In vitro evaluation of bio control agents against seed borne Alternaria carthami and Alternaria alternata causing leaf spot disease of safflower

Abstract

Biotic and abiotic stresses are major constraints in the production of safflower. Among biotic stresses apart from bacterial and viral diseases, many fungal diseases are of economic importance. Leaf spots were the most important and destructive disease of safflower. Leaf spots caused by Alternaria carthami Choudhury and Alternaria alternata are a serious threat to successful cultivation of safflower. For the management of leaf spot causing seed borne pathogens an experiment was conducted to study the efficacy of antagonistic organism against seed borne leaf spot causing pathogens of safflower. The bioagents i.e. Trichoderma viride, Trichoderma harzianum, Trichoderma hamatum, Trichoderma koningii, Pseudomanas fluorescens and Bacillus subtillius each @ 0.6 per cent were evaluated in vitro were found antifungal to A, carthami and A. alternata. However, Trichoderma harzianum was found most effective and recorded significantly highest mycelial growth inhibition of Alternaria carthami and Alternaria alternata of about 81.48 % and 83.70 % respectively over untreated control. The second and third best bioagents/antagonists found were Trichoderma viride and Trichoderma hamatum which recorded mycelial growth inhibition of Alternaria carthami 77.04 %, 70.74 % and Alternaria alternata 79.26 %, 74.08 % respectively.