Warts beset a fine old azalea
Q. I have a beautiful old azalea that has been dying back and now is almost completely dead. Very odd-looking, slightly raised, warty growths are covering the lower stems. Is this a disease, and will it affect my other nearby azaleas?
A. You are describing a bacterial disease known as crown gall that is native to Maryland soils and can infect and kill plants by entering through wounds made by insects, string trimmers and mulch. Carefully dig up the infected plant and as much soil as possible that surrounds the root system and discard with the trash. The disease can persist in the soil without benefit of a host plant. Do not plant azalea, rhododendron, forsythia or other susceptible plants in the same spot.
You may or may not see it on adjacent plants. Monitor your other azaleas and be prepared to prune out lower stems that develop galls.
Q. I am an eggplant lover and am already battling those little black flea beetles that make a zillion holes in my leaves. What can I do to get rid of them? I would like to avoid chemical sprays.
A. Rotenone, pyrethrum and neem are botanical insecticides that will give you some control if they are applied every seven days. Some gardeners cover their plants with floating row covers. The problem is that you can trap flea beetles and other pests underneath the cover and exclude bumblebees, which help pollinate the crop. Other gardeners have had success dusting their plants with wood ashes. It sounds crazy, but the ashes stick to the leaf surfaces and make it difficult for the beetles to feed. The ash barrier does not seem to reduce photosynthesis, as one might expect.
Q. I have two very healthy holly trees in my front yard and am only now noticing that many of the lower leaves have bites taken out of them. We do have deer in the neighborhood. Could they be responsible?
A. Those bites or notches were probably caused by the two-banded Japanese weevil, not by deer. The adult weevils feed in mid-June and are very cryptic, so it's not surprising that they went undetected. You could go out at night with a flashlight this June and try to find these small, dark-colored, oval-shaped insects. This pest poses no significant threat to large, healthy holly trees.
THIS WEEK'S CHECKLIST
1. Avoid using insecticides on plants when they are blooming to avoid harming pollinating insects.
2. Ignore the many different leaf and stem galls you may observe on elms, hickories, oaks and maples. They come in a wide variety of shapes, sizes and colors and may be unsightly but are harmless.
Backyard Q&A; is by Jon Traunfeld, regional specialist for the Home and Garden Information Center, Maryland Cooperative Extension Services 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.