Citrus canker is a plant disease caused by bacteria. The disease damages fruit, stems and leaves of citrus trees. Symptoms include lesions on the plant, pustules, craterlike impressions, discoloration, fruit drop and leaf drop. Citrus canker thrives in warm, wet conditions. Insects called leafminers infest citrus trees, leaving open woulds on the leaves and increasing the plant's susceptibility to citrus canker infections. While this disease is primarily cosmetic, prompt treatment prevents the disease from infecting nearby healthy trees.
Defoliate infected trees using high volumes of fertilizer or legal copper products. This process is a chemical treatment that causes the trees to drop their leaves, therefore allowing you to decontaminate the area and prevent the spread of disease to other plants while eliminating disease from that tree. Consult an extension agent or citrus grower for advice concerning how much product to use in your specific situation. Remove and burn any leaves that fall from the tree to prevent the spread of disease.
Prune trees back to remove infected branches, leaves and fruits. Remove and burn contaminated branches, leaves and fruits to prevent the disease from spreading. Treat the remaining tree with an antibacterial product recommended for citrus trees to eliminate future chance of disease.
Decontaminate any tools used for defoliation or pruning infected trees. This equipment must be thoroughly decontaminated to prevent disease from spreading to healthy plants, as well as to prevent the disease from reinfesting treated trees.
Add windbreaks, a fence or a row of other trees to prevent wind from reaching your citrus trees. This prevents the wind-borne disease from infecting your healthy trees.
Control pests on your citrus trees using pesticides. Insect pests, such as the leafminers mentioned earlier, leave wounds on the trees that invite infection. Elimination of the pests helps aid in prevention of canker disease.
Eliminate canker infestation completely by removing and burning any infested tree. This method is by far the most effective but also most extreme. It may be used as a last resort by those who have tried other methods and found the disease is still actively infecting other trees.