Ganoderma butt rot is caused by a fungus Ganoderma zonatum. The fungus degrades or rots the bottom four to five feet of the palm trunk.
All species of palms can be affected by this fungus. The fungus can cause a general degradation of the health of the palm, eventually leading to trunk rot.
As the disease progresses, a shelf-like formation called a conk can form on the lower trunk. Ganoderma cannot be diagnosed until the conk forms on the trunk, or rot is discovered when the palm is cut down.
The fungus spreads from spores released by the conk. There are currently no chemicals available to treat the fungus either for prevention or treatment once the disease is discovered.
It is unknown how much time is required for a tree to become infected until death. The fungus spores may exist in the soil for some time. The fungus remains inside the trunk of the palm until the conk appears, at which time the spores can spread to other palms.
All palms in the neighborhood should be monitored for conk development. This is needed for safety reasons, since the presence of conks means the interior of the lower palm truck is already rotting. Hurricanes or severe storms could cause the palms to snap off at the infected areas. There is no way to stop the infection, so any desire to keep the palm should be offset by the potential hazard of a rotted palm near your or your neighborhood homes.
The fungus will remain in the soil after a diseased palm is removed. Evidence has shown replanted palms will also become infected. No other plants appear to be susceptible to this fungus, so it is advised to replant with a different shrub or plant, just not another palm of any type.
Submitted by Randy Browning