• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.203-208
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• 2009

In order to elucidate the effect of spreader-stickers on the rainfastness of dithianon and chlorothalonil wettable powders, and to estimate the possibility of suggesting good new formulations, the fungicide residues on the leaf surface of hot pepper was assessed and compared after the drop-wise applications of fungicide suspensions containing spreader-sticker on leaf surface followed by artificial raining. Three commercial spreader-stickers, which were Cover, Reitron and Silwet, not only made the rainfastness of dithianon wettable powders worse on hot pepper leaf, but increasing their concentrations also accelerated it further. On the other hand, to chlorothalonil wettable powder, Reitron showed the 3-fold improvement of rainfastness. But, for the rest, there was no improvement as well. The effect of N-octylpyrrolidone (NOP) on rainfastness of both fungicides was excellent. Soybean oil formulations containing leaf-penetrable nonionic surfactant, which was either polyoxyethylene monotridecyl ether or polyoxyethylene monolauryl ether, improved dithianon rainfastness, but the ones containing conventional emulsifiers did not.

• Journal of Applied Biological Chemistry
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• v.52 no.3
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• pp.126-132
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• 2009

In order to elucidate the relationship between the rainfastness of fungicides and their water solubilities, the fungicide residues on the leaf surface of hot pepper was assessed and compared after the drop-wise applications of fungicide solutions on leaf surface followed by artificial raining. As the raining was progressed after application of aqueous acetone solution of fungicides, the residue levels of fungicides were drop rapid at the early stage of raining, but the decreasing rates of residue level were slowed down thereafter. The initial rainfastness was reversely proportional to the water solubilities of the fungicides. Whole amount of dimethomorph residue, which water solubility is 18 mg/L, was washed off by 2.5 mm of raining. Although WP formulations of fungicides showed remarkable decreases of rainfastness compared to the aqueous acetone formulations, the fungicides having low water solubility showed better rainfastness. Chlorothalonil and mepanipyrim suspension concentrates was better in rainfastness than their WP formulation, and the rainfastness of mepanipyrim suspension was reversely proportional to the median diameter of suspension particles in the range of 1 to 4 ${\mu}m$. In brief, the rainfastness of 5 fungicides tested on the pepper leaf was, in the early stage of raining, closely related to water solubility. But, as the raining is progressed, the effect of the unknown factor, which is related with the particle size of fungicides, becomes serious.

• Research in Plant Disease
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• v.20 no.3
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• pp.196-200
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• 2014

This study was carried out to determine the effect of mixing with paraffin oil on rainfastness of mancozeb on citrus fruits and assay the improvement of control effect of mancozeb against citrus melanose by mixing with paraffin oil. In artificial rainfall condition (7.2 mm/hr), the attached contents of mancozeb on detached fruits were the most in treatment of mancozeb 0.2% + paraffin oil 0.1% as the contents was $7.43{\mu}g/cm^2$ after treatment of rainfall for 10 hr. In open field condition, the contents of attached mancozeb on fruits were significantly more in treatment of mancozeb 0.2% + paraffin oil 0.1% or 0.25% than the other treatments 1, 15 and 25 days after treatment 2009 and 2010 seasons. The disease incidence was significantly lower in treatment of mancozeb 0.2% + paraffin oil 0.1% or 0.25% than treatment of mancozeb 0.2% only 2009, 2010 and 2011 seasons. Based on this study, it was suggested that the control effect of mancozeb against citrus melanose can be improved by mixing with paraffin oil.