Preparing for emerald ash borer

In early July, the emerald ash borer was confirmed in Brookings County. Officials at South Dakota State University, however, have been preparing for its arrival for around a decade.

Emerald ash borer is a boring beetle that feeds on all species of North American ash. It was first detected in the United States in 2002 and in South Dakota in 2018. It has since been identified in the South Dakota communities of Baltic, Brandon, Brookings, Canton, Crooks, Dakota Dunes, Lennox, Sioux Falls and Worthing, according to the South Dakota Department of Agriculture and Natural Resources.

Of the nearly 2,500 trees on the SDSU proper campus (excluding McCrory Gardens and the State Arboretum), 210 are ash, or around 9% of the tree population. In 2016, that percentage was closer to 20%.

This reduction in ash trees on campus was not by accident. Over the past five years, SDSU has removed almost 80 ash trees with scheduled removals for 60 more over the next two years.

The emerald ash borer has not yet made its way to campus, but it’s likely to emerge within a couple of years.

While many of the ash trees will be removed from campus, some “legacy trees” will remain under treatment, according to Tanner Aiken, project manager and horticulturist at SDSU. The oldest tree on campus is estimated to be a 145-year-old ash tree located north of The Barn.

“You can inject ash trees with an insecticide to prevent emerald ash borer from damaging the tree,” Aiken said. “But there is a cost associated with these treatments, and they must be continued every two years for the rest of the tree’s life. We are strategically trying to save a handful of older, including the oldest, ash trees on campus with injections. However, the best long-term strategy is species diversification.”

SDSU Facilities and Services has planted roughly 150 trees of varying species each year. 

Once an ash tree becomes infected, the tree becomes dry and brittle in a very short amount of time and can fail in unpredictable ways, according to Aiken.

“On campus, we want to remove them ahead of time, so they don’t decline to a dangerous point,” he said.

SDSU maintains its Tree Campus USA designation, an honor first awarded to the university in 2009. SDSU was the first campus in South Dakota recognized for its arbor efforts and is one of only 411 campuses nationwide with that distinction. The Arbor Day Foundation program provides a simple framework for colleges and universities to grow their community forests, achieve national recognition, and create a campus their students and staff are proud of.

During a July 18 tree removal on campus, Facilities and Services hosted interns from the South Dakota Department of Agriculture and Natural Resources to learn about the emerald ash borer and proper tree removal. The learning experience was organized by John Ball, professor, SDSU Extension forestry specialist and South Dakota Department of Agriculture and Natural Resources forest health specialist.