Question: My euonymus plants are dying. I looked closely and found some type of crust on their leaves. It looks like cigarette ashes stuck all over the leaves and stems. Is that responsible for the dieback, and what can I do?
Answer: That’s euonymus scale, an insect. No plant that we grow is any more susceptible to scale than euonymus, and that scale is responsible for the eventual death of probably 90 percent of the euonymus shrubs planted in Texas. Control it before it gets out of hand, either with a horticultural oil spray (a late-winter application is the very best control), or with a systemic insecticide applied during the growing season. For the record, dead scales won’t fall off. You can tell if they’re alive by rubbing them with your thumb. If they’re dry and flaky, they’re dead. If they’re moist and yellow several weeks after you treat, then you will need to treat again.