I live in NE GA and have 8 apple trees. 4 are blooming, but the 4 that are not have a black discoloration on the trunk. They are contiguous in line, separate from the 4 healthy ones. Is this a common fungal infection or insect infestation. One of the diseased trees has a 2" x 6" area on the trunk where the bark is gone and the wood is soft and rotten. There are alot of fresh woodpecker holes on this one tree. I could cut this half of the trunk, but this tree may be a goner. I do show one of the healthy ones with new bud/leaf growth. I have contacted the UGA cooperative extension service, but wanted a comparison opinion. Thanks in advance.