Chestnut Blight occurs in two forms. One that weakens the tree, another that kills it. You won't get both to occupy the same tree at the same time. Inoculating chestnuts with the weakening form is another method of saving it. In other words, sometimes you have to make the tree sick to keep it alive.
People who have chestnut trees often ask how to tell them apart. There are about a dozen ways, but the simplest way is to look at the vegetation. The above pic is American. Feel the underside of the leaves. Then look at the leaf petiole, buds, and new growth twigs. If it's American Chestnut, all parts will feel or look SMOOTH. If it's Chinese, all parts will be FUZZY.
Another rust called the White Pine Blister Rust affects White Pine and Gooseberry shrubs (Ribes). It was devastating to the White Pine industry in the Great Lakes, especially in Michigan. People simply went out and cut all the Gooseberry to save the White Pines.
Part 2 on this subject can be found here, under what's in a log