Over the past year I have had several calls of people concerned about the decline of their iconic Cabbage palms (Sabal palmetto) for no apparent reason. There is a relatively new palm disease that is affecting our cabbage (Sabal), Phoenix (date) palm population in Hardee County. It is a small organism called phytoplasma.
The disease in question is called Texas Phoenix palm decline. The bacterium causes wilting and eventual death and its treatment is unviable for most homeowners and land owners that enjoy the palms, characteristic icon of our region. The origin of this disease has been traced by DNA testing to the same phytoplasma that causes decline in Canary Island date palms in South Texas.
Mode of action
The bacterium colonizes the phloem of the plant (vascular tissue that carries substances produced in the leaves) of plants. Phytoplasmas are transmitted by piercing-sucking insects that feed on palm sap: planthoppers, and treehoppers.
It is not yet clearly known when this bacterium arrived in Florida, but in 2008 it had been identified in Hillsborough, Manatee, Pinellas and Sarasota Counties. By 2016 it had been detected in a total of 22 counties in our region including Hardee.
Symptoms of Texas Phoenix palm decline start with discoloration of the tips of older leaves. Infected leaves turn brown and gradually die-off. Infected palms exhibit a large proportion of brown leaves in the lower region of their canopy. The infection of mature palms leads to premature leaf drop and also fruit drop in a few days. This symptom is also accompanied by root rot.
There is no possible treatment if the plant spear dies (primary growth point). Plant disease management can be cumbersome for most homeowners and unfeasible for most producers since the treatment consists of using oxytetracycline hydrochloride, a broad spectrum antibiotic. If a palm is infected, but still has a green spear, the disease can be suppressed, but not eliminated. Antibiotic injections to the trunk of infected palms need to be administered every three to four months for the rest of the palm’s life. The only long-term disease management solution would be to breed for resistant strains of the susceptible palm cultivars.
Antibiotic treatments should be injected at a rate of 1-3 grams per palm as a preventive dose for healthy palms.
There is no vector control or insecticide treatment recommended for managing the spread of this disease due to the lack of feasibility of this strategy.
In conclusion, the palm decline that we are seeing in our area is a problem that has limited solutions. Keep in mind that there are many different palm cultivars that can replace sable palms. Choose wisely!
For further information on this topic, please call the UF/IFAS Extension Hardee County office at 863-773-2164. We are here to help.
Read more on this topic:
- UF/IFAS EDIS Publication: Texas Phoenix Palm Decline
- Texas A&M Extension Publication: Date Palm Lethal Decline in Texas Landscapes
- Louisiana Extension Publication: Texas Phoenix Palm Decline