Ganoderma on Palms Diagnostic Guide
Ganoderma butt rot (Ganoderma zonatum) is a lethal disease of palms. Symptoms may include wilting and/or general decline. The disease often forms a conk, called a basidiocarp, on the trunk. However, many diseased palms do not produce conks prior to death. Ganoderma is a white rot fungus that begins be degrading lignin followed by cellulose. Degrading internal lignin and cellulose within the palm affects water conducting parts of the plant, and predisposes the palm to trunk failure.
Trees at Risk
At least 65 species of palms throughout Florida, from Key West to Jacksonville to Pensacola. It is also known to occur in Georgia and South Carolina.
Signs of Damage
The conk is the most easily identifiable sign of this disease. The conk originates from fungal growth inside the palm trunk. The conk begins as a solid white mass which is soft to the touch. It will have an irregular to circular shape and is relatively flat on the trunk or stump. As the conk matures, a small shelf or bracket will start to form. The mature conk will have a shelf-like structure that is hard and appears to have a glazed reddish-brown top surface and a white undersurface.
Nutrient deficiency and root damage. Fruiting conk is a key distinguishing factor.
Field diagnosis of the diseases and the host plant are usually sufficient. It is difficult to sample for this disease if no conk is present.
This disease affects healthy trees in diverse environments. There is no known control. Remove, bag, and dispose of conks to reduce the amount of spore production. Preventatively remove palms displaying conks as they pose a risk of failure.
Other Treatment Strategy
Monitor trees for crown symptoms and conks.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org