Berries as red as Rudolph's nose glowing like holiday lights against layered branches of lustrous emerald foliage make Burford holly (Ilex cornuta "Burfordii) a year-end standout in gardens across U.S. Department of Agriculture plant hardiness zones 7 through 9. This medium-sized, easy-care tree thrives in full sun to part shade and well-drained soil. What you don't want to see, regardless of the season, is tiny white bugs dusting a Burford holly like winter's first snow.
Enemies in Armor
Flat, oval white bugs with single yellow or brown spots on the leaves of your Burford holly's lower branches are oleander scales. These pests construct predator-discouraging armor of their molted skins and attach to their 1/10-inch bodies. Like all scales, they drain sap from the plants through tissue-piercing, hollow mouthparts. You'll probably notice the yellow foliage falling from your holly as it becomes progressively weaker before you notice the oleander scales.
Cotton, Wax, Varnish and Soot
Two kinds of soft scale insects hidden beneath layers of waxy secretions infest Burford holly. Female cottony camellia scales lay eggs in 1/2-inch fluffy, white sacs. Their larvae, or crawlers, look like amber-colored moving specks. Bright-white wax scales cling to the plant like barnacles. Their dome-shaped covers measure up to 1/4 inch across. Even without their distinctive appearance, soft scales reveal themselves with their sticky, transparent waste. Called honeydew, the carbohydrate-dense goo looks like varnish and attracts layers of greasy, black sooty mold fungi. Although rarely fatal, prolonged soft scale attacks cause stunted growth and general weakening.
Guardians of the Goo
Honeydew-producing scales have staunch allies in the local ant population. To protect their sugary food supply, ants go to war against the lady bugs, lacewings and parasitic wasps that normally control scale populations. To keep the ants at bay, prune back branches touching the ground or nearby structures and wrap your holly’s trunk with heavy paper covered in petroleum jelly; ants become trapped as they cross the paper. An ant-free holly may attract enough beneficial insects to manage its scale infestation for you. Otherwise, you'll need another approach.
Scaling Back the Problem
If the scales are limited to a few of your holly's lower branches, scrape them off with a soft toothbrush or prune and dispose of the affected leaves. To manage a chronic problem without long-term damage to beneficial insects, suffocate the unprotected crawlers with horticultural oil. They typically hatch in spring or early summer; wrap infested branches with double-sided transparent tape and check weekly for orange or yellow specks. When their numbers begin dropping, they've started attaching to the plant to feed. Spray with a solution of 7 1/2 tablespoons -- or the manufacturer's recommended amount -- of horticultural oil per 1 gallon of water. Wearing protective clothing, treat your well-watered holly when the temperature is below 90 degrees Fahrenheit. Spray until the solution drips from its leaves and branches, and let the oil dry before allowing children or pets near the tree.
- Cal Poly San Luis Obispo Urban Forest Ecosystems Institute: SelecTree Tree Detail -- Burford Holly
- University of California Integrated Pest Management Pests in Gardens and Landscapes: Holly
- University of Georgia Department of Entomology: Scale Insects
- University of California Integrated Pest Management Pests in Gardens and Landscapes: Olive Oleander Scale
- Kentucky Nursery ListServ: Let's Talk: Be on the Lookout
- Living with Bugs: Cottony Scale Insects
- Virginia Cooperative Extension: Wax Scale
- University of California Integrated Pest Management Pests in Gardens and Landscapes: Scales
- University of California Integrated Pest Management Program: Pesticide Information -- Active Ingredient, Horticultural Oil
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