Euonymus scale – Control
Q: 1. My variegated euonymus has lots of little white dots under the leaves and it doesn’t look very healthy. Can you diagnose?
Q: 2. I have a row of golden euonymus shrubs that have developed scale on the leaves and a few of the short stems. If I cut the back the foliage drastically now, will this harm the shrubs?
A: In my experience, a heavy infestation of scale on euonymus is almost impossible to control without pruning to remove the majority of the leaves and insects first.
Euonymus grows vigorously, so pruning moderately in winter won’t hurt it terribly. You’ll get regrowth in spring and summer.
If your shrub is heavily infested, consider removing it and replacing with a holly or other plant.
If your shrub is only lightly infested, you can try the chemical route.
I recommend applying systemic insecticide imidacloprid (click for sources) in spring and also spraying what’s left of the shrub (after pruning) with horticultural oil (click for sources) three times per year (April, June, January). Be sure to follow label directions for hot weather application.
Also see Euonymus Scale