TYLCV – Tomato Yellow Leaf Curl Virus
TYLCV causes more severe symptoms and greater yield losses than Tomato Mottle Virus (ToMoV). It takes an estimated 15-30 minutes of SWF feeding to inoculate a plant. The SWF retains the virus, for several weeks. Symptoms will be visible in tomato in approximately 2-3 weeks after infection, a little longer than ToMoV.
Leaf symptoms include chlorotic margins, small leaves which are cupped, thick and rubbery. Tops of infected plants may took like a head of broccoli. The majority (up to 90%) of flowers abscise after infection, thus few fruit is produced. (TYLCV is very similar in its effects Bean Golden Mosaic Virus in that if young plants are affected, it is highly likely that fruit will not set).
TYLCV can affect more hosts than ToMoV, although crop plants are not considered with the exception of tobacco, which, like many of the weed hosts, do not show symptoms.
In Israel, weed hosts bridge the gap between tomato seasons. In the Dominican Republic, there is a government enforced whitefly free period. In Florida, we do not yet know the extent that weeds are a host, as many of our weeds do not grow in some of the countries where TYLCV is found.
This virus is not seed or mechanically transmitted. Whitefly transmission, however, is more efficient than for ToMoV. In greenhouse tests, 15 SWF were required for transmission, compared to 40 from ToMoV. Individual insects transmitted at 30-40%, compared to 5-10% for ToMoV.
Recommendations For Management
- Keep whitefly populations low especially in the first half of the season
- Use Admire in the transplants as soon as possible
- Use chemical control on all plantings of tomato and continue through final harvest and u-pick
- Isolate cherry tomato fields from large fruited plantings
- Delay fall plantings as much as is economically possible
- Learn to identify early symptoms of TYLCV and rogue Infected plants as soon as infections are identified throughout the season
- Pull plant from the bed and place in plastic bag at site, tie shut to prevent spread of any whiteflies to other plants, and discard in trash
- Plow under fields immediately after harvest to reduce whitefly populations and virus carry-over to the spring tomato crop and to other crops which are good hosts for whiteflies, and use the best sanitation practices
- Destroy volunteer tomato plants in and around fields
- Separate plantings of tomatoes in time and space from plantings of crop hosts which are good sources of whiteflies (ie. cabbage, cucurbits, potato)
- UV-reflective mulches will reduce landing of whitefties in your field and will help reduce incidence of both aphid and whitefly borne viruses including TYLCV.
- Destroy tomato volunteers throughout the season
- Delay spring plantings as long as is possible
- Use WF and virus free transplants
- Leaf symptoms: Chlorotic margins, leaves very small and cupped, thick and rubbery
- Plant symptoms: Stunting, more severe than that caused by ToMoV, like ToMoV, severity increases the younger the plant at infection; tops may look like broccoli
- Fruit symptoms: Majority of flowers abscise after infection, few fruits produced
- Host range: Broad
- Weed hosts: Unknown, but likely
- Whitefty transmission efficiency: In greenhouse tests 15 insects for 100% transmission; individual insects transmitted at 30-40%
- Seed transmission: No
- Mechanical transmission: Not under normal conditions