Control composition and control method for filamentous fungi of crops or plants

Abstract

To provide inorganic compound-based control agents and control methods for filamentous fungi of crops or plants, enabling liquid spraying.SOLUTION: A control composition for filamentous fungi of crops or plants, comprises an aqueous suspension containing iodic acid or periodic acid and an iodine-based metal salt selected from iodate metal salts and periodate metal salts having a solubility in water of less than 10 g / 100 g H2O.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition for controlling fungi in agricultural crops or plants and a method for controlling fungi. [Background technology]

[0002] Infectious diseases of agricultural crops and plants, such as sweet potato base rot and powdery mildew, are caused by filamentous fungi. Sweet potato base rot in particular has been spreading since 2018, and there are no effective control methods available, so the development of new control methods is desired. Various fungicides are used to control these diseases, but the highly effective synthetic organic compound pesticides are highly toxic and pose issues such as safety during spraying, reduced soil activity in the field, and safety as food.

[0003] Iodine and iodic acid are known to have disinfecting effects against viruses, molds (filamentous fungi), and bacteria, but have the problem that they are highly soluble in water and dissolve in water, reducing their disinfecting effects. In response to this, a technology has been reported in which iodic acid salts are supported on inorganic or organic materials such as fibers, fabrics, clothing, paper, synthetic resins, plastics, and building materials (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6644325 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the inorganic or organic materials carrying the iodate cannot be used for disinfecting agricultural crops or fields by spraying the liquid onto the materials. Therefore, an object of the present invention is to provide an inorganic compound-based agent for controlling fungi on agricultural crops and plants, which can be sprayed as a liquid, and a method for controlling fungi. [Means for solving the problem]

[0006] Therefore, the present inventors discovered that by using iodic acid or periodic acid in addition to a metal iodate or periodate with low water solubility to prepare a suspension containing these compounds, and spraying the suspension on crops or fields, the insoluble metal iodate or periodate coats the stems and leaves of the crops and the surface of the field. Furthermore, since natural metal elements and metal ions decomposed or eluted from fertilizers and disinfectants are present in the soil, the iodic acid or periodic acid that enters the soil chemically reacts with the metal elements and metal ions in the soil to gradually become insoluble metal iodate or periodate. Thus, the present inventors discovered that simply spraying the suspension on crops, plants, and fields can provide long-term disinfection effects from the surface to the soil of aboveground crops, plants, and fields. This led to the completion of the present invention.

[0007] That is, the present invention provides the following inventions [1] to [8]. [1] A composition for controlling fungi in agricultural crops or plants, comprising an aqueous suspension containing iodic acid or periodic acid and an iodine-containing metal salt selected from metal iodates and metal periodates having a solubility in water of less than 10 g / 100 g H2O. [2] The pesticide composition according to [1], wherein the iodine-containing metal salt is an iodine-containing metal salt selected from metal iodates and metal periodates having a solubility in water of less than 1 g / 100 g H2O. [3] The control agent composition according to [1] or [2], wherein the iodine-based metal salt is one or more selected from calcium iodate, iron (III) iodate, copper (II) iodate, potassium periodate, potassium iodate, sodium iodate, and magnesium iodate. [4] The control agent composition according to any one of [1] to [3], wherein the iodine-based metal salt is one or more selected from calcium iodate, iron(III) iodate, copper(II) iodate, and potassium periodate. [5] The control agent composition according to any one of [1] to [4], wherein the fungal infection disease is an infection disease selected from sweet potato base rot, powdery mildew, black spot, brown spot, downy mildew, gray mold, white root rot, purple root rot, sooty spot, anthracnose, and rice blast. [6] The control agent composition according to any one of [1] to [5], wherein the fungal infection disease is sweet potato root rot. [7] A method for controlling a fungal infection disease in agricultural crops or plants, comprising the step of applying the control agent composition according to any one of [1] to [6] to fungi in agricultural crops or plants. [8] The control method according to [7], wherein the application comprises spraying or coating the control agent composition on the stems, leaves, seed potatoes, seeds, or fields of the target crops or plants. [Effects of the Invention]

[0008] When the fungal control agent of the present invention is sprayed on agricultural crops or fields, the insoluble metal iodate or metal periodate coats the stems and leaves of the crops and the surface of the field. Because natural metal elements and metal ions decomposed or eluted from fertilizers and disinfectants are present in the soil, iodic acid or periodic acid that enters the soil chemically reacts with the metal elements and metal ions in the soil, gradually becoming insoluble metal iodate or metal periodate. Thus, simply by spraying the fungal control agent of the present invention on agricultural crops, plants, or fields, it exerts a long-term fungal disinfecting effect from the surface of aboveground crops, plants, and fields to the soil. The agent for controlling filamentous fungi of the present invention is particularly effective as an agent for controlling sweet potato base rot. DETAILED DESCRIPTION OF THE INVENTION

[0009] Terms used in this specification are used in the sense commonly used in the art unless otherwise specified.

[0010] In this specification, filamentous fungi are fungi that are composed of tubular cells called hyphae and live in the air, water, and soil. In this specification, the term "filamentous fungi" refers to filamentous fungi that infect agricultural crops and plants and cause diseases. Examples of specific target plants and diseases include sweet potato root rot on sweet potatoes; powdery mildew on strawberries, apples, peaches, pears, melons, pumpkins, roses, etc.; black spot on cucumbers, apples, peaches, pears, grapes, plums, etc.; brown spot on apples, grapes, sugar beets, etc.; downy mildew on grapes, cucumbers, Chinese cabbage, spinach, lettuce, radishes, etc.; gray mold on fruits in general, such as strawberries, lettuce, tomatoes, cyclamen, etc.; white root rot and purple root rot on fruits in general, such as asparagus; sooty spot on fruits in general; anthracnose on strawberries, apples, cucumbers, etc.; and rice blast on rice.

[0011] In this specification, control refers to preventing or suppressing the occurrence of the disease. As used herein, application refers to spraying or coating the control agent of the present invention onto the stems, leaves, seed potatoes, seeds, fields, etc. of target crops or plants. For example, in the case of sweet potato, examples include treatment of seed potatoes and spraying onto stems, leaves, and fields.

[0012] One aspect of the present invention is a composition for controlling filamentous fungi in agricultural crops or plants, which contains an aqueous suspension containing iodic acid or periodic acid and an iodine-containing metal salt selected from metal iodates and metal periodates having a solubility in water of less than 10 g / 100 g H2O. Another aspect of the present invention is a method for controlling a filamentous fungal infection disease in agricultural crops or plants, comprising a step of applying the control agent composition of the present invention to filamentous fungi in agricultural crops or plants.

[0013] The aqueous suspension used in the present invention contains iodic acid or periodic acid and an iodine-based metal salt selected from metal iodates and metal periodates having a water solubility of less than 10 g / 100 g H2O. That is, iodic acid or periodic acid and an iodine-based metal salt selected from metal iodates and metal periodates having a water solubility of less than 10 g / 100 g H2O are dissolved in water, and the aqueous suspension may further contain metal iodates or metal periodates that are not dissolved in water, as well as other insoluble components.

[0014] Both iodic acid and periodic acid are highly soluble in water and are dissolved in water. From the viewpoint of rapid action of disinfecting filamentous fungi, the content of one or two selected from iodic acid and periodic acid in the aqueous suspension of the present invention is preferably 0.002% by mass or more and 50% by mass or less, more preferably 0.005% by mass or more and 30% by mass or less, and even more preferably 0.01% by mass or more and 20% by mass or less.

[0015] The iodine-based metal salt used in the present invention may be at least one selected from metal iodates and metal periodates having a solubility in water of less than 10 g / 100 g H2O, preferably at least one selected from metal iodates and metal periodates having a solubility in water of less than 5 g / 100 g H2O, more preferably at least one selected from metal iodates and metal periodates having a solubility in water of less than 1 g / 100 g H2O, and even more preferably at least one selected from metal iodates and metal periodates having a solubility in water of less than 0.5 g / 100 g H2O. Examples of such iodine-based metal salts include one or more selected from magnesium iodate, sodium iodate, potassium iodate, calcium iodate, iron (III) iodate, copper (II) iodate, and potassium periodate. Among these, one or more selected from calcium iodate, iron (III) iodate, copper (II) iodate, and potassium periodate are more preferred, and calcium iodate is even more preferred from the viewpoint of obtaining a long-term disinfection effect and reducing the burden on the environment. Note that iodine-based metal salts have a lower solubility in aqueous solutions containing iodic acid, periodic acid, or other iodine-based metal salts than their solubility in water. Therefore, in the aqueous suspension of the present invention, iodine-based metal salts may exist undissolved in a content less than their solubility in water.

[0016] From the viewpoint of obtaining a disinfecting effect for a long period of time, the content of the iodine-based metal salt in the aqueous suspension is preferably 0.0001% by mass or more and 50% by mass or less, more preferably 0.001% by mass or more and 10% by mass or less, and even more preferably 0.002% by mass or more and 5% by mass or less.

[0017] The pH of the aqueous suspension is preferably 7 or less, more preferably 2 to 6.5, even more preferably 2 to 6, and even more preferably 2 to 5, from the viewpoint of obtaining an excellent fungal control effect.

[0018] The aqueous suspension may contain, in addition to the iodic acid or periodic acid and the iodine-based metal salt, the iodine-based metal salt and other insoluble components that are not dissolved in water. Here, examples of other insoluble components include raw materials for producing the metal iodate or metal periodate and metal compounds derived from the raw materials. Specific examples include calcium compounds, magnesium compounds, alkali metal compounds, iron compounds, and copper compounds. Among these, naturally derived components are preferred that can be sprayed on foliage or soil as a fungus control agent without imposing a burden on the environment, and calcium silicate, silica, calcium phosphate, calcium citrate, potassium chloride, and the like are preferred.

[0019] The aqueous suspension can be obtained by suspending iodic acid or periodic acid and an iodine-based compound selected from metal iodates and metal periodates having a solubility in water of less than 10 g / 100 g H2O in water. Specifically, iodic acid or periodic acid and metal periodate or metal iodate are suspended in water. Preferably, iodic acid or periodic acid and one or more compounds selected from magnesium iodate, sodium iodate, potassium iodate, calcium iodate, iron(III) iodate, copper(II) iodate, and potassium periodate are suspended in water. More preferably, iodic acid or periodic acid and one or more compounds selected from calcium iodate, iron(III) iodate, copper(II) iodate, and potassium periodate are suspended in water. Alternatively, a metal compound such as a calcium compound, an iron compound, a copper compound, or a potassium compound may be reacted with an aqueous solution of iodic acid or an aqueous solution of periodic acid to produce calcium iodate, iron(III) iodate, copper(II) iodate, or potassium periodate in the aqueous solution. For example, a specific example of producing a suspension containing iodic acid and calcium iodate is to react calcium silicate microparticles with an aqueous solution of iodic acid to produce calcium iodate in water. The reaction proceeds simply by stirring at room temperature and atmospheric pressure. The resulting suspension contains iodic acid, calcium iodate, silica, and calcium silicate. In the aqueous suspension containing iodic acid and calcium iodate obtained by this method, the suspended particles are less likely to settle and crystallization does not progress during storage, resulting in a stable suspension. According to this method, silica and calcium silicate microparticles remain in the suspension, and silica is known to be a component that strengthens plant stems. Therefore, the aqueous suspension of this embodiment can obtain the fungal disinfecting effect of iodic acid, the long-term fungal disinfecting effect of calcium iodate, and the plant growth effect of silica.

[0020] The average particle size of the water-insoluble component in the aqueous suspension of the present invention is preferably 1 to 500 μm, more preferably 1 to 200 μm, and even more preferably 1 to 100 μm, from the viewpoints of long-term suspension, ease of dispersion, etc. The average particle size in this specification is the volume-average particle size.

[0021] The aqueous suspension may contain various other ingredients in addition to the above-mentioned components, such as silica, insecticidal active ingredients, acaricidal active ingredients, nematicidal active ingredients, fungicidal active ingredients, plant growth regulators, phytotoxicity reducing ingredients, synergists, repellents, molluscicidal ingredients, insect pheromones, herbicidal active ingredients, and biological control materials.

[0022] Because the aqueous suspension contains the insoluble iodine-based metal salt, spraying the suspension on crops or fields coats the stems and leaves of the crops and the surface of the field with insoluble metal iodates or periodates. Because natural metal elements and metal ions decomposed or eluted from fertilizers and disinfectants are present in the soil, iodic acid or periodic acid that enters the soil chemically reacts with the elements and metal ions in the soil, gradually becoming insoluble metal iodates or periodates. Thus, simply by spraying the suspension on crops, plants, or fields, it exerts a long-term disinfecting effect on the surface of the crops, plants, and fields, from the soil to the soil.

[0023] The target diseases of the filamentous fungus control agent of the present invention are diseases of agricultural crops or plants caused by filamentous fungi, specifically, sweet potato base rot on sweet potato; powdery mildew on strawberries, apples, peaches, pears, melons, pumpkins, roses, etc.; black scab on cucumbers, apples, peaches, pears, grapes, plums, etc.; brown spot on apples, grapes, sugar beets, etc.; downy mildew on grapes, cucumbers, Chinese cabbage, spinach, lettuce, radishes, etc.; gray mold on fruits in general, such as strawberries, lettuce, tomatoes, cyclamen, etc.; white root rot and purple root rot on fruits in general, such as asparagus; sooty spot on fruits in general; anthracnose on strawberries, apples, cucumbers, etc.; and rice blast on rice. Of these, the control effect on sweet potato base rot is particularly excellent.

[0024] To control fungal diseases of agricultural crops or plants, the control composition of the present invention is applied to the fungi of the agricultural crops or plants. Specifically, this means spraying or coating the control composition of the present invention onto the stems, leaves, seed potatoes, seeds, fields, etc. of the target agricultural crops or plants. For example, in the case of sweet potato, examples include treatment of seed potatoes and spraying of seedlings, stems, leaves, and fields. In spraying of sweet potato seedlings, stems, leaves, or fields, the control composition of the present invention may be sprayed once or multiple times at a rate of 1 to 10,000 g per hectare. In addition, in treatment of sweet potato seed potatoes, 0.01 to 10,000 ppm may be applied. [Example]

[0025] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0026] Manufacturing Example 1 (1) 1 g of calcium silicate microparticles (xonotlite dry powder, manufactured by A&A Material Co., Ltd.) and 109 g of a 12 wt % aqueous solution of iodic acid were mixed at 20°C for 1 hour to produce iodine compound suspension A. This suspension contained approximately 1 wt % calcium iodate. Theoretically, it also contained unreacted calcium silicate microparticles and reacted silica.

[0027] Test Example 1 (Floatability evaluation test of iodine compound suspension) 50 mL of iodine compound suspension A was placed in a 50 mL measuring cylinder. This was placed in a box with a black background and lit from above. The stirring rod was removed from the measuring cylinder and the buoyancy was checked at intervals. The video was taken, and then the buoyancy was compared using still images. First, in the iodine compound suspension A that had been left standing for 168 days, no clumps such as adhesion to the container or aggregation were observed. To evaluate buoyancy, the suspension was stirred in a measuring cylinder, then left to stand and visually checked for transparency and the presence of precipitate. Iodine Compound Suspension A was confirmed to still be floating solids even after 1,190 seconds. Furthermore, 30 seconds after stirring, approximately 3 mL of precipitate formed in Iodine Compound Suspension A, but the suspension remained stable for the next 1,190 seconds.

[0028] Test Example 2 (Measurement of particle size distribution of iodine compound suspension) The liquid was mixed at high speed using a magnetic stirrer to prepare a suspension. The suspension was filtered, and the precipitate was collected. The precipitate was dried at 105°C for 24 hours. Since the dried precipitate was soluble in water, the suspension was prepared using ethanol as the dispersion solvent. The particle size distribution of the precipitate dispersed in the suspension was measured using a SALD-2200 (WingSALD II: Version 3.1.1) (Shimadzu Corporation). The particle size distribution of the precipitate from iodine compound suspension A was 34.176 μm (σ=0.276), and the average particle size was small. The particle size distribution was also leaning towards the small side. The floatability evaluation showed that iodine compound suspension A took a long time to settle, which was supported by the fact that iodine compound suspension A had a small average particle size. Iodine compound suspension A, which has these characteristics, is thought to have an average particle size range of approximately 20 to 45 μm.

[0029] Test Example 3 (Changes in pH and oxidation-reduction potential (ORP) of iodine compound suspension over time) The test sample was thoroughly stirred and 1 mL of the solution was dispensed using a micropipette. It was serially diluted 100-fold, 250-fold, and 500-fold with purified water. The pH and ORP were measured. As a result, as shown in Table 1, regardless of the dilution ratio, the pH and ORP did not decrease significantly 60 days and 168 days after preparation. Measurements were taken using a newly purchased tester 60 days and 168 days after preparation.

[0030] [Table 1]

[0031] Test Example 4 (Antibacterial test using Escherichia coli) Iodine compound suspension A was diluted with purified water to three levels: 100, 250, and 500 times, and provided to the testing institution. 10 mL of the liquid sample was placed in a petri dish, and 0.1 mL of bacterial suspension BGLB was added and stirred. After culturing at 35°C for 18 hours, 10-fold serial dilutions were made, and 1 mL of the diluted solution was mixed with standard agar medium. After culturing at 35°C for 22 hours, the amount of bacteria was measured. As a result, as shown in Table 2, high antibacterial activity was confirmed at all three dilution levels. 8 CFU / ml.

[0032] [Table 2]

[0033] Test Example 5 (Field test using sweet potato root rot fungus) (1) Exam period Test start date: July 6, 2023 - Test end date: November 15, 2023 The optimum growing season for sweet potatoes is said to be from early April to late September, but because root rot thrives in high temperatures and humidity, and rain causes spores to leak from infected areas and spread, farmers are taking measures to harvest earlier. (2) Planting sweet potato seedlings using root rot fungi and iodine compound suspension A The experiment was conducted outdoors in a contaminated field (andosol soil). 1) Sweet potato seedlings are sterilized in Koganesengan 2) 1 section 5m 2 15 seedlings were planted at a distance of 100cm between rows and 30cm between plants per 1m x 5m. 3) Five plots were randomly placed per level, and a total of 75 plants were planted. 4) The test bacteria is a liquid containing a stock strain of sweet potato root rot bacteria adjusted to a specified concentration. 5) Spread a predetermined amount of test fungus in a 20 cm width on the center of the soil surface of the previously cultivated furrow. 6) For the pesticide prototype, use iodine compound suspension A diluted 500 times. 7) The amount of spraying is 1m 2 per 1L 8) Spray a predetermined amount of the pesticide sample in a 20cm width on the center of the soil surface of the ridge where the test bacteria was sprayed. 9) Five randomly placed plots were left untreated without any pesticides. After the test began, the seedlings were regularly observed by a public institution. A damage index was calculated from the number of plants infected with root rot and from plants that had died due to causes other than root rot, and the overall evaluation result was presented as a control value. The practicality of the product was also judged based on the control value. Control value is an index used to evaluate the effectiveness of a pesticide in testing against pests and diseases. It is a numerical value that indicates the degree to which damage was reduced compared to damage in an untreated area, and is calculated using the following formula. Control value = 100 - (damage index of treated area / damage index of untreated area) x 100 (3) Test results The first cases of root rot were confirmed on August 23, 47 days after planting. The disease progressed slowly thereafter, and the field test showed little disease in the untreated plots 131 days after planting. The control value of 500 times diluted iodine compound suspension A was 20.8 on September 22nd, 29.8 on October 11th, 29.8 on October 24th, and 33.9 on November 15th. No dead plants were found, and although the control value was low, it was judged to be practical.

Claims

1. Iodic acid or periodic acid with a solubility in water of 10 g / 100 gH ２ 1. A composition for controlling fungi in agricultural crops or plants, comprising an aqueous suspension containing an iodine-containing metal salt selected from metal iodates having an iodine content of less than 0 and metal periodates.

2. The iodine-based metal salt has a solubility in water of 1 g / 100 gH ２ 2. The pesticide composition according to claim 1, which is an iodine-based metal salt selected from metal iodates and metal periodates having an iodine content of less than 0.

3. 2. The pesticide composition according to claim 1, wherein the iodine-based metal salt is one or more selected from calcium iodate, iron (III) iodate, copper (II) iodate, potassium periodate, potassium iodate, sodium iodate, and magnesium iodate.

4. 2. The pesticide composition according to claim 1, wherein the iodine-based metal salt is one or more selected from calcium iodate, iron(III) iodate, copper(II) iodate, and potassium periodate.

5. 2. The control composition according to claim 1, wherein the fungal infection disease is an infection disease selected from sweet potato base rot, powdery mildew, black spot, brown spot, downy mildew, gray mold, white root rot, purple root rot, sooty spot, anthracnose and rice blast.

6. The control composition according to claim 1, wherein the fungal infection disease is sweet potato root rot.

7. A method for controlling a fungal infection disease of agricultural crops or plants, comprising a step of applying the control agent composition according to any one of claims 1 to 6 to fungi of agricultural crops or plants.

8. The control method according to claim 7, wherein the application comprises spraying or coating the control agent composition onto stems, leaves, seed potatoes, seeds, or fields of the target crops or plants.

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