Composition for controlling fungal infections in agricultural crops or plants and method for controlling the same

Abstract

To provide an inorganic control agent and a control method which show a control effect on agricultural crops and plant fungal infectious diseases over a long period of time when sprayed on agricultural crops or soil. [Solution] A composition for controlling fungal infection diseases in agricultural crops or plants, comprising particles in which an inorganic iodine compound is supported on a silica-based inorganic porous body with a particle diameter of 1 mm or more and 6 mm or less.

Description

[Technical field]

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

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

[0003] Iodine and iodic acid are known to have disinfecting effects against viruses, molds (filamentous fungi), and bacteria, but there is a problem that they are highly soluble in water and dissolve in water, reducing the disinfecting effect. In response to this, an iodine-supported material (Patent Document 1) has been reported in which iodine is supported on an adsorbent material such as activated carbon or fiber so that iodine is not released into the air or water, and the acidity is adjusted so that iodate ions are not generated when iodine is supported. In addition, since the material is activated carbon powder, which disperses in the air or water, a material (Patent Document 2) has been reported in which an antibacterial and deodorizing mechanism is imparted by forming an iodate salt on the surface layer of a material such as calcium silicate. However, although hydraulic inorganic materials including calcium silicate react with water at room temperature and pressure and harden at room temperature and pressure, many of them are (weakly) alkaline, and after outdoor spraying, they are degraded by acidic soil, ultraviolet rays, climate change, etc., and therefore have insufficient durability. In addition, it has been difficult to inexpensively produce an acidic material suitable for forming iodate salts at room temperature and pressure. The applicant has therefore discovered that an antibacterial and disinfectant support in which an inorganic iodine compound is supported on a silica-based inorganic porous material derived from volcanic minerals, the antibacterial and disinfectant support being characterized in that the antibacterial and disinfectant support has a pH of 2 to 5, an oxidation-reduction potential in an oxidized state, and a bulk density of 0.4 to 1.5, has improved antibacterial activity and good usability, and has filed a patent application (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-125560 A [Patent Document 2] Patent No. 6644325 [Patent Document 3] Patent Publication No. 2022-24524 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the tests in Patent Documents 1 to 3 only examined whether the compounds act directly against Escherichia coli and viruses, and did not confirm whether they exert a fungal infection disease control effect over a long period of time when sprayed on agricultural crops or soil. Accordingly, an object of the present invention is to provide an inorganic control agent and a control method which are effective for controlling fungal infectious diseases in agricultural crops and plants over a long period of time when sprayed on agricultural crops or soil. [Means for solving the problem]

[0006] The present inventors have therefore discovered that by obtaining particles in which an inorganic iodine compound is supported on a silica-based inorganic porous body of a certain particle size and spraying the particles on agricultural crops, plants or fields, the inorganic iodine compound acts on the agricultural crops or plants over a long period of time, thereby providing an effect of controlling fungal infections in the agricultural crops or plants, and have completed the present invention.

[0007] That is, the present invention provides the following [1] to [9]. [1] A composition for controlling fungal infection diseases in agricultural crops or plants, comprising particles in which an inorganic iodine compound is supported on a silica-based inorganic porous body having a particle diameter of 1 mm or more and 6 mm or less. [2] The control composition according to [1], wherein the inorganic iodine compound is one or more selected from iodine, triiodide, iodic acid, periodic acid, and salts thereof. [3] The control composition according to [1] or [2], wherein the inorganic iodine compound is one or more selected from iodic acid and iodate salts. [4] The control agent composition according to any one of [1] to [3], wherein the particles carrying an inorganic iodine compound are particles having a pH of 3 to 7, an oxidation-reduction potential of +200 mV to +600 mV, and a bulk density of 0.35 to 2.2. [5] The control agent composition according to any one of [1] to [4], wherein the particle size of the silica-based inorganic porous material is 1 mm or more and 3 mm or less. [6] The control composition according to any one of [1] to [5], 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 blast. [7] The control agent composition according to any one of [1] to [6], wherein the fungal infection disease is sweet potato root rot. [8] A method for controlling a filamentous fungal infection disease in agricultural crops or plants, comprising a step of applying the control agent composition according to any one of [1] to [7] to filamentous fungi in agricultural crops or plants. [9] The control method according to [8], wherein the application comprises spraying or coating the control agent composition on stems, leaves, seed potatoes, seeds or a field of a target crop or plant. Effect of the Invention

[0008] When the fungal infection disease control agent of the present invention is sprayed on agricultural crops or fields, the inorganic iodine compound salt supported on the particles is gradually released and acts on the stems and leaves of agricultural crops and the surface layer of the field over a long period of time, and simply by spraying the agent on agricultural crops, plants or fields, it exerts a long-term fungal disinfecting effect from the surface layer of above-ground agricultural crops, plants and fields to the soil. The agent for controlling filamentous fungal infections of the present invention is particularly effective as an agent for controlling sweet potato root rot. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0010] In this specification, a filamentous fungus is a fungus that is composed of tubular cells called hyphae and lives in the air, water, and soil. In this specification, the filamentous fungus is intended to 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 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, coating, etc. of 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 potatoes, examples of this include treatment of seed potatoes and spraying onto stems, leaves, and fields.

[0012] One aspect of the present invention is a composition for controlling fungal infection diseases in agricultural crops or plants, which contains particles in which an inorganic iodine compound is supported on a silica-based inorganic porous material having a particle diameter of 1 mm or more and 6 mm or less. 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 composition of the present invention to a filamentous fungus in the agricultural crops or plants.

[0013] The composition for controlling fungal infection diseases in agricultural crops or plants of the present invention contains particles in which an inorganic iodine compound is supported on a silica-based inorganic porous body having a particle diameter of 1 mm or more and 6 mm or less. The particle size of the silica-based inorganic porous material used is preferably 1 mm or more and 6 mm or less, more preferably 1 mm or more and 4 mm or less, and even more preferably 1 mm or more and 3 mm or less, from the viewpoints of applicability and long-term sustained release of the active ingredient. From the viewpoint of environmental load, the silica-based inorganic porous material is preferably derived from a natural product, and examples thereof include those selected from pumice, crushed pumice, molded bodies of pumice or crushed pumice, and filled bodies of pumice or crushed pumice.

[0014] Pumice, also known as pumice, is a foamed, porous, mainly whitish pyroclastic rock. Minerals contained in pumice include pumice, dacite, rhyolite, plagioclase, hypersthene, augite, amphibole, quartz, cristobalite, apatite, felsic rock, basalt, andesite, biotite, orthopyroxene, clinopyroxene, obsidian, magnetite, volcanic glass, feldspar, scoria, tuff, pumice-bearing tuff, granite, andesite, and dacite. These include rock, granodiorite, pumice volcanic gravel tuff, float, halloysite, allophane, imogolite, gypsite, volcanic breccia, tuff breccia, tuff agglomerate, scaly tuff, gabbro, diorite, porphyry, potassium feldspar, zeolite, axenite, fluorite, porphyrite, welded tuff, reticulite, acid clay, silica, sinter, serpentine, etc. Specific examples of such pumice include Kanuma soil, Imaichi soil, Miya soil, foxtail soil (foxtail sand), Hyuga soil, Ezo sand, Fuji sand, Akadama soil, Kiryu sand, Kirishima Oike mullet, Sakurajima Taisho mullet, mullet, cola, ash stone, gravel, quail, gravel, akahoya, black soil, and black niga.

[0015] Among these silica-based inorganic porous materials, silica-based inorganic porous materials having a pH of 4 to 8, an oxidation-reduction potential of +100 mV to +500 mV, and a bulk density of 0.3 to 2 are preferred from the viewpoint of obtaining excellent control effect against fungal infections in agricultural crops or plants. The pH is preferably 4-8, more preferably 4-7, and further preferably 4-6. Here, the pH can be measured by mixing 10 g of the silica-based inorganic porous material with 50 ml of water at room temperature, shaking the mixture for 60 minutes, and using the resulting solution with a pH meter.

[0016] The redox potential of the silica-based inorganic porous material used must be on the oxidizing side in order to bring the redox potential of the inorganic iodine compound-supported particles (hereinafter also simply referred to as supported particles) into an oxidized state and obtain an excellent agricultural crop or plant filamentous fungal infection control effect due to the inorganic iodine compound supported in the particles. From the viewpoint of obtaining an excellent agricultural crop or plant filamentous fungal infection control effect, the redox potential is preferably +100 mV to +500 mV, more preferably +200 mV to +500 mV, and even more preferably +300 mV to +500 mV. Here, the redox potential can be measured by mixing 10 g of the silica-based inorganic porous material with 50 ml of water at room temperature, shaking for 60 minutes, and using the resulting solution with a redox potentiometer.

[0017] The bulk density of the silica-based inorganic porous material is preferably 0.3 to 2.0, more preferably 0.4 to 1.5, and even more preferably 0.6 to 1.2, from the standpoints of the agricultural crop or plant fungal infection control effect of the supported particles, strength, reduction in equipment wear and tear required for transporting and mixing raw materials and products, reduction in energy costs required for production and transportation, prevention of dust generation from raw materials, and ease of operation when spraying manually or by power in granular form. Here, the bulk density of the inorganic porous body is the loose bulk density. The loose bulk density of particles can be measured by filling the porous body under its own weight in a 500 ml measuring cylinder without compressing, shaking or vibrating it, determining the volume, and dividing the weight of the porous body used for filling by the volume.

[0018] The inorganic iodine compound supported on the silica-based inorganic porous material may be one or more selected from iodine, triiodide, iodic acid, periodic acid, and salts thereof, and more preferably one or more selected from iodic acid and iodate salts. In the support particles of the present invention, these inorganic iodine compounds are preferably present in the form of one or more selected from iodine, triiodide ions, iodate ions and periodate ions.

[0019] The amount of these inorganic iodine compounds supported on the support particles of the present invention is not particularly limited as long as it is an amount that shows an effect of controlling fungal infections in agricultural crops or plants, but is preferably 0.01 mass% or more, more preferably 0.1 mass% to 10 mass%, and even more preferably 0.2 mass% to 5 mass% relative to the amount of the support particles.

[0020] The above-mentioned support particles preferably have a pH of 3 to 7, an oxidation-reduction potential of +200 mV to +600 mV, and a bulk density of 0.35 to 2.2, from the viewpoint of obtaining an excellent effect of controlling fungal infections in agricultural crops or plants. The pH is preferably 3-7, more preferably 3-6, and further preferably 3-5. From the viewpoint of obtaining an excellent effect of controlling fungal infection in agricultural crops or plants, the oxidation-reduction potential is preferably +200 mV to +600 mV, more preferably +300 mV to +600 mV, and further preferably +400 mV to +600 mV. The bulk density is preferably from 0.35 to 2.2, more preferably from 0.45 to 1.65, and even more preferably from 0.7 to 1.3. Here, the pH, oxidation-reduction potential and bulk density can be measured in the same manner as for the silica-based inorganic porous material.

[0021] The supported particles of the present invention can be produced by supporting an inorganic iodine compound on a silica-based inorganic porous material having a particle diameter of 1 mm to 6 mm. More specifically, the supported particles can be produced by reacting the inorganic iodine compound dissolved or dispersed in a solvent with the silica-based inorganic porous material by mixing, coating, spraying, or impregnation. The inorganic iodine compound to be used may be one or more selected from iodine, triiodide, iodic acid, periodic acid, and salts thereof, and more preferably one or more selected from iodic acid and iodate salts. The solvent is preferably water or a polar solvent, more preferably water. The operations of mixing, coating, spraying, or impregnation are preferably carried out at room temperature (usually 5 to 35°C), and if drying is required, it is preferably carried out at room temperature to about 120°C. The amount of the inorganic iodine compound used is determined taking into consideration the amount to be supported.

[0022] Among the supported particles of the present invention obtained as described above, there are those with high hardness and those with low hardness depending on the characteristics of the silica-based inorganic porous body used as raw material.In the present invention, the supported particles are sprayed on agricultural crops or fields, and the inorganic iodine compound supported on the particles is gradually released and acts on the stems, leaves, and surface layer of agricultural crops for a long period of time.In view of this, the hardness in a dry state is preferably 2N or more and 70N or less, more preferably 10N or more and 60N or less, and even more preferably 20N or more and 50N or less. (Method of measuring particle hardness) Using a Kiya-type digital hardness tester KHT40N manufactured by Fujiwara Seisakusho Co., Ltd., measurements were taken of Hyuga soil and Kanuma soil particles in a dry state, dried at 60°C for 24 hours, and in a water-saturated state. For hardness measurements, one particle of each raw material was randomly selected, and a compressive load was applied to determine the load value when it was crushed. N=20 tests were performed. If the particles were soft and the load value of the hardness tester remained at the lower limit of the hardness tester and the particle deformed to less than half its initial size, it was deemed unmeasurable.

[0023] Since the inorganic iodine compound is supported on the obtained supported particles, when the supported particles are sprayed on agricultural crops or a field, the inorganic iodine compound salt supported on the particles is gradually released and acts on the stems and leaves of the agricultural crops and the surface of the field over a long period of time. Simply by spraying the particles on agricultural crops, plants or a field, a long-term fungal disinfecting effect is exerted from the surface of the above-ground agricultural crops, plants and fields to the soil, making it possible to prevent fungal infections in the agricultural crops or plants.

[0024] The target diseases of the filamentous fungal infection control agent of the present invention are diseases caused by filamentous fungi on agricultural crops or plants, and specifically include sweet potato base rot on sweet potato; powdery mildew on strawberry, apple, peach, pear, melon, pumpkin, rose, etc.; black spot on cucumber, apple, peach, pear, grape, plum, etc.; brown spot on apple, grape, sugar beet, etc.; downy mildew on grape, cucumber, Chinese cabbage, spinach, lettuce, radish, etc.; gray mold on fruits in general, strawberry, lettuce, tomato, cyclamen, etc.; white root rot and purple root rot on fruits in general, asparagus, etc.; sooty spot on fruits in general; anthracnose on strawberry, apple, cucumber, etc.; rice blast on rice, etc. Among these, the control effect against sweet potato base rot is particularly excellent.

[0025] To control fungal diseases in agricultural crops or plants, a step of applying the control composition of the present invention to fungi in agricultural crops or plants is carried out. Specifically, this means spraying or coating the control composition of the present invention on the stems, leaves, seed potatoes, seeds, fields, etc. of the target agricultural crops or plants. For example, in the case of sweet potato, the control agent composition of the present invention may be applied to seed potatoes, seedlings, stems, leaves, or fields by spraying. In the case of spraying to seedlings, stems, leaves, or fields of sweet potato, the control agent composition of the present invention may be applied once or multiple times at 1 to 10,000 L per hectare. In the case of seed potatoes of sweet potato, the control agent composition may be applied at 0.01 to 10,000 ppm. EXAMPLES

[0026] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0027] Example 1 (Iodate loading on borate) Using 60 g of dried bora earth with a particle size of 4 mm or less and 20 ml of iodic acid solution (concentration 3%) in a glass container, the bora earth was stirred while the iodic acid solution was gradually dripped in, so that the iodic acid solution was uniformly supported without remaining behind. The obtained supported particles maintained the granular shape before loading.

[0028] Example 2 (Supporting iodate on Akadama soil) In the same manner as in Example 1, 40 g of Akadama soil with a particle size of 6 mm or less was mixed with 20 ml of an aqueous solution of iodic acid (concentration 3%). The mixed Akadama soil became a slightly viscous paste-like mixture of particles. The particles carrying iodic acid salts in this Akadama soil could be separated into particles and powder by sieving.

[0029] Table 1 shows the pH, oxidation-reduction potential and bulk density of the silica-based inorganic porous materials used in Examples 1 and 2 and the resulting supports.

[0030] [Table 1]

[0031] Example 3 (Antibacterial activity test using Escherichia coli) The support particles A obtained in Example 1 were subjected to an antibacterial test against Escherichia coli. Antibacterial (E. coli) test method The support particles A were thoroughly dried at room temperature, 1 g of the particles was placed in a test tube, and the E. coli suspension (10 8 CFU / ml) was added and mixed well. After incubation at 35°C for 18 hours, 5ml of saline was added and washed out. 1ml of the washed out liquid was mixed well with standard agar medium and placed in a petri dish, incubated at 35°C for 22 hours, and the amount of bacteria was measured. As a result, as shown in Table 2, high antibacterial performance was confirmed from 0.05% by mass to 1.0% by mass. 8 CFU / ml.

[0032] [Table 2]

[0033] Example 4 (Field test using sweet potato root rot fungus) (1) Test period Test start date: July 6, 2023 - Test end date: November 15, 2023 The ideal growing season for sweet potatoes is said to be from early April to late September, but since base rot spreads easily in hot and humid environments and spores are released from the infected area by rainfall, farmers are taking measures to harvest early. (2) Planting sweet potato seedlings using root rot fungus and carrier particles A The study was conducted outdoors in a contaminated field (androsol soil). 1) Sweet potato seedlings are sterilized with sterilized Koganesengan 2) 1 section 5m 2 15 seedlings were planted at 100cm intervals per row (1m x 5m) and 30cm intervals between plants. 3) Five plots were randomly arranged 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 specified amount of test bacteria in a 20 cm width on the center of the soil surface of a previously cultivated furrow. 6) The pesticide prototypes used 1.0wt% and 0.5wt% supported particles A. 7) The amount of spray is 1m 2 per liter 8) Spray a specified amount of the pesticide prototype in a 20 cm 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 pesticide spraying. After the test started, 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 shown as a control value. In addition, the practicality of the product was judged based on the control value. The control value is an index used to evaluate the effectiveness of a pesticide when testing it against pests and diseases. It is a numerical value that indicates the degree to which damage was suppressed compared to that 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 outbreak of root rot was confirmed on August 23, 47 days after planting. The disease progressed slowly thereafter, and the field test showed little disease in the untreated area 131 days after planting. The control values ​​of supported particle A at 1.0 mass% and 0.5 mass% loadings were 100.0 and 62.5 on September 22nd, 72.3 and 80.9 on October 11th, 53.2 and 61.7 on October 24th, and 60.7 and 41.1 on November 15th. No withered plants were found, and the products were judged to be practical in all cases. Supported particles A have the advantage that iodine compounds dissolve little by little into the soil through the voids in the bora soil, causing no chemical damage to seedlings and maintaining an antibacterial effect for a long period of time.It has been confirmed that this particle is effective in preventing root rot disease without causing any chemical damage.

Claims

1. A composition for controlling fungal infection diseases in agricultural crops or plants, comprising particles in which an inorganic iodine compound is supported on a silica-based inorganic porous body having a particle diameter of 1 mm or more and 6 mm or less, the silica-based inorganic porous material is selected from pumice, crushed pumice, a molded body of pumice or crushed pumice, and a packed body of pumice or crushed pumice, The control agent composition, wherein the inorganic iodine compound is one or more selected from iodic acid and iodate salts.

2. The control agent composition according to claim 1, wherein the particles carrying the inorganic iodine compound have a pH of 3 to 7, an oxidation-reduction potential of +200 mV to +600 mV, and a bulk density of 0.35 to 2.2, The pH is a value measured by a pH meter using a solution obtained by mixing 10 g of the support particles in 50 ml of water at room temperature and shaking the solution for 60 minutes.

3. 2. The control agent composition according to claim 1, wherein the particle diameter of the silica-based inorganic porous material is from 1 mm to 3 mm.

4. 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.

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

6. A method for controlling a filamentous 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 5 to filamentous fungi of agricultural crops or plants.

7. The control method according to claim 6, wherein the application comprises spraying or coating the control agent composition on stems, leaves, seed potatoes, seeds, or fields of a target crop or plant.

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