Cranberry Rootworms – When To Apply Insecticide
Q: For the past two years cranberry rootworms have attacked my azaleas. There are lots of holes in the leaves. I have seen positive results from using granular systemic insecticide. Should I apply again in early spring and reapply every eight weeks or is this going to be a chronic issue?
A: Cranberry rootworms damage plants in two ways. The larvae live underground and chew on the roots. The adult snout weevils feed on leaves at night, leaving characteristic C-shaped holes. They retreat underground at dawn so they are rarely seen. Rhododendron, St. John’s wort and redbud are also attacked. You should see the disfigured leaves gradually disappear with only a yearly application of imidacloprid systemic insecticide.