We have the remnants(old stumps) of the original American chestnuts trees here on our property in the southern Appalacian Mountains of western North Carolina. Even 100+ years after the blight some of these stumps still have sucker growth, although they are short lived. When these suckers reach 1" to 2" in diameter the bark will errupt in leasions that will kill them eventually. The blight is an airborn fungi that kills the top growth but not the roots.
Invasive exotics, like the chestnut blight, kudsu, Japanese honeysuckle and many landscape plants and many animals are of our own doing. The chestnut blight came in on a shipment of chestnut lumber from China in the early 1900s.
Our newest "blight" here in our beautiful mountains is the Hemlock wholly adelgid which is killing all of our wild grown Canadian and Carolina hemlocks, changing the face of our woods forever.