In this Friday, Oct. 19, 2012 photo, an orange-black canker erupts on a hybrid chestnut tree in a test orchard outside Asheville, N.C. Entering through wounds in the bark, the fungus th

 

              In this Friday, Oct. 19, 2012 photo, an orange-black canker erupts on a hybrid chestnut tree in a test orchard outside Asheville, N.C. Entering through wounds in the bark, the fungus th
In this Friday, Oct. 19, 2012 photo, an orange-black canker erupts on a hybrid chestnut tree in a test orchard outside Asheville, N.C. Entering through wounds in the bark, the fungus threads its way through the straw-like vessels that carry water and nutrients from the ground to the tree's crown. As the tree responds to plug these holes, the blight works its way around the trunk "until it is completely girdled," William A. Murrill, the botanical garden's assistant curator, wrote in 1906. "The tree essentially commits suicide," said geoscientist Frederick Paillet, an emeritus professor at the University of Arkansas who has studied chestnuts for nearly a half century. (AP Photo/Allen Breed)