"Blonding" of Ash Bark

How can you tell if your ash trees have the emerald ash borer and are doomed?  Woodpeckers know, and they go after the larvae that are in the tree, just under the bark.  The woodpecker activity knocks off the gray outer layer of the bark, exposing the blonde color of ash bark.  Here is how it appears.   See this and you know you might as well be taking the tree down while the wood is still sound.