Why am I seeing so many dead trees around this year?


While there are many reasons that trees can decline and die, the dead trees you are seeing around town and along the roads are most likely Ash trees. Emerald Ash Borer (EAB) has moved into this area the last few years, and now we are really seeing the damage. Ash are native to our woodlands and were a commonly planted landscape and street tree before this exotic pest came along...

The Emerald Ash Borer is a wood boring insect that lays its eggs under Ash tree bark. The larvae eat the tissue under the bark and eventually girdle the tree. This pest is native to East Asia, and hitched a ride to this country in shipping materials. As is the case with many exotic invasives, there were no natural predators here to control the spread. The beetles are metallic green in color, and can fly a few miles to find more Ash trees. They also spread by people moving infested wood to other areas.

A tree that has EAB usually dies within 2-4 years. First you will notice the tree's crown die back from the top down, as the nutrient and water source is cut off by the tunneling larva. You may see sprouting of branches around the base as the tree tries a last ditch effort to survive. You will also see the bark start to split off and you may even see woodpeckers feeding high in the tree. By this stage the tree is pretty much a goner. There are chemical treatments available to try to save high value trees. They can be expensive, though, and are most successful when used as a preventative for a healthy tree. If you have an Ash tree on your property and it still looks healthy, you have a chance at saving it before the insects find it. At this point it's a matter of when, not if.

If you do lose a tree to EAB, be sure to replant with diverse tree species. We get into these problems of massive tree losses because we create monocultures with our overuse of certain tree species, through which insects and diseases can spread rapidly.

There are many other insects and diseases that can cause the same symptoms as EAB, so it's best to contact an arborist if you notice your trees are declining. They can accurately diagnose and offer options.