Solutions to common Palm problems

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FOR MANY PALM PROBLEMS

by Melissa Bartalos

Gainesville, FL--Ornamental palms, the dramatic symbol of the tropics, decorate landscapes and indoor spaces throughout the world. Commercially, palm production is one of the largest elements of the ornamental horticulture industry in Florida and Hawaii and has become increasingly bigger business across the nation and internationally.

But this striking and popular tree is often difficult to maintain--for example, palms are perhaps the most prone of all ornamental plants to nutritional disorders.

Addressing some of the most common palm problems, Ornamental Palm Horticulture, by Timothy K. Broschat and Alan W. Meerow, just released by the University Press of Florida, presents virtually everything ever published about the subject in a concise and readable format, illustrated with 110 color plates and 81 black-and white photographs.

Read on to learn about some of the most common palm problems, and find out what you can do to fix them. (Plate numbers in parentheses refer to color illustrations in the book.)

PROBLEM: How do I get rid of the spotting and webbing on my palm leaves? (plate 78)

SOLUTION: These signs of a spider mite infestation can be effectively treated with chemical miticides.

PROBLEM: The leaves have small yellow, orange, and bronze spots that cover almost the entire blade. How can this be treated? (plate 25)

SOLUTION: These symptoms point to potassium deficiency, one of the most widespread problems in all landscape and field-grown palms. Treatment usually requires soil applications of controlled-release potassium fertilizers. An application of a similar magnesium fertilizer is also recommended to avoid having an imbalance in the soil.

PROBLEM: I have found several caterpillars on my palm leaves and have noticed some damage to the fronds. (plates 77, 74)

SOLUTION: Caterpillars, butterflies, and moths are among the most destructive palm pests. Small infestations can be removed physically, but if the insects are in full force, they can do severe damage. The biopesticide Bacillus thuringenesis is effective on a wide variety of caterpillars.

PROBLEM: How do I get rid of the silver coating and small dots on my palm leaves? (plate 52)

SOLUTION: This problem is caused by Thrips, insects less than 2 mm long. Many broad spectrum insecticides, including malathion, will control this pest.

PROBLEM: My palms either die soon after sprouting or before they even surface. What causes this problem? (no illustration)

SOLUTION: This "damping off" could likely be a result of constantly wet soils that allow the growth of fungi, which cause seed loss. Seedlings should always be planted in clean pots or flats using clean substrates, preferably on benches, to reduce their chances of infestation.

PROBLEM: My palm leaves have a rough texture and several small yellow to brown spots that swell and rupture. How can this be treated? (plate 94)

SOLUTION: This disease, known as False Smut or Graphiola Leaf Spot, can be treated with three or four biweekly applications of protective fungicides such as mancozeb, copper, or propaconazole during active spore release periods.

PROBLEM: The trunk of my palm tree is stained with red streaks and some of the fronds have collapsed. Can the tree survive?
(plates 16, 17)

SOLUTION: Lightning frequently strikes tall palms, usually with fatal results. The only way to avoid this is to protect the tree with lightning grounds, though the practicality and effectiveness of this practice are questionable.

PROBLEM: How can I correct the stunted, deformed leaves on my palms? (plate 31)

SOLUTION: These symptoms are signs of calcium deficiency, which can be treated with calcium nitrate or sulfate. Prevent this disease by using dolomite in all potting substrates.

PROBLEM: My palm has yellow bands that run along the borders of the leaves. How can I treat this? (plates 32, 33)

SOLUTION: Yellow banding signals magnesium deficiency, which can be treated with soluble magnesium fertilizers like kieserite. Preventing the disease by using dolomite or magnesium is preferable because kieserite leaches rapidly through sandy soils.

PROBLEM: The leaves are crumpled and stuck together, and they have broken leaf tips. How can I treat this? (plate 46)

SOLUTION: This problem sounds like boron deficiency, which can be treated with soil or foliar applications of sodium borates or boric acid.

PROBLEM: After clearing up one palm problem, another usually appears soon after. How can I avoid these recurring problems? (no illustration)

SOLUTION: Maintaining a nutrient balance in the soil is a good way to avoid plant deficiencies. For example, when using a fertilizer high in potassium, supplement it with a magnesium fertilizer so there isn’t a big gap in the amounts of minerals.

PROBLEM: The leaves have thin, green veins, green spotting, and the ends are broken off. (plates 36, 37)

SOLUTION: These are signs of iron deficiency, but it usually is not caused by a lack of iron in the soil. It is often associated with waterlogged soils or excessive planting depth, which result in poor aeration and a reduction of Iron intake by the roots. Using nitrate-nitrogen in palm fertilizers will help prevent this problem. It can be corrected temporarily by soil or foliar applications of iron fertilizers, but the most effective long-term solution is to improve soil aeration. This may require replanting deeply planted palms at a proper depth or planting the tree on a berm or other raised site.

Ornamental Palm Horticulture

By Timothy K. Broschat & Alan W. Meerow

Publication date:
October 2000

ISBN 0-8130-1804-8

110 color photos, 81 b&w illustrations, tables, appendix, index, 336 pp. 6X 9 / Cloth $39.95

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PROBLEM: How do I get rid of the spotting and webbing on my palm leaves? (plate 78)
SOLUTION: These signs of a spider mite infestation can be effectively treated with chemical miticides.

PROBLEM: The leaves have small yellow, orange, and bronze spots that cover almost the entire blade. How can this be treated? (plate 25)
SOLUTION: These symptoms point to potassium deficiency, one of the most widespread problems in all landscape and field-grown palms. Treatment usually requires soil applications of controlled-release potassium fertilizers. An application of a similar magnesium fertilizer is also recommended to avoid having an imbalance in the soil.

PROBLEM: I have found several caterpillars on my palm leaves and have noticed some damage to the fronds. (plates 77, 74)
SOLUTION: Caterpillars, butterflies, and moths are among the most destructive palm pests. Small infestations can be removed physically, but if the insects are in full force, they can do severe damage. The biopesticide Bacillus thuringenesis is effective on a wide variety of caterpillars.

PROBLEM: How do I get rid of the silver coating and small dots on my palm leaves? (plate 52)
SOLUTION: This problem is caused by Thrips, insects less than 2 mm long. Many broad spectrum insecticides, including malathion, will control this pest.

PROBLEM: My palm leaves have a rough texture and several small yellow to brown spots that swell and rupture. How can this be treated? (plate 94)
SOLUTION: This disease, known as False Smut or Graphiola Leaf Spot, can be treated with three or four biweekly applications of protective fungicides such as mancozeb, copper, or propaconazole during active spore release periods.

PROBLEM: The trunk of my palm tree is stained with red streaks and some of the fronds have collapsed. Can the tree survive? (plates 16, 17)	SOLUTION: Lightning frequently strikes tall palms, usually with fatal results. The only way to avoid this is to protect the tree with lightning grounds, though the practicality and effectiveness of this practice are questionable.

PROBLEM: How can I correct the stunted, deformed leaves on my palms? (plate 31)
SOLUTION: These symptoms are signs of calcium deficiency, which can be treated with calcium nitrate or sulfate. Prevent this disease by using dolomite in all potting substrates.

PROBLEM: My palm has yellow bands that run along the borders of the leaves. How can I treat this? (plates 32, 33)	SOLUTION: Yellow banding signals magnesium deficiency, which can be treated with soluble magnesium fertilizers like kieserite. Preventing the disease by using dolomite or magnesium is preferable because kieserite leaches rapidly through sandy soils.

PROBLEM: The leaves are crumpled and stuck together, and they have broken leaf tips. How can I treat this? (plate 46)
SOLUTION: This problem sounds like boron deficiency, which can be treated with soil or foliar applications of sodium borates or boric acid.