Lethal Bronzing: A Destructive New Palm Disease
Lethal Bronzing, previously called Texas Phoenix Palm Decline, is a relatively new bacterial disease (called a phytoplasma) that is causing significant palm losses in Palm Beach County. Symptoms are similar to lethal yellowing, but affect a much smaller number of palm species. The damaged vascular system of the palm leads to wilting, and eventually death. University of Florida research is determining which sap feeding insect(s) may spread it. Affected species include Sabal (Cabbage), Queen, Pygmy Date and other Phoenix species, Christmas, Bismarck, Chinese Fan and Carpentaria palms.
Older fronds die first and may be reddish-brown, dark-brown or grayish depending upon which species is affected, and stage of infection. Symptoms can sometimes be confused with nutrient deficiencies like potassium, or Fusarium wilt. Flower spikes may die prematurely, and fruit may drop off prematurely.
What Can You Do?
The disease is confirmed by laboratory analysis of tissue extracted from the trunk. Remove and dispose of infected symptomatic palms. Administer antibiotic injections to non-symptomatic susceptible species growing around removed palms. Inject oxytetracycline at 3 grams per palm (1 gram for Christmas palm). It is not known if the oxytetracycline will help susceptible palm species already showing symptoms. However, once the palm spear leaf dies, the palm will die even if lower fronds are still green.
Additional information and photos can be found in the UF publication Texas Phoenix Palm Decline.