Ganoderma zonatum or ganoderma butt rot is a fungal disease that attacks palm trees. This species of Ganoderma kills mature palms by attacking the lower 4 to 5 feet of woody trunk. All palms in Florida are potential hosts for this fatal disease.
The genus Ganoderma is a group of wood decaying fungi; ganoderma zonatum is the only species of this fungus group that attacks palms. Once infected by ganoderma zonatum, the palm will die – there is no cure. There is no known chemical or cultural technique to prevent a palm from becoming infected. Healthy as well as stressed palms can be infected.
Once a palm is infected, the only known treatment is the complete removal of the palm from the landscape. The entire plant needs to be removed including as much of the root system as possible. The lower 5 feet of the palm needs to be burned or taken to the landfill. The root system should not be chipped by stump-grinding equipment.
The fungus will remain in the soil for some undetermined time period, so placing another palm in the same location is not recommend as the replacement palm will most likely succumb to the disease.
The symptoms shown by a palm infected by ganoderma zonatum will be a general decline. A palm with this disease will have green fronds hanging limp, or fronds that prematurely turn brown. The palm may only have a green center spike while all the other fronds are hanging down. Other than the decline of the palm there may be no outward side of the infection.
The fungus spreads by spores and an advanced infection may have a button shaped fungus or shelf-like growth on the lower trunk (see photo). Once this evidence is seen the palm is technically dead and the spores are released spreading the infection to other neighboring palms.
This disease can spread through entire neighborhoods. To combat the spread, neighbors need to be vigilant and inspect palms regularly. The negative effects of this disease is not just the premature death of palms but also the property damage potential that can occur when the palm that has its lower wood weakened by the disease becomes a projectile during a wind storm. For more complete information on this palm disease go to the University of Florida’s EDIS website, the URL is http://edis.ifas.ufl.edu/PP100.
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