|Every year for many years the new growth tips on my otherwise healthy boxwood shrubs curl into little balls. What causes this and how can I prevent it?|
|This is caused by the boxwood psyllid, a small green fly with transparent wings. The eggs are laid on boxwood tips and the larvae suck plant juices, causing the puckering and rolled tips. The larvae covers themselves with a cottony or waxy white material making it hard to get to the insect to kill it. You can hand shear the tips as soon as you see the larvae, making sure that you collect all the prunings and destroy them. Otherwise, you can try horticultural oil, making sure to spray the undersides of the leaves. This will suffocate the larvae.