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Pest and Disease

The Florida citrus grower battles a variety of pest and diseases on a daily basis. The state’s humid climate provides an inviting habitat to a wide range of bacteria and viruses that can cause significant damage to citrus trees. Fruit flies, tristeza, CVC, brown aphid and rust mites are just a handful of the pest and diseases that can effect a grower’s operation.

Currently, citrus greening (also known as HLB), citrus black spot and citrus canker are serious diseases facing the Florida citrus industry.

Citrus greening is a bacterial disease that greatly reduces production. Trees diagnosed with citrus greening often die within a few years. The disease, which is spread by the Asian citrus psyllid, presents no threat to humans or animals. The most characteristic foliage symptoms of citrus greening are the blotchy mottling of leaves and yellowing that may appear on a single shoot or branch.

Citrus Black Spot is a fungal disease marked by dark, speckled spots or blotches on the rinds of fruit. It causes early fruit drop, reduces crop yield and renders the highly blemished fruit unmarketable. While all commercial citrus cultivars are susceptible to citrus black spot, the most vulnerable are lemon and late-maturing citrus varieties like Valencia. Although disease symptoms are expressed clearest on the rinds of fruit, the risk of this disease spreading through fruit movement is minimal. The greatest risk of disease transmission is associated with the spores released from fallen, decomposing citrus leaves.

Canker is caused by a bacterium that creates lesions on the leaves, stems, and fruit of citrus trees, including oranges and grapefruit. While not harmful to humans, canker significantly affects the health of trees, causing leaves and fruit to drop prematurely. Wind and rain serve as the vector of canker.

The industry is now marshalling its resources to find short and long term solutions to each disease. More than 100 research projects are currently underway in an attempt to find scientific answers to greening and canker.

For more information on greening, black spot and canker visit the Florida Department of Agriculture and Consumer Services’ Division of Plant Industry