Killing Borers with a Girdle

Emerald Ash Borer- USFS

By now you probably have heard of the Emerald Ash Borer (EAB), an insect that is spreading across the US from Michigan where it was accidentally introduced, probably from packing material on a shipment from China.  It is killing ash trees and threatens to wipe them completely out.  As ash trees are a common urban planting as well as a source of wood for baseball bats, this news is disturbing.

Ash borers attack the tree by laying their eggs under the bark.  The larvae then tunnel around under the bark, effectively cutting off the tree's circulation.  As they arrived in the US without the predators that keep them under control in China, they are thriving.

Researchers in the Hudson Valley of New York are now experimentally releasing three types of Chinese wasps known to attack the borer's larvae or their eggs.  This approach has to be monitored carefully to be sure that they don't have a similar effect on our beneficial native insects.

They also are trying a unique approach to reduce the EAB numbers.  They are girdling selected trees, removing 18" bands of bark to weaken the tree.  EAB tends to proliferate in damaged trees and they hope to concentrate the larvae in these trees and then destroy the trees with their larval nursery.

While these experiments go on, our only protection in Missouri is the distance the EAB requires to move from tree to tree.  The biggest risk is in accidentally importing diseased wood, allowing the beetle to migrate through several states.  This is the reason we urge everyone to not transport firewood from other areas.

Story derived from an article in the the Wall Street Journal, available to subscribers.