Have two firs side by side planted 18 years ago from same grower. Now 20 feet tall one is showing healthy bud break right now and is obviously robust with good color. It's brother doesn't even have swelling buds on the tree and has some slight die back at the top. Should I waste no time in removing the one? We are outside Pittsburgh and our soil is clay. They are on a well drained slope. I had two other Frasers die elsewhere in the yard some years back.