Exserohilum rostratum: the incitant of oat leaf blight in Himachal Pradesh, India

Abstract

During the 2023-24 rabi season, severe leaf blight symptoms were observed on fodder oat (Avena sativa L.) cultivated in Himachal Pradesh, India, a major fodder-producing state in the north-western Himalayan region. Disease incidence varied from 40 to 60% across four surveyed fields of Amb (Una) under cool temperatures, high relative humidity and prolonged leaf wetness. Symptoms initially manifested as small, purple, oval to elongated lesions with grey centres that coalesced, causing extensive leaf blighting. The pathogen was isolated from infected leaf tissues and identified as Exserohilum rostratum based on cultural, morphological, and molecular characteristics. Pathogenicity was established through artificial inoculation of healthy oat plants, which reproduced typical symptoms within 7 days, followed by re-isolation of the fungus. This study presents the first report of leaf blight in fodderoat caused by E. rostratum in Himachal Pradesh, India.