Bill Tindall, E.Tn.
From the most recent TN Forestry Notes publication:
In 2010, a potentially devastating black walnut disease was discovered in east Tennessee. Known as Thousand Cankers Disease (TCD), the disease spreads as walnut twig beetles chew tunnels into branches and carry with them a fungus. The fungus creates branch cankers that eventually kill trees. The spread of the disease over the past few years seems to have subsided in the eastern US, a phenomenon that may be related to climate. More favorable weather (cooler temperatures and higher rainfall) have improved growing conditions, and the disease is fading (Jackson Landers, June 2019,