Effect of physical parameters on the sporulation and mycelial growth of Alternaria brassicae causing Alternaria leaf spot of mustard

In the present investigation, mycelial growth of A. brassicae at different temperature viz., 20, 25, 30, 35 and 40°C were tested in vitro. At different temperatures, maximum mycelial growth at 25°C (88.22 mm) followed by 30°C (81.25 mm) and minimum mycelial growth was observed at 40°C (61.09 mm). Among the tested pH level (6.5, 7.0, 7.5, 8.0 and 8.5), highest mycelial growth was observed at 6.5 pH (86.03 mm) followed by 7.0 pH (72.89 mm) and minimum mycelial growth at 8.5 pH (42.15 mm). Various carbon and nitrogen sources were used to test the best suited for mycelial growth of the pathogen. Among the used carbon sources, highest mycelial growth of A. brassicae was observed in glucose (83.14 mm) followed by maltose (79.68 mm) and minimum in fructose (70.87 mm). In all the used nitrogen sources, highest mycelial growth was observed in L-alanine (83.39 mm) followed by L-arginine (74.34 mm) and lowest mycelial growth in Amonium nitrate (45.99 mm).