ltd., purity 99.5%) were each dissolved in purified water to prepare methionine solutions at concentrations of 0.5 ppm, 5 ppm, 50 ppm, 500 ppm, and 5000 ppm. (3) 100 μL of the nematode suspension was poured into each well of a 96-well plate (round-bottom, water-repellent coating) using a glass pipette. In addition, 100 μL of each concentration of methionine solution was added to each well. Therefore, the methionine concentrations at the time of immersion of the nematodes were 0.25 ppm, 2.5 ppm, 25 ppm, 250 ppm, and 2500 ppm, respectively. 100 μL of purified water was added to the control (0 ppm, CTL). The number of tests was n = 4. (4) 1, 3, 4, and 7 days after immersion in the methionine solution, the number of surviving nematodes was counted under transmitted light using a stereomicroscope. Nematodes that were moving and those with bent bodies were considered to be alive. Those that were straight were considered to be dead.

[0055] 2. Results The results are shown in Tables 1 and 2 below and Figures 1 and 2. Table 1 and Figure 1 show the relationship between the concentration of each isomer of methionine and the survival rate of nematodes after 1 day and 4 days. Table 2 and Figure 2 show the change in survival rate of nematodes over time for 2500 ppm and 250 ppm. Each value is an average value.

[0056]

[0057]

[0058] Contrary to expectations based on the prior art, the results show that the L-methionine form exhibited concentration-dependent contact toxicity to Meloidogyne incognita one day after immersion, whereas the D- and DL-methionines did not. However, after four days of immersion, both the D- and DL-methionines exhibited concentration-dependent contact toxicity. Looking at the results by concentration, at a concentration of 250 ppm, the survival rates of nematodes exposed to the L- and DL-methionines showed similar trends over time, reaching approximately 40% after four days but not reaching 0%. Meanwhile, at 2500 ppm, the survival rate of the L-methionine reached 0% after four days, whereas the D- and DL-methionines remained around 60% after four days and remained above 0% even after seven days. These results demonstrate that the L-methionine form has superior nematode-inhibitory effects compared to the D- and DL-methionines.

[0059] In addition, from the approximate formula of the graph in Figure 1, the LD for each optical isomer of methionine is 50 For L-methionine after 4 days, the LD 50 On the other hand, the LD of D-methionine and DL-methionine after 4 days was estimated to be 60 ppm (corresponding to a field treatment amount of 3 kg / 10 a). 50 The DL-methionine was calculated to be 19,000 ppm (corresponding to a field treatment amount of 950 kg / 10 a) and 1,100 ppm (corresponding to a field treatment amount of 55 kg / 10 a), respectively. Half of the DL-methionine was L-methionine, and the LD 50 Considering that the concentration was 60 ppm, the DL-LD 50 The concentration of the D-isomer should be 120 ppm, twice that of the L-isomer, but in reality it was about 9 times that value. This suggests, without being bound by theory, that the D-isomer may inhibit the inhibitory effect of the L-isomer on nematodes.

[0060] The aqueous solution concentration (ppm) was converted to the amount to be treated in the field as follows: Since the rotary tillage depth is approximately 15 cm, if the depth of the field to be mixed is 15 cm, then 10 a (1000 m 2) is 150,000 kg. As soil also contains a lot of air, if we assume its density to be 1 kg / L, the volume will be 150,000 L. Furthermore, the weight moisture content of the black soil that is common in Japan is around 30%, meaning that water accounts for approximately one-third of the soil weight. Therefore, the concentration of the methionine solution (ppm = mg / L) multiplied by the soil volume of 150,000 L and divided by 3 is the soil volume per 10 a (1000 m) of field. 2 ) was the processing amount per

[0061] Example 2 Effect of the Ratio of L- and D-Methionine on Suppression of Meloidogyne incognita The results of Example 1 suggested that the D-methionine may be inhibiting the inhibitory effect of the L-methionine on nematodes. Therefore, the ratio of the L- and D-methionine was gradually changed to evaluate the effect of the D-methionine on the nematode inhibitory effect of the L-methionine.

[0062] 1. Test Method: (1) Meloidogyne incognita (MAFF108258 strain) was added to tap water to prepare a 250 nematode / mL suspension. This suspension was then stored at 10°C until use. (2) A total of 0.24 g of L-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%) and D-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%) were dissolved in 100 mL of purified water at weight ratios of 100:0, 99:1, 95:5, 85:15, 75:25, and 50:50, respectively, to prepare six 2400 ppm methionine solutions, with the L-methionine content ranging from 100 wt% to 50 wt% relative to the total methionine. 10 mL of this 2400 ppm solution was diluted with 10 mL of purified water to prepare a 1200 ppm solution. Furthermore, 5 mL of the 2400 ppm solution was diluted with 15 mL of purified water to prepare a 600 ppm methionine solution. (3) 100 μL of the nematode suspension was poured into each well of a 96-well plate (round-bottom, water-repellent finish) using a glass pipette. 100 μL of each concentration of methionine solution was then added to each well. Thus, the methionine concentrations upon immersion of the nematodes were 300 ppm, 600 ppm, and 1200 ppm, respectively. 100 μL of purified water was added to the control (0 ppm, CTL). The number of tests was four. (4) Immediately after immersion in the methionine solution (day 0), and 1, 3, and 6 days later, the number of surviving nematodes was counted under transmitted light using a stereomicroscope. Surviving nematodes were assessed in the same manner as in Example 1, test method 1 (4).

[0063] The results are shown in Tables 3 to 5 below and in FIG.

[0064]

[0065]

[0066]

[0067] Tables 3 to 5 and FIG. 3 show that the nematode-inhibiting effect increases with increasing L-methionine content. Furthermore, all aqueous solutions containing 75 to 100% by weight of the L-methionine exhibited a higher nematode-inhibiting effect than an aqueous solution containing 50% by weight of the L-methionine (i.e., the DL-methionine). In particular, aqueous solutions containing 99% and 100% by weight of the L-methionine exhibited a high nematode-inhibiting effect at all concentrations, and the nematode survival rate after 6 days was nearly 0% at 600 ppm (equivalent to a field treatment rate of 30 kg / 10 a) and 1200 ppm (equivalent to a field treatment rate of 60 kg / 10 a). These results demonstrate that the composition of the present disclosure can provide excellent nematode-inhibiting effect by containing more than 50% by weight of L-methionine based on the total weight of methionine, and that this effect is enhanced with increasing L-methionine content.

[0068] Example 3 Comparison of the Nematode Inhibitory Effect of Methionine Aqueous Solution with Optical Isomers (2) From the results of Example 1, it was found that in the case of L-methionine, the nematode survival rate changed significantly between 250 ppm and 2500 ppm. Therefore, the concentration of the methionine aqueous solution was changed and tests were conducted in the same manner as in Example 1 to evaluate in more detail the relationship between the methionine concentration and the nematode inhibitory effect.

[0069] 1. Test Method The test was carried out in the same manner as in Example 1, except that aqueous methionine solutions were prepared at concentrations of 600 ppm, 1200 ppm, 1800 ppm, 2400 ppm, and 5000 ppm.

[0070] 2. Results The average values ​​of the results obtained are shown in Tables 6 to 8 below.

[0071]

[0072]

[0073]

[0074] Looking at the results after 4 days in Table 6, it was found that in the case of L-methionine, 900 ppm was as effective as 2500 ppm. 2This corresponds to 45 kg of L-methionine per 10 a. Furthermore, it was shown that L-methionine has a sufficient inhibitory effect against nematodes even at 300 ppm (equivalent to 15 kg / 10 a). On the other hand, with D-methionine and DL-methionine, the survival rate after 4 days exceeded 50% at most concentrations. These results indicate that L-methionine has a superior nematode inhibitory effect even at lower concentrations than D-methionine and DL-methionine.

[0075] Example 4 Comparison of the Nematode Inhibitory Effect of Methionine Aqueous Solution by Optical Isomers (3) Examples 1 to 3 demonstrated the inhibitory effect of L-methionine when it was in contact with nematodes for a long period of time. Therefore, the inhibitory effect of L-methionine on nematodes (Meloidogyne incognita) after short-term contact was evaluated by shortening the contact time.

[0076] 1. Test Method The test was carried out in the same manner as in Example 1, except that the concentrations of the methionine aqueous solution were set to 0 ppm, 300 ppm, 600 ppm, 1200 ppm, 1800 ppm, 2400 ppm, and 4800 ppm, and the test time was set to 4 hours. The test was carried out in duplicate.

[0077] 2. Results The results are shown in Table 9 below and in Figure 4. The results are average values.

[0078]

[0079] The results showed that 4 hours after contact with the methionine aqueous solution, the survival rate of the L-isomer decreased in a concentration-dependent manner. Furthermore, at all concentrations, the survival rate of nematodes was lower for the L-isomer than for the D- and DL-isomers. These results indicated that the L-isomer has a superior nematode-inhibiting effect at all concentrations compared to the D- and DL-isomers. The logarithmic approximation line of the L-isomer (y = -16.28ln(x) + 127.2, R 2 = 0.66), the LD of the L-form after 4 hours 50 was calculated to be 115 ppm. 2 ) is equivalent to 6 kg.

[0080] Example 5 Evaluation of the inhibitory effect of methionine on Meloidogyne nigra Using Meloidogyne nigra as the nematode, the inhibitory effect of each optical isomer of methionine was evaluated.

[0081] 1. Test Method The test was carried out in the same manner as in Example 1, except that the concentrations of the prepared methionine aqueous solutions were 300 ppm, 600 ppm, 1200 ppm, and 1800 ppm, and that Meloidogyne xanthoides (strain MAFF108260) was used as the nematode. The number of surviving nematodes was counted 1 day and 4 days after the start of the test.

[0082] 2. Results The results are shown in Table 10 below and in Figure 5. The results are average values.

[0083]

[0084] Only L-methionine showed an inhibitory effect against Meloidogyne nigra after 1 day. Furthermore, L-methionine showed excellent inhibitory effect against Meloidogyne nigra after 4 days. On the other hand, D-methionine and DL-methionine showed no inhibitory effect after 1 day, and although a decrease in survival rate was observed after 4 days, the effect was slight. These results suggest that L-methionine is effective against a wide range of root-knot nematodes, not just Meloidogyne incognita.

[0085] Example 6 Evaluation of the inhibitory effect of methionine on Meloidogyne arenariae Root-knot nematode Meloidogyne arenariae root-knot nematode was used as the nematode, and the control effect of each optical isomer of methionine was evaluated.

[0086] 1. Test Method D-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%), L-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%), and DL-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%) were used as optical isomers of methionine. The test was conducted in the same manner as in Example 1, except that the concentrations of the prepared methionine aqueous solutions were 300 ppm, 600 ppm, 1200 ppm, 1800 ppm, 2400 ppm, and 4800 ppm, and that Meloidogyne arenaria (strain MAFF108262) was used as the nematode. The number of surviving nematodes was counted 3 hours, 2 days, and 3 days after the start of the test.

[0087] 2. Results The results are shown in Table 11 and FIG.

[0088]

[0089] As shown in Table 11 and Figure 6, 3 hours after immersion, the D- and DL-methionine forms showed high nematode survival rates at all concentrations. On the other hand, the L-methionine showed a high nematode-inhibiting effect, and this effect increased roughly in proportion to the concentration. Even after 2 and 3 days, the survival rates of nematodes treated with the D-methionine were maintained at a high level. In contrast, the survival rates of nematodes treated with the DL-methionine decreased in a concentration-dependent manner up to 1200 ppm, but at 2400 ppm, the survival rates recovered and showed high values. Without being bound by theory, it is possible that the presence of high concentrations of the D-methionine nematode nematode suppressed the inhibitory effect of the L-methionine. On the other hand, after 2 and 3 days, the survival rates of nematodes treated with the L-methionine nematode were maintained at a low level at all concentrations. These results demonstrate that the composition of the present disclosure also exhibits a high inhibitory effect against the root-knot nematode.

[0090] Example 7 Comparison of the control effects of optical isomers of methionine against Meloidogyne incognita D-, L-, and DL-methionine were added at various concentrations to soil inoculated with Meloidogyne incognita, and the effect on the degree of damage caused by root clubs in tomatoes was evaluated.

[0091] 1. Test Method (1) Soil for growing sweet potato root-knot nematodes (MAFF108258 strain, purchased from the National Agriculture and Food Research Organization Gene Bank), commercially available black soil, and horticultural seedling soil (manufactured by Hokusan Co., Ltd.) were mixed in a 1:1:1 ratio to prepare nematode-contaminated soil. (2) D-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%), L-methionine (Asuka Animal Health Co., Ltd., purity 99.6%), and DL-methionine (Asuka Animal Health Co., Ltd., purity 99.5%) were each dissolved in ion-exchange water to a concentration of 0.5% (w / v) to prepare a 0.5% methionine aqueous solution. (3) To 600 mL of nematode-contaminated soil, 8 mL, 16 mL, and 24 mL of 0.5% methionine aqueous solution were added and mixed. Each of these solutions was used to prepare 10 a (1000 m) of soil. 2 This corresponds to 10 kg (67 ppm), 20 kg (133 ppm), and 30 kg (200 ppm) of methionine per 10 ... A single cherry tomato (variety: Regina, Sakata Seed) planted 24 days after sowing was planted in each pot. The pots were placed in a glasshouse and grown for 21 days (maximum temperature 35°C, average temperature 28°C). During growth, the soil was watered once a day to prevent the surface from drying out. The number of tests was n=3. 21 days after the start of growth, the roots were removed from the pots. The soil was removed by rinsing with water in the shower, and the degree of root gall damage was confirmed by visual observation for each condition.

[0092] 2. Evaluation method The degree of damage caused by root clubs was evaluated using the Zeck scale (Zeck, W.M. (1971): Pflanzenschutz-Nachichten. Bayer AG, 24, 141-144.) into the following 11 levels. The average value and standard deviation (SD) of the three plants were calculated from the obtained scores. 0: No root clubs were observed. 1: A few small root clubs could be observed with careful observation. 2: A few small root clubs similar to those in 1 were easily observed. 3: There were many small root clubs, some of which had fused together. Root function was almost intact. 4: There were many small root clubs, and some large root clubs. Most of the roots were functioning. 5: 25% of the roots were heavily clubbed and not functioning. 6: 50% of the roots were heavily clubbed and not functioning. 7: 75% of the roots are heavily galled, and the ability of the roots to regenerate has been lost. 8: There are no healthy roots, and the plant's nutrient absorption is inhibited. The stems and leaves are still green. 9: The root system is completely covered with galls and is rotting. The plant is dying. 10: Both the plant and the roots are dead.

[0093] 3. Results The results are shown in Tables 12 and 13 below and in Figure 7. Photographs of the collected roots are shown in Figures 8 and 9.

[0094]

[0095]

[0096] Regarding nematode density, L-methionine and DL-methionine caused significantly lower nematode density than D-methionine at any methionine concentration, indicating that the nematode-inhibiting effect of D-methionine is significantly lower than that of the L- and DL-methionine.

[0097] With regard to the degree of root club damage, at 200 ppm, both methionines were effective in controlling root club damage compared to the control. Meanwhile, at 133 ppm, high control effects were observed for L- and DL-methionine, but D-methionine was less effective than L- and DL-methionine. At 67 ppm, both methionines showed lower values ​​compared to the control, but L-methionine showed significantly higher control effects than D- and DL-methionine. These results indicate that L-methionine exerts a higher nematode control effect at low concentrations than D- and DL-methionine. In particular, 67 ppm L-methionine suppressed root club damage to the same extent as 133 ppm DL-methionine, suggesting that the use of L-methionine for nematode control can reduce the amount used compared to previously suggested methods using DL-methionine, resulting in cost savings.

[0098] Example 8 Comparison of Control Effect of Optical Isomers of Methionine on Root-Knot Meloidogyne Arenariae D- and L-methionine were added to soil inoculated with Root-Knot Meloidogyne arenariae, and the effect on the survival rate in the soil was evaluated.

[0099] 1. Test Method: (1) Nematode nematodes (MAFF108262 strain, obtained from the National Agriculture and Food Research Organization (NARO) Gene Bank) were propagated on tomatoes planted in andosol. The soil was sieved through a 2.5 mm mesh sieve to remove the roots. (2) A portion of the soil prepared in step (1) was removed, and the number of nematodes in the soil was measured by separating them using the Bellman funnel method. First, 20 g of soil was placed on a mesh tray lined with paper, immersed in a glass funnel filled with water, and left to stand for 3 days. The nematode larvae were separated into vials attached to the funnel's stem. The nematode larvae that settled in the vials were collected and counted using a plankton counting slide. (3) An appropriate amount of the sieved soil from step (1) was mixed with commercially available andosol adjusted to a moisture content of 33% to prepare nematode-infested soil with an initial density of 2.5 nematodes per gram of soil. (4) 1 g each of D-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%), L-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%), and DL-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%) was dissolved in 50 mL of purified water to prepare a 2% methionine solution. This was further diluted 10-fold to prepare a 0.2% methionine solution. (5) Treatment concentrations were 100 mg / L (equivalent to a field treatment rate of 15 kg / 10 a) and 200 mg / L (field treatment rate of 30 kg / 10 a). For the 100 mg / L (15 kg / 10 a) treatment, 30 mL of 0.2% methionine solution was sprayed onto 600 mL of nematode-infested soil, followed by 30 mL of water. For the 200 mg / L (30 kg / 10 a) treatment, 600 mL of nematode-infested soil was sprayed with 60 mL of 0.2% methionine solution. For the control (CTL) treatment, 60 mL of water was sprayed. The soil was mixed by placing it in an air-inflated plastic bag and rotating it. To simulate the conditions of vinyl mulch treatment, the resulting soil was placed in a sealed plastic bag and left at 25°C for 3 days. (6) Nematodes were isolated from the soil using the Bellman funnel method, as in step (2), and the number of nematodes in the soil was measured. The number of tests was n = 3 (soils 1 to 3).

[0100] 3. Results The results are shown in Table 14 below. The control value was calculated using the following formula: Control value (%) = (1 - mean number of nematodes under each condition / mean number of nematodes in the control) x 100

[0101]

[0102] A higher control value was observed with L-methionine compared to D-methionine. In particular, the nematode density was 0 at a treatment concentration of 30 kg / 10 a with L-methionine. On the other hand, the control value was low with D-methionine, and at a treatment concentration of 15 kg / 10 a the control value was negative. These results demonstrate that L-methionine has a higher inhibitory effect against the root-knot nematode than D-methionine.

[0103] Example 9 Comparison of the inhibitory effects of optical isomers of methionine on root-knot nematode damage in sweet potato Since the demand for nematode control agents is particularly high in sweet potato cultivation, L- and DL-methionine were added to soil inoculated with nematodes to evaluate the effect on the degree of root-knot damage in sweet potato.

[0104] 1. Test Method: (1) Meloidogyne incognita (strain MAFF108258, obtained from the National Agriculture and Food Research Organization Gene Bank) was propagated on tomatoes planted in andosol. The soil was sieved through a 2.5 mm mesh to remove roots. (2) Nematodes were isolated using the same procedure as in the Bellman funnel method described in Procedure (2) of Example 8, and the number of individuals was counted using a plankton counting slide. (3) Test nematode-contaminated soil was prepared using the same procedure as in Procedure (3) of Example 8. The initial nematode density was 1.25 individuals per gram of soil. (4) 0.9 g each of powdered L-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%) and DL-methionine (Tokyo Chemical Industry Co., Ltd., purity >99.0%) was mixed with 99.1 g of andosol to prepare soil containing 9% methionine. (5) The treatment concentration was 100 mg / L (corresponding to a field treatment rate of 15 kg / 10 a). 100 g of soil containing 9% methionine was added to 9 L of nematode-infested soil, which was then placed in an air-inflated plastic bag and mixed by rotating. (6) 3 L planters were filled with nematode-infested soil containing either the L- or DL-methionine isomer, and a single sweet potato vine (variety: Takakei No. 14) was planted in each. The control was an untreated (CTL) planter using soil without methionine. The number of tests was n = 3 (strains 1 to 3). The planters were placed in a glasshouse and grown for 52 days (maximum temperature 35°C, average temperature 28°C). During growth, the soil surface was watered once daily to prevent drying. (7) After 52 days of growth, the roots were removed from the pots. The soil was removed by showering, and the vines and potatoes were detached from the roots. The washed roots were stored in a freezer at -20°C until the number of root galls was counted. The thawed roots were cut into 5 mm lengths, suspended in water, transferred to a tea strainer, and squeezed to remove the water. The weight (g) of the whole root was measured, and 2 g of each was taken and the number of root galls and egg sacs was counted. Egg sacs whose presence was estimated based on traces of peeling left on the root galls were also included. When two or more egg sacs or their peeling traces were found on one gall, the number of root galls was equal to the number of egg sacs. The number of root galls and egg sacs per plant was calculated by multiplying the number of root galls and egg sacs per 2 g by the weight (g) of the whole root and then dividing by 2.

[0105] 3. Results The results are shown in Tables 15 and 16 below. The control value was calculated using the following formula: Control value (%) = (1 - mean number of galls or egg sacs / mean number of galls or egg sacs in the control) x 100

[0106]

[0107]

[0108] In sweet potatoes treated with DL-methionine, the number of galls and egg sacs was equivalent to that of CTL, and the control value was negative. In contrast, the number of galls and egg sacs was reduced in sweet potatoes treated with L-methionine, and the control value was higher than that of DL-methionine. These results indicate that L-methionine can provide nematode suppression effects in sweet potatoes compared to DL-methionine.

[0109] Example 10 Comparison of Nematode Control Effect Between L-Methionine Powder and Aqueous Solution L-methionine was applied to soil in different forms to evaluate its effect on nematode control.

[0110] 1. Test Method: (1) Nematode-infected soil was prepared by mixing sweet potato root-knot nematodes (strain MAFF108258) with commercially available sterilized andosol to achieve a nematode density of 20 individuals / 20 g of soil. (2) The nematode-infected soil was treated with L-methionine under the following conditions A to C. The control (CTL) was soil not treated with L-methionine. (A: Powder Incorporation Treatment) 4 g of sand containing a 100-fold dilution of L-methionine was mixed with 600 mL of nematode-infected soil to achieve an L-methionine concentration of 67 ppm (equivalent to a field treatment of 10 kg / 10 a). Water was added to the mixture to adjust the soil moisture content to 32%, and the mixture was placed in a sealed plastic bag and allowed to stand at 25°C for 3 days. Four days after mixing with L-methionine, the soil was filled into pots and used to grow tomatoes. (B: Aqueous Solution Mixing Treatment) L-methionine was dissolved in ion-exchanged water to prepare a 0.5% methionine aqueous solution. 8 mL of this methionine aqueous solution was mixed with 600 mL of nematode-infested soil to adjust the L-methionine concentration to 67 ppm. Water was added to adjust the soil moisture content to 32%, and the mixture was placed in a sealed plastic bag and left at 25°C for 3 days. Four days after mixing with L-methionine, the soil was filled into pots and used to grow tomatoes. (C: Irrigation Treatment) 600 mL of nematode-infested soil was filled into pots. 8 mL of 0.5% methionine aqueous solution was diluted with water to 50 mL and sprayed onto the soil surface using an electric sprayer. The following day and the day after, 50 mL of water was sprayed onto the soil surface in the same manner. (3) One cherry tomato (variety: Regina) planted 31 days after sowing was planted in each pot prepared in step (2) and cultivated for 24 days in a thermostatic chamber at 25°C under the illumination of an LD light for plant growth. After 24 days, the roots were removed from the pot, the soil was washed off with a shower, and the number of root galls was counted under a stereomicroscope. Conditions A to C were performed in n = 3, and the control was performed in n = 4.

[0111] 2. Results The results are shown in Table 17. The number of root galls is the average, and the ratio to CTL indicates the ratio (percentage) of the number of root galls under each condition to the number of root galls in the control. The control value is the value obtained by subtracting the ratio to CTL from 100%.

[0112]

[0113] Under all conditions, L-methionine showed superior inhibitory effects compared to the control, but particularly high inhibitory effects were observed under conditions A (powder mixing treatment) and B (aqueous solution mixing treatment).

[0114] Example 11 Evaluation of the Nematode-Suppressing Effect of L-Methionine The inhibitory effect of root clubs on L-methionine in powder form was evaluated by varying the amount applied to the soil. A similar test was also conducted with DL-methionine, and the inhibitory effects were compared.

[0115] 1. Test Method: (1) Sweet potato root-knot nematodes (MAFF108258 strain) were grown on cherry tomatoes (variety: Regina) in a planter filled with andosol. The soil containing the sweet potato root-knot nematodes was diluted with commercially available sterilized andosol to prepare nematode-infested soil with a nematode density of 20 nematodes per 20 g of soil. (2) L-methionine powder was diluted 100-fold with sand, and 3 g and 4 g of sand were mixed with 600 mL of nematode-infested soil. The L-methionine concentrations were 50 ppm and 67 ppm (equivalent to 7.5 kg and 10 kg per 10 a of soil, respectively, designated "L7.5" and "L10"). For comparison, DL-methionine powder was mixed with 600 mL of soil to a concentration of 67 ppm (DL10). The control was soil without methionine (CTL). The soil was placed in a plastic bag and left sealed for three days. (3) Four days after mixing the methionine and soil, each soil was filled into a pot. A single cherry tomato (variety: Regina) planted 31 days after sowing was planted in each pot and grown for 24 days under LED plant growth lights in a constant temperature room at 25°C. After 24 days, each root was removed from the pot, the soil was washed off with a shower, and the number of root galls was counted under a stereomicroscope. The test was performed with n = 3 (n = 4 for CTL only).

[0116] 2. Results The average number of root galls under each condition is shown in Table 18 and Figure 10. In addition, the control value for each condition was calculated from the obtained number of root galls. The formula for calculating the control value is as follows. Figure 10 shows the number of root galls and the control value as a graph. Control value (%) = (1 - number of root galls under each condition / number of root galls in the control) x 100

[0117]

[0118] The number of root galls was lowest for L-methionine at 67 ppm and 50 ppm, in that order. The root gall control value exceeded 70%. These results suggest that L-methionine exerts an excellent nematode control effect at low concentrations. On the other hand, at 67 ppm of DL-methionine, the control value was only 23%. This suggests that a sufficient control effect cannot be obtained with lower concentrations of DL-methionine.

Claims

1. A composition for controlling nematodes comprising methionine, said methionine comprising more than 50% by weight of L-methionine based on the total weight of said methionine.

2. The composition of claim 1, wherein said methionine comprises 75% or more by weight of L-methionine based on the total weight of said methionine.

3. The composition of claim 2, wherein said methionine comprises 95% or more by weight of L-methionine based on the total weight of said methionine.

4. The composition of claim 1, wherein the methionine comprises up to 100% by weight of L-methionine based on the total weight of the methionine.

5. The composition of claim 1, wherein the methionine comprises D-methionine.

6. The composition of claim 1, wherein the nematode is a root-knot nematode.

7. The composition according to claim 6, wherein the root-knot nematode is Meloidogyne incognita, Meloidogyne northernis and Meloidogyne arenariae.

8. Field 1000m 2 2. The composition according to claim 1, applied in an amount equivalent to 5 to 40 kg of L-methionine per plant.

9. The composition of claim 1 in the form of a powder.

10. A method for controlling nematodes, comprising: 2 % L-methionine based on the total weight of said methionine.

11. The method of claim 10, wherein the methionine comprises 75% or more by weight of L-methionine based on the total weight of the methionine.

12. The method of claim 10, wherein the methionine comprises up to 100% by weight L-methionine.

13. The method of claim 10, wherein the nematode is a root-knot nematode.

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