Self-dispersible nanocrystals of azoxystrobin and cyproconazole with increased efficacy against soilborne fungal pathogens isolated from peanut crops

Self-dispersible nanocrystals of azoxystrobin and cyproconazole were obtained by combining wet bead milling and spray-drying. Nanocrystals formulations were characterized and evaluated by their antifungal activity against S. minor and S. rolfsii. The mean particle sizes of azoxystrobin and cyproconazole nanosuspensions were 172.78 and 277.37 nm. Milling rotational frequency and milling time were the most significant process parameters. The contents of azoxystrobin and cyproconazole in their solid formulations were 45.3 and 43.3% w/w. Spray-drying increased the particle size of fungicide nanocrystals (azoxystrobin, 323.68 nm; cyproconazole, 456.53 nm). The method of production showed a solid yield of 44.5% for azoxystrobin and 34.5% for cyproconazole. The methodology used in this study does not affect the crystallinity of fungicides. Nanocrystal formulations remarkably improved the performance of fungicides and have no negative consequences on peanut growth. The use of self-dispersible nanocrystals is presented as a potential technology to increase the efficacy of fungicides. (C) 2020 Elsevier B.V. All rights reserved.