The Effects of the American Chestnut on Trees

The American Chestnut went extinct because of the fungus. It just ran down the east coast and killed all the American Chestnuts. And that happened to run again around the turn of the last century, but it happened within decades. Is that common that fungal infections happen so quickly? I think that it would depend on, you know, it's producing a lot of spores; if they grew really thick then it wasn't difficult for the fungus to spread from one tree to another.