Lace Bugs

(June 2012)

My azalea leaves are turning white and gold. When I look at them up close there is nothing on the top, but the bottom leaves have black specks. What can I do to save them? They struggled last summer but I finally thought they were coming out of it and now this! Help.

I think you have a case of lacebugs—the most common insect on azaleas. These insects normally start feeding in May and don’t get to the level they are now until late July or August. Unfortunately, just like everything else, they started their season early and have continued. They begin by feeding on the undersurface of the leaf, sucking sap out of the foliage. In the beginning, you get a few white specks on the upper surface of the leaf. As populations build up, the small white specks merge together and pretty soon the leaf has a white or bronzish appearance. It won’t kill a plant, but heavy infestations do cut down on the amount of chlorophyll in the leaves which can impact overall growth and health. Once the damage is done, those leaves will not re-green, but the new foliage should begin to grow in green and healthy once you control the insects. Orthene or a similar systemic insecticide should slow them down. If you have lacebugs every year, using a product containing imidacloprid (Merit or Bayer Advanced Tree and Shrub insecticide) can help in the early spring. Continue to water the plants as needed this summer.

(February 2011)

I am enclosing some pictures from my son's yard in North Little Rock. He bought the house in July. There is a large tree in the yard and closer to the house, right in front of the porch are large Azaleas. They look like they have been there many years. Some of them are dying. I am enclosing pictures of the diseased ones. Is there any way to save them? The last picture is from my house in North Little Rock. My husband says they are supposed to turn that dark purple. Only a small bit of mine are the dark purple. The rest of the plants are green. I treat mine with Bayer 12 month tree and shrub protect and feed when I see lace bugs on them. However I think what my son has is Rust? And the Bayer does not say it treats Rust. Help.

From the pictures, the azaleas look fairly healthy—especially yours. If you grow dark pink, red or purple azaleas, they should take on a dark reddish color for the winter. Some varieties do this more than others, but should turn every year--this is their natural winter color. Even the plants from your son’s yard look like they still have ample foliage and flowers on the tip of the branch. I do think there is some lacebug damage, and the plants look a bit sparse closer down the branch. Allow them to bloom this spring and then selectively prune the branches to encourage more fullness. When the pruning is done by an electric hedge trimmer, all the growth begins at the tips of the branches. Selective pruning lets you cut each branch to a different length, which should encourage fuller foliage and a fuller flowering plant. The Bayer product you are using is only for insects, it will not control diseases. I would suggest that you monitor the new foliage and see if there is damage when it begins to grow. Last summer was miserable for our plants, and if the house was for sale, chances are, no one was taking care of the plants, so they may be struggling. If the new growth comes out with spots or doesn’t begin growing well, take a sample to your local county extension office for correct diagnosis, before spraying. You could also bring some samples of the branches to the Arkansas Flower & Garden Show at the Statehouse Convention Center in LR Feb.25-27. Our plant pathologist Sherrie Smith will be there with her microscope and can give you her diagnosis. Sherrie will be in our extension garden on the show floor. You will have to buy a ticket to get in, but there is plenty to see and do.

(June 2010)

I hope you can shed some light on my problem. I have a 30 foot azalea bed along the east wall of the garage that has been there for 20 years. It has always done very well, but last fall I noticed the leaves got bronzy. This spring they flowered, but were not as good. I have always pruned about every 3 years so this year it was time. Now they really look dead. I have watered and fertilized. Can you tell from the attached photo's what the problem is, and what I might do about it.

You had a severe case of lacebug damage on your azaleas. Usually the damage makes the plants look bad, but rarely does it kill them. I just wonder if possibly the excess rain and then cold winter, coupled with the stressed plants, made the damage worse. Did you spray with anything? I would prune them back hard now--take off up to one third or more and then fertilize. Azaleas are broadleaf plants which have dormant buds, so even if they look bare, they can recover, but prune ASAP to allow for recovery time. You can prevent lacebug damage with Imidacloprid (commonly called Merit or Bayer Advanced Tree & Shrub Insecticide). Let’s see how they bounce back this growing season.

(July 2010

The leaves on my azaleas are turning white. I do not know how or what to do to them. I do not want to lose them. Help!

Check the backs of the leaves. I would bet they have small black or brown specks there and are rough to the touch. Lacebugs are the culprit. These tiny insects have translucent lace-like wings and feed on the undersurface of azaleas. As they feed, they suck sap out of the foliage. The beginning infestations leave a few white specks on the surface, but repeated feeding gives the overall surface of the leaf a white or silverish appearance. Left unchecked there are numerous generations each season. Spraying now with a systemic insecticide such as Orthene can slow them down. If you get the problem every year, try a preventative treatment of Imidacloprid next spring or early summer. This systemic insecticide is applied around the drip line of the shrub, absorbed by the plant, and should give you a season free of the problem. The damage that has been done to your plants will not go away, but you should not see new damage after spraying.

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