1Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore-641003.
2Advanced Centre for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi1-100012.
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.
Mottle streak disease is becoming a threat to finger millet cultivation in Tamil Nadu. The ruling varieties PR 202, GPU 45, Co 14 and K7 were susceptible to the disease with incidence ranging from 17.5 to 23%. Initial symptoms of the disease were noticed in the field after 45 days of sowing and four stages of symptom development viz., mottling, streaking, striping and yellowing were observed. Presence of bacilliform Rhabdovirus particles was invariably associated with leaf dip preparations of samples collected at all the stages of infection. The virus infection in field led to reduction in plant height (31.7%), productive tillers (29.0%), leaves (29.1%), leaf area (23.0%), and root length (37.9%). The infection also reduced the 1000grain weight (9.48%) and grain yield per plant (38.7%). However, total tillers and nodal branches/tiller were more in diseased plants. Transmission studies held in glasshouse revealed that the virus was not sap transmissible either to monocots, dicots and weeds. The leafhopper Cicadulina bipunctella was found to transmit the virus effectively up to 80 per cent. The virus – vector relationship revealed that 72 h of acquisition access period, 5 days of inoculation access period and nearly 30 days of incubation in the host were required for efficient transmission and symptom development. A positive correlation was found to exist between the vector population and disease incidence in the field. The virus has not yet been fully characterized, but studied properties suggest that it belongs to the plant rhabdoviruses (ICTVdB virus code-01.062.0.00.318).
