Update: Cedar Rapids finds second case of emerald ash borer in less than two years

CEDAR RAPIDS - The second case of emerald ash borer in city limits since fall 2015 has officials predicting a dramatic loss of ash trees within two years.

The tree-killing pest could change the look of the city, particularly in certain neighborhoods built in the 1950s through the early 1980s where ash are most abundant, said Todd Fagan, city arborist.

'We refer to it as a slow moving natural disaster,” Fagan said. 'It needs to be taken pretty seriously. It will be a pretty dramatic shift in how the city looks.”

City forestry workers noticed evidence of the exotic beetle, whose larvae attack ash from the inside while taking down a dying tree, in the southwest quadrant between the Cedar Rapids Ice Arena and Jefferson High School on Monday.

A resident had called with concerns about the condition of the tree along the street. At first glance, the tree was on the decline but without evidence of the pest. Up close while taking down the tree, crews saw 'textbook” evidence of the insect, Fagan said.

Further inspection in the surrounding area revealed no other cases of emerald ash borer, but they plan to stay vigilant, Fagan said.

The ash borer larvae creates galleries that block the flow of moisture and nutrients, essentially starving the tree and making the trunk and limbs brittle and susceptible to breaking apart. Dead branches near the top of a tree, leafy shoots sprouting from the trunk, bark splits exposing larval galleries, extensive woodpecker activity and D-shaped exit holes are possible signs of an infected tree.

Emerald ash borer has quickly spread across Iowa having been found in 51 counties since first arriving in 2010, a state official said. Iowa has roughly 52 million rural ash trees and 3.1 million urban ash trees accounting for 16 to 17 percent of all trees in Iowa, according to tree inventories that have been conducted.

Transportation of firewood by humans has been blamed as a major cause of the spread.

State and local officials anticipate the frequency of cases in Cedar Rapids will ramp up over the fall and next summer and eventually major losses in the ash tree population two summers from now.

'Now that the newest tree has been determined to have ash borer, I would anticipate more and more trees will become visible later this summer and fall and more next year,” said Mike Kintner, the emerald ash borer coordinator for the Iowa Department of Agriculture and Land Stewardship. 'That is the struggle with this pest once it shows up. Trees deteriorate quickly.”

The first case in Cedar Rapids was identified by the Interstate 380 rest stop on the south edge of town in October 2015, but until this week no positive findings had been made in the core of the city, Fagan said.

'This find gave us a location in town,” Fagan said. 'We've known it's here for the past several years, but we didn't know where it is.”

Emerald ash borer presents little evidence for the first several years as the infestation grows. By the fifth year, problems become apparent and by the seventh or eighth year, the decline of the tree is pervasive, he said.

Ash trees account for roughly 17 percent or about 7,400 of the 43,000 trees maintained by the city, according to tree inventory conducted by the city. They were a popular choice particularly from the 1950s to the early 1980s because they grow quickly, provide attractive fall colors and resisted disease, Fagan said. They continued to be planted until the first cases of emerald ash borer showed up nationally in 2002.

The city has been bracing for the arrival of emerald ash borer by diversifying its tree stock through planting 25 to 30 different species each year, removing 2,000 declining ash trees, chemically treating some ash trees to buffer the decline, and regular inspections. A contract is scheduled for approval next month to plant more than 1,000 trees in fiscal 2018, Fagan said.

'We go around and take out things struggling already,” Fagan said. 'We will continue on with the plan we are using already, looking at the inventory. We are not going to start cutting down all of the ash trees.”

Five sites in Iowa have been selected for introduction of a stingless wasp, which is a natural enemy of the beetle, Kintner said. Cedar Rapids could potentially be a candidate for the parasitic wasp, but is not at this time.

Residents are responsible for ash trees on their own property, and can discuss concerns about ash trees in their parkway by contacting the city arborist at 319-286-5747. More information is available on the city's website at cedar-rapids.org/EAB and www.iowatreepests.com.

l Comments: (319) 339-3177; brian.morelli@thegazette.com