I'm not sure how this relates to any of this, but it is interesting. There is a mycologist (fungi guy) named Paul Stamets who recently wrote a book called Mycelium Running. In it he discussed endophytes, fungi that inhabit plants, but don't cause disease, though in trees, they may cause conks, the woody fruiting body found on tree trunks.
He specifically mention a call he got from a man that managed a chestnut orchard in Quebec. This manager stated that chaga, a conk or sclerotium of what he considered an endophyte, Inonotus obliquus would prevent Chestnut blight. He said he had packed lesions of infected chestnut trees with a poultice of ground up chaga, after which the trees healed and recovered, free of blight.
I don't quite know what to make of this, but there you are, another anecdotal cure.
Ray