Author(s): GR Vishwas Gowda, Suresh D Ekabote, Gangadhara Doggalli, D Gireesha, Santhoshinii Elango and Kiran Amarshetti

Abstract: Coconut (Cocos nucifera L.) is referred to as a 'KalpaVriksha' in ancient Indian literature, which implies a tree that gives all of life's basic necessities. Grey leaf blight, caused by Pestalotiopsis sp., is one of the most serious fungal diseases affecting coconut. Grey blight symptoms include minute yellow or brown dots encircled by a greyish ring on the leaflets. The cultural features of the pathogen were examined on five non-synthetic/semi-synthetic (Potato dextrose agar, Oatmeal agar, Bennet's agar, Host leaf extract agar and Sabouraud's dextrose agar) and two synthetic solid and liquid media (Richards' agar and Czapek's (Dox) agar). In which Pestalotiopsis sp. exhibits the highest myceial growth and sporulation on Potato dextrose agar (90 mm), Oatmeal agar (90 mm), and Sabouraud's dextrose agar (90 mm) and the least myceial growth and sporulation on host leaf extract agar (84 mm) and Richard's agar (67.50 mm). The pathogen was incubated at various temperatures (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C) and pH (3, 4, 5, 6, 7, and 8), in order to determine the optimum pH and temperature for their growth. Physiological studies revealed that the ideal pH and temperature for Pestalotiopsis sp. growth are 5 to 6 and 20 to 25 °C, respectively.

DOI: 10.33545/26174693.2024.v8.i3j.846