Toxicity evaluation of hexaconazole controlled release formulations in field pea (Pisum sativum) against powdery mildew by laboratory bioassay and field efficacy

Hexaconazole, a triazole systematic fungicide highly efficient against ascomycetes, basidiomycetes, and imperfect fungi and widely used to control the fungal pathogens on a variety of crops and fruits. In the present study, hexaconazole was microencapsulated and controlled release performance was studied in laboratory and field experiment. Morphology and characteristics properties were investigated by the Fourier Transform Infrared (FTIR) Spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and Optical Microscopy. The controlled release rate and release kinetics were studied by applying the Korsmeyer–Peppas model. The obtained microcapsules have excellent encapsulation efficiency (up to 96%) and controlled release properties for the extended period of time (33% release of hexaconazole in 30 days). The release properties can be altered by the altering the polymer to active agent loading. Also, the encapsulation increases the stability of the hexaconazole and remains in the capsules for a longer time. Compared to hexaconazole-EC and technical hexaconazole, microencapsulation results in the longer durability of hexaconazole and hence reduced in the repeated applications. The lethal concentration of the hexaconazole to control the 50% colony growth inhibition was observed to be 0.435 and 0.489 mg a.i./L for A. Solani and S. Rolfsii, respectively.