Sabal palms under siege

Deadly disease could progress to trees in South Florida.


A mysterious new microscopic palm tree killer hasn't reached South Florida yet, but it's on the move from the Tampa Bay area.

It joins the other problems attacking our palms, such as lethal yellowing, ganoderma butt rot and red mites.

But this newest unnamed disease is going after the state tree, the native sabal palmetto palm, also known as the cabbage palm. The sabal is our most commonly used native palm in the landscape. It has a full canopy of several dozen leaves and a trunk that is often covered with boots or a crisscross pattern of split leaf bases.

"There are lots of unknowns when it comes to this disease," said Denise Feiber, a spokeswoman for the Division of Plant Industry for the Florida Department of Agriculture and Consumer Services. This will make it especially hard to detect and manage, she added.

Here's what scientists do know:

Where it has struck: The disease has been found on the west coast of Florida, with a substantial number of cases reported in Manatee and Hillsborough counties. The farthest east it has been observed is just outside the northeast corner of Okeechobee County. It has not yet reached South Florida, but there is no reason to think that it won't make its way here eventually, especially with the way palms are transplanted around the state.

What it is: A lethal phytoplasma disease. A phytoplasma is a bacterium without a cell wall.

What it resembles: Preliminary analysis indicates it is the same bacteria that causes Texas Phoenix Palm Decline, which is killing phoenix palms in Florida as well as in Texas. It also can affect some queen palms. It is a similar, but genetically different bacterium from the one that causes lethal yellowing, another fatal palm disease.

They don't know what causes it and how to stop it.

"We are concentrating on discovering what kind of vector spreads this disease," Feiber said. "Most likely, it is a plant-hopping insect of some kind."

Once scientists nail down the insect that causes the fatal disease, they can work on finding a predator or biological control, she added. There is no way of determining how long that will take, but it doesn't seem to be something that is going to happen overnight.

The symptoms can be similar to run-of-the-mill palm disorders, such as nutritional deficiencies.

According to a paper by Nigel Harrison and Monica Elliott from the University of Florida, this is the way an infected tree will look:

"The overall effect on a full, untrimmed cabbage palm canopy is as follows: the oldest leaves will appear to be grayish-brown in color, then an unusually large number of leaves in the middle of the canopy will be reddish-brown or bronze in color, with a few young, green leaves in the upper canopy, along with a dead or dying spear leaf." (Tan instead of green).

The number of discolored fronds will be considerably more than you typically see on a palm shedding its lower fronds due to age or one suffering from nutritional deficiencies.

The tree also will lose its fruit all at once during fruiting season, and the flowers will die quickly, too.

It takes a laboratory analysis to definitively determine the bacteria's presence. This involves drilling into the trunk of the tree and getting a clean sample and sending it for analysis, which can be an involved process, according to Feiber. For more information on how it's done, go to

However, no one is recommending that homeowners start drilling into their palms, especially in areas like South Florida where the disease has not yet spread.

Feiber suggests those with suspect palms who live in affected areas or in counties bordering affected areas should call their county extension agent. She said sending digital photos to the extension office would be a better first step than sampling.

Unfortunately, the disease is fatal, and contagious, so as soon as it is determined that your tree has it, it should be removed.

Christine Winter Juneau is a National Wildlife Federation habitat steward and the president of the Parkland Garden Club. You can reach her at

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