Effect of culture media and environmental factors on mycelial growth and pycnidial production of Lasiodiplodia theobromae in physic nut (Jatropha curcas).

Physic nut (Jatropha curcas) is an important commercial bio-diesel plant species and is being advocated for development of waste and dry land. The collar and root rot caused by Lasiodiplodia theobromae is an important soil borne disease which causes considerable yield loss in this crop. In this study, the effects of culture media, temperature, photoperiod, carbon and nitrogen sources and pH on mycelial growth and pycnidial production were evaluated. Among the growth media tested, potato dextrose agar supported the highest growth followed by potato sucrose agar and corn meal agar. Among several carbon sources tested, carboxy methyl cellulose and sucrose were found superior for growth and pycnidial production. The nitrogen sources viz., ammonium oxalate and ammonium dihydrogen phosphate were recorded maximum mycelial growth and pycnidial production. The fungus grows at pH 5.0-9.0 and optimum growth was observed at pH 7.0.