Studies on the relative reaction of onion genotypes against purple blotch disease

Studies on the relative reaction of onion genotypes against purple blotch disease

1986

A:PS

Onion genotypes evaluated against natural attack of purple blotch disease incited by Alternaria porri. under field conditons. The intensity of the disease varied with the genotype and the year. Of 18 test genotypes raised for bulb crop, non was found to be resistant (below 5%). Two genotypes viz., VL-1 and Sel-2-4-1 were moderatley rsistant (MR = 5 - 15% intensity) while three were highly susceptible (HS is greater than or equal to 25% intensity) and the remaining 9 susceptible (S = 15 - 25% intensity). Of 15 genotypes tested for their reaction to purple blotch. Five (VL-1, Sel-102, Sel Ratnar, Poona Prize Taker and Puna Red Large Globe) were moderately resistant. Three genotypes (VL 67, N-53, Onion Local White) behaved highly susceptible and the remaning were susceptible. In seed production trial, the umbel withering disease was noticed in serious form particularly in those covered with muslin cages. The isolations yielded A. porri, the pathogencity of which was proved by spray inoculations on umbels. The varietal differences in susceptibility were also recorded. Varieties Pb. Sel-3, Pusa Ratnar and Pb. Sel-5 remained relatively free from the disease, whereas, the others were either susceptible or highly susceptible. The pathogen caused typical purple blotch symptoms on onion leaf/stalk. [AS]

v.13(2):304-309, VEGETABLE SCIENCE

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