Physiological Characterisation of Alternaria brassicicola causing Alternaria Leaf Spot in Cabbage

Cabbage is a cool season crop grown in temperate regions and belongs to family Brassicaceae. In Kerala, cabbage is grown in an area of 197 ha and major cultivated regions were Idukki and Wayanad districts. The leaf spot of cabbage is caused by Alternaria brassicicola is a widespread disease affecting the yield of cabbage. This disease can be managed by using fungicides or bioagents but the efficacy of these measures depend on host pathogen interaction, which is influenced by environmental factors. The present study was undertaken to study the effect of Temperature, pH levels and Light intensity on the growth of A. brassicicola as the growth and development of pathogen was influenced by the environmental factors. Studies on physiological characters revealed that optimum temperature for the growth of A. brassicicola was 250C. The pathogen was completely inhibited at 350C and moderate growth was recorded at 200C and 300C. The ideal pH for the growth of pathogen was 5.5 and 6. The optimum light intensity favoured the growth of pathogen was normal day and night condition (20 lux) followed by dark. The growth and sporulation was affected at higher light intensities.