lots of american chestnut sprouts here, they get 4-10" in diameter, then die from blight. there are however a few trees that get to 20". We now think they are gradually developing immunity, but it must happen soon. the sprouts are coming up from root stock that has been in the ground over 100 years and will die soon. The blight cannot kill the roots due to a competing organism that will kill the blight as it goes below the surface.