Studies on host range and seed transmission nature of Alternaria alternata (Fr.) Keissler causing leaf blight of Isabgol

Abstract

From the present investigation of host range, it can be concluded that Alternaria blight pathogen of Isabgol could produce visible symptoms on all the species except Ashwagandha. However, the appearance of symptoms was observed after 7-12- days of inoculation on these plants compared to 5-7- days in Isabgol. Hence, leaf blight of Isabgol (Alternaria alternata) has a wide host range. Seed is one of the important sources of external and internal mycoflora. With the help of two methods viz. SBT and PDA plate method, it was observed that six fungi i.e. A. alternata, Fusarium oxysporum, Aspergillus niger, Aspergillus flavus, Curvularia lunata and Penicillium spp. were frequent in all the tests. The Blotter and PDA proved to be an effective method to detect the mycoflora. However, the blotter test proved generally more sensitive, as the frequency of fungi recorded was higher in this test than PDA. Per cent frequencies of all species isolated from sterilized seeds were low as compared to unsterilized seed samples which happen quite naturally. All these mycoflora were examined for their pathogenic ability on Isabgol. Seeds and plants were inoculated with the mycoflora and closely observed for their disease reaction. It was observed that out of six fungi only A. alternata gave pathogenic reaction on the Isabgol and the pathogen is seed borne in nature. © 376.