White fuzz invades azaleas, and leaves black coating


August 01, 1999

Q. While watering my azaleas this summer I've noticed small, white, fuzzy things sitting at the spot where the twigs are joined. Recently, I've seen a strange black coating on some leaves. What's going on? Is this cause for alarm?

A. Those fuzzy things are the egg sacs of azalea bark scale. Tiny nymphs left the egg sacs in June and then began feeding on your azalea leaves. The black coating is sooty mold, a harmless fungus that grows on the plant sap excreted by the scale.

If you see a large number of egg sacs and if there is leaf yellowing, spray your azaleas with a dormant oil this fall to kill overwintering nymphs. Apply the same treatment to affected rhododendrons.


1. Pick vegetables and fruit plants as they ripen. Overripe fruits on plants or lying on the ground will attract yellow jackets, fruit flies and other pests.

2. Clean out dead plants from backyard ponds, and fill ponds with fresh water if you notice a drop in the water level.

Garden tips are provided by the Home and Garden Information Center of the Cooperative Extension Service of the University of Maryland. For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507, or visit its Web site at www.agnr.umd.edu/ users/hgic.

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