President’s Corner – April 2024 – Lethal Bronzing Disease in Palms

When you look around Viera, as well as much of Florida, you see a lot of palm trees. All different kinds of palm trees. Palm trees elicit visons of a tropical paradise, warm breezes, beaches, and vacations. Here in Florida, we are lucky to have them as part of our normal landscape. So much so, we even take them for granted a little bit. However, like most living things, palm trees are subject to diseases that kill them. Lately, our community has seen an uptick in a disease called lethal bronzing. The disease, as its name suggests, is lethal and there is no cure once a tree is infected.

Lethal bronzing was first detected in Hillsborough County in 2006. Since then, it has spread to about half of Florida’s counties, including Brevard. Although it was first discovered in Canary Date Palms, it has now spread to other species of palms including Christmas Palm, Bismarck Palm, Pindo Palm, Carpentaria Palm, Coconut Palm, Chinese Fan Palm, Edible Date Palm, Pygmy Date Palm, Wild Date Palm, Fiji Fan Palm, Buccaneer Palm, Mexican Palmetto, Cabbage Palm, Queen Palm, and Chinese Windmill Palm. It is expected that the disease will continue to spread to other species of palms found in Florida.

Per the University of Florida, IFAS, lethal bronzing disease is caused by a phytoplasma, an unculturable bacterium that has no cell wall. Phytoplasmas live in the part of the plant where sap is transported. Phytoplasmas are transmitted to plants by piercing-sucking insects that feed on the sap. The insects spread the phytoplasma from plant to plant as they visit different hosts during their feeding activities. Planthoppers and leafhoppers are the main groups of insects that transmit phytoplasmas. Because the disease is transmitted by insects, it can appear anywhere and, as previously indicated, is always lethal.

The reason I am writing this article on this subject is so that Viera residents can keep an eye on their palm trees and closely look for the tell-tale signs of the disease in the hopes that we can reduce or stop the spread. We watch the palms in the common areas very closely for this disease but we also want our residents watching their palms too.

Once a palm is infected, it needs to be removed right away. If you do have lethal bronzing with other palms nearby, there are antibiotic treatments that you can give those trees to give them a fighting chance. But, we all have to be vigilant and watch out for it. As far as symptoms, here ais some information from the University of Florida to help you spot problems: If flower spikes are on the palms, they tend to turn black and die. If any fruit, it usually drops prematurely. Later, symptoms begin with the older, lower fronds sometimes turning a subtle bronzish (looks more reddish-brown-grayish to some) before they turn fully grey and die. The central spear leaf usually dies by this time. Symptoms progress over about a 4-5 month period before the palm is completely dead. However, single trunk palms are effectively dead once the spear leaf or leaves die, even if there are still some green lower fronds. Symptoms are often confused with nutrient deficiencies like potassium, or Fusarium fungal wilt on susceptible palms. Potassium deficiency can be distinguished from lethal bronzing because the potassium usually takes multiple years of deficiency between symptoms first appearing and palms dying.

Here is a group of pictures I took from the IFAS website to show examples of palm trees with lethal bronzing.

In closing, lethal bronzing is here in Viera. We have already had to take down several trees with this disease. Just please be aware that it is out there and to keep a close eye on your palm trees.

So, until next time, please remember … “Life is better where there are palm trees.” ― Unknown

Eva M. Rey, President
Central Viera Community Association, Inc.