Ganoderma zonatum

Symptoms of Ganoderma zonatum are general decline in the health of the plant, wilting and discoloration of the leaves and slow growth. However, this is noticeable in many different plant diseases and can not be used as a diagnosis tool. There are only two ways to fully identify G. zonatum. One is the basidiocarp (or conk) forming on the plant with the other viewing the internal rotting of the palm on the inside once it has been cut down.[1]

Growing on a sabal palm at Terra Ceia Preserve State Park in Manatee County, Florida

The fungus is spread between the plants due to the spores produced in the basidiocarp. The spores land on the soil and germinate. The hyphae then grow over the plant roots and up into the woody trunk. The fungus damages the palm trunk closest to the soil first, expands in diameter and moves up the center of the trunk causing a cone like shape of infected trunk. When the basidiocarp emerges it is at the highest point when the fungus will internally grow.

There is currently no method for the control of G. zonatum once it has been identified.[1] However minimizing the amount of moisture can decrease the risk of a palm becoming infected by the fungus. In places where a palm has been infected with G. zonatum, no other palm should be planted as the spores can survive in the soil. Some other prevention methods are

• Avoid injury to the trunks of palm trees.
• Be careful when using lawnmowers and other gardening equipment.
• Consult forestry officers after infestation and seek their advice.

After fungal infection, the wood above the butt area can be easily mulched with caution, but for the lower 4–6 feet (1.2–1.8 meters) extreme care should be taken to prevent the fungus from spreading.[1] Dispose of the wood by wrapping it in plastic. Use sterile tools and gloves. Sterilize your tools before using them on other healthy palms.