Management of Alternaria Blight of Linseed

A disease of linseed, characterized by blighting of all or some of the aerial plant parts with Alternaria lini as a predominant pathogen of vegetative parts and A. linicola of reproductive parts, were of common occurrence in mid-eastern India. Highest intensity was recorded in 15 October sown crop followed by gradually declining disease intensity in later sown crops. Highest seed yield was obtained in 5 November sown crop followed by 25 October and 15 November sown ones. Out of200 genotypes tested, 6, namely, Accession No. 2921, Ayogi, BAD 610A, EC 44, EC 544 and ES 44 expressed consistent resistance to the disease. Iprodione 50 WP (0.2%) spray resulted in lowest foliar blight intensity of 22.4% and bud damage of 22.7% alongwith highest test weight of 6.5 g and seed yield of 1435 kg ha⁻¹. It was closely followed by mancozeb 75 WP (0.25%) spray having a foliar blight intensity of 29.1%, bud damage of 24.4%, test weight of 6.1 g and seed yield of 1233.3 kg ha⁻¹. Iprodione gave the highest net return of Rs. 6932.9 ha⁻¹. Mancozeb with the most favourable cost-benefit ratio of 1:3.1, proved most economical.