Marked with a red and white ribbon that indicates it is being treated with a pesticide, Kane County Forest Preserve District Ben Haberthur, a restoration ecologist, shows one of the 30 mature Blue Ash trees they are trying to protect from the Emerald Ash Borer beetle at Johnson's Mound Forest Preserve on Thursday, October 11, 2012 in Elburn. | Steven Buyansky~Sun-Times Media
www.treebenefits.com — on the economics of saving a tree
www.eabindiana.info — about research on the pest, including a “decision guide” for local government.
http://extension.entm.purdue/edu/treecomputer/ — a formula for determining which trees need immediate removal, or will respond to treatment
Updated: November 13, 2012 6:24AM
The good news in the battle against the emerald ash borer is there is hope for the future. The bad news is, the Fox Valley and the rest of the Chicago area continue to be in the midst of what is an infestation of historic significance.
“Think of it like a tidal wave,” said Cliff Sadof, a professor at Purdue University in Indiana. “You want to protect your trees in a bunker. After the wave goes over, you can poke your head out. Right now, you should be in a bunker mentality.”
Sadof recently addressed a group of Chicago area municipal leaders, staff members and forestry staff at a symposium on treatment possibilities that might save ash trees rather than have them cut down.
The symposium was held in Hazel Crest, a south suburb that is the site of a treatment research trial started in 2007. The trial is being conducted by the Morton Arboretum, the village of Hazel Crest, the U.S. Department of Agriculture, Davey Tree Expert Co. and Rainbow Treecare.
Sadof has been collecting data and doing research on possible treatment alternatives since the emerald ash borer was first discovered in the early 2000s in Michigan and Indiana. The bug was first spotted in Illinois in a subdivision west of St. Charles in June 2006.
“I would hope that you understand that it is indeed possible to save trees,” Sadof said.
New information and development of pesticides and how they can be used have made treatment a viable alternative to cutting down trees — depending on the size and age of the tree, and how long it has been infested.
Tree ‘death curve’
One of the pieces of newer information is what is dubbed the exponential death curve, developed in the last couple of years to show how the beetle’s infestation progresses. The curve can tell a specific city, county or region where it is in its infestation, which can guide that jurisdiction in how to deal with the trees.
One of the things the curve shows is how infestation starts slowly but, at a certain point, kicks in and suddenly becomes very destructive. For instance, the curve for the Upper Huron River Watershed in southeast Michigan — Detroit and that area in Michigan are ground zero for the beginning of the emerald ash borer infestation in America — shows the infestation beginning in 1994 and progressing slowly through 2002.
At that point, eight years into the infestation, less than 10 percent of trees had died.
That number began to rise quickly, though, and by 2004 the death percentage was at about 20 percent of trees. But by 2006, the death percentage rose exponentially to almost 80 percent of trees and onto 100 percent by 2010.
Infestation in Illinois was not discovered until 2006 in the Windings subdivision in Campton Township, west of St. Charles.
When that infestation was confirmed by the state, the Kane County Forest Preserve District did a quick survey of the Campton Forest Preserve just across the street and found infestation there.
“We got hit so fast that there might have been insecticides, but nothing was approved for use,” said Drew Ullberg, Kane Forest District director of natural resources. “We had literally thousands of ash trees in parklands and on public lands that succumbed so quickly.”
What that means is the infestation was probably well along the curve by the time it was discovered, and it didn’t take long for it to spread. While infestation was discovered only in Campton at first, it was quickly found in a grove at the Dick Young Forest Preserve west of Batavia, and was in four preserves by 2007.
“Now it’s basically everywhere,” Ullberg said.
At that point, the district began a program of managing the hazard trees — ones in more public areas of the preserves — by cutting them down to make sure they didn’t fall on someone. The district would monitor the better trees.
How many trees?
In 2010, Ullberg began a conservation program at Johnson’s Mound Forest Preserve in Elburn and in another preserve, on about 200 blue ash trees. He chose the blue ash because they demonstrated more strength against the infestation than other ash trees.
About 200 blue ash trees are being treated, which Ullberg admits “doesn’t sound like very many.” But he said that at the very least, he hopes to use those trees to save the genetic strain and keep the ash “as a legitimate species for the future,” after the infestation has passed.
Officials in the fight against the emerald ash borer said the key to any program is to first do a rigorous survey of the ash trees in a given community. The survey needs to determine how many ash trees a community has, how many are infected and what condition the trees are in.
“The pattern of tree loss is the ultimate decider for the decision you get to make,” said Jim Zwack, director of technical services for The Davey Institute. “The key is where you are on the curve.”
Ullberg said the forest district did a survey and found about 10,000 ash trees in the more public areas of the preserves. But that did not count the more natural areas, where it was almost impossible to do a complete survey.
“Maybe if I could hire 10 more people, then call me in five years, and I could give you an accurate count,” he said.
That more accurate count for all forest preserve lands is likely in the tens of thousands, Ullberg said. The district already has taken down thousands of trees.
The situation is different in Naperville and Elgin, where programs that combine cutting down trees with treatment will save thousands of ash trees.
In Elgin, Jim Bell, director of the city’s Forestry Department, said an assessment shows the city is “just entering the curve.” That has allowed the city to treat between 1,500 and 1,700 of its 6,900 ash trees to date.
The combination of catching the infestation in an earlier stage, and the greater amount of information available now, has worked in both cities’ favor.
“When the infestation was discovered in the Windings, they were thinking, ‘Cut down ash trees,’ ” Bell said. “The recommendation wasn’t for treating at that time.”
Naperville has what might be considered the poster child program for treatment.
In 2008, when the city first discovered its infestation, it did an inspection and inventory, had the state install traps to determine the extent of the beetle’s presence, removed and disposed the trees it had to, and started treating all parkway ash trees within a half-mile radius of the discovered infestations.
In 2012, the program was expanded to include treatment of all healthy parkway ash trees. Naperville uses a hybrid of three chemicals to treat trees, depending on their size.
Naperville has 16,300 ash trees, most of which the city will treat. Officials there anticipate taking down about 700 trees.
Cost a factor
Of course, a key factor in deciding on treatment is the economics. Naperville has determined that it would take much more money over time to remove all the ash trees. Its treatment program for 2012 costs about $480,000. That will be only about $175,000 in the second year because one of the treatments is done every two years.
The estimated cost to remove all the trees and replace them was almost $14 million.
In replacing ash trees in any area, officials said they are planting a diverse number of species.
“We want a diversification of no more than 10 percent of any one species,” Elgin’s Bell said. “In Elgin, we discovered that 13 to 14 percent of our forest was ash, and in some communities it’s been as much as 29 to 30 percent. Diversification limits the exposure to infestation that comes in.”
No one knows what that next infestation could be, and it may not be for many years.
No one recalls a situation like this, affecting one species, since Dutch Elm disease swept across America more than 50-60 years ago.
“Emerald ash borer is a pest of historical significance,” said Zwack, of the Davey Institute. “And hopefully, it’s a once-in-a-lifetime pest.”