Emerald ash borer moves closer to South Dakota
SIOUX FALLS (AP) — An insect that could threaten one of South Dakota's most populous tree species moved even closer to the state in the past year.
The emerald ash borer last year was found in Union County in southwestern Iowa, as well as in Boulder, Colo. South Dakota State University forestry expert John Ball told the Argus Leader newspaper (http://argusne.ws/1d0xv8a ) that he thinks the Asian beetle will be found in South Dakota within five years.
"All it takes is one person bringing in some firewood from an area currently infested, or even pallet wood that has the bark attached, and we have the infestation," he said. "Boulder is the best example that it's not a gradual spread."
The emerald ash borer was discovered in Michigan in 2002 and has since spread, killing tens of millions of trees in several states, including Minnesota. Beetle larvae destroy ash trees by tunneling under the bark.
Ball estimates that ash trees make up almost one-third of all the trees planted in South Dakota communities. They're also a common windbreak species in rural areas of the state, and they grow in abundance along creeks and rivers.
Officials in Sioux Falls estimate that ash make up half of the trees along the city's roads and streets and at least one-fourth of city park trees. The city has been encouraging the planting of other species.
"We'd like to have (ash trees) down to 5 percent," said Duane Stall, forestry supervisor for the Department of Parks and Recreation.
Tim Tiahrt, owner of Dakota Tree Nursery in Renner, said he is moving away from growing ash trees for sale.
"We have been tapering it back over the last five years now," he said. "We are not planting any new ones, and what we have is almost gone."
However, ash trees still are in demand by people in need of landscape and shelter belt trees, Tiahrt said.
"It's a wonderful tree, a great tree for this area," he said.
Ash trees can be treated with a pesticide, though it costs about $200 per tree. It also is too early for such measures, according to Ball.
"Do not treat for emerald ash borer until it is found in an adjacent county," he said. "While I know people are already treating for emerald ash borers in Sioux Falls, this is very premature."