Citrus Variegated Chlorosis

CVC Symptoms

• Citrus trees affected with CVC develop sticky light brown lesions on leaf surfaces, especially on the underside of the leaves. The lesions may spread and result in leaf death over time. Fruits become stunted and don't reach their full size at maturity, and they develop a higher sugar content and hardened peels. Overall tree health declines as twigs and branches die back and the canopy becomes thin. CVC doesn't typically kill citrus trees, but instead it greatly reduces their annual fruit yield and overall health.

Susceptible Varieties

• CVC can infect any type of citrus tree, but sweet oranges (Citrus sinensis), which grow in U.S. Department of Agriculture plant hardiness zones 9 through 11, suffer the most damage and are at the greatest risk of infection. Lemons (Citrus limon) and mandarin oranges (Citrus reticulata), both hardy in zones 9 through 11, are more tolerant of the disease although they suffer some decreased fruiting. No citrus variety is fully resistant to the affects of CVC.

Infection Causes

• The bacterium Xylella fastidiosa causes CVC. It infects the vascular system of the citrus plant and quickly spreads to every part of the tree. Transmission of the bacteria can occur at grafting, so it's important to purchase only certified nursery stock that is grafted onto disease-free wood. The bacteria are also spread by glassy-wing sharpshooters. These 1/2-inch-long pests have brown bodies, white abdomens and yellow spots on their heads. They feed on the sap of in the tree's leaves, so they can quickly spread bacteria throughout a large area.

Prevention and Management

• Currently, no cure for CVC is known, so prevention is the best course of action. If CVC is suspected, you must report it immediately to your extension office. Purchasing trees from certified nurseries further helps prevent the chances of bringing CVC into your home orchard. Glassy-wing sharpshooter control can help prevent CVC. Pesticides aren't usually recommended for home orchards because the pesticides also destroy parasitic wasps, such as Gonatocerus walkerjonesi, which naturally control pest populations.