Study on effect of host age and Host rang of Alternaria porri

Abstract

Alternaria blight is the most serious and devastating diseases of niger caused by Alternaria porri (Ell.). The genus Alternaria Nees ex Fr. is widely distributed in all over the world and is represented by number of species. The genus occupies a prime position and is significantly important as its members are well known in causing wide spread diseases of economic plants such as cereals, oil crops, spices, vegetables and ornamentals Niger crop was found to be more susceptible at 40-days. At this age, plants showed 38.31 per cent disease severity and 25 hrs of latent period as compared to 15-days-old plants which recorded the 10.74 per cent disease severity and 45 hrs of latent period.From the study of the host range of A. porri it was found that A. porri produced visible symptoms on all the tested crops. The symptom expression took longer time 12-14 days in Safflower and Sunflower, 10-12 days in chili and cotton, 9-10 days in clusterbean and 8-9 days in brinjal and tomato. Disease severity was also recorded on 1-5 scale and found that highest per cent disease index was recorded in onion (43.33 per cent) followed by garlic (36.51%) and minimum PDI was recorded in sunflower (26.44%).From the result it was concluded that A. porri have wide host range.