Morpho-Molecular Characterization and In vitro Management of the Pestalotiopsis palmarum (Cooke) Steyaert Causing the Grey Blight of Coconut

Abstract

The solitary species of the genus Cocos is the coconut palm (Cocos nucifera L.). The coconut palm is affectionately known as "Kalpa Vriksha," which translates to "the tree of heaven. The causal organism of grey blight was identified based on the morphological characteristics i.e., five-celled conidia had three middle cells that ranged in colour from light brown to dark brown further confirmed through PCR analysis as Pestalotiopsis palmarum. In cultural characteristics, maximum radial growth occurred in PDA, with V-8 juice agar showing the least growth (65.00 mm). The optimal pH for pathogen growth was 6 (338.11 mg). Fungicide evaluation revealed ziram as highly efficient among non-systemic fungicides, while carbendazim and thiophonate methyl were most effective among systemic ones. Trifloxystrobin 25% + tebuconazole 50% EC emerged as the most effective combi product, inhibiting pathogen growth by 88.02%. Among bio-agents, T. viride-2 displayed the highest mycelial inhibition (71.30%). Turmeric exhibited the highest botanical efficacy (48.03%), whereas lantana had the least impact (3.37%).