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Tomato Chlorotic Spot Virus

New Virus of Concern for Several Crops

See It??  Report It!!

Margaret Tuttle McGrath

Plant Pathology and Plant-Microbe Biology Section, SIPS,

Cornell University, Long Island Horticultural Research and Extension Center

3059 Sound Avenue, Riverhead, NY 11901; mtm3@cornell.edu

2016

This article is also available as a PDF version

Photographs courtesy from: Dr. Shouan Zhang, Tropical Research & Education Center, University of Florida, IFAS, Homestead, FL 33031-3314

There is a new virus to be on the outlook for:  Tomato Chlorotic Spot Virus (TCSV).  While it has primarily been affecting tomatoes in south Florida, it has the potential to be moved elsewhere, it has a wide host range, and it can be very destructive.  Florida growers have sustained great losses, thus this is an important disease to be aware of.  TCSV was confirmed on tomato in a high tunnel in Ohio in 2013, documenting its ability to affect crops outside of Florida.

TCSV is related to Tomato Spotted Wilt Virus (TSWV) and Impatiens necrotic spot virus (INSV), which already occur widely in the USA.  All are tospoviruses and are spread by thrips.   Groundnut ring spot virus (GRSV) is another new tospovirus.  All three viruses occur in Florida; TCSV is now the dominant one.  Western flower thrips have been increasing in occurrence in parts of the northeastern USA due to insecticide resistance, thus providing an opportunity for TCSV to be readily spread if it is introduced to the region.  Common blossom thrips has also been confirmed to be an important vector of TCSV.

TCSV was first detected in the USA in Florida in 2012, but may have been present a few years earlier and mis-diagnosed as GRSV.  Just two years later it was causing extensive plant loss with symptoms starting to develop only about three weeks after transplanting.  Nearly all plants have been observed affected in a planting.

SymptomsTCSV causes symptoms that are similar to those caused by TSWV.  Both viruses cause upper leaves to develop brown (necrotic) tissue often in patterns as is typical with viruses.  Chlorotic spots and ringspots as well as mosaic also develop sometimes with TCSV.  This disease can progress rapidly causing bronzing , wilting, and deformation of leaves, and death of terminal leaves and stems.  Necrotic rings develop on fruit rendering them unmarketable.  When infection occurs before flowering, plants can be severely stunted and produce few if any flowers, and eventually die.  Only fruit developed symptoms during the outbreak in Ohio in 2013.

Long distance movementTCSV could be introduced to the northeast in seedlings of tomato or another host plant produced where the virus is already established.  Global movement of plants has become commonplace.  Ornamental plants were also being produced in the high tunnel with affected tomato plants in Ohio, and thrips were numerous.

Other Susceptible Plants.  The name suggests TCSV is a disease of tomato; however, when a plant is specified in a virus name it is designating the first host identified for the virus.  TCSV has been detected in pepper (bell and chili), lettuce, long bean (Vignaun guiculata), weeds (jimsonweed), and ornamental plants including lisianthus, annual vinca (Catharanthus roseus), hoya (Hoya wayetii), and Christmas cactus (Schlumbergera truncate).  Tomatillo, tobacco, petunia, eggplant, escarole, beans, peanut, and impatiens were found to be susceptible as well when inoculated as part of a host range study.

TCSV Detection.   Currently-available immunostrips for detecting TSWV, such as those marketed by Agdia Inc., will also give a positive result for a plant infected by TCSV because these viruses are so closely related.   Thus it is not possible to determine if a plant is infected with TCSV or TSWV with the immunostrips.  Procedures have been developed to distinguish them as part of a national project on TCSV (see next paragraph)

See Virus Symptoms??  Report It!!.   If you see symptoms that could be TCSV or TSWV, please report to Meg at mtm3@cornell.edu or 631-727-3595 or to your local extension specialist.  There is funding for testing samples as part of a project underway through 2018.  Knowledge about occurrence of a new virus is critically important for management, thus testing is an important component of the project.

Management.   Plant viruses can be difficult to manage because insect vectors often transmit viruses quickly, limiting the usefulness of insecticides.  Focus is on avoiding the virus, thus the current emphasis on monitoring to obtain understanding of TCSV occurrence. 

Where Did TCSV Come From?   New tospoviruses can be created when a plant is infected by more than one tospovirus as a result of these viruses being able to exchange segments of their genome (reassortment).  There are eight species recognized presently.  TCSV was detected in Brazil and Argentina before Florida.

Photographs courtesy from: Dr. Shouan Zhang, Tropical Research & Education Center, University of Florida, IFAS, Homestead, FL 33031-3314

Following photographs are of ornamental and bell pepper plants that became infected naturally (not inoculated) in a commercial planting.

Photographs courtesy from: Dr. Shouan Zhang, Tropical Research & Education Center, University of Florida, IFAS, Homestead, FL 33031-3314

Additional information.  

http://edis.ifas.ufl.edu/pp306 Tomato Chlorotic Spot Virus By Jane E. Polston, Erin Wood, Aaron J. Palmateer, and Shouan Zhang.  PP306.  IFAS Extension, University of Florida. 

A New Tomato Virus in Florida presentation file by Jane E. Polston (PDF)