Forest study targeting ash borer infestation

Pittsburgh Post-Gazette

“Herd immunity” holds that as long as a large majority of a group is vaccinated or inoculated, even the unimmunized minority will mostly be protected.

It’s a concept that applies to control and containment of a host of human diseases like polio, measles, mumps and rubella, but not usually invasive insect pests like the emerald ash borer. Until now. A multiyear, multi-agency, experimental field study underway in the Allegheny National Forest is seeking to determine how fast the ash borer is moving through the forest and how many ash trees in a stand must be treated with insecticide to save the stand.

Positive findings from the four-year study, funded with a $67,000 grant from the U.S. Forest Service’s State and Private Forestry branch, have the potential to help forest managers save more of the trees in the 32 states where the ash borer has been found so far.

“Herd immunity is the unique thing we’re looking at in this study. We are trying to determine if we treat a bunch of the trees in a certain area, do the untreated trees also get protection,” said Kathleen Knight, a U.S. Forest Service research ecologist and a project leader.

The shiny green Asian beetle first arrived in North America in Detroit in 2002, as an accidental stowaway in shipping materials. Since then it has killed hundreds of millions of the 8.7 billion ash trees in the U.S., spreading rapidly into 32 states and southern Canada.

It has the potential to transform the hardwood forests of North America to an extent not