In-vitro Assessment of Different Culture of Media on the Isolation and Purification of Cauliflower Alternaria Leaf Spot Disease Caused by Alternaria brassicicola (Schwein)

Alternaria leaf spot of cauliflower caused by Alternaria brassicicola (Schwein.) Wiltshire, is a significant disease of cauliflower in the Kanpur region. In the current study the pathogenic fungus was purified from infested cauliflower leaves on potato dextrose agar medium, Following inoculation on healthy cauliflower seedlings the pathogenicity of the causal agent was demonstrated. The results revealed that the fungus was Alternaria brassicicola based on common symptoms on foliage, microscopic findings, and culture characteristics of the fungus. Based on microscopic observation, the causal agent was identified as Alternaria brassicicola (Schwein.) Wiltshire. To proceed to the isolation and purification of the fungus, eight culture media were tested among which the potato dextrose agar medium was found most suitable and encouraged maximum radial mycelial growth (89.07mm) of A. brassicicola. The second best was Corn Meal Agar medium (67.46mm), followed by Potato carrot agar medium (54.83 mm), Rose Bengal agar (53.00 mm), Czapex dextrose agar (40.40 mm), Yeast Extract Agar (32.28 mm), and Nutrient Agar (24.28 mm), While minimum (22.16 mm) growth was recorded in Starch Agar. Thus, potato dextrose agar can therefore be used in the isolation, purification and pathogenicity of A. brassicicola.