Ganoderma butt rot is a relatively new and lethal disease of Florida palm trees. It is caused by a fungus, Ganoderma zonatum, which invades the base or butt of palm trees up to a height of three to four feet above the ground. The disease was first discovered in Florida in 1994 and in only a few years it has spread to infect palms throughout the state. At this time, it cannot be said with certainty that there are any palm trees resistant to ganoderma butt rot. The ganoderma zonatum fungus most often invades a palm tree by means of a wound at the base of the tree. The fungus then begins to rapidly work its way through the tree’s butt area essentially rotting the wood. Once the fungus has worked its way through the centre of the tree to the surface, it forms a fruiting body called a ‘conk’, a spongy, whitish mushroom-like growth which grows to form a horizontal disc extending out from the bark. Treatment Unfortunately, there is currently no effective treatment for ganoderma butt rot. By the time the conk has appeared on the bark, the tree is effectively dead and must be removed.