Feature Article - for release the week of September 28, 2008

Dan Culbert - Extension Horticulture Agent  

 

Citrus Canker comes home

Last week a bag of orange fruit and leaves arrived on my desk.  The brown raised spots surrounded by yellow halos gave it away, and local experts confirmed what was going on.  It’s that problem that neither the homeowner nor the county agent really wants – Citrus Canker.

It’s actually not surprising – given all the rain and wind that have visited our area recently.  Unfortunately, the heroic effort to eradicate citrus canker from Florida has been lost, and the result is that growers and dooryard growers alike now have to cope with this plant disease. 

Today’s column is a reminder to keep looking for outbreaks of canker and offers suggestions on what can be done once infected fruit are found in the dooryard. Much of it was written by former St. Lucie Citrus Agent Jack Hebb.

 

A Homeowner's Responsibility With Citrus Canker  

Florida's Treasure Coast is still home to many  citrus groves that make up a multi-billion dollar industry.  The many services and spin-off support industries add  to our local economy and employ thousands of local workers.  We all benefit from our citrus industry, and need to do our part, whenever possible, to protect it.

Homeowners are usually very proud of the various varieties of citrus that can be grown in a Florida dooryard.   Bragging rights belong to the gardener who can show his northern neighbors the prettiest and the best citrus fruit.  They are equally effected by this tree killing disease. 

While Florida is a great place for growing citrus, Florida's climate also supports certain pests and diseases that challenge a citrus tree's ability to survive. Among the list of these problems, citrus canker is near the top of the list . Citrus canker is a highly contagious disease that attacks the fruit, the stems, and the leaves, as well as causes lesions to the fruit. The disease is not harmful to humans, but will dramatically affect the health and vitality of citrus trees.

Unlike most citrus diseases, which are predominantly fungi (plant-like), citrus canker is caused by a bacteria.  It is microscopic organism (unseen by the human eye), and can be spread by wind, rain, humans (contact), landscaping (trimming, chipping, cutting, or pruning citrus trees), and fruit removal (peeling, buying, selling, transporting, picking, etc.).

Because the disease is bacterial in nature, the current remedies for its management are still prevention by decontamination (chemical antibacterials), or control sanitation (fire). The best choice is decontamination by using antibacterials rather than  tree destruction. The latter choice (removal and burning) involves the removal of nearby citrus trees that have a high probability of infection.

Researchers are on the verge of introducing some limited genetic resistance into new trees and may soon release some new anti-bacterial sprays to help reduce the spread of canker.  But at this time they are still testing these alternatives, which are several years away from release.

 

Canker Management

For homeowners, the following recommendations can help reduce the spread of canker:

·         If you suspect any part of a citrus tree of harboring canker, please do not remove the leaves, fruit, or limbs.  Leave them alone and promptly place a call our office. We will help to confirm the disease.

·         Do Not, and I repeat, Do Not, remove suspicious citrus tree parts and transport them to another location.

·         In neighborhoods where canker has been identified, homeowners working around citrus trees should help prevent the potential spread of this disease by washing any gardening clothes in a hot water with laundry soap immediately following outdoor chores. A personal disinfectant for hand and exposed skin washing is soap and water followed by a liquid bleach (Clorox) disinfectant at a rate of 1 oz. of Clorox to 1 gallon of water.

·         Landscape tools (pruning shears, clippers, etc.) need to be cleaned as well.  Use liquid bleach at the rate of about 6 oz. of Clorox to 1 gallon of water. Be sure to wash tools of any visible residue before dipping in the Clorox solution.

·         Yardmen, landscapers, etc. who prune or cut citrus trees or work around citrus trees need to practice the same measures as cited above.

All neighborhood residents need to be on the lookout for suspicious looking lesions on their citrus trees. We need to be alert and aware, because the spread of citrus canker can further impact one of Florida's most important agricultural industries as well as a dooryard fruit enjoyed by homeowners across this state.  

I’ve placed more information on our Okeechobee Citrus Canker web page, http://okeechobee.ifas.ufl.edu/Okeechobee.Citrus.Canker.htm.  If you need additional information on citrus canker, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 3 PM on Tuesday afternoons.  Go Gators! 

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Trade  names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean. Last update: 09/29/2008.  This page is maintained by Dan Culbert