Florida Palms and Lethal Bronzing
For those of us fortunate to live in the Sunshine State, palm trees are a cherished part of our every day lives.
Lethal bronzing, a fatal disease, poses a threat to our beloved Florida palms.
As the name implies, lethal bronzing can be fatal to palm trees. This disease, formerly known as Texas Phoenix palm decline, is caused by phytoplasmas (parasites of the plant phloem tissue that can reproduce inside the cells of a host) which are most likely transmitted through planthoppers. This destructive disease is an issue predominantly in Tampa and the southern region of Florida due to the year-round warm temperatures which allow planthoppers to thrive all year.
Some symptoms of lethal bronzing include:
- Premature drop of fruits, underdeveloped or dying flowers
- Foliage discoloration starting with the lowest (and oldest) fronds that progresses up through the higher fronds
- Death of the palm’s spear leaf (its youngest leaf, typically in the center of the canopy)
- Indicators of this include the spear leaf appearing tan rather than green, wilting, or breaking off
(University of Florida, Institute of Food and Agricultural Sciences, 2021)
Preventive care is your palm’s best defense
Diagnosing lethal bronzing can be particularly tricky since early symptoms are often mistaken for nutrient deficiency or overpruning. In the onset of the disease, much of the damage occurs inside the palm and may not be overtly visible. Once the disease has reached the spear leaf, the palm has essentially died as all leaf production will cease. At this point, palms may then develop root rot – a distinguishing element from another palm disease called lethal yellowing which does not cause root decay.
Prevention is key to protect palms from lethal bronzing
There isn’t a cure for this disease yet, so once a palm is infected there is very little chance of saving it. Healthy palms that are regularly fertilized have a much smaller chance of contracting lethal bronzing. Professional arborists with expertise in palm disease can provide preventive trunk injections and help identify the disease’s early indications through routine monitoring and close examination.
