Preserve healthy cabbage palms

November 20, 2008

This op-ed appeared Nov. 20, 2008 in The Miami Herald.

By: Jack Putz
Francis E. ”Jack” Putz is a professor of botany at the University of Florida in Gainesville.

If you look out your window right now, chances are you’ll spot a Sabal palmetto, the scientific name of the cabbage palm, the state tree of Florida and South Carolina. Now imagine the landscape without these icons of the tropics.

Unfortunately, that possibility is very real. A bacterial disease that experts are calling ”Texas Phoenix Palm Decline” is chomping its way through cabbage palms out in the woods and in manicured landscapes in at least Hillsborough, Polk, Desoto, Pinellas, Sarasota and Manatee counties. If you want to see what this tiny monster can do, feast your eyes at the devastation along Interstate 75 around Tampa.

I’m too young to remember when the American chestnut succumbed to a Chinese fungus, but I do remember losing American elms to another exotic insect. Last year I saw the pitiful remains of what I remember as cool shady hemlock groves in Connecticut, prey to an introduced insect called the hemlock wooly adelgid. Right now in North Florida and South Georgia, you can see dead redbay trees, killed by an exotic fungus carried by an exotic ambrosia beetle.

I do not want cabbage palms to suffer the same fate.

The ”emerging pathogen” — a generic term for any introduced insect, fungus or other pest — wreaking havoc among cabbage palms in Central Florida is a fascinating creature. It is a phytoplasma related to the one that caused lethal yellowing of coconuts and other palms in South Florida. Because these phytoplasmas cannot yet be cultured, identification involves sequencing their DNA using polymerase chain reaction or PCR techniques, which is not cheap.

Given that it may take an infected palm a year or more to show symptoms and that few palms have been tested, it is hard to gauge the gravity of the problem, but hundreds of trees have already died.

Researchers from the University of Florida and the Florida Department of Agriculture and Consumer Services are busily trying to discover the vector for this disease. They suspect an insect called a plant hopper, but are not sure which. But one indisputable vector is the trucks that carry diseased palms at 70 miles per hour north on I-75.

To avoid the grim scenario of cabbage palm annihilation, if the authorities discover an infected palm in a nursery, the site is quarantined for six weeks. Much harder to control are the palm diggers out in the woods, yanking palms and trucking them around the state and beyond.

We are not certain that our cabbage palms are in jeopardy, but this seems like a clear case in which the ”precautionary principle” should be invoked. If the threat is real, the cost of doing little or nothing is just too large to consider. Perhaps I am just another shrill environmentalist spouting gloom-and-doom, but it seems reasonable to wonder, what can be done? Short of quarantining the entire six-county area where the Texas Phoenix Palm Disease is already taking its toll, vigilance is our best defense.

If you are purchasing palms, be sure you know the source and avoid buying plants from infected areas. If the leaves of your palms turn yellow and then the spear leaf dies, call the FDACS Division of Plant Industry (352-372-3505) as quickly as possible. If the palm is determined to be infected, have it destroyed straightaway, lest it infect its neighbors.