Investigation of thrips population and Tomato spotted wilt virus incidence in processing tomatoes in the Central Valley of California

• Published in: Phytopathology Vol. 99; no. 6; p. S9
• Main Authors: Batuman, O, Turini, T A, LeStrange, M, Stoddard, S, Miyao, G, Ullman, DE, Gilbertson, R L
• Format: Journal Article
• Language: English
• Published: 01.06.2009
• Subjects: Bunyaviridae; Frankliniella occidentalis; Lycopersicon esculentum; Tomato spotted wilt virus; Tospovirus; USA, California; USA, California, Central Valley
• ISSN: 0031-949X

Tomato spotted wilt disease caused by Tomato spotted wilt virus (TSWV; genus Tospovirus; family Bunyaviridae) has recently emerged as an economically important disease of processing tomatoes in California. TSWV is effectively transmitted by western flower thrips (WFT; Frankliniella occidentalis), and replicates in both the thrips vectors and the plant hosts. To develop an improved understanding of this disease in California, population densities of WFT and TSWV incidence were monitored in processing tomato transplant-producing greenhouses and associated fields in the Central Valley of California in 2007 and 2008. Thrips were monitored in tomato flowers and with yellow sticky cards, whereas as TSWV incidence was assessed with sensitive indicator plants and field surveys. Transplants had low populations of thrips and no evidence of TSWV infection. In the field, thrips populations were extremely low during the winter and gradually increased in the spring (March/April) then peaked in May-July. Thrips populations in 2008 were four-fold greater than in 2007. TSWV did not appear until late April to mid-May, but appeared in all monitored fields, though at relatively low incidences (3-19%). Surveys for reservoir hosts revealed low rates of TSWV infection in weeds (<0.1%), with higher rates observed in potential bridge crops, such as radicchio. Based upon these findings, an integrated pest management strategy for TSWV in the Central Valley of California is proposed.