Rotten butts – the heartbreak of Ganoderma
By Ralph E. Mitchell
To newcomers and long-time residents alike, palms make Florida a paradise to the eye and spirit. Unfortunately, there is a “little devil” of a disease that attacks our palms – Ganoderma butt rot! This fungus needs a palm host to attack and a suitable environment to develop. This is a disease of mature, woody palms only; young palms are not affected. However, Ganoderma butt rot can affect all palms and is fairly common; especially with Queen and Canary Island Date palms in our area. Accordingly, it behooves the gardener to be aware and maybe even take steps to reduce its occurrence in other palms.
Ganoderma butt rot is prevalent throughout Florida. As mentioned earlier, a fungus causes this disease, which decays the wood of the palm. Often the first thing that is observed is what is called a conk or basidiocarp – this is very diagnostic and can’t be missed. The conk starts as a button-like growth that forms near the base of the trunk. This “mushroom manifestation” eventually changes into a “shelf” fungi; half-moon in shape and up to eight inches wide and two inches thick. Spores of the Ganoderma fungi are released from these structures. This shelf structure is in fact the “flower” of the fungi that is actively growing inside the palm.
This fungus is doing all types of bad things to the palm host. It destroys the woody tissue and water-conducting tissue. This damage shows up as wilting and off-colored foliage. This decline may take years to fully develop and it appears that the disease begins and stays low in the trunk. Studies have shown that Ganoderma only develops five feet up into trunk. To date, no common denominator has been identified as to how palms get the disease. Monitor your palms for conks and remove them when noticed. These conks can produce millions of spores that can infect other palms. Place these conks in a trash container that goes to a landfill. Do not allow the conks to be placed in a composting unit, as the spores are likely to survive. A palm that has an identified conk should be removed as it can blow over in a storm. Cut the palm as close to the ground as possible so that little infected trunk material will remain. Also remove the roots if possible. Dispose of the diseased portion of the trunk (lower four to five feet of trunk) in a legal landfill or incinerate it. The remainder can be chipped for mulch. There are no fungicide recommendations for this disease.
Sadly, you should not replace another palm in a spot previously occupied by a diseased palm as the disease can survive in the soil. Use any other woody, non-palm plant as a replacement. It may also be a good idea to develop a “Community Conk Control” program within your neighborhood with the cooperation of interested palm owners. While there is no cure for this disease, cooperative monitoring may help reduce infestations. For more information on all types of palm pests in our area, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer. Don’t forget to visit our other County Plant Clinics in the area. Please check this link for a complete list of site locations, dates and times – https://sfyl.ifas.ufl.edu/media/sfylifasufledu/charlotte/docs/pdf/Plant-Clinics-Schedule1.pdf. Our Eastport Environmental Demonstration Garden is always open to the public outside the gate at 25550 Harbor View Road. Master Gardener volunteers tend this garden on Tuesday mornings from 8 to 10 am and are available for questions. Ralph E. Mitchell is the Director/Horticulture Agent for the UF/IFAS Charlotte County Extension Service. He can be reached at 941-764-4344 or firstname.lastname@example.org.
Elliott, M. L. & Broschat, T. K. (2018) Ganoderma Butt Rot of Palms. The University of Florida Extension Service, IFAS.