Palm trees are a beautiful addition to any landscape, providing shade, tropical vibes, and a unique touch to any space and will grow in many different places, including some colder regions you might not expect. However, like any plant, they are susceptible to a range of pests and diseases that can cause harm which you need to look out for.

In my guide, I will discuss some of the most common palm tree pests and diseases, as well as other problems that palm trees may encounter. I’ll cover everything from identifying the signs of a sick palm tree, to understanding the causes and treatment options for each problem, including yellowing and brown leaves.

Some of the pests and diseases I will cover include palm leaf scales, spider mites, leaf spot disease and fusarium wilt. Here are the main pests and diseases you may find on your palm tree and a few other problems that arise as well.

Pests that attack palm trees

Palm leaf scale insects

Scale insects love to suck the sap out of your palm plant through the leaves and the stems. They’re actually fond of doing this to a lot of different plants. There are about 25 different species of them including palm leaf scale insects, all with a waxy shell that is resistant to spray treatments. They leave behind a clear and sweet sticky substance called honeydew on the leaves. This isn’t harmful in its own right, but it does attract black sooty mould and ants. Regular monitoring and early intervention are crucial for controlling palm scale insects and protecting the health of your palm trees.

What to do

Treating palm scale insects requires a multi-step approach. The first step is to physically remove as many scales as possible by scraping them off with a brush or a dull knife. Then, apply horticultural oil or insecticidal soap to the affected areas, ensuring the entire palm is covered, if possible or in most affected areas. I recommend repeating the treatment every 7-10 days for 2-3 weeks to ensure that all scales and any new hatchlings are killed. Regular monitoring and early intervention are crucial for controlling palm scale insects and protecting the health of your palm trees.

I have a complete article that helps you identify if scale insects are your problem and gives advice on what to do about them. Please read Identifying and controlling scale insects for all the details.

Mealy bugs

Mealybugs are another sap-sucking insects that can cause significant damage to palm trees. They are small, soft-bodied insects that feed on the sap of the tree, causing stunted growth, yellowing leaves, and a general decline in the tree’s health. Mealybugs also excrete a sticky substance known as honeydew, which can attract other pests and promote the growth of sooty mold, a fungal disease that can further harm the tree.

What to do

Controlling mealybugs on palm trees requires a multi-step approach, much like that of scale insects, as discussed previously. The first step is to physically remove as many of the insects as possible by gently wiping them off the leaves and stems with a cotton swab or soft brush. Then, apply horticultural oil or insecticidal soap to the affected areas, ensuring that the entire tree is covered. Repeat the treatment every 10 days for 2-3 weeks to ensure that all mealybugs and any new hatchlings have all been removed.

Red spider mites

While not an insect (they are spiders), spider mites love houseplants of all kinds, including your palm tree, and they are more common on palm trees grown indoors. You need a magnifying lens to see them there that small but there usually in large numbers, and it’s usually the web they form you see first.

What to do

Head over to the article mentioned above – Orange tree pests and diseases – Identify and Treatment – and check out the Spider mites section. To quick answer is you can jet them off with water or treat them with horticultural oil or insecticidal soap. If you have a bad infestation, you can also consider using a pesticide spray, but I always try to avoid this when possible.

Palm tree diseases

Fusarium wilt

Fusarium wilt is a devastating fungal disease affecting many palm tree species. It is caused by the soil-borne fungus Fusarium oxysporum, which infects the palm tree through its roots and then spreads throughout the vascular system. The disease causes the leaves to turn yellow and wilt, eventually leading to the tree’s death. Unfortunately, there is no cure for Fusarium wilt, and infected trees must be removed to prevent the disease from spreading to other trees. Prevention is critical, and it’s essential to practice good sanitation practices and avoid planting susceptible palm species in soil with a history of the disease.

Leaf spot on palm tree leaves

Cercospora Leaf Spot is a fungal disease that particularly attacks plants in shady locations. It’s not fatal to your palm tree but it does spread rather quickly. You may first notice brown spots on the underneath of old leaves at the bottom of the palm tree. but also check the flowers and the stems. The spots may have purple halos around them. There could also be purple spots on their own with grey centres.

The leaves eventually turn yellow and fall off the plant. You may end up with a plant without many leaves.

What to do

Remove any infected leaves as soon as you see them. (See How to trim and prune a palm tree for help with this.) Use an organic fungicide on the remaining plant – copper sulphate or potassium carbonate work well with this problem.

As a last resort, use a general chemical fungicide.

Root rot

Root rot is a common fungal disease that many plants can get. It’s a result of over-watering your plant. It starts in the root ball of the palm tree, so it’s not immediately visible. The roots become saturated with water and turn black or brown and become water-logged and mushy. The disease may spread upwards through the stem (which often becomes soft) to the leaves, which turn yellow, then brown and then die.

What to do

This is such a widespread disease that I wrote an entire article on what to do about root rot. You can read all about it in Phytophthora Root Rot – prevention and treatment.

Problems

These problems are in addition to palm tree pests and diseases. Many of the problems with palm trees manifest with the leaves turning yellow or brown, this is probably the most common problem. I have a whole guide covering these symptoms. Please head over to Why is my palm plant turning yellow or brown? to see if any of these causes affect your palm tree. For most people, yellowing leaves is actually due to incorrect watering of lack of nutrients, both of which can be resolved with a little know how.

Leaves wilting

Additionally, if your palm leaves are wilting but haven’t turned yellow yet, water-logging may be a problem. That’s when the soil isn’t draining away any excess water, or you’re watering your plant too much. This results in the palm roots standing in a pool of water which prevents them from utilising oxygen. This is fairly common with pot grown palms where there is not sufficient drainage because there is either no holes in the pot, they are blocked, or poorly draining soil was used, such as garden soil which is why I usually recommend John Innes potting compost.

Alternatively, this could also be an indication of the opposite situation – that you’re not watering your plant enough.

What to do

Check the moisture level of the soil. If it’s dry, water the plant and increase your watering schedule. If it’s wet, read Phytophthora Root Rot – prevention and treatment to find out what to do.

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