Have Fungus, Will Travel: Tree-killing disease jumps to Tennessee and Kentucky

by | Aug 7, 2019

An unwelcome sight has plagued our coastal forests for years now. Dead redbay trees line the roadways and mar our coastal forests in southeastern N.C. These trees are dead because of an invader—a non-native fungus carried from tree to tree by the invasive redbay ambrosia beetle. This fungus causes laurel wilt disease and infected redbays die in a matter of weeks.

Until last year, laurel wilt disease was only known to kill redbay trees in N.C. However, in 2018, the disease was confirmed in sassafras in N.C. for the first time, coming after other southern states confirmed the same in years prior. With this news, risk that the disease could go beyond the coastal plains increased. Redbay is a coastal species, but sassafras is found throughout the state.

But now, the threat is even greater. Not only have we thought sassafras across the whole state was at risk, but the fear has been realized.

“If laurel wilt could make it [to Tennessee and Kentucky], it could be anywhere in North Carolina.”

Kelly Oten, North Carolina Forest Service

In July 2019, laurel wilt disease was found in Tennessee and Kentucky, over 200 miles from the nearest confirmed location. “This jump is an eye-opening event,” says Kelly Oten, Forest Health Monitoring Coordinator with the N.C. Forest Service. “If laurel wilt could make it that far, it could be anywhere in North Carolina.”

After years of seeing laurel wilt kill redbay in our coastal plains, we are bracing ourselves for more widespread mortality in sassafras. Oten says that identifying symptoms of the disease in sassafras may not be as straight-forward as it is in redbay. “In sassafras, leaves will wilt and lose greenness, looking like fall color but during the wrong time of the year.” Not only do the dead, wilted leaves not stay attached to the tree as they do in redbay, but the vascular streaking is not as pronounced (seen right). “This might make it more challenging to identify the disease in sassafras.”

So, keep your eyes peeled. This invasive insect has made it very clear that is has fungus, will travel.

Laurel wilt disease made a huge range jump when it popped up in Kentucky and Tennessee (circled in red) in July 2019. Finding it so far from other positive sites reinforces the idea that this disease could show up anywhere.