Ash-killing bug opens second Iowa front

The emerald ash borer has opened a second front in its war on one of Iowa's most popular hardwood trees.

After the tree-killing beetle established a beachhead along the Mississippi River in far northeast Iowa in 2010, state officials announced Tuesday that they have positively identified an infested ash tree 186 miles down river in Burlington.

“It was not too big a surprise,” given that an infestation had already been documented 28 miles away in Galesburg, Ill., state forester Paul Tauke said.

EAB, widely considered one of the most destructive forest pests ever in North America, kills all ash species by larval burrowing under the bark and eating the actively growing layers of the tree.

A concerned Burlington homeowner notified the city of an ash tree in decline, according to State Entomologist Robin Pruisner.

The 35-foot-tall tree had all the hallmarks of an EAB infestation – dead branches at the top, green sucker branches near the base and larval feeding galleries beneath the bark –and the actual beetle was confirmed, she said.

A quarantine on the movement of hardwood firewood, ash logs and wood chips will be enacted, but it remains to be seen if it will be implemented only in Des Moines County or regionally, Pruisner said.

Iowa's first EAB infestation was found on Henderson Island in the Mississippi River in Allamakee County in 2010.

The ash borers have since moved slightly inland, according to Rob Meinders, state plant health director for the U.S. Department of Agriculture. The signature purple monitoring traps have captured borers in both Lansing and New Albin, he said.

The 340 traps deployed this year have all been negative on the first check, Meinders said.

Burlington city forester Casey Chadwick said a survey will be undertaken to assess the extent of the infestation among the estimated 800 ash trees on city property and 2,000 ashes on private residences.

Most of the ash trees on city property will be removed and replaced with less vulnerable trees in the next three to four years, Chadwick said.

Iowa has an estimated 52 million rural ash trees and approximately 3.1 million more ash trees in urban areas, according to the USDA Forest Service.

The Iowa Legislature has appropriated funds to help pay for monitoring the spread of the pest but nothing yet to defray the cost of local governments in removing and replacing ash trees.

Trees Forever is working with statewide partners to help communities and homeowners prepare for the significant loss of ash trees and to be proactive about planting a diversity of new species in their place, said the group's president, Sharon Ramsay.

“We're also working with communities, tree groups and Iowa's state legislators to address the anticipated costs of ash tree removal, disposal and replacement. Smaller communities just don't have the staff or resources to handle this looming threat, and state funding and cost share will be needed to help address all of these issues,” she said.

During the past four years, the city of Cedar Rapids has removed about 800 street ash trees -- most in declining condition -- and replaced them with different species of trees. The city likely has about 20,000 ashes among its 80,000 to 100,000 street trees, according to city officials.

Pruisner said all Iowans are strongly cautioned not to transport firewood across county or state lines, since the movement of firewood throughout Iowa or to other states poses the greatest threat to quickly spread EAB even further.

EAB, an eastern Asia native, was detected in the United States near Detroit, Mich., in 2002. It has since spread to 19 states and two Canadian provinces and has killed millions of trees in the Midwest.

Treatments against EAB are too late this year, according to ISU Extension and Outreach Entomologist Mark Shour.

“If you are within 15 miles of Burlington and have a healthy ash tree, preventive treatments can be made mid-April to mid-May 2014,” he said.