Image courtesy David Cappaert – Michigan State University, Bugwood.org
As Christmas presents go, this one is fairly terrible.
It’s a billion dollar problem, and only half an inch long. The Emerald Ash Borer (EAB) has now surfaced in Union County, in south-central Iowa.
EAB is “about the length of President Lincoln’s image on a penny,” according to State Entomologist Robin Pruisner, who adds that the spread of EAB could mean the end of Iowa’s ash trees. She points to extreme weather in the past few years, between droughts and floods, which causes tree health to decline. Trees under stress are attractive to EAB, and Pruisner says stress appears to exacerbate the damage EAB causes to ash trees.
“For some reason, we can’t find an infestation until it’s 4 or 5 years old,” Pruisner adds. “Couple that will all the additional stresses on the trees, and I think we’re finally, maybe, at that tipping point where we’ve got that age of infestation, and the trees are kind of in a death spiral from all the stresses that they’ve been in.”
EAB has been confirmed in Allamakee, Des Moines, Jefferson, and Cedar counties in eastern Iowa, but yesterday’s announcement revealed its presence in south-central Union County as well. Officials says the jump to central Iowa is likely due to transported firewood, but DNR Forest Health Specialist Tivon Feely says the precise qualities that make ash trees so attractive to urban areas have obscured the seriousness and extent of infestations.
“One of the reason that ash was planted so heavily, especially in urban communities,” says Feely, “is because they are such a tough tree; they callous over a wound very quickly. That’s something that they’ve been doing in Iowa, where Emerald Ash Borer has been there, and it’s kind of hidden the damage that we would expect to see.”
Feely adds that with the recent drought, EAB populations have built up to the point that they are becoming more visible.
Perhaps most alarming, EAB poses a significant monetary threat to urban areas that have invested in ash trees for public places.
“We estimate that there’s about 3.1 million urban ash trees,” DNR State Urban Forester Emma Hanigan says, “and I think that’s that’s a conservative number. Removals can vary, but we estimate that they’re about $1000: the cost to landowners is going to be in the billions of dollars.”