11 Palm Tree Diseases: Signs and Treatment

Palm trees can appear very easy to care for, but they may need a keen eye and constant inspection when it comes to diseases and infections. Palm trees are susceptible to several diseases, nutritional problems, and insect infestation. The diseases affect different palm tree parts, including the palm’s leaves, stems, and roots.

Most diseases and even pests attack weak palm trees. Sometimes, you might not know the disease is there if you’re learning how to care for your palm tree. For instance, the growth rate in palm trees can be affected by diseases. When growth is stunted, it could easily mean the plant is diseased.

Palm Tree Diseases and Treatments

Some palm tree diseases are more deadly than others. Some are irreversible, while others are not. However, with the proper care, the tree will recover. Also, with the correct care routines, most of these palm diseases are preventable.

Here are the most common palm tree diseases:

1. Leaf spots and blights

It is sometimes hard to spot the leaf spot fungi by only looking at the visual symptoms. Leaf spots can appear oily, circular or elongated and form at the underside of the fronds. They first appear as small water-soaked spots and increase as the disease continues to spread. The spots turn brown, yellow, black or gray, with the outer ring having a different color.

These spores are usually spread by water, wind, and poorly sanitized pruning equipment. Fortunately, in most cases, leaf spots can’t kill a palm tree.

Treatment for Leaf Spot

You can treat leaf spot fungus on palm trees successfully if you start the regime early enough. Here’s how to treat your palm tree:

• Prune away the most infected fronds. In cases of severe damage, use fungicidal sprays that have copper.
• Apply a copper fungicide to get rid of leaf spot disease in palm trees.

Copper fungicides are the only fungicides allowed if the palm fruits are to be used for food purposes.

Prevention

Don’t let the water wet the palm foliage to prevent leaf spots when irrigating. Water your palms in the morning to ensure they don’t remain wet overnight. Also, try fertilizing the palms to boost their vigor and enable them to fight the leaf rots more effectively.  

Sanitize your pruning tools to prevent the disease from spreading to other types of palm trees in your yard.

2. Ganoderma butt rots

Ganoderma butt rots is a deadly palm disease caused by a fungus called Ganoderma zonatum. This fungal disease affects different types of palm trees – both indoor and outdoor varieties.

It invades the tree’s base to a height of 3-4 inches above the ground, works its way through the woody palm tree tissue, thus preventing the plant from transporting water up to the stem.

Signs

Signs of ganoderma butt rots in palm trees include:

• Withering with older fronds bending easily.
• Stunted new growth.
•  Leaves turning yellow or pale green in color.
• Rotting roots
• Weakened trunk.

Depending on when the disease attacked the plant, the trunk may collapse, the head of the palm fall off, and roots become severely rotten.

One way to check if your palm tree is suffering from ganoderma butt rot is to tap the trunk. While the trunk may seem solid, it will produce a hollow sound when tapped – if it is diseased.

The disease can lead to the death of your palm tree depending on the age of the tree and the environmental conditions.

Treatment

Unfortunately, there’s no chemical treatment for the ganoderma butt rot disease. To prevent the disease, remove and destroy any stumps, root systems and trunk of dead plants in the landscape. During the planting period, avoid inflicting any injury to the plant. Also, conduct regular yard maintenance using string weed eaters.

 Since ganoderma pathogens survive in the soil, don’t plant any other palm in the same location.

3. Bud Rot

Bud rot is a palm tree disease caused by either fungal or bacterial pathogens. Normally, it occurs after a period of excess rain or tropical storm. The bacterial rots happen after the bud has been damaged by cold weather. Once the infection occurs, it’s unlikely to reverse the situation.

Symptoms

Here are the symptoms of bud rot in palm trees:

• Lack of new crown growth.
• Young fronds and buds start showing black lesions
• Wilting young buds and fronds
• A slimy rot on the buds of the affected palm trees.

The buds are often affected by a firm rot that may turn slimy later after the secondary invaders. Old fronds remain green for several months and are often the last to die.

Treatment and prevention

To prevent infection, avoid overhead irrigation whenever possible. Remove any infected plants and destroy them to reduce the further spread of the disease. Apply preventative fungicides containing copper for the plants exposed to these diseases.

Always apply the fungicide and spray at the right intervals according to the directions on the labels.

4. False Smut

False Smut is also known as graphiola leaf spot as graphiola species cause the disease. It’ is a cery common palm tree disease in areas with high humidity. False smut affects only the palms of the Aceraceae family.

Symptoms

Once infected, the leaves develop small, black wart-like structures that appear on both leaf surfaces. The black spots may have tiny filaments. Often, the youngest leaves don’t show any sign.

Treatment

Remove any severely affected leaves to minimize the spread of the disease. Do not remove too many fronds, as this may be more damaging to the palm tree than the disease. Since palm trees are easily susceptible to nutritional deficiencies, removing the fronds can easily weaken the tree and worsen the existing problems.

Prevention

• Improve air circulation – To prevent the disease, properly space your palm to allow for plenty of air circulation and reduce the humidity.
• During irrigation, avoid wetting the fronds.

5. Fusarium Wilt

Fusarium wilt is a palm tree fungus caused by Fusarium oxysporum. The disease has different strains that are specific to the various species of palm trees. Since it has no cure, your palm tree will likely die when affected by fusarium wilt disease.

Signs

The signs include discolored, brown and wilting fronds. The palm then loses its green color and eventually dies. The symptoms normally start near the bottom of the fronds before making their way upwards.

There is no cure for the disease, and once affected, you may need to get rid of the tree.

Care and prevention

However, you can extend the plant’s life span by providing the proper care to the plant.Here are a few tips to care for your palm trees and prevent fusarium wilt:

• Remove the affected fronds and dispose of them carefully to avoid spreading the disease to other palm trees.
• Water and fertilize the tree just enough to prevent excesses.
• Apply a fungicide that contains thiophanate-methyl regularly to prevent fungal attacks.

Although the fungicide won’t cure the fusarium wilt, it helps prevent and treat other opportunistic infections like pink rot that often weaken the plant.

6. Lethal Yellowing

Phytoplasma, a microscopic organism, causes lethal yellowing disease in palm trees. The disease attacks the plant in phases. The disease is spread by planthoppers and affects many varieties of palm trees.

Since the planthopper (Haplaxius crudus) is native to Florida, palm trees in Florida are highly susceptible to the effects of this palm tree infection.

Signs and symptoms

• Fruit drop: The first and the most obvious phase is the premature drop of almost all the fruits on the plant.
• Black patches on fruits: The fallen nuts have browned areas or blackened areas in places where they were attached to the stem.  
• Wilting flowers: All new male flowers in the plants often blacken from the tips and wilt before dying.
• Yellowing of leaves: The fronds turn yellow, with the yellowing starts from the fronds before advancing to the top of the tree. Insects majorly spread the disease.

Treatment

If the infection is slight, root injections could help in treating the tree. However, if most of the palm tree is affected by lethal yellowing disease, it needs to be removed and replaced with resistant species. This also prevents the further spread of illness to other palms.

7. Pink Rot

Pink rot is considered a secondary disease, and it can affect any part of the palm tree. Since palm trees can’t repair wood tissues, they are likely to be attacked by pink rot when pruned too severely or damaged.

Signs

The disease results in stunted or deformed growth, leaf spots and rots. The most obvious sign is the visible pink spore masses. Sometimes, pink rot produces a brown syrup–like ooze.

Treatment and prevention

To prevent pink rot disease in palm trees, always keep the palms as healthy as possible or plant the tree at a deeper depth. Most palm tree roots spread at a depth up to 36 inches or more.

Also, avoid injury to the palm tree with pruning tools or any other gardening materials.  After pruning, apply fungicide to protect the tree. Always follow the label instruction to apply the correct amount of fungicide at the right intervals.

8. Diamond Scale

Diamond scale is caused by a fungus called phaeochoropsis neowashingtoniae. It produces diamond-shaped fruiting, normally on the palm trees’ foliage. The disease is more common in coastal areas and some inland valleys.

Signs

Tiny watery-looking dark spots form and grow to diamond-shaped fruiting on the lower and upper surfaces of the leaves and leave stalks. The leaves first turn yellow before browning.

Prevention

To prevent further spread, replace the badly infected trees with resistant species.  Always strive to keep the unaffected trees healthy and supply water as needed. Check on the drainage and correct it if necessary as overwatering can worsen diamond scale in palm trees.

9. Sooty Mold

Sooty mold is a fungal disease that feeds on the honeydew produced by palm aphids, mealybugs, and scale insects. It appears as black or ashy gray mold on fronds. Although it doesn’t cause major harm to a palm tree, its sight is often ugly.

Signs

Sooty mold disease forms a black covering on the leaves and is associated with the infestation of insects. The soot appears on the trunk but mostly on the leaf surface. The mold easily washes off the palm leaves as it does not attack the plant directly.

To prevent the disease from reoccurring, control the sucking insects that produce honeydew – such as aphids. For smaller palms, sprayers are effective.

However, for mature and taller palms, use systemic treatments as they are difficult to spray.

10. Root Rot Disease

Anaerobic conditions due to overwatering or waterlogging cause root rot in many plants. Palm trees are especially highly prone to root rot when growing in poorly-draining soil.

Signs and symptoms of root rot

The symptoms include:

• The tree rotting at the base
• Mushy, rotting roots
• Stunted growth
• Leaves turning yellow
• Infected roots are dark and soft as compared to healthy ones.

Treatment

To treat the affected plants, trim away the infected roots using pruning shears. Cut the roots as closely as possible to the root ball and dispose of them carefully. Replant the palm tree in another area and give it new life. Lastly, apply fungicides like the thiophanate-methyl to cure this plant.

11. Thielaviopsis Trunk Rot

Thielaviopsis trunk rot is a palm disease caused by the fungus called thielaviopsis paradoxa. The disease causes the palm tree trunk to collapse on itself. The major sign is always stem bleeding, with the lowest leaves hanging down the canopy and dying prematurely.

The fungus affects fresh trunk wounds. Sometimes the canopy suddenly falls off the trunk, despite appearing healthy, before collapsing.

Once infected, get rid of the palm and destroy the diseased trunk portion. To prevent the disease, limit the man-made wounds on the trunk, especially on the upper third of the trunk.

How can you tell a palm tree is diseased?

Depending on the disease, impact and nature, a palm tree will depict different signs. Here are the signs your palm tree is diseased:

• Older fronds withering or roping
• Stunted growth
• Leaves turning yellow or pale green
• General discoloration of the plant
• Spotted or frizzled fronds

When a palm starts showing one or some of these symptoms, something is wrong with it. It is best to check the plant for problems and see if you can help it recover. Keep in mind that some common palm tree diseases such as root rot are caused by poor care practices such as overwatering your palm trees.

Palm tree diseases often attack weakened trees. Healthy palms resist pests and also diseases. Therefore, it is important to keep your palm trees healthy through proper care – provide the right growing conditions, water adequately, and fertilize when necessary. Catching the diseases early and starting the treatment immediately reduces the impact the disease might cause to the tree.