Morphological and molecular characterization of alternaria isolates causing purple blotch disease of onion

Purple blotch is the most destructive disease commonly prevailing in almost all onion growing pockets except in very cool production areas of the world. The present study was carried out to understand the diversity in Alternaria population causing purple blotch disease of onion. Out of fifty six geographical Alternaria isolates of Karnataka seventeen were selected as descriptive isolates based on morphological characteristics for understanding the genetic variability.