Impact of variety selection and insecticide programs on Tomato spotted wilt virus symptom expression in central California

• Published in: Acta horticulturae no. 1081; pp. 59 - 68
• Main Authors: Turini, T. A, Strange, M. Le, Gilbertson, R. L
• Format: Journal Article
• Language: English
• Published: International Society for Horticultural Science 01.01.2015
• Subjects: crop yield; dimethoate; field experimentation; financial economics; foliar application; genes; growers; integrated pest management; planting; risk; thiamethoxam; Tomato spotted wilt virus; tomatoes; vector control; California
• ISSN: 0567-7572
• DOI: 10.17660/ActaHortic.2015.1081.4

Tomato spotted wilt virus (TSWV), a thrips-transmitted virus, can cause substantial economic loss to processing tomato growers in California. Field studies were conducted at the University of California West Side Research and Extension Center to evaluate varietal selection and vector control as useful components of an integrated pest management strategy in this production area. Ten to 16 varieties were compared in 13 field trials conducted from 2007 to 2012. Entries with single gene resistance to TSWV (SW5) were included as were varieties without SW5 resistance. Tomato spotted wilt virus symptoms were observed in all variety comparisons. Varieties with SW5 had no TSWV symptoms. All non-SW5 varieties expressed symptoms, but differences among entries lacking SW5 were demonstrated. For each entry evaluated in a minimum of 3 trials, a TSWV-susceptibility risk was assigned based on incidence of TSWV symptoms. Insecticide program impact on TSWV expression, and tomato yield and quality were evaluated in trials conducted from 2009 to 2012. Treatments were arranged in a split-plot design. Main plot treatments were drip applied programs (thiamethoxam 3-4 weeks after planting both with and without a subsequent application of dinotefuron 3-4 weeks later) applied over 3 beds of 100 m of row per plot. Sub-plot treatments were rotations of foliar applied insecticides; spinetoram and dimethoate rotations applied 2 or 5 times at 10 day intervals beginning three weeks after planting. Main plot and subplot untreated control treatments were included. Foliar programs reduced TSWV incidence during three or four years. Neonicotinoid injections were similar to untreated controls. Effective and sustainable management will depend upon multiple tactics, which include varietal selection and insecticide treatments. This information is being used as components of a risk scale being developed to enable producers to anticipate high risk situations.