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State official: Bleak outlook for emerald ash borer

South Dakota State University Extension Forestry Specialist John Ball speaks to a group of people about the emerald ash borer disease Thursday at Dakotafest in Mitchell. (Marcus Traxler / Republic)

John Ball didn't come to Dakotafest on Thursday with much good news.

Ball, who works for South Dakota State University Extension as a forestry specialist, said the emerald ash borer's arrival in the state is bad news for landowners and farmers who own ash shelterbelts.

"You're in big trouble and that's not what you wanted to hear," Ball said.

The state had its first confirmed case of the tree-killing insect in May in northern Sioux Falls, likely brought to the state through pallet wood, not firewood. Restricting the movement of ash wood and firewood remains the best tactic to slow the movement of the emerald ash borer, so Minnehaha County and the northern portions of Turner and Lincoln counties have observed a quarantine on firewood all summer.

Ball compared the spread of the borer to a smoldering fire. He said the insects can live in the tree for three to four years before a landowner notices the difference. Within five years, Ball said, the tree can be dead.

Communities located west of Sioux Falls don't need to do anything yet, but should have a plan in place, Ball said, about what they'll do when the trees start dying. Once that happens, landowners either need to treat the tree or tear it down.

"There's no prize and your neighbors are going to hate you," Ball said of finding emerald ash borer in trees.

Ball's best advice for residents with affected trees is to pick their favorites for ash trees, and be prepared to set up a college-like savings fund for their trees.

The costs to apply treatments to trees are generally $200 to $400 per tree. For example, a tree that is already affected with the emerald ash borer would require injections to preserve the tree. That product calls for pesticide injections every other year for 10 years, and then every four years after that for the rest of time, meaning just 10 years of treatment could cost upward of $1,000 per tree.

The other option to stop the spread of the disease is to cut those trees down, which could be a tough decision for many farmers who have used ash trees for shelterbelts. Ash trees have been good for that task in rural, windy South Dakota because they can average 40 to 60 feet tall or higher.

"South Dakota has an awful lot invested in ash trees," he said. "The concern is rural, because we're not talking two or three trees. There will be whole shelterbelts of ash trees that will be affected."

The state might have been fortunate to wait out the emerald ash borer as long as it did. The insect from Asia originated in Michigan in the mid-1990s and has reached more than 30 states, killing more than 100 million ash trees.

Ball said that, unlike a dead cottonwood tree, emerald ash borer trees will eventually fall down after dying, making them dangerous in urban areas.

There was also advice for municipalities around the state. Ball recommended that cities prepare rules to require only licensed applicators to work in the city to treat the trees, to make sure only good-faith businesses are working. Residents can live 10 to 15 miles away from an affected tree and not have any concerns, because the insects move slowly.

"If you live in Davison County, or pick a county, you might still have 10 years," he said. "It's not a moment of panic but it's a moment to start making decisions."

But Ball noted that the costs to remove trees will go up once it's found, so a preemptive decision on ash trees might not be a bad idea. So far, residents have been cautious and following the rules, which has appeared to keep movement in check, Ball said.

"South Dakotans are pretty good at that," he said. "Nobody wants to create problems, so they're not taking firewood to state parks or anything like that."