No plant is as closely associated with Florida as a palm tree – the native sabal palmetto is the state tree, in fact! While this and several other species of palm are hardy even into the cooler regions of the panhandle, there are occasionally problems that arise with them. Palms tend to be sturdy in the wind, handle salt spray, and deal with drought without much issue. A few diseases can strike them, however, and the fungal pathogen Ganoderma zonatum is one of them.
Symptoms of a tree infected with Ganoderma butt rot. Image credit: M.L. Elliott
Ganoderma butt rot, caused by this pathogen, can affect any palm tree no matter the species. It only attacks palms, so nearby hardwoods or conifers are safe from it. As a fungal disease, it spreads by spores, which are produced on a conk (a type of mushroom that is wide and flat, usually growing on decaying wood). By the time the conk is visible on the trunk of a palm, the damage is done. The fungus slowly rots away the lower four to five feet of the trunk, working invisibly until it is ready to reproduce. The trunk of the palm will not become soft or spongy as the disease develops. There may be other outward symptoms of the disease, including slower growth, off-color foliage, and wilting and dying of fronds starting from the older bottom fronds. These symptoms occur with other diseases and problems as well, making it difficult to diagnose Ganoderma butt rot until the conk is visible.
A conk will start out as a small, white, button-like growth on the trunk. As it grows, it expands, flattens out, and develops a brown or reddish-brown coating on top. Old conks turn fully brown. It is uncertain how long it takes a newly infected palm to develop conks; it may be months or even years.
Once a tree is infected with this fungus, there is no cure. Removal of the tree is the only option, and as much of the trunk, stump, and roots as possible should be taken out. Conks may form on stumps after the palm is cut down, which can help to spread the disease. The fungus, unfortunately, persists in the soil even after the palm is removed, so infected palms should be replaced with other types of plants.
A small, relatively newly formed conk.
Frustratingly, the disease is difficult to predict. There do not seem to be any conditions that favor the disease in particular – it has been observed on otherwise healthy plants as well as stressed ones, and on naturally growing palms as well as those that have been transplanted. Still, keeping plants of any sort as healthy as possible can help them to resist pests and diseases, so fertilize, irrigate, and prune palms properly.
While palms may survive, or even thrive, for years in climates cooler than those to which they are native, eventually they may experience temperatures cold enough to cause injury. The January 21st snow and wind chill is likely to take a toll on many of the palms in Northwest Florida. We have experience with this since it also happened in January 2014 and December of 2022. Unfortunately, much of the damage in 2014 was not evident for 18-24 months and we are not out of the window for 2022. Healthy palms can hold on with stored food reserves, but repeated events can continue to weaken them. When cold damage is severe, plant tissues are destroyed and water uptake into the plant may be reduced for years. Many times, it is only the protected bud that will remain alive. These palms can still be saved if the bud remains alive. Winter is not over, even though the temperatures are now creeping higher and higher. So, evaluate what damage you may already have and prepare for any additional, yet to come. Here’s a reminder of what to do.
One of the most common problems associated with freezes is that the freeze-killed lower portion of the spear leaf is degraded by secondary fungi and bacteria that are always present in our natural environment. Palm owners are often anxious to trim off the damaged leaves following a cold weather event. Avoid the temptation to remove these fronds until danger of additional freezes has passed. Even dead leaves provide insulation to the critical bud. As the weather warms, the dead fronds need to be removed from around the bud so that the spear can begin to dry out. Drenching the bud area with a copper fungicide will reduce the secondary microbes. Repeat applications will need to continue as the palm leaves develop. Copper fungicides, unlike other fungicides, are active against bacteria and fungi. Be cautious to not use a copper nutrient spray rather than a fungicide. Delay fertilizer application until new fronds have developed. The best analysis for palms is 8-2-12 + 4Mg. Utilization of proper palm fertilization can improve cold hardiness of palms.
Palm trunk decay appeared 2 years after 2014 freeze.
Palms damaged by cold can still show symptoms six months to three years following a freeze. New leaves in the spring may appear misshapen. Usually, the palm will outgrow the damage. However, sometimes the palm loses its ability to take up water. If there is a sudden collapse of the fronds in the crown during the first hot days, the palm may die. There is nothing that can be done to save the palm.
Palms in North Florida suffered serious damage as a result of freezing weather in December 2022. As spring approaches, we will be looking to see if the palms will recover. Learn what to do now and what to expect from your palms with UF IFAS Extension Escambia County.
Palm trees are great for adding a tropical feel to your landscape. For the most part, they are easy to care for, however there are a number of environmental and nutritional factors that can affect palm tree growth. Extended drought conditions can cause palm trunk to contract or shrivel and extended periods of moisture can cause trunks to swell and crack.
A palm tree with an irregularly shaped trunk due to water stress. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Palm trees are monocots and do not have lateral meristems or vascular cambium. In dicot and coniferous trees these structures produce additional xylem (water transport structures) internally and phloem (nutrient transport structures) and bark externally. This means that once the apical meristem (frond producing portion of the palm) dies, the tree dies. It also means that wounds to the trunks of palms are visible for life instead of healing over like in dicots. If you were to cut the top out of a red maple, a number of it’s branches would fight to take over as the main trunk. If you were to cut the top out of a palm tree , you would be left with a dead snag for a tree. Palms certainly have unique structures and growing habits. Visit this publication from Dr. Timothy Broschat for more information on palm tree anatomy and morphology.
A palm tree with a wound near the base of its trunk. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Palm trees display nutritional disorders differently from other trees. Their nutritional balance gets disrupted if too much nitrogen is applied. This often happens when high nitrogen turfgrass fertilizers are applied near palm plantings. The recommended palm fertilizer is 8-2-12 (nitrogen-phosphorus-potassium) plus 4 magnesium all available in 100% slow release form. A soil test is recommended to determine if other micronutrients are needed in addition to magnesium.
Potassium-deficient older leaf of Dictyosperma album (hurricane palm) showing translucent yellow-orange spotting. Photo Credit: Timothy K. Broschat, University of Florida/IFAS
This article provides just a glimpse of some of the common issues that affect palms. For more information on what could be going on with your palm trees and general palm tree care please visit Ask IFAS: Palm Care.
The ancient cycad, coontie, is a hardy and attractive plant for Florida landscapes. Photo credit: Carrie Stevenson, UF IFAS Extension
The plant has a crazy-sounding name, more like some little animal you’d find in Australia than a native plant. However, an ancient Florida plant it is, and a tough one at that. Growing close to the ground, it most resembles a large fern or a sago palm, if the sago had smooth, rounded leaf edges. Like the sago, the coontie (Zamia floridana) is a cycad—a group of palmlike plants that have been around so long that triceratops and stegasauruses ate them! Coonties are the only cycads native to North America, found in the states and island nations like Cuba and the Bahamas.
Male cones (strobilus) of coontie are thinner and shorter than female cones. Photo credit: Dan Culbert, UF IFAS
Another interesting feature of the coontie is its seed cones. These are large reddish orange cones that resemble magnolia seedpods. Both sexes of plant produce them in clusters ranging from one to five of the 2-7” long cones. Cones from the male produce pollen, while females produce seeds. If you are interested in attracting wildlife to your yard, the coontie provides good low-growing cover for birds and small mammals. It is also the preferred food for the caterpillar of the rare Atala butterfly. Members of the Timucuan and Calusa tribes ground up the starchy root of the coontie as a flour. However, the root contains a toxin and if it is not removed first, ingestion could result in severe abdominal pain and vomiting. From the late 1880’s through World War I, a large starch industry existed in Florida, producing flour from the coontie root.
Adult female atala butterfly, showing royal blue streak on forewings. Photo credit: Sandy Koi, University of Florida
At home in drier soil conditions like oak hammocks and pinelands in north central Florida, these plants can also adapt to a variety of soil pH types. Coonties are drought, cold, and salt tolerant, thus a great landscape choice for coastal landscapes near the Gulf or a bay. The plants are very long-lived and adaptable. In fact, the book Florida’s Best Native Landscape Plants notes it is “Very hardy and easy to care for. Will grow well in any part of Florida, even outside its normal range. An exceptional replacement for the closely related, often used, but non-native sago palm.” In other words, this is an ideal landscape plant that should be used more throughout Florida.
