1Department of Plant Pathology, Agriculture College Raichur, Karnataka, India.
2AICSIP, MRA, UAS, Dharwad, Karnataka, India.
3RARS, Raichur, Karnataka.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Northern Karnataka is a traditional sunflower growing belt, includes Bijapur, Raichur and Gulbarga districts. Roving survey was conducted in these areas during 2003–04 and 2004–05, to monitor the incidence of sunflower necrosis disease, caused by Tobacco streak virus. The characteristic symptoms were chlorosis of leaves, necrosis on part of leaf lamina, twisting of stem necrosis extending to petiole and stem, necrosis of growing tip, partial twisting of capitulum, necrosis of bracts and capitulum, reduced head size, partial seed filling are predominant. During 2003–04 the disease incidence was maximum in Gulbarga district (10.48%) followed by Raichur and Bijapur district. Among the taluk's, Lingsugur (25.12%) Raichur district recorded the maximum incidence followed by Shahapur (21.99%) of Gulbarga district. Where as during 2004–05, the maximum disease incidence was in Gulbarga district (38.44%). Shahapur taluk recorded 54.25 per cent. A strong association of higher disease incidence and presence of necrosis symptoms in Xanthium strumarium on the bunds was observed. The yield loss was estimated from the plants infected at 30, 45 and 60 days after sowing, and found out to be 96.72, 67.77 and 49.01 percent, respectively, where as the reduction in oil content was 50.97, 28.43 and 23.68 percent against healthy plants.
