Palm Diseases and Nutritional Problems in South Carolina

Quick Guide: Palm Diseases and Nutritional Problems

Affected Plants: Palms (Arecaceae family), including sabal palmetto (Sabal palmetto), pindo palm (Butia capitata), Chinese fan palm (Chamaerops humilis), and Washington palm (Washingtonia robusta)
Primary Disease Types: Leaf spots, false smut (Graphiola leaf spot), Ganoderma root and butt rot, bud rot
Primary Insect Pests: None discussed in this factsheet
Primary Causes: Fungal pathogens, bacterial pathogens, excessive moisture, poor air circulation, nutrient deficiencies, improper fertilization
Most Important Prevention Strategy: Maintain proper cultural care, avoid overhead irrigation, and follow a balanced palm fertilization program
Chemical Control: Copper-based fungicides may help prevent some palm diseases when applied according to label directions

Palm trees grown in the landscape appear carefree, but they are susceptible to many diseases, insects, and nutritional problems.

Avoid many of these problems by following recommended cultural practices to keep plants healthy and vigorous.

More information on growing outdoor palms successfully is available in Palms & Cycads (HGIC 1019).

Palm Diseases: Leaf Spots on Palm Trees

Leaf spot diseases are common fungal problems caused by several pathogens that affect many palm trees in South Carolina landscapes.

Symptoms

Symptoms may appear similar regardless of the specific fungus involved.

Leaf spot symptoms on palm trees may include:

• Circular to elongated spots on fronds
• Brown lesions on leaves
• Oily or water-soaked appearing spots
• Scattered spotting across older foliage
• Premature decline of affected fronds

It is difficult to identify the exact fungal pathogen based on visual symptoms alone.

Prevention & Treatment

Most leaf spot diseases are cosmetic and rarely kill established palm trees.

Cultural Controls

• Avoid overhead irrigation that wets palm foliage.
• Improve air circulation around palms through proper spacing.
• Remove severely damaged fronds only when necessary.
• Avoid excessive pruning, which can weaken palms already affected by nutritional deficiencies.

Healthy palms are less susceptible to severe leaf spot outbreaks.

Chemical Control

Fungicides are usually unnecessary unless disease severity becomes significant.

Copper-based fungicides may help suppress leaf spot diseases on palm trees. See Table 1: Copper Fungicides for Palm Disease Control for example products.

If palm fruits are intended for food use, copper fungicides are the only approved fungicide option mentioned in this factsheet.

Apply all fungicides according to label directions regarding:

• Application rate
• Spray interval
• Safety precautions

Palm Diseases: False Smut on Palm Trees

False smut, also known as Graphiola leaf spot, is a fungal disease that commonly affects palms in humid regions of South Carolina.

Cause

False smut leaf spot is caused by Graphiola species fungi.

The disease affects palms in the Arecaceae family, including:

• Chinese fan palm (Chamaerops humilis)
• Jelly or pindo palm (Butia capitata)
• Sabal palmetto (Sabal palmetto)
• Washington palm (Washingtonia robusta)

Disease development is favored by:

• High humidity
• Poor air circulation
• Wet palm fronds

Symptoms

False smut symptoms on palm trees may include:

• Small black, wart-like structures on fronds
• Raised black spots erupting through leaf surfaces
• Fine threadlike filaments emerge from spots
• Symptoms appearing on older fronds first
• Little to no spotting on newly emerging leaves

Disease symptoms may occur on both upper and lower leaf surfaces.

Prevention & Treatment

False smut is usually more damaging to the palm’s appearance than to its overall health.

Cultural Controls

• Space palms to improve airflow.
• Avoid overhead irrigation whenever possible.
• Reduce prolonged moisture on fronds.
• Remove severely infected fronds when practical.

Avoid excessive frond removal, as palms are sensitive to nutrient deficiencies, and over-pruning may further weaken the tree.

Chemical Control
Fungicides are usually not necessary, but may help prevent disease spread during the spring.

Copper-based fungicides labeled for palm disease management may be used preventatively.

See Table 1: Copper Fungicides for Palm Disease Control for example products.

If palms produce edible fruits, copper fungicides are the only fungicides referenced in this factsheet for use on food-producing palms.

Apply all fungicides according to label directions regarding:

• Timing
• Spray intervals
• Application rates
• Safety precautions

Palm Diseases: Ganoderma Root and Butt Rot on Palm Trees

Ganoderma root and butt rot is a deadly fungal disease that causes internal trunk decay and decline in many palm species.

Cause

Ganoderma root and butt rot is caused by the fungus Ganoderma zonatum.

This fungus survives in:

• Soil
• Dead palm roots
• Palm stumps
• Decaying trunk tissue

Infection commonly occurs through wounds or injuries to the trunk or root system.

Symptoms

Symptoms of Ganoderma root and butt rot on palm trees may include:

• Withering and drooping of older fronds
• Fronds collapse and droop parallel to the trunk
• Pale green or yellow new growth
• Stunted growth
• Collapse of the palm canopy or trunk
• Hollow-sounding trunk when tapped
• Internal dark brown trunk discoloration
• Severe root decay

Over time, shelf-like spore-producing fungal structures called conks may develop on the trunk.

Palm decline and death may occur gradually over three to four years, depending on:

• Palm age
• Environmental conditions
• Extent of internal decay

Prevention & Treatment

There is no chemical cure for Ganoderma root and butt rot once a palm becomes infected.

Cultural Controls

• Remove and destroy infected stumps, trunks, and root systems promptly.
• Avoid injuring palms during planting and maintenance.
• Protect trunks from string trimmer and lawnmower damage.
• Minimize stress to existing palms through proper cultural care.

Because Ganoderma survives in the soil, avoid planting another palm in the same location after removal of an infected tree.

Chemical Control
No effective fungicide treatment is currently available for Ganoderma root and butt rot on palm trees.

Preventive cultural practices are the primary management strategy for this disease.

Palm Diseases: Bud Rot on Palm Trees

Bud rot is a serious palm disease that damages the growing point of palm trees and can quickly lead to plant death.

Cause

Bud rot on palm trees may be caused by:

• Phytophthora species
• Thielaviopsis species
• Various bacterial pathogens

Disease development is often associated with:

• Tropical storms
• Excessive rainfall
• Prolonged wet conditions
• Cold damage to palm buds

Bacterial bud rot commonly develops after cold injury weakens the growing point.

Symptoms

Symptoms of bud rot on palm trees may include:

• Black lesions on buds and young fronds
• Wilting of newly emerging leaves
• Firm rot of the bud
• Slimy tissue, as secondary organisms invade
• Progressive death of younger foliage
• Older fronds remaining green temporarily
• Eventual collapse of the entire canopy

Older fronds may remain green for several months and are often the last leaves to die. In advanced stages, only the trunk may remain.

Prevention & Treatment

Bud rot progresses rapidly, and infected palms rarely recover once symptoms become severe.

Cultural Controls

• Avoid overhead irrigation whenever possible.
• Reduce prolonged moisture around developing fronds.
• Remove and destroy severely infected palms promptly.
• Improve drainage where excessive soil moisture is common.

Prompt removal of infected palms may help reduce disease spread to nearby susceptible palms.

Chemical Control
Preventative copper-based fungicide treatments may help protect palms exposed to favorable conditions for disease.

See Table 1: Copper Fungicides for Palm Disease Control for example products.

Apply at intervals sufficient to protect new developing tissue.

Apply all fungicides at the rates and spray intervals specified on the label.

Palm Nutritional Problems on Palm Trees

Palm nutritional problems are common in South Carolina landscapes and are often caused by improper fertilization, poor soil conditions, or nutrient imbalances.

Palms are frequently deficient in essential minerals in the landscape.

Common Nutritional Deficiencies

• Nitrogen (N)
• Potassium (K)
• Magnesium (Mg)
• Manganese (Mn)

Less Common Nutritional Deficiencies

• Boron (B)
• Calcium (Ca)
• Copper (Cu)
• Zinc (Zn)

Nutrient deficiencies in palm trees may result from:

• Insufficient soil nutrients
• Nutrient imbalances
• Poor soil aeration
• High soil pH
• Excessively deep planting

The following sections describe the most common nutritional deficiencies affecting palm trees in South Carolina landscapes.

Palm Nutritional Problems: Potassium Deficiency on Palm Trees

Potassium (K) deficiency is perhaps the most widespread and serious nutritional problem affecting palm trees in coastal South Carolina landscapes.

Symptoms

Symptoms first appear on the oldest leaves and affect progressively younger leaves as the deficiency becomes more severe.

Common symptoms include:

• Translucent yellow to orange spots on leaves
• Black or necrotic spotting
• Brown dead tissue along leaflet margins and tips
• Frizzled or withered leaf tips
• Burnt appearance on older foliage
• Yellow-greenish discoloration along the midrib
• Progressive decline affecting newer fronds over time

Symptoms are typically more severe at leaf tips and margins and less severe near the base of the leaf.

Potassium deficiency can eventually be fatal to the palm.

Prevention & Treatment

Early nutrient correction is important because damaged fronds will not recover after symptoms develop.

Cultural Controls
Potassium deficiency is more likely in sandy soils because potassium leaches rapidly from the soil.

In heavier clay soils, potassium leaching is reduced. Potassium deficiency in clay soils is more often associated with insufficient potassium fertilization.

Palms growing in lawns may become potassium deficient because many turfgrass fertilizers contain high nitrogen and relatively low potassium levels.

• Fertilize palms separately from surrounding turfgrass.
• Use fertilizers formulated specifically for palm trees.

Palms require fertilizer formulations with potassium levels equal to or greater than nitrogen levels.

For additional palm fertilization guidance, see Palms & Cycads (HGIC 1019).

Chemical Control
Potassium deficiency can be corrected with applications of sulfur-coated, slow-release potassium sulfate fertilizers.

To help prevent a potassium-to-magnesium imbalance:

• Apply slow-release magnesium simultaneously with potassium treatments.

Although damaged fronds will not recover, healthy new growth should gradually replace affected foliage after treatment.

Palm Nutritional Problems: Manganese Deficiency on Palm Trees

Manganese (Mn) deficiency is a serious nutritional disorder that can become fatal to palm trees if left untreated.

Symptoms

Symptoms first appear on the newest leaves.

Common symptoms include:

• Interveinal chlorosis (yellowing between the veins)
• Interveinal necrotic streaking
• Frizzled or distorted emerging leaves
• Withered or scorched leaf tissue
• Reduced leaf size

In advanced cases, newly emerging fronds may appear severely deformed and scorched.

Prevention & Treatment

Prompt correction of manganese deficiency is important because severe deficiency can permanently weaken or kill palm trees.

Cultural Controls
Manganese tends to leach more rapidly from sandy soils, making deficiency more common in these conditions.

Manganese deficiency is commonly associated with soil pH above 6.5 because manganese becomes less available to plants at higher pH levels.

Additional contributing conditions include:

• High water tables
• Poor drainage
• Excessive soil phosphorus

Have a soil test performed to determine soil pH and determine whether adjustments are needed.

For more information on adjusting soil pH, see Changing the pH of Your Soil (HGIC 1650).

Chemical Control
Manganese sulfate applications to the soil or foliage may help prevent or correct manganese deficiency.

Apply:

• One teaspoon of manganese sulfate per gallon of water
• To the soil around the palm
• Two or three times per year

Example manganese sulfate products include:

• Tecmangam
• Southern Ag Manganese Sulfate

Apply all products according to label directions and recommended rates.

Palm Nutritional Problems: Iron Deficiency on Palm Trees

Iron (Fe) deficiency is a common nutritional disorder that primarily affects the appearance and growth of newly emerging palm fronds.

Symptoms

Symptoms of iron deficiency on palm trees first develop on the newest leaves.

Common symptoms include:

• Interveinal chlorosis (green veins surrounded by yellow tissue)
• General yellowing of young foliage
• Reduced leaf size
• Tip necrosis on new fronds

As iron deficiency becomes more severe, new leaves may develop extensive tip necrosis and become progressively smaller.

Iron deficiency is primarily a cosmetic problem, and palms often survive if the underlying soil conditions are corrected.

Prevention & Treatment

Iron deficiency in palms is most often associated with poor root function rather than a lack of iron in the soil. Compacted soils, overwatering, deep planting, and damaged root systems can reduce a palm’s ability to absorb nutrients.

Iron deficiency is much less commonly caused by an actual shortage of iron in the soil.

Cultural Controls

• Improve soil drainage around palms.
• Avoid overwatering and soil compaction.
• Plant palms at the correct depth.
• Protect root systems from mechanical damage.

Chemical Control
In alkaline soils, chelated iron fertilizers may help improve iron availability to palm roots.

Temporary symptom relief may be achieved with:

• Chelated iron foliar sprays
• Iron sulfate foliar sprays

Foliar treatments may temporarily improve symptoms, but long-term correction requires improving soil aeration or correcting planting depth problems.

Apply iron sulfate at:

• ½ teaspoon per gallon of water

Spray foliage to runoff and follow label directions.

Palm Nutritional Problems: Nitrogen Deficiency on Palm Trees

Nitrogen (N) deficiency is a nutritional disorder that causes pale foliage and reduced growth in palm trees, especially in sandy or nutrient-poor soils.

Symptoms

Symptoms of nitrogen deficiency on palm trees may include:

• Uniform light green foliage
• General yellow-green discoloration
• Reduced growth

Symptoms usually develop gradually across the entire canopy rather than appearing only on older or younger leaves.

Nitrogen deficiency is generally less severe in landscape palms than potassium or manganese deficiency.

Prevention & Treatment

Regular fertilization during the growing season helps prevent nitrogen deficiency in palm trees.

Cultural Controls
Nitrogen deficiency is more common in:

• Light or sandy soils
• Nutrient-poor planting sites
• Container-grown palms
• Landscapes with insufficient fertilization

Most palm species require relatively low levels of nitrogen compared to turfgrass.

• Fertilize palms regularly during active growth.
• Use fertilizers formulated for palms when possible.
• Monitor container-grown palms and palms growing in sandy soil more closely for nutrient deficiencies.

For additional palm care information, see Palms & Cycads (HGIC 1019).

Chemical Control

Fertilizers containing nitrogen will generally improve leaf color quickly.

Nitrogen should be supplied in a slow-release form whenever possible.

Nitrogen deficiency can usually be corrected with fertilizers containing slow-release nitrogen.

New foliage should gradually return to a healthier green color following proper fertilization.

Palm fertilizers should provide balanced nutrition and slow nutrient release.

Palm Nutritional Problems: Magnesium Deficiency on Palm Trees

Magnesium (Mg) deficiency is a common nutritional disorder that is never fatal and is primarily a cosmetic problem in landscape palms.

Symptoms

Symptoms first appear on the oldest leaves and gradually progress to younger foliage.

Common symptoms include:

• Marginal chlorosis on older leaves
• Broad lemon-yellow bands along leaf margins
• Green centers within affected leaves
• Distinct separation between yellow and green tissue

If leaflet tips are also necrotic, potassium deficiency may be present on the same leaves.

Leaves affected by magnesium deficiency will not recover and must be replaced by new healthy foliage.

Prevention & Treatment

Affected leaves will not recover after treatment and must be replaced by new healthy foliage.

Cultural Controls

• Test the soil to identify pH imbalances and nutrient deficiencies.
• If soil pH is low, adjust according to soil test recommendations using dolomitic limestone.

Chemical Control
Magnesium deficiency may be prevented or corrected with:

• Kieserite (magnesium sulfate)
• Epsom salts (magnesium sulfate)
• Southern Ag Magnesium Sulfate

Epsom salts (magnesium sulfate) and similar products are highly water-soluble and may leach rapidly from sandy soils.

Recommended treatment includes:

• 2 to 4 pounds of magnesium sulfate per tree
• Combined with controlled-release potassium
• Applied four times per year

Coated or uncoated “prilled” (pelletized) kieserite can be applied to prevent or correct magnesium deficiency, but it may be difficult to find.

Avoid using magnesium oxide in neutral or alkaline soils, as it is poorly soluble under those conditions.

Palm Nutritional Problems: Boron Deficiency on Palm Trees

Boron deficiency is an uncommon nutritional disorder that can cause abnormal leaf growth, trunk distortion, and bud injury in palm trees.

Symptoms

Symptoms may include:

• Small leaves
• Crumpled leaves
• Sharp bends in the trunk
• Horizontal trunk growth
• Bud necrosis
• Bud death

Prevention & Treatment

Cultural Controls
Boron can become toxic to palm trees when applied in excessive amounts.

Avoid excessive boron applications, as it can become toxic to palm trees at relatively low concentrations.

Palm fertilizers should contain only small amounts of boron.

Chemical Control
Because boron can become toxic at relatively low levels, palm fertilizers should contain only small amounts of boron.

The following materials may be used when boron deficiency is confirmed:

• Sodium borates
• Boric acid
• Borax
• Solubar

Apply at:

• 2 to 4 ounces per tree

Follow all label directions and precautions.

Palm Nutritional Problems: General Fertilizer Recommendations for Palm Trees

A consistent fertilization program is the most effective way to prevent nutritional deficiencies in landscape palm trees.

Fertilizer Program for Established Palm Trees

Palm nutritional deficiencies are easily prevented by following a yearly fertilization program.

Mature palms in the landscape should be fertilized with a complete granular palm fertilizer, often called a “palm special.”

To maintain a steady supply of nutrients:

• Apply palm fertilizer 3 to 4 times per year
• Fertilize only during the growing season (April through September)

Recommended Fertilizer Analysis

Research from the University of Florida recommends a fertilizer analysis of:

• 8-2-12-4 (N-P-K-Mg)

This fertilizer ratio is designed to provide balanced nutrition for landscape palm trees.

Apply fertilizer at:

• 1.5 pounds per 100 square feet beneath the palm canopy

Use a slow-release fertilizer that also contains essential micronutrients.

Micronutrients should include:

• Manganese (Mn)
• Boron (B)
• Copper (Cu)
• Zinc (Zn)
• Iron (Fe)

Fertilizing the Root Zone

Palm roots often extend far beyond the trunk.

Roots of larger palm trees may extend:

• 30 to 50 feet from the trunk

For best results, fertilize the entire root zone beneath and beyond the canopy.

If centipedegrass grows within 30 feet of the palm:

• Do not exceed 1 pound per 100 square feet over the lawn area.
• Limit applications to 3 per season.

Fertilizing Newly Planted Palm Trees

Newly planted palms require a modified fertilization schedule.

• Do not fertilize newly planted palms immediately after planting.
• Do not fertilize newly planted palms until after they produce a new spear leaf.
• Fertilize only during the growing season.

Adjust fertilizer rates and treated areas according to palm size and establishment stage.

Example Palm Fertilizer Products

An example of a well-balanced palm fertilizer is PalmGain 8-2-12-4 Plus Minors polymer-coated, sulfur-coated slow-release fertilizer containing:

• Magnesium
• Manganese
• Boron
• Copper
• Zinc
• Sulfur
• Iron

Product examples are provided for informational purposes and do not imply endorsement by Clemson Extension.

Alternative Fertilization Program

If a palm-specific fertilizer is unavailable:

• Apply 12-4-8 slow-release fertilizer every two months during the growing season.
• Apply Epsom salts at 2 to 4 pounds per tree during the months between fertilizer applications.
• Apply a micronutrient product during the same months as the Epsom salts applications.

Southern Ag Essential Minor Nutrients is an example of a micronutrient product.

Product examples are provided for informational purposes and do not imply endorsement by Clemson Extension.

Recovery from Nutrient Deficiencies

Supplemental magnesium and complete micronutrient amendments are important components of palm fertilization programs.

Once symptoms of a deficiency become visible, it may take six months or longer for a palm tree to recover after nutrient deficiencies are corrected.

Palm Disease Management: Fungicides for Palm Disease Control

Fungicides

The following copper-based fungicides are examples of products labeled for the management of certain palm diseases. Always read and follow all label directions before applying any pesticide.

Table 1. Copper Fungicides for Palm Disease Control

Active Ingredient	Example Product Names
Copper-based Fungicides	Bonide Captain Jack’s Liquid Copper Fungicide
	Bonide Copper Fungicide Spray or Dust Ready to Use
	Camelot O Fungicide/Bactericide
	Espoma Organic Copper Soap Ready-to-Use Fungicide
	Monterey Copper Fungicide Garden Spray Liqui-Cop
	Natural Guard by ferti-lome Copper Soap Fungicide Concentrate
	Natural Guard by ferti-lome Copper Soap Fungicide Ready to Use Southern Ag Liquid Copper Fungicide

Application Notes

• RTU (Ready-to-Use): Pre-mixed spray bottle intended for direct application.
• Concentrate: Product mixed with water before application.
• Wettable Powder: Product mixed with water and applied with a sprayer.

Important Limitations

Control of diseases on large palm trees may not be practical because achieving adequate fungicide coverage of the foliage can be difficult.

Pesticide Disclaimer

As with all pesticides, read and follow all label instructions and precautions.

Sources:

1. Broschat, T.K., and Meerow, A.W. 1992. Palm Nutrition Guide. University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), SS-ORH-02.
2. Elliott, M.L. 2006. Bud Rots of Palm. University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), PP-220.

Pesticides are updated annually. Last updates were made on 6/26 by N. Jordan Franklin.

Originally published 01/00