Controlling rice blast in vitro and in vivo with extracts of Azadirachta indica

Water and ethanol leaf extracts, and oil extract of seeds of Azadirachta indica (neem) significantly reduced the in vitro radial growth of Pyricularia oryzae and the development and spread of blast disease in rice plants in the greenhouse. Oil extracts exhibited the best control of the pathogen and subsequent disease followed by ethanol extract, cold water and then hot water extracts. The oil, ethanol and cold water extracts of neem compared favourably with carbendazim at 0.1% a.i in controlling the pathogen in vivo. Neem appears to have the potential to be used for managing rice blast in the field. (C) 2000 Elsevier Science Ltd. All rights reserved.