From the Archives: Citrus Canker

Citrus canker is caused by a bacteria that eats the flesh and leaves of fruit. This bacteria is not harmful to humans and the fruit is still edible. However, the fruit is now difficult to sell due to the ugly sores that are created by the canker bacteria. This bacteria can also cause fruit to drop from the tree prematurely stopping it from ripening.

In the early 1900s, there was a widespread outbreak of canker throughout Florida. Frank Starling was hired by the Florida Citrus Growers and the Citrus League to see if he could aid in the battle against canker. Between 1913 and 1933, the state of Florida spent approximately $1.3 million in their attempts to eradicate canker. During this battle against canker, infected trees were burnt down to ensure that they could not spread the bacteria to other trees in the area. It is speculated that the canker bacteria traveled to the States via citrus seedlings from Japan.

There was a reemergence of citrus canker in the 1980s, and it was declared eradicated in 1994. However, there was a report of canker in Miami-Dade County the following year, in September 1995. Before the eradication efforts were successful, a hurricane spread the bacteria to several other counties. By 2005, $2.1 million worth of commercial grade citrus had been destroyed. In 2006, the eradication efforts were forced to stop because it had become impossible to eradicate canker due to how widespread it had become.

Currently, canker is still active in citrus groves with the majority of infections taking place between April and July. Growers have learned how to deal with the bacteria; applying copper containing products periodically to produce has been known to deter canker in citrus. Although, it should be noted that copper is not a guaranteed deterrent to the bacteria. As there are no known cures to the bacteria, these methods will have to be sufficient for the time being.

Written by Tanzy Zviitwah, Florida Citrus Hall of Fame Fellow
In partnership with Florida Southern College’s McKay Archives Center
Spring 2024

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Sources:

Dewdney, M. M., M. Zekri, P. D. Roberts, and J. D. Burrow. “Homeowner Fact Sheet: Citrus Canker.” UF IFAS Extension, University of Florida, June 4, 2018. https://edis.ifas.ufl.edu/publication/PP116. 

 

Mack, Thomas B. Citrifacts. Bartow, Florida: Associated Publications Corporation, 1992.