In vitro evaluation of bio control agents against Alternaria alternata (Fr.) Keissler, causing Leaf Blight disease of Chrysanthemum

Abstract

Biotic and abiotic stresses are major constraints in the production of chrysanthemum. Among biotic stresses apart from bacterial and viral diseases, many fungal diseases are of economic importance. Leaf blight was the most important and destructive disease of chrysanthemum. Leaf blight caused by Alternaria alternata (Fr.) Keissler a serious threat to successful cultivation of chrysanthemum. For the management of Alternaria leaf blight causing foliar disease, an experiment was conducted to study the efficacy of antagonistic organism against Alternaria blight. The bio-agents i.e. Trichoderma asperellum, T harzianum, T hamatum, T Koningii, T lignorum, T virens, Aspergillus niger, Pseudomonas fluorescens and Bacillus subtilis etc. were evaluated in vitro, found antifungal to A. alternata. However, T. asperellum was found most significant with highest mycelial growth inhibition (80.10%) of the test pathogen. The second and third most inhibitory antagonists found were Aspergillus niger and T. koningii with mycelia growth inhibition of 79.44 and 77.25%, respectively