CHARACTERIZATION AND MANAGEMENT OF BUD BLIGHT DISEASE OF SOYBEAN IN INDIA

Bud blight disease (BBD) of soybean (Glycine max L. Merr.) showed litt le or no transmission via seeds from naturally infected plants. This i s consistent with the presence of Peanut Bud Necrosis Tospovirus (PBNV ) which has been investigated recently in the Chhaitisgarh region of I ndia and is not seed-borne. Various host species were tested in host r ange studies. Of these, the bud blight pathogen infected only four spe cies, producing chlorotic/necrotic rings/spots on Chenopodium amaranti color Coste & Reyn, Nicotiana glutinosa L., Vigna unguiculata (L.) Wal p. cv. C 152 and systemic infection in Arachis hypogea. Parts of the s eed from diseased soybean examined by transmission electron microscopy and immunosorbent electron microscopy revealed no virus particles. Ex tracts from the first trifoliate leaf were more infectious (14.7 local lesions) on local lesion hosts than those from the second trifoliate leaf (1.33 local lesions) and the extracts from the third trifoliate l eaf were not infectious. Soybean germplasm lines/cultivars, namely KHJ B 1, JS 84-1 and JS 71-05, were not infected, whereas JS 81-227, ES 5, JS 2, JS 79-81 and JS 340 were highly resistant to bud blight under n atural field conditions with location severity indices of 3.91 out of 9.00. The number of plants with bud blight infections was significantl y high when the crop was at the flowering and pod initiation stages. H owever, the number of infected plants was significantly lower when the crop was at the pre-bloom and podding stages. Similarly, infected pla nts were significantly more common in JS 75-46 than in JS 335.