 You especially want to check to see whether or not those large limbs are dead. A sign of that is that there's no new growth on those limbs. Kevin Brassler with Washington Consumers Checkbook says, sometimes diagnosing and treating trees can be difficult. Ask a professional for help. When people come out to check your trees, you want to actually make sure they're sending certified arborists. If a tree care service suggests trimming limbs or even removing a tree altogether, it's definitely worth getting several opinions.