JP2024052428A - Agricultural and horticultural fungicide containing iron-polyphenol complex and disease control method using said agricultural and horticultural fungicide - Google Patents

Abstract

[Problem] To provide a highly practical agricultural and horticultural fungicide that easily and stably exerts the fungicidal function of divalent iron for a long period of time, and to provide a method for controlling bacterial or fungal diseases in the seeds of plants such as grains and vegetables using the agricultural and horticultural fungicide. [Solution] The agricultural and horticultural fungicide contains an iron-polyphenol complex (iron PP) obtained by reacting iron or an iron compound with a polyphenol source (PP), wherein the iron concentration in the iron-polyphenol complex (iron PP) is 1 to 20% by mass, and the iron concentration in the agricultural and horticultural fungicide is 0.1 to 20% by mass. [Selected Figure] None

Description

The present invention relates to an agricultural and horticultural fungicide containing an iron-polyphenol complex and a disease control method using the fungicide.

In recent years, technology that utilizes the bactericidal properties of divalent iron as a bactericide has been expected in fields such as agricultural applications. Specifically, for example, Patent Document 1 discloses a Fenton reaction catalyst that uses ground and roasted coffee beans (particularly coffee grounds) or tea leaves (particularly tea leaves) as a supply source for a reducing component, mixes the supply source for the reducing component with a supply source for iron containing divalent or trivalent iron in the presence of water, and uses the resulting reaction product (iron-polyphenol) as an active component, and a sterilization method that uses this Fenton reaction catalyst to generate hydroxyl radicals (.OH) from hydrogen peroxide.

Patent Document 2 describes a cucumber powdery mildew control agent that contains trivalent iron ions, hydrogen peroxide, etc., and discloses a technology that generates large amounts of OH radicals through a photo-Fenton reaction.

Non-patent literature 1 discloses the bactericidal action and phage inactivation using iron (II) ascorbate, and it is believed that the divalent iron contained in iron (II) ascorbate generates free radicals inside and outside the bacterial cells, which then act.

Hydroxyl radicals (.OH), which are the direct agent of the sterilization method described in Patent Document 1, are known to be the most powerful chemical substance with oxidizing properties, but their production requires hydrogen peroxide or a substance that generates hydrogen peroxide, and they cannot be generated by iron-polyphenol alone. Therefore, in actual use, it lacks the convenience of being able to sterilize with a single agent. Furthermore, hydrogen peroxide and the substance that generates it are peroxides, so care must be taken when storing and handling them.

However, in the sterilization method described in Non-Patent Document 1, ferrous iron is unstable and easily oxidized, and in water or in a humid environment, it changes to ferrous iron in an extremely short time and easily loses its sterilizing activity.

JP 2011-212518 A JP 2014-94895 A JP 2020-158448 A

Akira Murata, Toshikatsu Hidaka, Kozo Kanda, and Tomio Kato, "Fungicidal action and mechanism of action of ferrous iron", Bulletin of the Faculty of Agriculture, Saga University, ed., Faculty of Agriculture, Saga University, 2008, Vol. 93, pp. 141-155

The problem that the present invention aims to solve is to provide a highly practical agricultural and horticultural fungicide that easily and stably exerts the bactericidal function of divalent iron for a long period of time, and to provide a method for controlling bacterial or fungal diseases in plants such as grains and vegetables using the agricultural and horticultural fungicide.

A fungicide using an iron-polyphenol complex (iron PP) was prepared as a fungicide for grain seeds, etc., and an agricultural and horticultural fungicide was discovered that has effective fungicidal activity and causes no visible damage to plants, and a method for controlling bacterial or fungal diseases using said fungicide was developed. That is, the gist of the present invention is as follows.

1. An agricultural and horticultural fungicide containing an iron-polyphenol composite material (iron PP) obtained by reacting iron or an iron compound with a polyphenol source (PP),
The iron concentration in the iron-polyphenol composite material (iron PP) is 1 to 20% by mass,
The agricultural and horticultural fungicide has an iron concentration of 0.1 to 20 mass%.

2. An agricultural and horticultural fungicide containing an iron-polyphenol complex (iron PP) as an active ingredient, the iron concentration in the agricultural and horticultural fungicide being 0.1 to 20% by mass.

3. An agricultural and horticultural fungicide in which the iron concentration is 1 to 20% by mass.

4. Agricultural and horticultural fungicides whose source of polyphenols (PP) is coffee or tea.

5. A method for controlling bacterial or fungal diseases using the agricultural and horticultural fungicide.

6. The method for controlling a bacterial disease, wherein the bacterial disease is rice bacterial grain rot, rice brown stripe disease, or rice bacterial seedling blight.

7. The method for controlling a fungal disease, wherein the fungal disease is rice bakanae disease, rice blast disease, or rice brown spot disease.

The agricultural and horticultural fungicide of the present invention is a fungicide that can easily and stably exert the fungicidal function of divalent iron for a long period of time, and is useful as a fungicide for use in a method for controlling bacterial or fungal diseases with little phytotoxicity.

The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be implemented in various forms within the scope of the gist of the invention.

The agricultural and horticultural fungicide of the present invention contains an iron-polyphenol composite (iron PP) obtained by reacting iron or an iron compound with a polyphenol source (PP).

The "iron-polyphenol composite" (iron PP) of the present invention can be any known "iron-polyphenol" or composition or composite containing "iron-polyphenol", but it is preferable to use an iron-polyphenol composite manufactured and prepared by the method described in detail in Patent Document 3.

The "iron or iron compound" that is the raw material for the iron-polyphenol composite material (iron PP) of the present invention can be any iron or iron compound. Examples include metallic iron; water-soluble iron compounds such as iron(III) chloride and iron(III) sulfate; water-insoluble iron compounds such as iron(III) oxide, iron(III) nitrate and iron(III) hydroxide; natural iron ores such as pyrite, marcasite, siderite, magnetite and goethite; natural products such as iron-containing soil, heme iron and shells; and compounds obtained by dissolving these in acid. Of these, iron(III) chloride, iron(III) sulfate and other iron(III) compounds are preferred, with iron(III) chloride being more preferred.

The polyphenol source (PP) used in the present invention is not particularly limited as long as it is a material that contains polyphenols or is capable of producing polyphenols. Examples include woody or grassy materials or processed materials thereof, grain raw materials such as malt, barley, and wheat, coffee beans, tea leaves, hops, and wine lees. Coffee beans and tea leaves are preferred. These can also be used in combination.

Examples of coffee beans include raw coffee beans, dried coffee beans, roasted coffee beans, roasted and ground coffee beans, the extract obtained by soaking these in water (drinkable coffee), the dried powder of the extract, coffee grounds, etc. Examples of tea leaves include raw tea leaves, dried tea leaves, fermented tea leaves, the extract obtained by soaking these in water (drinkable green tea, black tea, oolong tea, etc.), the dried powder of the extract, tea leaves, etc.

The coffee grounds or used tea leaves may be used before or after extraction, or may have had their moisture content adjusted by heating or other procedures before or after extraction. When using pre-extracted grounds or used tea leaves, it is preferable to use non-standard products that are not intended for use as beverages as the polyphenol source (PP) for use in the present invention, from the viewpoint of effective use of resources, rather than those intended for use as beverages.

The iron-polyphenol (iron PP) composite material of the present invention has, for example,
The iron or iron compound aqueous solution or dispersion is brought into contact with a polyphenol source (PP) to obtain a reaction product, which is then heated for a certain period of time (e.g., 70° C. or higher and 200° C. or lower) and dried to a certain water content (e.g., 20% by mass or lower, preferably 15% by mass or lower). A specific production method is preferably the method described in Patent Document 3.

The iron-polyphenol complex (iron PP) of the present invention is produced by the above-mentioned production method, and then contains divalent iron ions (water-soluble iron ions) resulting from the reduction of the trivalent iron derived from the iron or iron compound. Whether the iron-polyphenol complex has been stably synthesized can be confirmed by subjecting the product to a pH stability test.

The iron-polyphenol composite material (iron PP) of the present invention varies depending on the drying time during production, and the storage conditions and storage period after production, so it may be dried or replenished with moisture as appropriate during the storage process, during transportation, or before use as an agricultural or horticultural fungicide.

The concentration of divalent iron contained in the produced iron-polyphenol composite (iron PP) can be analyzed by a method such as the well-known silver phenanthroline colorimetric method (Patent Document 3). The production of iron-polyphenol reduces almost all of the trivalent iron to divalent iron.

The amount of polyphenols contained in the produced iron-polyphenol composite can be measured using known analytical methods such as the Folin-Denis method (Patent Document 3).

The iron-polyphenol composite (iron PP) of the present invention preferably has an iron concentration of 1 to 20% by mass. More preferably, it is 2 to 10% by mass.

The agricultural and horticultural fungicide containing the iron-polyphenol composite material (iron PP) of the present invention preferably has an iron concentration of 0.1 to 20% by mass.

It is more preferable that the agricultural and horticultural fungicide containing the iron-polyphenol composite material (iron PP) of the present invention has an iron concentration of 0.1 to 20% by mass as an active ingredient, and it is even more preferable that the iron concentration of the agricultural and horticultural fungicide is 1 to 20%.

The agricultural and horticultural fungicide of the present invention may be mixed with a solid or liquid carrier, and may contain other components such as water and, if necessary, additives (auxiliaries) such as surfactants, dispersants, penetrants, spreading agents, thickeners, antifreeze agents, binders, anticaking agents, antidecomposition agents, preservatives, antisettling agents, and antifoaming agents.

The agricultural and horticultural fungicide of the present invention can be formulated in various forms by adding the above-mentioned additives (auxiliaries). Specific formulations of the fungicide include liquids, emulsions, hydrated powders, suspensions (aqueous suspension formulations), water-soluble granules, water-dispersible granules, emulsions, suspoemulsions, powders, granules, and gels. It can also be used in any form, enclosed in a water-soluble package, or as a wet powder dressing.

The agricultural and horticultural fungicide of the present invention can be used by diluting it with water so as to contain, specifically, an iron-polyphenol complex (iron PP) concentration of 10 to 1000 times, preferably 10 to 200 times.
The iron concentration in the diluted solution is preferably 0.001% by mass to 2% by mass (10 ppm to 20,000 ppm).

The bactericidal effect of the iron-polyphenol complex (iron PP) of the present invention depends on the concentration of the iron-polyphenol complex (iron PP), the treatment time, and temperature, as well as the type of pathogenic bacteria or fungus being targeted, and therefore it is necessary to set an appropriate concentration, treatment time, and treatment temperature taking these factors into consideration. This is due to the bactericidal mechanism of the divalent iron contained in the iron-polyphenol complex (iron PP). It is believed that the divalent iron in the iron-polyphenol complex (iron PP) acts on the cell surface of pathogenic bacteria and the like, damaging and depolymerizing DNA through a free radical reaction mechanism involving active oxygen species, thereby exerting a bactericidal effect. Polyphenols stably maintain divalent iron through their reducing action.

The agricultural and horticultural fungicide containing the iron-polyphenol complex (iron PP) of the present invention can be used for the sterilization treatment of seeds of grains, vegetables, and various other plants, but is not particularly limited to crops, and is more preferably used for the sterilization treatment of grain seeds such as rice, wheat, and barley.

When the iron-polyphenol composite material (iron PP) of the present invention is diluted and used in a method for sterilizing grain seeds, it is preferably used for pre-soaking treatment or treatment during germination. The temperature for pre-soaking treatment is preferably 10 to 15°C. The time for pre-soaking treatment is preferably 60 minutes to 48 hours, more preferably 60 minutes to 24 hours.

When the iron-polyphenol composite material (iron PP) of the present invention is used during germination treatment, it is preferable to use warm water at about 30°C to 32°C for the germination treatment. The germination treatment time is preferably 60 minutes to 24 hours.

In the present invention, the type of disease of grain seeds is highly effective against those caused by bacterial diseases and fungal diseases. Examples of bacterial diseases include rice bacterial grain rot, rice brown stripe disease, and rice bacterial seedling blight, and the present invention is more effective against rice bacterial grain rot. Examples of fungal diseases include rice seedling disease, rice blast disease, and rice leaf spot disease, and the present invention is more effective against rice seedling disease.

In the method of sterilization using the agricultural and horticultural fungicide containing the iron-polyphenol composite material (iron PP) of the present invention, the seeds may be immersed in the iron-polyphenol composite material as is, or may be placed in a cloth bag or net before treatment.

The fungicidal effect of the agricultural and horticultural fungicide of the present invention is evaluated using a control value. The control value is an index that indicates the degree of control effect of a treated area against damage caused by bacteria, fungi, etc. in a non-treated area, and generally, a higher control value indicates a higher control effect.
It is calculated by the formula: Control value = (100 - (disease incidence in treated area/disease incidence in untreated area) x 100). A higher control value indicates a higher control effect.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[Production Example 1]
<Production of iron-polyphenol composite material (iron PP)>
The above-mentioned coffee (before use) (hereinafter, used in the comparative example) which was a non-standard product was charged as a polyphenol source (PP) in the drum of a coating machine (manufactured by Keibunsha Seisakusho Co., Ltd., model: KC-152(S)). While the coating machine was operated and the drum was rotated, a 10% by mass aqueous solution of iron (III) chloride (Kanto Chemical Industry Co., Ltd.) was sprayed from a spray container for spraying agricultural chemicals onto the coffee, with the entire amount of the aqueous solution being sprayed within about 10 minutes. The coffee was transferred to a tray in a plastic bag, and the tray was wrapped in a 45 L plastic bag, and the opening of the plastic bag was tied. The wrapping was placed in a hot air dryer set at 95°C and heated for 3 hours. After the heating time had elapsed, the plastic bag was removed, and the coffee on the tray was dried in the hot air dryer at 95°C for about 2 days to obtain an iron-polyphenol composite material (iron PP). The moisture content of this iron-polyphenol composite (iron PP) was confirmed to be 6% by mass or less using a moisture meter (Kett Electric Laboratory, infrared moisture meter, model: FD-220).

<Measurement of Fe(II)/[Fe(II)+Fe(III)] concentration ratio>
The iron-polyphenol composite sample was dispersed in water, and the concentration ratio of Fe(II) to the total amount of Fe(II) and Fe(III) in the aqueous solution of iron-polyphenol dissolved in water was measured by phenanthroline colorimetry using a spectrophotometer (U-1800, Hitachi High-Technologies). As a result of the concentration ratio measurement, about 3 kg of iron-polyphenol composite (iron PP) containing iron (highly containing divalent iron) with Fe(II)/[Fe(II)+Fe(III)] of about 90% to 95% was obtained.

[Formulation Examples 1 to 3 and Formulation Comparative Examples 1 to 3]
The iron-polyphenol composite (iron PP) was prepared so that the iron concentration (mass%) contained therein was the composition shown in Table 1, and Formulation Example 1 (iron PP 2%), Formulation Example 2 (iron PP 4%), and Formulation Example 3 (iron PP 8%) were prepared. In addition, as comparative controls, Formulation Comparative Example 1 (iron (II) sulfide), Formulation Comparative Example 2 (polyphenol source (PP)), and Formulation Comparative Example 3 (commercially available rice seed disinfectant (product name: Techlead C Flowable, ingredients: ipconazole, cupric hydroxide)) were prepared.

[Example 1]
<Rice bacterial grain rot control test>
[Treatment at the time of germination]
The iron-polyphenol composite materials (iron PP) of formulation examples 1 and 2 in Table 1 were diluted 60-fold and 120-fold with water to prepare diluted solutions. Iron (II) sulfide of formulation comparative example 1 was diluted 1,800-fold with water. 45 mL of each of these diluted solutions was placed in a 100 mL beaker, and 12 g of rice grains contaminated with bacterial grain rot were immersed in the solutions (treatment at the time of germination) to examine the control effect. The rice grains used were soaked at 15°C. The soaking (treatment at the time of germination) was carried out at 32°C for 24 hours.
The germinated rice seeds were sown in a plastic case 1/12 the size of a seedling box filled with culture soil, kept at 32° C. for 2 days, and then kept in a greenhouse.
23 days after sowing, the rate of diseased seedlings was examined, and the control value was calculated from the degree of disease.
The chemical damage was evaluated by counting the number of germinated seeds, and the germination inhibition rate (%) was calculated by the following formula, assuming the number of germinated seeds in the untreated area to be 100.
Germination inhibition rate (%) = (1 - (number of germinations in treated area/number of germinations in untreated area)) x 100 (%)
The efficacy was judged based on the control value, and the phytotoxicity was judged based on the germination inhibition rate (%), according to the criteria shown in Table 2. The test results are shown in Table 3.

As can be seen from Table 3, the agricultural and horticultural fungicide containing the iron-polyphenol composite material (iron PP) of the present invention is more effective than Comparative Example 1.

[Example 2]
<Rice bacterial grain rot control test>
[Treatment at the time of germination]
The iron-polyphenol complexes (iron PP) of formulation examples 2 and 3 in Table 1 were diluted 40-fold and 120-fold with water to prepare diluted solutions. The polyphenol source (PP) PP of formulation comparative example 2 was diluted 60-fold with water. Techlead C Flowable of formulation comparative example 3 was diluted 200-fold with water. 45 mL of each of these diluted solutions was placed in a 100 mL beaker, and 12 g of rice grains contaminated with rice bacterial rot were immersed in the solution (treatment at the time of germination) to examine the control effect. The rice grains used were soaked at 15°C. The soaking (treatment at the time of germination) was carried out at 32°C for 24 hours.
The germinated rice seeds were sown in a plastic case 1/12 the size of a seedling box filled with culture soil, kept at 32° C. for 2 days, and then kept in a greenhouse.
23 days after sowing, the rate of diseased seedlings was examined, and the control value was calculated from the degree of disease.
The chemical damage was evaluated by counting the number of germinated seeds, and the germination inhibition rate (%) was calculated by the following formula, assuming the number of germinated seeds in the untreated area to be 100.
Germination inhibition rate (%) = (1 - (number of germinations in treated area/number of germinations in untreated area)) x 100 (%)
The efficacy was judged based on the control value, and the phytotoxicity was judged based on the germination inhibition rate (%), according to the criteria in Table 2. The test results are shown in Table 4.

From Table 4, it can be seen that the agricultural and horticultural fungicides containing the iron-polyphenols of the present invention have a control effect equal to or greater than that of commercially available products.

[Example 3]
<Rice bakanae fungus disease control test>
[Treatment at the time of germination]
The iron-polyphenol complexes (iron PP) of formulation examples 2 and 3 in Table 1 were diluted 40-fold and 120-fold with water to prepare diluted solutions. The polyphenol source (PP) PP of formulation comparative example 2 was diluted 60-fold with water. Techlead C flowable of formulation comparative example 3 was diluted 200-fold with water. 45 mL of each of these diluted solutions was placed in a 100 mL beaker, and 12 g of rice grains contaminated with rice seedling disease were immersed in the solution (treatment at the time of germination) to examine the control effect. The rice grains used were soaked at 15°C. The soaking (treatment at the time of germination) was carried out at 32°C for 24 hours.
The germinated rice seeds were sown in a plastic case 1/12 the size of a seedling box filled with culture soil, kept at 32° C. for 2 days, and then kept in a greenhouse.
23 days after sowing, the number of diseased seedlings was counted, and the control value was calculated from the diseased seedling rate.
The chemical damage was evaluated by counting the number of germinated seeds, and the germination inhibition rate (%) was calculated by the following formula, assuming the number of germinated seeds in the untreated area to be 100.
Germination inhibition rate (%) = (1 - (number of germinations in treated area/number of germinations in untreated area)) x 100 (%)
The efficacy was judged based on the control value, and the phytotoxicity was judged based on the germination inhibition rate (%), according to the criteria in Table 2. The test results are shown in Table 5.

From Table 5, it can be seen that the agricultural and horticultural fungicide containing the iron-polyphenol of the present invention has the same control effect as commercially available products.

The agricultural and horticultural fungicide containing the iron-polyphenol composite of the present invention is useful as a fungicide that utilizes the fungicidal function of divalent iron and can be used simply and stably for a long period of time. Furthermore, the disease control method of the present invention that uses the fungicide causes little phytotoxicity to plants such as grains, controls seed-borne diseases such as fungal diseases or bacterial diseases in grain seeds, and is effective as a disease control method that causes no phytotoxicity to plants such as grains. The agricultural and horticultural fungicide of the present invention can also be applied to vegetables, fruit trees, fruits, etc.

Claims (7)

An agricultural and horticultural fungicide containing an iron-polyphenol composite material (iron PP) obtained by reacting iron or an iron compound with a polyphenol source (PP),
The iron concentration in the iron-polyphenol composite material (iron PP) is 1 to 20% by mass,
The agricultural and horticultural fungicide has an iron concentration of 0.1 to 20 mass%. The agricultural and horticultural fungicide according to claim 1, which contains an iron-polyphenol complex (iron PP) as an active ingredient, and the iron concentration in the agricultural and horticultural fungicide is 0.1 to 20 mass %. The agricultural and horticultural fungicide according to claim 1 or 2, wherein the iron concentration in the agricultural and horticultural fungicide is 1 to 20 mass %. The agricultural and horticultural fungicide according to claim 1 or 2, wherein the polyphenol source (PP) is coffee or tea. A method for controlling bacterial or fungal diseases using the agricultural and horticultural fungicide according to claim 1 or 2. The bacterial disease is rice bacterial grain rot, rice brown stripe disease, or rice bacterial seedling blight;
The method for controlling a bacterial disease according to claim 5. The fungal disease is rice seedling disease, rice blast disease, or rice brown spot disease;
The method for controlling a fungal disease according to claim 5.