Lace Bug on Azalea

Asked October 16, 2020, 8:03 PM EDT

Hi there. I have two large, old, azalea's that are key to the design of my front entrance landscape. I have no idea what these azalea are, they came with the house when I purchased it. The one is a pale green foliage and I noticed the damage three years ago. The other, with small, dark foliage, was not affected. I was able to keep things in control by spraying soap, twice in spring. But this year there have been multiple infestations over the summer and now the other azalea is showing damage as well. What's the latest on lace bug control on azalea? I prefer to use non or less toxic pesticides like neem oil and soap but this is going to be a lot of work and for these two specific plants I may need to turn to chemical control. Thanks for the help.

Lane County Oregon

1 Response

There aren't any new treatments for this bug. You mentioned using several cultural controls that can be helpful but hopefully you have also tried out strong water sprays on multiple occasions. Hit both upper & undersides of leaves when you spray. This may help reduce overall lace bug populations, not endanger natural predators, and reduce need for other treatments.

Make sure shrubs are not water-stressed during these less than normal rainfall times which can leave them more susceptible to these bugs. Try irrigating every two weeks if necessary.

If you can't accept the level of lace bug damage you're still seeing, you could consider a systemic like dinotefuran (this is a neonicotonoid which is very toxic to pollinators like bees) with strict application restrictions. This systemic is only active for the season in which it's applied. If it's applied to the soil around the azalea according to label instructions AFTER the azalea and any other adjacent plants have completely finished flowering, it should not be a threat to pollinators. Do NOT use any other systemics like imidacloprid because they may be active for several seasons and thereby pose a long term hazard to pollinators like bees.

Here also is information on lace bugs from the PNW Insect Management Handbook that lists some lace bug resistant azalea cultivars.
https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/azalea-rhododendron-azal...