FloridaGardener's Blog
Mar 14

Written by: host
3/14/2010 5:48 PM

Remember when all of Florida was in an uproar over citrus canker? Remember the eradication efforts and outraged citizens protesting their right to keep their prized citrus trees and the state chopping them down and taking them away, by law?

First a review of what citrus canker is. Citrus canker is a disease affecting citrus species that is caused by the bacterium Xanthomonas axonopodis (Xa). Citrus canker cannot infect people or animals. Infection from citrus canker causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit. Canker significantly affects the vitality of citrus trees, causing leaves and fruit to drop prematurely; a fruit infected with canker is safe to eat but considered too unattractive to be sold. (Link to an earlier article about citrus canker from

Lemon Blossom on citrus canker infected tree.Citrus canker infected lemon fruit.Lemon fruit infected with citrus canker.

Citrus canker is believed to have originated in South East Asia and is extremely persistent when it becomes established in an area. Florida has had bouts of fighting citrus canker at least 7 times since the first infection was discovered in the state in 1910.


Citrus canker is alive and well in Florida. Eradication efforts to control it failed when the Federal Gavernment cut-off spending to gain control of the disease. Now thousands of door yard and grove citrus trees are infected and slowly dying from citrus canker. Does this mean the end of citrus trees in Florida? Buh-bye famous Florida orange, icon of the “Sunshine State”?


Scientists in citrus growing regions around the world are searching for citrus resistant to the disease caused by Xa. They have discovered that Citron (C. medica) and Mandarins (C. reticulata) tend to be resistant to citrus canker and that Calamondin  (X Citrofortunella) and Kumquat (Fortunella spp.) are highly resistant. (Source: Citrus Canker, Wikipedia). Indian scientists have discovered about 8 cultivars of lemon and acid lime that are resistant to citrus canker. (Source: Evaluation of lemon cultivars and acid lime × lemon hybrids for resistance to Xanthomonas axonopodis pv. Citri M. B. N. V. Prasad, Roopali Singh, A. Rekha and Ramesh Chand; Indian Institute of Horticultural Research, Bangalore, India). With all of this work taking place we should shortly be seeing Xa resistant citrus trees for sale, so one should not lose hope!


But until the time that citrus canker resistant plants become available to the public, we will have to deal with our ugly Xa infected citrus. The good news is that my lemons still taste good with a shot of tequila and a lick of salt.

Sliced lemon fruit infected  with citrus canker.


Happy Gardening!


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