Evaluation of antagonistic potential of bio-agents against anthracnose of French bean Colletotricum lindemuthianum

Abstract

The French bean (Phaseolus vulgaris) is one of the most widely grown grain legume crop around the world covering an area of about 28 million hectares with an annual production of 20 million tones (FAO 2016). French bean suffers from many diseases caused by fungi, bacteria, viruses, nematodes and abiotic stresses. Among the fungal diseases anthracnose, are the most prevalent ones.Colletotrichum lindemuthianum attack on the bean leaves, causes dark brown necrotic lesions and decrease leaf photosynthesis activity. Yield loss is due to early leaf senescence and plant death, shrunken seed and an increase in the amount of diseased seed that has lesions on its coat. Such beans have a repulsive appearance and are not preferred by consumers. The disease is characterized by serious leaf spotting ultimately resulting in ‘shot hole’ symptoms and finally defoliation which affects the yield greatly. In the present investigation five bio-agents viz., Trichoderma viridae, Trichoderma harzianum, Chaetomium globosum, Pseudomonas fluorescence and Bacillius subtilis were evaluated to see the efficacy against C. lindemuthianum through dual culture technique under in-vitro conditions. The present inhibition of mycelial growth of pathogen by bio-agents was recorded after 48, 96, and 168 hrs. At 96 hours of inoculation, maximum % inhibition of C. lindemuthianum was recorded by Trichoderma viridae (49.25%) which were significantly superior from all the tested bio-agents, followed by P. fluorescence (46.95%) while at 168 hours of inoculation, maximum % inhibition of C. lindemuthianum was recorded by Chaetomium globosum (59.50%) followed by P. fluorescence (58.14%) and Trichoderma viridae (57.04%).