Emerald ash borer (EAB) is redrawing forests, urban streets and residential landscapes across much of the US and Canada. New research from Purdue University shows that municipalities that take steps to save EAB infested trees early on can save money compared to the cost of replacement.
The Purdue team co-led by Dr. Cliff Sadof and Dr. Matt Ginzel respectively in the Department of Entomology and Department of Forestry and Natural Resources, developed a model to help foresters predict the progression of ash decline over time. The research team was tasked with examining early EAB infestation and developing a system to estimate canopy decline over time. The percentage of damaged ash trees in a city typically doubles every year.
“Damaged trees are often not noticed until they have lost 30% of their canopy. Unfortunately, by then it’s usually too late to save them from EAB,” Sadof said.
Although it is possible to protect the remaining green canopy in infested trees, the damage that has already occurred increases the potential for loss of structural integrity and aesthetic value.
The researchers developed a model for predicting the progression of the decline and eventual death of infested ash trees and validated it with two kinds of data – the removal of 14,000 ash trees destroyed by the EAB in Fort Wayne and the accumulation of ash trees in Indianapolis and Lafayette that lost at least 30 percent of their canopy.
“By systematically surveying ash trees, a community can figure out where they are in the progression of ash decline,” Sadof said. “We hope that putting a timeline on the wave of ash destruction could get communities to start saving their trees before it is too late.”
The researchers also developed a web-based EAB cost calculator that compares annual and cumulative costs involved in saving or replacing trees. They determined that strategies relying mostly on saving ash trees were less expensive and produced a larger “forest” than strategies that involved removing and replacing trees.
The EAB attacks and kills the trees of most North American ash species. Potential for much more destruction is great because there are about 8 billion ash trees in North America.
Purdue Extension’s Tree Doctor app can help foresters better communicate the specific levels of canopy loss they are seeing in infested ash trees. The app, for iPhone and Android users, covers over 200 tree problems in more than 60 kinds of trees.
The research, titled “Tools for Staging and Managing Emerald Ash Borer in the Urban Forest,” has been accepted by the journal Arboriculture & Urban Forestry for publication this fall.
NewTerrain July 1, 2016.