Watch citrus trees for signs of disease

Craig Roussel and Mariah Simoneaux LSU AgCenter
Citrus canker on leaves.

Citrus canker, a highly contagious bacterial plant disease, has reappeared in Louisiana. The disease, which had not been seen in the state since 1940, was detected in Orleans Parish in the summer of 2013. Over the past three years it has been confirmed in seven South Louisiana Parishes, including Jefferson, Orleans, Lafourche, Plaquemines, St. Bernard, St. Charles, St. John, and more recently St. James Parish.

Homeowners and producers with citrus trees should be aware of the symptoms of this devastating disease. Symptoms of citrus canker will typically begin on the leaves and fruit as tiny raised blisters or lesions. Lesions are visible on both sides of the leaf and will have a corky texture. A bright yellow halo will surround each lesion. Similar lesions can be found on the tree’s twigs and branches, but the bright yellow halo will be absent. As the disease progresses, trees will experience leaf loss, twig dieback and premature fruit drop.

The citrus canker bacteria is dispersed by windblown rain, lawnmowers, other landscaping equipment, and people. Trees are infected through natural openings and wounds, and the bacteria can be spread very easily from tree to tree. Simply touching an infected tree and then another tree can spread the disease. Insects do not carry citrus canker. Citrus canker can infect all citrus varieties. A few of the most susceptible varieties are grapefruit, trifoliate orange, Key lime and navel orange.

If you believe a tree is infected it is extremely important that you do not transport samples to any location. Instead, report trees that may have symptoms. Please contact the Horticulture & Quarantine Division of the Louisiana Department of Agriculture and Forestry at 225-952-8100, Phil Staudermann with USDA at (225) 298-5410, or the Ascension Parish LSU AgCenter extension office at (225) 621-5799.