First report of fruit rot caused by Phytophthora parsiana Mostowf., D.E.L. Cooke and Banihash, on arecanut in Western-Ghats of Southern India

Arecanut is an important commercial plantation crop in India, and many farm families depend solely on the arecanut industry. In July 2018, immature nuts were shed heavily due to fruit rot disease in the Western-Ghats region. Though the symptoms were suggestive of common fruit rot disease, they appeared to be unusual. The associated pathogen was isolated from the infected tissue using the standard isolation technique, and an oomycete fungus was consistently isolated from infected nuts. Based on the colony and spore morphology, the pathogen was identified as Phytophthora sp. and by multi-gene sequencing (ITS, β-tub, TEF-1α, and Cox-II) confirmed it as Phytophthora parsiana. The pathogenicity of the isolate (P25) was established by inoculating healthy arecanut fruits with the pin-prick method. To our knowledge, this is the pioneering work that represents the first report of Phytophthora parsiana infecting arecanut in Western-Ghats of Southern India.