Optimization of Cultural Conditions for Cochliobolus heterostrophus Isolates from Infected Maize Plants from Different Agricultural Zones of Pakistan.

ABSTRACT

Southern corn leaf blight caused by Cochliobolus heterostrophus is a major foliar disease of maize crop in Pakistan. The disease affects leaves, leaf sheaths, ears and maize grains. Suitable physiological conditions which include different nutrient media, temperature, pH, carbon and nitrogen sources were determined for growth and reproduction of the pathogen. Among all media used viz, the best supporting medium was found to be Richard’s agar for the growth of pathogen after 7 days of incubation. Different temperatures (20, 25, 30 and 35ºC) were selected for mycelia growth of the pathogen, among which maximum growth was found to be at 30ºC (80 mm colony size) and minimum at 35ºC (35 mm). Maximum radial colony growth of the pathogen was observed at neutral pH (80 mm). Sucrose and potassium nitrate (KNO3) were found to be the most appropriate sources of carbon and nitrogen respectively.