Bad news for ash trees: Emerald ash borer sightings jump to 18 counties

A recent spate of confirmed emerald ash borer infestations, including the first identified in rural Iowa, indicates the state has reached a tipping point in its efforts to contain the spread of the tree-killing pest, State Entomologist Robin Pruisner said Monday.

'Hold on to your seat belts,” State Forester Paul Tauke said during a telephone news conference to announce that the ash borer has been found in five southern Iowa counties, catapulting the number of Iowa counties with confirmed infestations from 13 to 18.

'We are seeing the ash borer population growing at an exponential rate, and we will continue to see more counties (in which the pest has been confirmed) at a more rapid rate in 2015,” said Tauke, chief of the Department of Natural Resources Forestry Bureau.

The 13 previously confirmed infestations were all in cities and towns, where trees come under more frequent and regular scrutiny. The five most recent infestations - in the contiguous counties of Lucas, Appanoose, Mahaska, Marion and Monroe - include three in rural areas.

That's significant in part because about 95 percent of the state's estimated 55 million ash trees grow in rural timbers and woodlots.

Though treatment of woodland ash is cost-prohibitive, Tauke said DNR district foresters can help landowners prepare management plans that would encompass pre-emptive ash removal and diverse species replacement.

If EAB follows the same course in Iowa as in other states, 99.9 percent of the state's ash trees will die, he said.

The loss of rural ash trees, while a blow to diversity, would not entail the expensive tree removals required to mitigate hazards in urban areas, Tauke said.

The recent surge began Nov. 25 when eight larvae were collected as part of an investigation in eastern Lucas County.

A forestry contractor conducting a timber stand improvement project found many dead ash trees with heavy woodpecker flecking on privately owned timber on the western edge of Lucas County.

Investigators noted a number of ash trees in advanced decline, suggesting that the invasive beetle had been there for several years, prompting them to expand their search.

Additional larvae were found in ash tree on public property in Monroe County, near the Lucas site.

In Marion County larvae were found in a heavily-flecked ash tree on state property on the edge of Marysville. In Appanoose County larvae were found in a tree along train tracks in Moravia. In Mahaska County larvae were collected from a tree on private property on the north side of Eddyville.

'Obvious signs of infestation were found in hundreds of contiguous acres across multiple counties,” said DNR district forester Jeremy Cochran.

Because early signs of infestation are not easily detectable, 'the farthest extent of the infestation remains unknown,” he said.

Tivon Feeley, the DNR's forest health program leader, said it's difficult to identify comparatively new infestations. Trees may be infested for five or more years before woodpecker flecking, the most obvious symptom, becomes noticeable, he said.

After the seventh year of an infestation, 'tree mortality goes dramatically upward and the infestation becomes large and obvious,” Pruisner said.

Some of the infested trees are within a few miles of Stephens State Forest, whose seven units cover more than 15,000 acres in Lucas, Clarke, Monroe, Appanoose, and Davis counties.

Area forester Jessica Flatt said regular surveillance has found no trees with definitive symptoms, but 'we are seeing a lot of bark flecking, and we're guessing it's probably in the state forest.”

In 2010, when the state's first infestation was confirmed in Allamakee County, Iowa became the 14th EAB-infested state. Today that number stands at 24.

A statewide quarantine issued in February restricts movement of hardwood firewood, ash logs, wood chips, and ash tree nursery stock out of Iowa into non-quarantined areas of other states.