NFREC Extension Report No:   2005-9                                        October 2005

Recommended Management Strategies for Tomato Spotted Wilt on Tomato Caused by Tomato spotted wilt virus (TSWV)

Tim Momol, Steve Olson, and Joe Funderburk, University of Florida, NFREC, Quincy, FL

Tomato spotted wilt caused by tomato spotted wilt virus (TSWV) infects tomatoes and a wide range of other crops across temperate, subtropical and tropical regions throughout the world.  Other major crops susceptible to TSWV infection include pepper, peanut, tobacco, lettuce, potato and chrysanthemum.  Spotted wilt incidences of 20-60% have lead to major losses in tomato in the southeastern U.S. making TSWV one of the most economically destructive plant viruses in recent times.  In Florida, TSWV causes economic losses in tomatoes, especially in the northern part of the state while in the southern part, it is generally only a sporadic problem. Symptoms on leaves (Fig. 1) and fruits (Figs. 2 and 3) will help to do diagnose this disease.

Preplant

•     Choose resistant cultivars (i.e., Amelia, Crista, BHN-640)

•     Consider an effective weed control in and around tomato fields

•     Do not plant tomatoes near TSWV susceptible crops (i.e., peanut, tobacco)

•     Avoid excessive nitrogen rates

•     Use highly reflective UV mulch (metalized mulch). This mulch keeps soil cooler than black, gray or white mulch. For early plantings in Spring (North Florida) or Winter (South Florida) use “Heat Stripe I” (metalized mulch with black stripe in the middle).

Use of metalized mulch will reduce the application rate of MeBr/pic, therefore saving cost and reducing chemical use.

Production

•     Apply Actigard (Syngenta) every 14 days, start early, use label rates. Actigard is primarily used for bacterial spot control, but has added benefit for TSWV management.

•     Monitor for vector thrips (Frankliniella occidenatlis, F. fusca, F. bispinosa), apply  vector-thrips specific insecticides, to reduce adult  and larvae (mainly to reduce secondary spread).

•     Continue an effective weed control in and around tomato fields.

After harvest

•     Plow under crop residue immediately.

•     Start with suitable rotation and/or cover crops (i.e., rye for winter, sudan-sorghum for summer in north Florida) to reduce volunteers and weeds that support TSWV and vector thrips.

Fig. 1. Foliar symptoms of tomato spotted wilt.

Fig 2.  Symptoms on immature young fruit.

 Fig. 3. Symptoms on fruit

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