The pygmy date palm (Phoenix roebelenii) is an easy-care compact palm. Its size makes it ideal for containers indoors and in small yards. Outdoors, it grows in U.S. Department of Agriculture plant hardiness zone 10 in partial or full sun. A healthy plant can grow up to 12 feet tall with a crown of 3-foot leaves. Pygmy date palms resist most diseases except the fungal disease Pestalotiopsis palmarum.
The Pestalotiopsis genus includes numerous fungi that attack palm trees. Pestalotiopsis palmarum targets pygmy date palms more than other palms according the University of Florida Institute of Food and Agricultural Sciences. The fungus spores travel via wind, rain and splashing water. The disease is a wound parasite, attacking injured areas of plants. Wounds may originate from pests, nutrient deficiencies and garden tools used in plant care. Pests that attack pygmy palms include red date scale (Phoenicococcus marlatti). The scale damages leaf tissue. Nutrient deficiencies cause leaves to yellow and crinkle.
The symptoms of Pestalotiopsis palmarum may occur on many leaves at once, especially on young trees, and lead to blight. The disease begins as small, yellow or dark spots. The spots grow, and eventually merge and spread to every part of the leaf. The coalesced large spots look like dead pale or gray areas with a dark outline. The spots spread to the petioles, the stalks connecting the leaf blades to stems.
The blight on the leaves and stems adversely affects the plant’s vascular tissue, spreading damage to the buds of younger leaves, and stunting their growth. When the buds of plants get damaged, the plant stops growing, because new leaves do not form. When Pestalotiopsis palmarum becomes severe enough to cause bud rot in young or mature plants, the palm can die.
Managing Pestalotiopsis palmarum involves maintaining ideal conditions for plant health. The disease travels through water movement, so gardeners should limit overhead watering, and give plants plenty of space so air can circulate between them. Disinfecting your garden tools between use and taking care to prevent injuries when pruning also help. Prune and destroy diseased leaves to limit the spread of spores. Maintaining healthy soil conditions prevents nutrient deficiencies. Fertilizing plants three times a year should be sufficient. Fungicides can only help prevent the disease from occurring. Once a plant is infected, fungicides do not cure Pestalotiopsis palmarum.
- Floridata: Phoenix Roebelenii
- University of Florida IFAS Extension: Pestalotiopsis (Pestalotia) Diseases of Palm
- University of Florida IFAS Extension: Phoenix roebelenii: Pygmy Date Palm
- UC IPM Online: Pests in Gardens and Landscapes: Palm Diseases in the Landscape
- UC IPM Online: Pests in Gardens and Landscapes: Scales
- University of Florida IFAS Extension: Scale Insect Killing Pygmy Date Palms
- Trees of the California Landscape; Charles Hatch; 2007
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