Since 2015, the invasive azalea lace bug (Stephanitis pyrioides) has been causing serious damage to azaleas and rhododendrons in our state, including in the Arboretum. A tiny aphid relative, the lace bug removes chlorophyll from Rhododendron foliage, weakening the plants and causing white stippling on the tops of affected leaves.
Several years ago, Arboretum Plant Health Care Specialist Ryan Garrison began a research project on the grounds to understand the seasonality of the insect, so he could discover the best time of year to control it. He also wanted to examine the susceptibility of various Rhododendron species and varieties to the pest to help focus treatments on the most vulnerable plants—and inform gardeners about more resistant alternatives.
In the latest issue of the Arboretum Bulletin, Ryan discusses his personal research journey and the published results of his study. He includes a list of rhodies and azaleas that suffered no observable damage from the insect during the two-year study.