First report of crown rot of coconut (Cocos nucifera L.) caused by Neodeightonia phoenicum in India

During February-March 2022, farmers reported about the rapid drying and rotting of the crown, and eventual death of coconut (Cocos nucifera L.) palms in and around Kannur and Kasaragod districts of Kerala state, India. The symptoms included drying and drooping of leaves, sudden nut fall, and rotting followed by the toppling of the crown portion within a quick span of 2–3 months. Initial disease symptoms were observed as leaf blight starting from outer leaves. Diagnostic field survey was carried out in 12 different Panchayats experiencing crown rot disease, recording an average disease incidence of 9.5%. A series of cultural, morphological, and molecular characterizations using multi-gene phylogeny (ITS, tub2, tef-1α) and pathogenicity assays with Koch’s postulates confirmed the association of Neodeightonia phoenicum as the causal organism of crown rot disease. To the best of our knowledge, this study confirms the first report of crown rot disease in coconut caused by N. phoenicum. Root treatment with Hexaconazole was effective in controlling the disease under in vivo conditions, achieving 99% recovery.