I have some Red-twigged Dogwoods that keep getting extensive black areas on the upright growth which causes the leaves to wilt and that whole area of growth to die. I have trimmed the dead areas out as they happen, but then another area will become effected. I have lost 1/2 of the bush this Summer. Today, I found small black ant-like bugs burrowed into the dead wood. Don't know if that they are the cause of the blackened dead growth or if they came later. What is it and how do I treat it?
