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.
This disease affects healthy trees in diverse environments. There is no known control. Remove, bag, and dispose of conks to reduce amount of spore production. Preventatively remove palms displaying conks as they pose a risk of failure.
Other Treatment Practices
- Monitor trees for crown symptoms and conks.
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
Photo: Sabal palm with wilted and desiccated leaves due to Ganoderma zonatum infection.
Photo: Beginning symptoms of Ganoderma butt rot
Trees At Risk
At least 65 species of palms.
- Ganoderma butt rot is primarily spread by spores produced in the conk.
- These spores mix into the soil, germinate, and the hyphae then infect palm roots.
- The fungus uses the roots to move into woody trunk tissue.
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