Influence of culture media and environmental factors on mycelial growth and sporulation of Lasiodiplodia theobromae in coconut

Abstract

Lasiodiplodia theobromae is a cosmopolitan tropical and subtropical plant pathogen. The pathogen was isolated from infected coconut for the first time in Tamil Nadu and the pathogen did not sporulate or sporulated poorly in common media, which hinders in identification and characterization of L. theobromae in vitro. Hence the influence of factors such as culture media, pH, temperature and light on mycelial growth and sporulation were evaluated in the present study. Among several media tested, potato dextrose agar medium was found to be the most suitable for mycelial growth and sporulation of L. theobromae. The fungus grows at pH 4.5-8.5 and optimum growth was observed at pH 7.0. The fungus grows at temperatures ranging from 15o to 40oC, with optimum growth at 28oC and no growth was noted at 40oC. There was no significant effect of different light period on growth of L. theobromae. However exposure to continuous light enhanced sporulation.