Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
TSWV and IYSV continue to cause economic damage to several crops in the US. While TSWV is a constraint to production of pepper, peanut (groundnut), tobacco, and tomato in the southeastern US, IYSV has become the biggest production constraint to seed and bulb onion production in the Pacific Northwest. Thrips vectors that are important in TSWV epidemiology include western flower thrips (Franklienella occidentalis) and tobacco thrips (F. fusca), whereas onion thrips (Thrips tabaci) is the only confirmed vector of IYSV. In the case of TSWV, interdisciplinary research to determine the biological, epidemiological and molecular aspects of the virus, and identification of certain risk factors that influence the final disease incidence resulted in formulating an integrated disease management strategy. Management tactics for TSWV include growing resistant cultivars, thrips management, use of SAR activators and plastic mulch. Grower adoption of these tactics was found to be high attesting to the effectiveness and practicality of this approach. In the case of IYSV, however, control options are limited. Not much is known about the role of thrips vectors in disease epidemiology. While new alternate hosts are being reported, their role in virus and thrips life cycle remains to be determined. Lack of field resistance to IYSV in commercial onion cultivars combined with prevalence of thrips vector populations, overlapping bulb and seed onion crops could be leading to the disease outbreaks observed in recent years. At present, growers are advised to avoid plant stressors such as poor soil fertility, lack of irrigation, and poor sanitation.
