Palms create an exciting tropical atmosphere in your home, if they stay healthy. Too often those vibrant green fronds give way to brown tips, yellow bands, speckles, stipples and silvering. Take the time to familiarize yourself with the signs of the most common ailments and you'll be prepared to treat them when they appear. Better yet, prevent them.
Also known as Graphiola leaf spot, false smut causes palm leaves to develop a rough texture along with small spots, yellow to brown in color range, which swell and burst. Authors Timothy K. Broschat and Alan W. Meerow, in their book "Ornamental Palm Horticulture," recommend treating this disease with "three or four bi-weekly applications of protective fungicides such as mancozeb, copper or propaconazole during active spore release periods."
Fungi in general can cause a "damping off" effect in which the seedling palms die before surfacing or shortly thereafter. Infected soil combined with wet conditions often results in fungi-related seed loss. To prevent this, ensure all planting containers and media are sterile. Fungi can take hold and rot the crown or roots of established plants if you transplant them prematurely, transplant them into soggy conditions or bury the growing point when you transplant. Avoid "over-potting" and use a well-draining substrate when transplanting.
When purchasing a new palm house plant, inspect carefully to avoid introducing pests into your home. Thrips cause a recognizable spotted silver coating on palm leaves. Mealy bugs form colonies that look like white, cottony patches on the undersides of leaves. Two-spotted spider mites, hard to spot until they get out of control, reveal themselves by their fine white webbing on the undersides of the leaves. If your palms develop signs of infestation, treat them with a broad spectrum insecticide labeled for use with the identified pest. Ensure good soil drainage to avoid poisoning your palm with insecticide build-ups.
Indoor palms, like all house plants, are susceptible to salt build-up: a toxic accumulation of trace minerals from daily watering or regular fertilizer applications. Brown-edged leaves are early indications of toxic salt build-up. Leach the excess salts from your palms three times a year to prevent saline toxicity. Take them outside, water them thoroughly (Jungle Music recommends 10 to 15 times) and spray the foliage. Let the plants drain before bringing them back inside.
Other Signs of Nutrient Imbalance
Potted palms need regular feeding. Otherwise they will begin to show signs of nutrient deficiency. Stunted, deformed leaves indicate a lack of calcium. Magnesium deficiency can be identified by the broad yellow bands that develop along the borders of leaves. Crumpled, stuck-together leaves with broken tips may point to a boron deficiency.