First Report on Characterization and In Vitro Management of Anthracnose of Fishtail Palm (Caryota mitis) Caused by Colletotrichum manihotis in India

Abstract

Fishtail palm (Caryota mitis), characterized by its distinctive goldfish tail like leaflets, is a popular ornamental plant that is frequently affected by anthracnose disease. The present study, conducted during 2022, investigated disease symptomatology, pathogen isolation, pathogenicity and identification along with the evaluation of growth media, temperature effects, growth characteristics, biomass production and fungicide efficacy. The causal pathogen was identified as Colletotrichum manihotis based on conidial dimensions and cluster analysis. Among the four-culture media evaluated, potato dextrose agar (PDA) resulted in the highest mycelial expansion and an incubation temperature of 28°C was found to be optimal for growth. On PDA, oat meal agar (OMA) and Czapek Dox agar (CDA), C. manihotis produced whitish, cotton-like mycelia, whereas no such growth was observed on malt extract agar (MEA). In terms of biomass yield, potato dextrose broth (PDB) proved to be the most effective medium when incubated at 24°C and 28°C. Among the fungicides evaluated, difenoconazole 25% EC was the most effective, completely inhibiting mycelial growth at 100 ppm with an EC₅₀ value of 13.3 ppm, whereas mancozeb 50% WP required 400 ppm with an EC₅₀ value of 38.5 ppm. Based on the available literature, this appears to be the first documented scientific evidence of anthracnose in fishtail palm caused by Colletotrichum manihotis in India, thus addressing a critical knowledge gap and offering foundational insights for future disease management   strategies.