Palm Tree Diseases: Signs, Symptoms, and Prevention

Palm trees are pretty easy to care for. But, even though they're low maintenance, they're still susceptible to several palm tree diseases, including fungal and bacterial infections. One of the best ways to keep your palms free of disease is to keep them healthy by providing the right nutrition and environmental conditions. Here’s a look at 10 common palm tree diseases and how to treat and prevent them.

1. Leaf Spot and Leaf Blight

There are many different leaf spots and leaf blights, but the symptoms and treatments are generally very similar. Fungal pathogens cause leaf spot in palm trees. While all palms are at risk and should be considered potential hosts, juvenile trees and weaker, sicklier trees are most at risk. 

2. Ganoderma Butt Rots

Caused by the fungus Ganoderma zonatum, ganoderma butt rot attacks the trunks of palms up to 4 inches above the ground. It inhibits the plants' ability to move water up the trunk by infecting the woody tissue and blocking the structures that transport water. This is not a soft rot so, although infected, the trunk does not develop soft spots.

3. Palm Bud Rots

Bacterial or fungal pathogens can cause bud rots and most commonly attack after heavy rains or tropical storms. 

4. Fusarium Wilt

Caused by the fungus Fusarium oxysporum, fusarium wilt causes brown, wilted fronds.

5. Lethal Yellowing

Lethal yellowing is caused by a microorganism called phytoplasma and is spread by planthoppers, a common palm tree pest. To accurately identify lethal yellowing, you need to observe the disease progression and combination of symptoms, as no single symptom is enough to give you an accurate diagnosis.

6. Pink Rot

Pink rot is an opportunistic disease that tends to attack already weakened or damaged palms. It can also infect areas damaged by aggressive pruning, as palm trees can't repair their own woody tissues. This fungal disease causes stunted growth, deformations, and leaf spots.

7. Diamond Scale

Caused by the fungal pathogen phaeoisariopsis neowashingtoniae, diamond scale produces large numbers of small, diamond-shaped fruiting bodies on the leaves of afflicted palms. The disease rarely causes tree death, but it does weaken the tree and make it susceptible to other, more dangerous diseases and infections. 

8. Sooty Mold

Sooty mold is a fungal disease that doesn't directly attack the palm. It's caused by aphids, mealy bugs, and scale insects who feed on the palm leaves and leave behind honeydew, a sweet, syrupy substance, on which sooty mold quickly takes hold.

9. Root Rot

Root rot isn't strictly a disease. Instead, it's a preventable problem caused by consistent overwatering or poorly draining soil.

10. Thielaviopsis Trunk Rot

Caused by thielaviopsis paradoxa, this fungal trunk rot causes trunk collapse and tree death. This particular fungus infects wounds in the tree's trunk.

Preventing Diseases in Palm Trees

Aside from providing the right nutrition and environmental conditions, there are a few other things that you can do to reduce the chances of your palms getting infected.

You should also practice proper tool sanitization, cleaning the blades of pruners, for example, thoroughly between uses to reduce the risk of spreading diseases from one tree to another.

When you water, don't let the soil splash up onto the palm foliage, as soil-borne pathogens can quickly infect the trees this way. Irrigate low to the ground or use drip irrigation. 

Fertilize your palm trees adequately, using a high-quality product, but don't over-fertilize, as this can cause additional problems.

Give your palms plenty of room. Don't crowd them. Proper palm spacing ensures adequate airflow, which is important because it creates a less hospitable environment for fungal spores that like dark, damp spaces.

Prune palm trees conservatively at the right time of year, and avoid injuring the trunk.

If you’re concerned about the health of your palm tree, a palm tree specialist near you can assess it and suggest a treatment plan to keep it healthy.