Dr.S.C.DubeyBrajesh Patel2024-07-012024-07-011997https://krishikosh.egranth.ac.in/handle/1/5810211232Broad Bean (Vicia faba L.) is an important pulse crop gown in India and abroad. In plateau region of Bihar, it is grown specially for vegetable purposes. During survey, it was found to be severely Infected with blight caused by Alternaria alternata (Fr.) Keissler. Disease incidence and intensity varied from 18.7 to 55.3 per cent and 16.8 to 58.2 per cent, respectively in different localities of Ranchi and other districts of Bihar. Symptoms appeared as circular to irregular necrotic lesions from the tip or margin of leaves. These lesions gradually increased or coalesce and become enlarged, dark brown to gray in colour with indistinct zonations and abundant sporulation. In dry weather, the necrotic tissues crack and become ragged. The brown infected leaves wither and de follate. Dark brown to black, circular to irregular lesions also appear on stem and pods. The pathogen was isolated on potato dextrose agar medium and pathogenicity was proved followed by Koch's postulates. On the basis of the morphological characters of mycelium and conidia produced in nature as well as in culture the pathogen was identified as Alternaria alternata (Fr.) Keissler. Six different solid and liquid media were evaluated for the mycelial growth and conidial production of the pathogen. Potato dextrose agar supported maximum growth (94.3 mm) and excellent sporulation of the pathogen followed by Richards' (86.7 mm) and Sabouraud's agar (82.3mm).EnglishThesis