QUESTION
My Palm leaves are turning brown. Does it have a disease, or a nutrient deficiency?
ANSWER
Before providing an answer, we must ask a few questions of our own.
- How often should a palm be fertilized?
- What do you use when you fertilize?
- Have you assessed your soil for pH and nutritional content?
We need to know this before we can properly address the question. Nutrient deficiencies in palms can look like disease. We want to rule out nutritional issues before moving to diseases. Palms need to be on a fertilization schedule. Once a plan shows a nutritional issue, it can take 2-3 years before the canopy regains a healthy appearance. A University of Florida study on palm fertilization found an 8-2-12+4 to be the best overall palm fertilizer. Why assess soil pH and nutrient content? Having soil pH that is off can lock up nutrients, making them unavailable to the plant.
If a plan is deficient in nutrients, we can work to mitigate that issue. Make sure you fertilize regularly, with the right fertilizer, and at the right rate. Read the package label for proper application. Apply with a spreader to ensure even distribution. Contact your local UF/IFAS Extension office if you need help with this.
Next, let us talk about diseases. There are several diseases that impact the Florida palms. Most are lethal. Currently there are six common diseases causing issues across the state.
Lethal bronzing (Phytoplasma bacterium) is one of the more prevalent diseases. Larry Figart did a great job going over this in detail in an accompanying article, so I will not go into detail here.
Let us look at the other five:
Thielaviopsis Trunk Rot (Thielaviopsis paradoxa) is caused by fungal spores that attach to open wounds on the palm, like a cut from a green leaf. This disease causes a collapse of the trunk after early leaf death. You may notice a fermented fruit smell coming from a wound in the trunk. The best way to prevent this is to not over prune. Remember, only take off fully brown leaves. There is no cure for or treatment for this disease.
Rachis Blight (Multiple fungi) is the only disease that is not a guaranteed death sentence, but it does require testing. Both Rachis Blight and Fusarium wilt (below) have the same outward symptoms in the early stages. Both diseases present with one side of the leaf (left or right) turning brown, while the other side remains green. Testing is the only way to know which disease you have. Apply fungicide to protect new growth. Watch your palm. It can weaken over time with this disease.
Fusarium Wilt (Fusarium oxysporum f. sp. palmarum). Fusarium wilt takes only 2-3 months from the first symptom to full palm death. There is no cure. Evaluate your palm with the UF diagnostic lab to learn if your palm has this disease, or rachis blight.
Ganoderma Butt Rot (Ganoderma zonatum). This fungus attacks the lower 4-5 feet of many palm species. Symptoms include leaf discoloration and wilt. Mushroom conks form in advanced cases. These spread the spore to other palms in the area. If your palm ever gets a mushroom like this, remove the tree and roots as soon as possible. The palm should be incinerated to reduce speed. Do not plant another palm in that location. Once established, the disease resides in the soil.
Phytophthora Bud Rot (Phytophthora palmivora) is another fungal disease. The fungi is spread by wind, water, and soil. As the name suggests, you will notice symptoms at the terminal bud, with the center spear dying. A dead-center spear does not always mean you have this disease, as several nutrients, such as boron and magnesium, can impact the spear as well. A lab test would confirm an accurate diagnosis. If caught early, fungicide may help.
Remember, DO NOT prune green leaves off your palm. You are taking away nutrients from your plant, while also leaving wounds that can attract disease-carrying pests. Removing affected fronds may take away diagnostic information needed by professionals to determine if there is an issue with your palm. One way to prevent the accidental spread of several of these diseases is to ensure tools are sanitized between use on different plants.
If you have questions about your palms, contact your local UF/IFAS Extension office, an ISA Certified Arborist, or a professional tree-care specialist for help.
