Composite particle

Abstract

To provide a technique that allows further enhancement in a rate of reduction of agrochemicals as chemical agents.SOLUTION: A composite particle contains a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility of 1 mg / L or more and 100 mg / L or less at 20°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to composite particles and the like.

Background Art

[0002] Sustainable agriculture is essential for achieving "zero hunger", one of the 17 Sustainable Development Goals adopted by the United Nations General Assembly. The world population is predicted to increase to nearly 9.8 billion by 2050, and to ensure a stable supply of food, it is necessary to increase agricultural production by at least 50% from the 2012 level by the middle of this century. On the other hand, biodiversity, agricultural land, oceans, and forests are being depleted at an unprecedented rate. Therefore, it is essential to improve agricultural productivity to feed the continuously increasing population. Worldwide, on average 35% of crop yields are lost due to pre-harvest plant diseases. Pesticides are sprayed annually at a cost equivalent to approximately $4 billion to prevent or reduce losses due to plant diseases, contributing to the improvement of agricultural yields and quality. However, approximately 90% of the pesticides are lost during application due to volatilization, decomposition, photodegradation, leaching, and runoff, and less than 0.1% of the pesticides ultimately reach the intended harmful biological targets. That is, only a very small amount of the sprayed pesticides reaches the target, and the rest may contaminate the environment and have a serious impact on the food chain and human health. In addition to the impact on non-target species, the ubiquitous presence of pesticides in the environment leads to the emergence of pesticide resistance in pathogens, insects, and weeds. From the above, the development of new and more value-added pesticides is desired, but the development of new pesticide active ingredients is highly difficult and not easy to bring to market. Therefore, technologies that can achieve high functionality at low cost using existing active ingredients are expected.

[0003] As a method for solving these problems, a pesticide delivery system (PDS) using carrier particles has attracted attention. So far, slow release and photodegradation resistance have been reported by encapsulating pesticides in porous silica or polyurea. Encapsulating pesticides using biodegradable materials as carrier particles can also be expected to improve safety. PLGA is a polymer excellent in biodegradability and biocompatibility and has attracted attention in the pharmaceutical field as a carrier for plasmids and anticancer agents. The present inventor has reported that by encapsulating a drug with extremely low water solubility (cyazofamid, water solubility at 20°C is about 0.1 mg / L) in PLGA particles, the pathogenic control effect of the oomycete on plants is improved (Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Non-Patent Document 1, when the pesticide reduction rate by encapsulating a drug in PLGA particles, that is, when a certain pathogen control effect is exhibited using PLGA particles encapsulating the drug, the drug concentration is defined as concentration A, and when an equivalent pathogen control effect is exhibited using the drug not encapsulated in the particles, the drug concentration is defined as concentration B, the value calculated by the formula: [(concentration B - concentration A) / concentration B] × 100 is about 50%.

[0006] The present inventor aims to provide a technique capable of further increasing the pesticide reduction rate of a drug.

Means for Solving the Problems

[0007] As a result of intensive research in view of the above problems, the present inventor has found that the above problems can be solved if it is a composite particle containing a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility at 20°C of 1 mg / L or more and 100 mg / L or less. Based on this finding, the present inventor has further conducted research and as a result, completed the present invention. That is, the present invention includes the following aspects.

[0008] Item 1. Composite particles containing a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility at 20°C of 1 mg / L or more and 100 mg / L or less.

[0009] Item 2. The composite particles according to Item 1, wherein the water solubility at 20°C of the horticultural fungicide is 2 mg / L or more and 20 mg / L or less.

[0010] Item 3. The composite particles according to Item 1, further containing a water-soluble polymer.

[0011] Item 4. The composite particles according to Item 1, wherein the weight average molecular weight of the lactic acid-glycolic acid copolymer is 2000 or more and 100000 or less.

[0012] Item 5. The composite particles according to Item 1, wherein the molar ratio of the glycolic acid unit to the lactic acid unit in the lactic acid-glycolic acid copolymer is 0.1 to 10.0.

[0013] Item 6. Particle diameter D p50 The composite particles according to Item 1, wherein the particle diameter is 500 nm or less.

[0014] Item 7. The composite particles according to Item 1, wherein the content of the horticultural fungicide is 10% by mass or more and 95% by mass or less with respect to 100% by mass of the composite particles.

[0015] Item 8. A pesticide containing the composite particles according to any one of Items 1 to 7.

[0016] Item 9. The pesticide according to Item 8, which is in a liquid state.

[0017] Item 10. The pesticide according to Item 8, which is for controlling diseases caused by filamentous fungi.

Advantages of the Invention

[0018] According to the present invention, it is possible to provide a technique capable of further increasing the pesticide reduction rate of a drug. Specifically, it is possible to provide composite particles containing a drug, a pesticide containing the composite particles, a method for producing the composite particles, and the like.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0020] In this specification, the expressions "containing" and "comprising" include the concepts of "containing", "comprising", "consisting essentially of", and "consisting only of".

[0021] In one aspect, the present invention relates to composite particles (which may also be referred to as "the composite particles of the present invention" in this specification) containing a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility at 20°C of 1 mg / L or more and 100 mg / L or less. This will be described below.

[0022] The lactic acid-glycolic acid copolymer is a copolymer of lactic acid units and glycolic acid units, and is a polymer sometimes referred to as PLGA.

[0023] The lactic acid unit is of the formula (a):

[0024]

Chem.

[0025] and is the unit represented by it.

[0026] The glycolic acid unit is of the formula (b):

[0027]

Chem.

[0028] and is the unit represented by it.

[0029] The weight average molecular weight of the lactic acid-glycolic acid copolymer is not particularly limited as long as it can form particles. The said weight average molecular weight is, for example, 1000 or more and 500000, preferably 2000 or more and 100000 or less, more preferably 3000 or more and 60000 or less, still more preferably 4000 or more and 40000 or less, even more preferably 5000 or more and 30000 or less, and particularly preferably 5000 or more and 25000 or less.

[0030] The weight average molecular weight of the lactic acid-glycolic acid copolymer can be measured by the GPC (gel permeation chromatography) method.

[0031] The molar ratio of glycolic acid units to lactic acid units in the lactic acid-glycolic acid copolymer is not particularly limited, and is, for example, 0.1 or more and 10.0 or less. In one aspect, the molar ratio is preferably 0.2 or more and 5.0 or less, more preferably 0.3 or more and 3.0 or less, still more preferably 0.4 or more and 2.5 or less, even more preferably 0.5 or more and 2.0 or less, particularly preferably 0.6 or more and 1.7 or less, particularly more preferably 0.7 or more and 1.5 or less, particularly still more preferably 0.8 or more and 1.3 or less, and particularly preferably 0.9 or more and 1.2 or less.

[0032] The molar ratio of glycolic acid units to lactic acid units in the lactic acid-glycolic acid copolymer can be measured by subjecting the lactic acid-glycolic acid copolymer to quantitative NMR.

[0033] The structure of the terminal of the lactic acid-glycolic acid copolymer is not particularly limited, and may be, for example, a carboxy group derived from lactic acid or glycolic acid, or an alkyl ester of the carboxy group.

[0034] The lactic acid-glycolic acid copolymer may be a single species or a combination of two or more species.

[0035] The lactic acid-glycolic acid copolymer can be produced according to or in accordance with known methods. Also, commercially available products can be used as the lactic acid-glycolic acid copolymer.

[0036] The horticultural fungicide is a fungicide used in the cultivation of vegetables, fruit trees, garden trees, flowers, etc., and is not particularly limited as long as it is used for such purposes.

[0037] The fungicidal targets of the horticultural fungicide are not particularly limited as long as they are plant pathogens, and examples include filamentous fungi, oomycetes, etc. Among these, filamentous fungi are preferred from the viewpoint of being particularly suitable for the composite particles of the present invention.

[0038] Examples of the filamentous fungi include plant pathogenic filamentous fungi belonging to the genus Botrytis, plant pathogenic filamentous fungi belonging to the genus Colletotrichum, plant pathogenic filamentous fungi belonging to the genus Fusarium, and plant pathogenic filamentous fungi belonging to the genus Pyricularia.

[0039] Examples of the plant pathogenic filamentous fungi belonging to the genus Botrytis include Botrytis aclada, Botrytis byssoidea, Botrytis cinerea, Botrytis convoluta, Botrytis diospyri, Botrytis elliptica, Botrytis fabae, Botrytis galanthina, Botrytis gladiolorum, Botrytis paeoniae, Botrytis polyblastis, Botrytis sp., Botrytis squamosa, and Botrytis tulipae.

[0040] Plant pathogenic filamentous fungi belonging to the genus Colletotrichum include Colletotrichum actinidiicola, Colletotrichum acutatum, Colletotrichum aenigma, Colletotrichum ampelopsidis, Colletotrichum belamcandium, Colletotrichum boninense sensu lato, Colletotrichum capsici, Colletotrichum carthami, Colletotrichum caudatum, Colletotrichum chrysanthemi, Colletotrichum circinans, Colletotrichum coccodes, Colletotrichum coffeanum, Colletotrichum corchori, Colletotrichum crassipes, Colletotrichum cypripedii, Colletotrichum daphnicola, Colletotrichum dematium, Colletotrichum destructivum, Colletotrichum durionis, Colletotrichum echinochloae, Colletotrichum elasticae, Colletotrichum fatsiae, Colletotrichum fioriniae, Colletotrichum fuscum, Colletotrichum gloeosporioides, Colletotrichum godetiae, Colletotrichum graminicola, Colletotrichum hibisci, Colletotrichum higginsianum, Colletotrichum horii, Colletotrichum hydrangeae, Colletotrichum kahawae, Colletotrichum karstii, Colletotrichum koyasuensis, Colletotrichum lappae, Colletotrichum liliacearum, ColletotrichumExamples include lilii, Colletotrichum lindemuthianum, Colletotrichum malvarum, Colletotrichum medicaginis-denticulatae, Colletotrichum metake, Colletotrichum moricola, Colletotrichum morinum, Colletotrichum musae, Colletotrichum nigrum, Colletotrichum nymphaeae, Colletotrichum orbiculare, Colletotrichum panacicola, Colletotrichum paniculatae, Colletotrichum pehkinense, Colletotrichum phaseolorum, Colletotrichum sansevieriae, Colletotrichum sasicola, Colletotrichum siamense, Colletotrichum sophorae-japonicae, Colletotrichum spaethianum, Colletotrichum spinaciae, Colletotrichum sublineolum, Colletotrichum tabacum, Colletotrichum theobromicola, Colletotrichum trichellum, Colletotrichum trifolii, Colletotrichum tropicale, Colletotrichum truncatum, Colletotrichum villosum, and Colletotrichum yoshinoi.

[0041] Examples of phytopathogenic filamentous fungi belonging to the genus Fusarium include Fusarium acuminatum, Fusarium ananatum, Fusarium anguioides, Fusarium arthrosporioides, Fusarium asiaticum, Fusarium avenaceum, Fusarium brasiliense, Fusarium commune, Fusarium conglutinans var. betae, Fusarium cuneirostrum, Fusarium decemcellulare, Fusarium dimerum var. dimerum, Fusarium foetens, Fusarium fujikuroi, Fusarium graminearum, Fusarium guttiforme, Fusarium lactis, Fusarium lagenariae, Fusarium lateritium, Fusarium merismoides, Fusarium oxysporum, Fusarium pallidoroseum, Fusarium pallidum, Fusarium phaseoli, Fusarium phyllophilum, Fusarium poae, Fusarium proliferatum, Fusarium redolens, Fusarium ricini, Fusarium roseum, Fusarium solani, Fusarium striatum, Fusarium subglutinans, and Fusarium verticillioides.

[0042] Examples of phytopathogenic filamentous fungi belonging to the genus Pyricularia include Pyricularia grisea, Pyricularia higginsii, Pyricularia oryzae, Pyricularia panici, and Pyricularia zingiberis.

[0043] In addition to these, examples of plant pathogenic fungi include fungi belonging to the genus Phytophthora, the genus Alternaria, the genus Cladosporium, the genus Claviceps, the genus Sclerotinia, the genus Septoria, the genus Pseudoperonospora, and the genus Puccinia.

[0044] In one aspect of the present invention, particularly when using penthiopyrad or a drug that exerts a bactericidal action through a similar pathway, the targets for sterilization preferably include fungi belonging to the Basidiomycetes (such as Gymnosporangium asiaticum, Puccinia graminis, etc.), fungi belonging to the Ascomycetes (such as Podosphaera aphanis, Colletotrichum acutatum, Didymella bryoniae, Sclerotinia sclerotiorum, Guignardia bidwellii, Venturia inaequalis, Monilinia fructicola, Venturia pirina, Alternaria alternata, etc.), fungi belonging to the Deuteromycetes (such as Botrytis cinerea, Alternaria solani, Marssonina coronaria, Alternaria tomatophila, Alternaria mali, Cercospora viticola, Rhizoctonia solani, etc.).

[0045] As general horticultural fungicides, specifically, for example, benalaxyl, benalaxyl-M or kiralaxyl, oxadixyl, furaxyl, metalaxyl, metalaxyl-M or mefenoxam, ofurace, benomyl, carbendazim, fuberidazole, thiabendazole, thiophanate, thiophanate-methyl, diethofencarb, zoxamide, ethaboxam, penthiopyrad, fluopicolide, fenamacril, benodanil, benzovindiflupyr, bixafen, boscalid, carboxin, fenfluram, fluopyram, flutolanil, fluxapyroxad, flutriafol, isofetamid, isopyrazam, mepronil, oxycarboxin, penthiopyrad, penflufen, pidiflumetofen, sedaxane, difenoconazole, pyraclostrobin, pyraoxystrobin, pyribencarb, triclopyricarb, trifloxystrobin, cyazofamid, amisulbrom, binapacryl, meptyldinocap, dinocap, fluazinam, ametoctradin, cyprodinil, mepanipyrim, pyrimethanil, streptomycin, blasticidin S, kasugamycin, oxytetracycline, fenpiclonil, fludioxonil, quinoxyfen, proquinazid, chlorothalonil, dimethachlon, iprodione, procymidone, vinclozolin, edifenphos, iprobenfos, pyrazophos, isoprothiolane, biphenyl, chloroneb, dichloran, quintozene, tecnazene, tolclofos-methyl, etridiazole, iodocarb, propamocarb, prothiocarb, azaconazole, bitertanol, bromoconazole, cyproconazole, difenoconazole, diniconazole, diniconazole-M, epoxyconazole, etaconazole, fenarimol, fenbuconazole, fluquinconazole, quinconazole, flusilazole, flutriafol, hexaconazole, imazalil, imibenconazole, ipconazole,Metconazole, Microbutanyl, Nuarimol, Oxpoconazole, Oxpoconazole fumarate, Pefurazoate, Penconazole, Prochloraz, Propiconazole, Prothioconazole, Pyriofenox, Pyrisoxazole, Shimeconazole, Tebuconazole, Tetraconazole, Triadimefon, Triadimenol, Triflumizole, Tricyclazole, Carpropamid, Diclocymet, Phenoxanil, Tolprocarb, Acibenzolar-S-methyl, Probenazole, Thiadinyl, Isothianyl, Laminarin, Mancozeb or Maneb, Manneb, Methylam, Propineb, Thiram, Dineb, Ziram, Ferbam, Captan, Captahol, Folpet, Fluorfolpet, Guazatine, Iminoctadine, Iminoctadine albesilate, Iminoctadine triacetate, Basic copper chloride, Cupric hydroxide, Basic copper sulfate, Organic copper compounds, Bis(ethylenediamine) copper(II) dodecylbenzenesulfonate complex salt, Sulfur, Fluorimide, Chlorothalonil, Dichlofluanid, Tolylfluanid, Anilazine, Dithianon, Quinomethionate, Extract from cotyledons of Vigna angularis seedlings (BLAD), Diclobentiazox, Fenpicoxamid, Diphenamidtron, Bupirimate, Dimethirimol, Ethirimol, Triphenyltin acetate, Triphenyltin chloride, Triphenyltin hydroxide, Oxolinic acid, Hymexazole, Octilinone, Phosphorous acid, Sodium phosphite, Ammonium phosphite, Potassium phosphite, Techlofthalam, Triazoxide, Flusulfamide, Diclomezine, Silthiopham, Diflumetorim, Metasulcarb, Ciflufenamid, Metrafenone, Pyriofenone, Dodine, Flutianil, Ferimzone, OxathiapiprolinExamples include tebufloquin, picarbutrazox, validamycins, simoxanil, quinofumelin, pyrapropion, ipfencarbazone, pyridachlometyl, methyltetraprole, imiproflam, fluindapyr, isoflupiprazam, aminopyrifen, etc.

[0046] Examples of horticultural fungicides include, for example, succinate dehydrogenase inhibitors, Qo inhibitors, demethylation inhibitors, melanin biosynthesis inhibitors, disease resistance inducers, etc. Examples of succinate dehydrogenase inhibitors include, for example, penthiopyrad, flutolanil, mepronil, fluopyram, thifluzamide, benzovindiflupyr, bixafen, fluxapyroxad, flametopyr, isopyrazam, penflufen, sedaxane, etc. Among them, penthiopyrad is preferred. Examples of Qo inhibitors include, for example, azoxystrobin, metominostrobin, orysastrobin, etc. Examples of demethylation inhibitors include, for example, cyproconazole, difenoconazole, epoxiconazole, etaconazole, fenbuconazole, hexaconazole, imibenconazole, ipconazole, metconazole, microbutanil, propiconazole,simeconazole, tebuconazole, prothioconazole, etc. Examples of melanin biosynthesis inhibitors include, for example, pyroquilon, tricyclazole, diclocymet, tolprocarb, etc. Examples of disease resistance inducers include, for example, probenazole, tiadinil, isothianil, etc.

[0047] The horticultural bactericide used in the present invention has a water solubility at 20°C of 1 mg / L or more and 100 mg / L or less. In the prior art (Non-Patent Document 1), a chemical agent with extremely low water solubility (cyazofamid, water solubility at 20°C is about 0.1 mg / L) was used. In this case, the pesticide reduction rate of the chemical agent was relatively low. In the present invention, by using a chemical agent with a water solubility of a certain level or more and capable of forming composite particles with a lactic acid-glycolic acid copolymer by a poor solvent dilution method using water as a poor solvent, it has been found that the pesticide reduction rate of the chemical agent can be further increased. The water solubility at 20°C of the horticultural bactericide is preferably 1 mg / L or more and 50 mg / L or less, more preferably 1 mg / L or more and 30 mg / L or less, still more preferably 1 mg / L or more and 20 mg / L or less, even more preferably 2 mg / L or more and 20 mg / L or less, particularly preferably 3 mg / L or more and 20 mg / L or less, preferably 3 mg / L or more and 15 mg / L or less, preferably 3 mg / L or more and 12 mg / L or less, preferably 4 mg / L or more and 12 mg / L or less, preferably 4 mg / L or more and 10 mg / L or less, from the viewpoint of the pathogenic control effect.

[0048] The molecular weight of the horticultural bactericide used in the present invention is not particularly limited as long as it can form composite particles with a lactic acid-glycolic acid copolymer by a poor solvent dilution method using water as a poor solvent. The molecular weight is, for example, 1000 or less, preferably 100 or more and 1000 or less, more preferably 100 or more and 700 or less, still more preferably 200 or more and 700 or less, even more preferably 200 or more and 500 or less.

[0049] The horticultural bactericide may be a single species or a combination of two or more species.

[0050] The horticultural bactericide can be produced according to or in accordance with a known method. Also, a commercially available product can be used as the horticultural bactericide.

[0051] The content of the horticultural bactericide is not particularly limited, but is, for example, 10% by mass or more and 95% by mass or less based on 100% by mass of the composite particles of the present invention. From the viewpoint of the pathogen control effect, the content is preferably 20% by mass or more and 90% by mass or less, more preferably 40% by mass or more and 80% by mass or less, still more preferably 50% by mass or more and 75% by mass or less, and particularly preferably 60% by mass or more and 70% by mass or less.

[0052] The content of the horticultural bactericide with respect to 100% by mass of the composite particles of the present invention can be calculated by measuring the weight of the horticultural bactericide in the particles and the dry weight of the particles according to the method described in 1.3 of the examples described below, and dividing the former value by the latter value.

[0053] The composite particles of the present invention can contain other components in addition to the above-described components (lactic acid-glycolic acid copolymer and horticultural bactericide). Examples of other components include water-soluble polymers.

[0054] Examples of the water-soluble polymer include polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl caprolactam, poly(meth)acrylic acid, polyacrylamide, and the like. Among these, from the viewpoint of safety and the like, polyvinyl alcohol and polyvinyl pyrrolidone are preferably mentioned, and polyvinyl alcohol is particularly preferably mentioned. In addition to the above, examples of the water-soluble polymer also include natural water-soluble polymers such as polysaccharides, and semi-synthetic water-soluble polymers such as derivatives of polysaccharides (for example, hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), and sodium carboxymethyl cellulose (Na-CMC), etc.).

[0055] The weight average molecular weight of the water-soluble polymer is not particularly limited. The weight average molecular weight is, for example, 1000 or more and 500000, preferably 5000 or more and 100000 or less, more preferably 10000 or more and 50000 or less, and still more preferably 15000 or more and 30000 or less.

[0056] The weight average molecular weight of the water-soluble polymer can be measured by the GPC (gel permeation chromatography) method.

[0057] When the composite particles of the present invention contain a water-soluble polymer, the water-soluble polymer may be a single species or a combination of two or more species.

[0058] When the composite particles of the present invention contain a water-soluble polymer, the mode of arrangement of the water-soluble polymer is not particularly limited, and examples thereof include a mode of covering the surface of the particles. Thereby, the adhesiveness to the plant body can be further improved.

[0059] Other components other than the water-soluble polymer are not particularly limited as long as they do not significantly inhibit the particle formation of the composite particles of the present invention.

[0060] The total content of the lactic acid-glycolic acid copolymer and the horticultural bactericide (when including the water-soluble polymer, the total content including the water-soluble polymer) is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, particularly preferably 98% by mass or more, based on 100% by mass of the composite particles of the present invention.

[0061] The particle diameter D of the composite particles of the present invention p50 is not particularly limited, and is, for example, nano size (less than 1000 nm). The particle diameter D p50 is preferably a smaller value, for example, preferably 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 150 nm or less. Thereby, the adhesiveness to the plant body can be further improved. The particle diameter D p50 has no particular lower limit, and is, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm.

[0062] The particle diameter D p50 can be measured according to the method described in Example 1.8.

[0063] The composite particles of the present invention can be produced by a poor solvent dilution method. Specifically, the composite particles of the present invention can be produced by a method including mixing a good solvent solution containing a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility of 1 mg / L or more and 100 mg / L or less at 20°C with a poor solvent solution that is water or an aqueous solution.

[0064] In one aspect, the present invention relates to a method for producing the composite particles of the present invention (which may also be referred to as "the production method of the present invention" in this specification), including mixing a good solvent solution containing a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility of 1 mg / L or more and 100 mg / L or less at 20°C with a poor solvent solution that is water or an aqueous solution.

[0065] In one aspect, the composite particles of the present invention are composite particles obtained by the method.

[0066] As the good solvent, a solvent that can well dissolve the lactic acid-glycolic acid copolymer and the above horticultural fungicide can be used, preferably acetone. In addition to acetone, for example, polar solvents such as tetrahydrofuran, acetonitrile, and dimethyl sulfoxide can also be used.

[0067] The concentration of the lactic acid-glycolic acid copolymer in the good solvent solution is, for example, 1 g / L or more and 50 g / L or less, preferably 3 g / L or more and 30 g / L or less, more preferably 5 g / L or more and 20 g / L or less, and particularly preferably 7 g / L or more and 15 g / L or less.

[0068] The concentration of the above horticultural fungicide in the good solvent solution is, for example, 1 g / L or more and 100 g / L or less, preferably 3 g / L or more and 50 g / L or less, more preferably 5 g / L or more and 30 g / L or less, still more preferably 7 g / L or more and 20 g / L or less, and particularly preferably 8 g / L or more and 15 g / L or less.

[0069] When producing the composite particles of the present invention containing a water-soluble polymer, an aqueous solution containing the water-soluble polymer is used as the poor solvent solution. The concentration of the water-soluble polymer in the aqueous solution is, for example, 5 g / L or more and 60 g / L or less, preferably 10 g / L or more and 40 g / L or less, more preferably 10 g / L or more and 30 g / L or less, and particularly preferably 15 g / L or more and 25 g / L or less.

[0070] The volume ratio of the poor solvent solution to the good solvent solution is, for example, 1 or more, preferably 2 or more and 500 or less, more preferably 5 or more and 300 or less, still more preferably 10 or more and 200 or less, even more preferably 20 or more and 150 or less, and particularly preferably 30 or more and 100 or less.

[0071] The method of mixing the good solvent solution and the poor solvent solution is preferably a method of adding (preferably dropping) the good solvent solution to the poor solvent solution. At this time, it is preferable to stir the added side (poor solvent solution). By mixing the two solutions, turbidity occurs, and thereby the composite particles of the present invention are formed.

[0072] The production method of the present invention further preferably includes stirring for a certain period of time (for example, 5 minutes or more, 10 minutes or more, 20 minutes or more, and also 5 hours or less, 3 hours or less, 2 hours or less, 1 hour or less). Thereby, the particles can be stabilized, and when using a water-soluble polymer, the water-soluble polymer can be adhered to the particles.

[0073] The production method of the present invention can include post-treatment such as purification treatment as necessary. Examples of such treatment include treatment for removing components such as drugs and copolymers that are not forming particles (for example, centrifugation, dialysis, etc.), and treatment for dispersing in a solvent (for example, water).

[0074] The composite particles of the present invention have an excellent pathogen control effect and can be used as agricultural chemicals. Therefore, in one aspect, the present invention relates to an agricultural chemical (which may also be referred to as "the agricultural chemical of the present invention" in this specification) containing the composite particles of the present invention.

[0075] The target plants of the pesticide of the present invention can be appropriately selected according to the type of horticultural fungicide and are not particularly limited. For example, it can be widely applied to angiosperms (dicotyledons, monocotyledons, etc.). Specific examples include solanaceous plants such as tomatoes, peppers, chili peppers, and eggplants; cucurbitaceous plants such as cucumbers, pumpkins, melons, and watermelons; cruciferous vegetables such as cabbages, broccoli, and Chinese cabbages; leafy or aromatic vegetables such as celery, parsley, and lettuce; alliums such as leeks, onions, and garlic; legumes such as soybeans, peanuts, kidney beans, peas, and azuki beans; other fruit vegetables such as strawberries; root vegetables such as daikon radishes, turnips, carrots, and burdocks; tuberous plants such as taros, cassavas, potatoes, sweet potatoes, and yams; leafy vegetables such as asparagus, spinach, Komatsuna, mizuna, purslane, nasturtium, Japanese butterbur, perilla, etc.; flower crops such as Turkish carnations, stocks, carnations, and chrysanthemums; cereals such as rice, wheat, barley, oats, corn, and quinoa; lawn grasses such as bentgrass and Korean lawn grass; oil crops such as rapeseed and peanuts; sugar crops such as sugarcane and sugar beets; fiber crops such as cotton and rush; forage crops such as clover, sorghum, and dent corn; deciduous fruit trees such as apples, pears, grapes, and peaches; citrus fruits such as Satsuma mandarins, lemons, and grapefruits; root vegetables such as ginger, taro, and sweet potato; flowering shrubs such as roses and hydrangeas, etc.

[0076] The pesticide of the present invention can be used for disease control.

[0077] Examples of the pathogenic bacteria causing diseases include the above-mentioned plant pathogenic bacteria.

[0078] The diseases targeted by the pesticide of the present invention can be appropriately selected according to the type of horticultural fungicide and are not particularly limited. Examples of the diseases include gray mold, powdery mildew, scab, gray star disease, sclerotinia, damping-off, bacterial wilt, downy mildew, anthracnose, vine blight, vine splitting disease, phytophthora blight, ring spot disease, wilt disease, root rot, seaweed disease, sooty mold, brown rot, red star disease, red rust, black mold, monilia disease, Dallas spot disease, leaf blotch, leaf mold, black spot, brown spot, brown patch disease, etc.

[0079] The pesticide of the present invention may consist only of the composite particles of the present invention, or may contain components (additives) other than the composite particles of the present invention. Examples of the additives include carriers, fixing agents, dispersants, auxiliary agents, etc. Examples of the carriers include solid carriers such as talc, bentonite, clay, kaolin, diatomaceous earth, white carbon, vermiculite, and silica sand; liquid carriers such as water-soluble polymer compounds (polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, etc.), water, vegetable oil, and liquid animal oil. Examples of the fixing agents include casein, gelatin, gum arabic, and alginic acid. Examples of the dispersants include alcohol sulfates, polyoxyethylene glycol ethers, etc. Examples of the auxiliary agents include carboxymethyl cellulose, starch, lactose, etc. The above additives can be used alone or in appropriate combinations according to their respective purposes.

[0080] The form of the pesticide of the present invention is not particularly limited and can be appropriately selected according to the target disease and is not particularly restricted. Examples of the form include liquid (such as aqueous liquid, oily liquid, emulsion liquid, etc.), semi-solid (such as paste, gel, etc.), solid (such as powder, granule, capsule, etc.).

[0081] The concentration of the above-mentioned horticultural fungicide in the pesticide of the present invention can be appropriately selected according to the type of horticultural fungicide and is not particularly limited. The concentration can be, for example, 0.001 mg / L or more and 500 mg / L or less, 0.01 mg / L or more and 100 mg / L or less, or 0.02 mg / L or more and 20 mg / L or less. The pesticide of the present invention can exhibit a higher disease control effect even when the content of the horticultural fungicide is less than that in the case of using the horticultural fungicide alone (without compound granulation). When a certain pathogen control effect (for example, the growth inhibition rate measured according to or in accordance with 2.3 of the examples is 80-90%, and the infection prevention rate measured according to or in accordance with 2.4 of the examples is 80-90%) is exhibited using the composite particles of the present invention, the drug concentration in this case is defined as concentration A, and when the same pathogen control effect is exhibited using the drug not encapsulated in the particles, the drug concentration in this case is defined as concentration B, the value calculated by the formula: [(concentration B - concentration A) / concentration B]×100 (pesticide reduction rate, unit: %) is, for example, 80% or more, preferably 90% or more, more preferably 95% or more, still more preferably 97% or more, and particularly preferably 98% or more.

[0082] The application mode of the pesticide of the present invention is not particularly limited as long as the composite particles of the present invention can reach the plant pathogen. The application mode is not particularly limited as long as it is a mode known (or a mode to be developed in the future) as the use mode of the pesticide. For example, spraying, dripping, coating, mixing or dissolving into the plant growth environment (in soil, water, solid medium, liquid medium, etc.) can be mentioned.

Examples

[0083] Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited by these examples.

[0084] 1. Experimental method 1.1 Experimental samples The agrochemical used was Penthiopyrad (PP), provided by Mitsui Chemicals Crop & Life Solutions, Inc. Penthiopyrad is an amide fungicide with poor solubility in water at 20°C of 7.53 mg / L, and is therefore provided as a flowable formulation in which a dispersant is added and the fungicide is suspended in water to form a liquid. A commercially available flowable formulation, Affet Flowable (Mitsui Chemicals Crop & Life Solutions), which contains Penthiopyrad as the active ingredient, was used for comparison. The content of the active ingredient Penthiopyrad is 20.0%, and it also contains surfactants. The plant used was tomato (variety: Momotaro Hope), and the plant pathogen was Botrytis cinerea ATCC 46522 strain. Acetone, acetonitrile, polyvinyl alcohol (PVA) with a degree of polymerization of approximately 500 (weight-average molecular weight 22,000), formamide, glycerol, and α-bromonaphthalene were purchased from Fujifilm Wako Pure Chemical Industries, Ltd. (Osaka, Japan), polylactic acid-glycolic acid copolymer (PLGA) with a 50:50 ratio of lactic acid and glycolic acid and a weight-average molecular weight of 7000 to 17,000, coumarin 6, and calcofluor white were purchased from Sigma-Aldrich (St. Louis, MO, USA), and potato dextrose broth (PDB) was purchased from BD Difco (Franklin Lakes, NJ, USA). The purchased reagents were used as received.

[0085] 1.2 Cultivation of Botrytis cinerea and preparation of spore and mycelium suspension The Botrytis cinerea was cultured in the dark at 25°C using potato dextrose agar (PDA) medium containing PDB and 1.5 wt% agar. After one week of culture, 1 / 2 PDB (a liquid medium in which PDB was diluted 1 / 2 with water) was added to the agar plate on which spores had formed, and the spores were scraped off with a T-shaped spreader and a spore concentration of 1 × 10 was measured using a hematometer. 6A suspension of 1000 spores / mL was prepared. A 6 mm diameter paper disk (PP disk) (antibiotic test filter paper, Toyo Roshi) was immersed in the spore suspension to prepare a PP disk containing spores of Botrytis cinerea. The PDA agar medium on which Botrytis cinerea was cultured was punched out with a straw and dispensed into 1 mL of DW. After stirring with a vortex mixer, the supernatant was collected and used as a mycelium suspension of Botrytis cinerea.

[0086] 1.3 Synthesis of penthiopyrad-encapsulated PLGA nanoparticles Penthiopyrad-encapsulated PLGA nanoparticles were synthesized by the poor solvent dilution method. The synthesis procedure is as follows. 500 μL of an acetone solution containing penthiopyrad bulk material (0-40 mg) and PLGA (5 mg) was dropped into 19.5 mL of a 2 w / v% PVA aqueous solution and stirred (200 rpm) at room temperature for 30 minutes. The resulting particles were centrifuged at 15,000 rpm for 10 minutes at 4°C, and the supernatant was decanted to remove unencapsulated penthiopyrad. The pellets after centrifugation were vacuum dried to measure the dry weight of the resulting particles. The encapsulation efficiency of penthiopyrad was evaluated by dissolving the pellets in acetonitrile and measuring the maximum absorption wavelength of 227 nm (molar extinction coefficient is 1.51 × 10) using an absorption spectrometer. 4 The concentration of penthiopyrad was calculated by quantifying the amount of penthiopyrad in units of L / (cm mol). The pellets were redispersed in pure water and adjusted to the desired penthiopyrad concentration before use. To observe the behavior of PLGA particles, the green fluorescent reagent coumarin 6 (5 μg) was dissolved in acetone instead of penthiopyrad bulk compound, and green fluorescent PLGA nanoparticles were synthesized by the same procedure as above.

[0087] 1.4 Exposure of PLGA nanoparticles to Botrytis cinerea Fluorescent PLGA nanoparticles were added to the mycelium suspension (1.2 above) and exposed for 30 minutes. The cell walls were then stained with 0.5 μL of 1 mg / mL calcofluor white, and the localization of the PLGA nanoparticles was observed using a confocal laser scanning microscope (CLSM) (Olympus, FV-1000D).

[0088] 1.5 Growth inhibition experiment of Botrytis cinerea 0.1 mL of pesticide was sprayed onto the PDA medium and air-dried. Next, a PP disk containing spores of Botrytis cinerea was placed at the center of the PDA medium, and it was left standing in the dark at 25°C. Starting from 3 days later, the PDA medium was photographed daily with a digital camera, and the infection area was calculated by image analysis using ImageJ. The growth inhibition rate of Botrytis cinerea was calculated based on the colony area when using DW as the reference (100%). As the pesticide, a suspension of penthiopyrad-encapsulated PLGA particles with the penthiopyrad concentration adjusted to 0 - 100 mg / L was used. Also, the control effects were compared by conducting the same experiments on a commercially available flowable formulation (FL) and pure water (DW).

[0089] 1.6 Infection prevention experiment of Botrytis cinerea 0.1 mL of pesticide was sprayed onto the leaf surface of tomato (cut leaf), left standing on an agar plate and air-dried, then a PP disk immersed in the spore suspension was placed on the leaf surface, and it was left standing in the dark at 25°C. Starting from 3 days later, the leaf surface was photographed with a digital camera, the outline of the leaf was shaped using ImageJ, and the infection area was calculated by image analysis by binarizing the leaf surface. Also, an infection prevention experiment was conducted using potted tomatoes. After spraying 0.1 mL of pesticide per leaf and air-drying, a spore suspension (1×10 6 conidia / mL) dispersed in 1 / 2 PDB at 0.1 mL per branch was sprayed, and it was cultivated under the conditions of 25°C, relative humidity 80%, 12 hours in the light, and 12 hours in the dark using an artificial weather chamber (Nippon Medical Chemical Instruments Co., Ltd., LPH-241SP). Starting from 3 days later, the disease incidence was calculated using the following formula.

[0090]

Equation

[0091] Here, the disease index was set as follows: 4: more than 25% infected, 3: more than 10% and less than 25%, 2: more than 3% and less than 10%, 1: less than 3%, 0: no infection.

[0092] 1.7 Characterization The particle size distribution and electrophoretic mobility (EPM) of PLGA nanoparticles and spores of Botrytis cinerea were measured using a zeta potential and particle size measurement system (Otsuka Electronics, ELS-Z). The zeta potential of PLGA nanoparticles and spores dispersed in water was estimated from the EPM using the Smoluchowski equation.

[0093] Using a dynamic contact angle measurement device, the contact angles of PLGA nanoparticles, Botrytis cinerea, and tomato leaves were measured by the droplet method of dropping a droplet formed at the tip of a needle onto the sample surface, and the surface tension was estimated using Young-Dupre's equation. Polar solvents with different polarities (water, formamide, glycerol, α-bromonaphthalene) were used for the droplets. For PLGA nanoparticles, previous literature values were used. Botrytis cinerea cultured on PDA medium for 7 days was used. Furthermore, using the obtained surface tension, ΔG was estimated as the sum of the surface free energy changes of non-polar interaction (LW) and acid-base polar interaction (AB) given by the following equation, and the thermodynamic adhesion characteristics were evaluated. Total was estimated and the thermodynamic adhesion characteristics were evaluated.

[0094]

Equation

[0095] Here, the subscript B means B. cinerea or tomato leaf, L means water, and S means PLGA nanoparticles.

[0096] 2. Experimental results and discussion 2.1 Exposure of PLGA nanoparticles to Botrytis cinerea Figure 1 shows the CLSM images when green fluorescent PLGA nanoparticles labeled with coumarin 6 were exposed to the hyphae of Botrytis cinerea. It was observed that the green fluorescent PLGA nanoparticles were localized inside the cell wall fluorescently colored blue with respect to the hyphae of Botrytis cinerea. From this, it was found that biodegradable PLGA nanoparticles are effective as carrier particles for delivering pesticides to filamentous fungi.

[0097] The contact angles of Botrytis cinerea, PLGA nanoparticles, and tomato leaves are shown in Table 1, and the surface tensions estimated using the Young-Dupre equation based on the measured contact angles are shown in Table 2. The water contact angles of Botrytis cinerea and tomato leaves were hydrophobic, at over 90 degrees. On the other hand, even though PLGA is a hydrophobic polymer, the water contact angle of PLGA nanoparticles was hydrophilic, at 52 degrees. This is because hydrophilic PVA is adsorbed onto the surface of the PLGA nanoparticles. Next, Table 3 shows the change in Gibbs free energy when PLGA nanoparticles adhere to the surfaces of Botrytis cinerea and tomato leaves. ΔG Total was negative. This suggests that the PLGA nanoparticles are thermodynamically favorable for adhesion to Botrytis cinerea. In addition, ΔG Total The zeta potential of PLGA nanoparticles and Botrytis cinerea (spores) is shown in Table 4. As both are negatively charged, electrostatic repulsion acts, but according to the DLVO theory, there was no potential barrier that prevented the two from approaching each other. This is because the particle diameter of the PLGA nanoparticles is small. Therefore, it is presumed that the PLGA nanoparticles that thermodynamically adhered to the surface of Botrytis cinerea were taken up into the cells by endocytosis.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] [Table 4]

[0102] 2.2 Synthesis of penthiopyrad-encapsulated PLGA nanoparticles The number-based median diameter D of the penthiopyrad-encapsulated PLGA nanoparticles synthesized by the poor solvent dilution method was determined by changing the concentration of penthiopyrad dissolved in acetone. p50 And the encapsulation efficiency of penthiopyrad are shown in Figs. 2 and 3, and the geometric standard deviation σ g is added and summarized in Table 5. Also, the median diameter of the generated particles was about 100 nm under the condition that the penthiopyrad concentration was 4 to 20 g / L, but it was found that the diameter increased when the concentration was 40 g / L or more. The geometric standard deviation σ g was 1.2 to 1.3 regardless of the penthiopyrad concentration. The encapsulation efficiency of penthiopyrad was the highest at about 76% under the condition that the penthiopyrad concentration was 10 g / L. It is speculated that the low encapsulation efficiency under the condition of 4 g / L was due to the low precipitation rate caused by the dissolution of penthiopyrad. On the other hand, when the penthiopyrad concentration was 20 g / L or more, it was speculated that the penthiopyrad not encapsulated in PLGA was granulated and aggregated with the PLGA particles, resulting in an increase in the particle diameter. From the above, penthiopyrad-encapsulated PLGA nanoparticles were synthesized under the condition that the penthiopyrad concentration in the acetone solution was 10 g / L, where the generated particles were small and the encapsulation efficiency was high. The particle size distribution of the obtained penthiopyrad-encapsulated PLGA nanoparticles is shown in Fig. 4. The penthiopyrad-encapsulated PLGA nanoparticles are spherical, with the number-based median diameter D p50 = 110 ± 9 nm, the geometric standard deviation σ g = 1.20, the surface potential was -22 ± 2 mV, and the encapsulation efficiency of penthiopyrad was 79.4 ± 2.6%. In the following experiments, the penthiopyrad-encapsulated PLGA nanoparticles synthesized under these conditions were adjusted to a predetermined concentration and then used in the experiments.

[0103]

Table 5

[0104] 2.3 Growth inhibition of Botrytis cinerea Figure 5 shows the time course of the infection area of ​​Botrytis cinerea when the concentration of penthiopyrad-encapsulated PLGA nanoparticles was changed from 0 to 100 mg / L and sprayed on PDA agar medium. The infection area of ​​DW without pesticide spraying was set as 100%, and the growth inhibition rate on the third day was plotted against the concentration of penthiopyrad. The growth inhibition rate was almost constant when cultured for 3 to 5 days. From these results, when the growth inhibition rate of penthiopyrad-encapsulated PLGA nanoparticles and the flowable agent FL were compared at the same penthiopyrad concentration, it was found that the growth inhibition rate of Botrytis cinerea was clearly improved by encapsulating penthiopyrad in PLGA. Since there was no difference in the infection area when PLGA nanoparticles not encapsulated with penthiopyrad and DW were sprayed, it was confirmed that PLGA nanoparticles are not toxic to Botrytis cinerea. In addition, the concentration of penthiopyrad encapsulated in PLGA that gave the same growth inhibition rate of 85% as FL 100 ppm was about 1 ppm. This suggests that encapsulating penthiopyrad in PLGA can reduce the use of pesticides by approximately 99%.

[0105] 2.4 Infection prevention of Botrytis cinerea The effect of encapsulating agrochemicals in PLGA nanoparticles on the prevention of infection of plants by Botrytis cinerea was examined using cut leaves of tomatoes and tomatoes grown in pots. Figure 7 shows the change in the infection area over time when cut leaves of tomatoes sprayed with penthiopyrad at concentrations ranging from 0 to 100 mg / L were inoculated with Botrytis cinerea spores. Figure 8 shows the infection prevention rate on the fourth day, calculated with the infection area of ​​DW not sprayed with pesticide as 100%, plotted against the penthiopyrad concentration. As in the growth inhibition experiment of Botrytis cinerea using PDA agar medium, it was found that the infection prevention rate of Botrytis cinerea was clearly improved by encapsulating penthiopyrad in PLGA. In addition, the concentration of penthiopyrad encapsulated in PLGA, which gave an infection prevention rate of 83%, the same as FL 100 ppm, was about 1 ppm. This suggests that encapsulating penthiopyrad in PLGA can prevent infection with a reduction in pesticide use of about 99%.

[0106] Next, Figure 9 shows the disease severity when spores of the gray mold fungus were inoculated onto pot-grown tomatoes sprayed with penthiopyrad-encapsulated PLGA nanoparticles, and Figure 10 shows the infection prevention rate on the 4th day calculated with the disease severity of DW set at 100%. Similar to the growth inhibition experiment using agar medium and the infection prevention experiment using tomato leaf discs, it was demonstrated that the encapsulation effect of penthiopyrad in PLGA was high also in pot-grown tomatoes. Also, when comparing the three types of control experiments at FL 100 ppm, it was found that the control rate of FL decreased by about 15% in pot cultivation. On the other hand, there was almost no decrease with PLGA encapsulating penthiopyrad. This is presumably because the leaves in pot cultivation are inclined, so liquid spray pesticides tend to flow down by their own weight, but the amount of adhesion was improved by using PLGA as carrier particles.

Claims

1. Composite particles containing a lactic acid-glycolic acid copolymer and a horticultural fungicide having a water solubility at 20°C of 1 mg / L or more and 100 mg / L or less.

2. The composite particles according to Claim 1, wherein the water solubility at 20°C of the horticultural fungicide is 2 mg / L or more and 20 mg / L or less.

3. The composite particles according to Claim 1, further comprising a water-soluble polymer.

4. The composite particles according to Claim 1, wherein the weight-average molecular weight of the lactic acid-glycolic acid copolymer is 2,000 or more and 100,000 or less.

5. The composite particles according to Claim 1, wherein the molar ratio of the glycolic acid unit to the lactic acid unit in the lactic acid-glycolic acid copolymer is 0.1 to 10.

0.

6. Particle diameter D p50 The composite particle according to claim 1, wherein p50 is 500 nm or less.

7. The composite particles according to Claim 1, wherein the content of the horticultural fungicide is 10% by mass or more and 95% by mass or less based on 100% by mass of the composite particles.

8. A pesticide containing the composite particles according to any one of Claims 1 to 7.

9. The pesticide according to Claim 8, which is in a liquid state.

10. The pesticide according to Claim 8, which is for controlling diseases caused by filamentous fungi.

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