New Virus Detected In South Florida Tomatoes

Recent sample testing results show South Florida tomatoes are under attack. Tomato spotted wilt virus (TSWV), groundnut ringspot virus (GRSV), and tomato chlorotic spot virus (TCSV) have been putting a damper on tomato production this spring season. Aside from these notorious suspects, a new malady has been added to the mix.

Fruiting vegetable crops in South Florida have been extensively surveyed for the emerging thrips-transmitted over the past four years as part of several research projects by UF/IFAS and USDA-ARS. During surveys in fall 2013, a symptomatic tomato plant and fruit samples were collected in Miami-Dade County by Glades Crop Care Inc. and in Palm Beach County by growers and USDA-ARS scientists from Ft. Pierce that did not test positive for any of the usual tospoviruses.

According to a report from Scott Adkins, USDA-ARS research plant pathologist, this was surprising because the symptoms of virus-like necrosis on leaves, petioles and stems, and necrotic rings or spots on fruits were similar to those induced by TCSV and GRSV.

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Tomato necrotic streak virus symptoms

Photo by Scott Adkins

Further testing by scientists at FDACS-DPI and USDA-ARS eliminated all of the other tomato viruses known in Florida. Eventually, a new ilarvirus species was identified for which the name tomato necrotic streak virus (TomNSV) is proposed.

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Symptoms of TomNSV in the field have been reproduced by inoculation of greenhouse tomato plants with symptomatic field samples. TomNSV is a distant relative of tobacco streak virus (TSV), which is the cause of bean red node.

Adkins reports now that TomNSV has been identified, scientists have been able to test other previously collected samples for this new virus. TomNSV has subsequently been detected in similarly symptomatic tomato samples collected from the spring and fall seasons of 2014 in Palm Beach County. No detections have been made in 2015.

No natural hosts for TomNSV other than tomato have been identified to date.

A FDACS-DPI Specialty Crop Block Grant is funding current studies to examine other hosts for both TomNSV and TSV, and to determine the mode of transmission of these viruses in Florida.

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