Pest Of The Month: Tomato Chlorosis Virus
June 1, 2008 
Identification
Tomato chlorosis virus (ToCV) is a relatively new disease in Florida that is being seen with increasing frequency in some areas. The leaves of infected plants become yellow or red between the veins, stunted, and rolled. Onset of disease appears to occur during the short day-length period of late December–February. Symptoms are typically most apparent on middle to lower parts of plants, while new growth may appear normal. Lower leaves develop a progressive, interveinal chlorosis, often with necrotic flecking. Symptoms resemble those caused by magnesium deficiency in tomato, but are less uniform within a leaflet or among leaflets on a leaf. As the disease progresses, interveinal necrosis can occur, and the leaves become characteristically brittle, thick, and crisp. Fruit size and number appear reduced by virus infection.
Survival And Spread
This virus is transmitted by various species of whitefly. Studies indicate that the banded wing whitefly (Trialeurodes abutilonea) and silverleaf whitefly (Bemisia tabaci biotype B) are highly efficient vectors of ToCV. B. tabaci biotype A and T. vaporariorum are less efficient vectors.
Management
Neonicitinoid-based products are most frequently used for whitefly control, and can be applied as a foliar spray, a seed treatment, or through drip application. While insecticides effectively reduce whitefly populations, such control methods are relatively inefficient for control of viruses, since whiteflies can transmit a virus before being killed by an insecticide. Unfortunately, most whitefly-transmitted criniviruses do not produce symptoms until three to four weeks after infection occurs. Therefore, infection can be widespread by the time symptoms are observed and control measures are implemented.
Growers can also minimize exposure to this virus by avoiding overlap with other susceptible crops. Avoid using infected transplants. Roguing of infected plants and general whitefly control may help reduce virus spread.
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