Proportional dominance of Alternaria linicola and Alternaria lini in infected tissues and evaluation of linseed (Linum usitatissimum L.) germplasm against Alternaria blight

Alternaria blight of is an important disease of Linseed (Linum usitatissimum L.) that hampers its productivity and oil content. During severe infections, spots coalesced and covered the large area of the leaves. Field experiments were conducted during 2015-16 and 2016-17 to evaluate the performance of promising lines/varieties of linseed against Alternaria blight disease. Microscopic examination of pathogens in diseased tissue reveled that Alternaria linicola Groves & Skolko and Alternaria lini Dey were two fungi associated with the spots on leaves and capsules. Studies of relative dominance of pathogens associated with the diseased tissue revealed the dominance of Alternaria linicola (95.86-98.63%) in comparison to Alternaria lini (1.31-4.14%) during different growth period of linseed crop. Sixty-three genotypes were evaluated against this disease under artificial epiphytotic condition to known the level of resistance and susceptibility in different genotypes under artificial inoculated conditions. Out of Sixty-three genotypes screened, 2 genotypes namely –LCK-152, LCK-7002, rated as resistant, under both the years. While 4 genotypes namely- BUAPUR LOCAL, CR-M-6X22-9, EC-9832, OLC-48 in 2015-16 and 3 genotypes in 2016-17 rated under highly susceptible lines against this disease.