Originally published in Spring, 2020, edition of Woods Reader Magazine.
When you think of Florida, most people think of beaches and palm trees. There are 11 native palm tree species in Florida, and dozens more have been imported for landscaping ornamentals. Even the state tree is the ubiquitous Sabal, or Cabbage, Palm.
But all is not well with the palms of Florida. Disease and insects are impacting the state’s palm trees.
The beautiful native coconut palms have all but disappeared in south Florida, victims of a disease known as “Lethal Yellowing”. Imported Jamaican coconut palms have so far proven resistant. Now a similar disease, “Lethal Browning”, is impacting Date and Sabal palms in the central part of the state. Also called “Texas Phoenix Palm Decline”, the disease is likely spread by microscopic insects, what researchers call “planthoppers”. The disease was originally found in the Tampa Bay area, but has spread rapidly across the central part of the state to Orlando, and up and down the central Florida Atlantic coast. The outbreak, although widespread, is denser in some areas more so than others.
University of Florida Entomologist Brian Bahder is leading the investigation. “This is a lethal infection. At this time we have no cure”. But Bahder says there is some hope for controlling the disease by injecting healthy palms with an antibiotic every couple of months. He says there has been early success with the antibiotic keeping the healthy trees from becoming infected. He’s still researching whether the injections, in heavy doses, can be a cure on already affected trees.
Bahder says there is some research that shows the disease can be transmitted from tree to tree, not just by insects. He says there is no data presently to suggest climate change helps the disease spread, but “warmer weather allows insects to move farther north”.
Other attacks on palms come from fungus, microscopic insects, tiny bacteria, and nematodes. Researchers at the University of Florida, and even arborists at Walt Disney World, are leading the effort to identify and solve the palm mysteries.
The likeliest target for attack is the Cabbage (Sabal) palm, the most common palm in the state. Tiny caterpillars attack the trees all over Florida. They rarely kill the tree, but do destroy the blossoms. The stately Royal Palm is infected with a rare bug that lays a single egg a day only on Royal Palms. The bugs don’t kill the tree but cause unsightly dead palm fronds.
The ugliest culprit is the Giant Palm Borer, which feasts on many varieties of palms by drilling a quarter sized hole in the tree.
A few years back a palm wilt disease killed off Queen and Mexican fan palms in Central and South Florida. Researchers determined the disease was spread in fungal spores by wind and rain. There is no cure and affected palms have to be removed quickly before the disease spreads.
There is also a threat of importing diseased palms into the state from other states and countries. The red ring nematode, a microscopic roundworm, is responsible for killing Oil and Coconut palms in South and Central America. So far Florida is not affected by the potentially devastating nematodes. But researchers fear that it can migrate to Florida, and be spread by a native weevil that feeds on palms. They are working with palm experts in Mexico, Central America, and the Caribbean to keep the disease from spreading.
Palm health requires some supplemental care, because some palms, especially the imported ones, need extra nutrition to thrive in Florida’s sandy chalky loam soil. Researchers have found that treatments with fertilizers lead to healthier palms.
No one is saying climate change is causing the problems for Florida palms, but nobody is ruling it out either. More studies are being done.
Meanwhile, all hope is not lost. You can still plop your beach chair down in the shade of a palm tree and enjoy that Pina Colada.