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City Prepares for Foreign Invasion

Categories: Indianola, Warren County

The City of Indianola has been a leader in raising awareness about the approaching danger of the Emerald Ash Borer (EAB). The beetle originated in Asia, and was discovered in southeastern Michigan in 2002, when ash trees in the area began dying at an alarming rate.

Since 2002, EAB has killed tens of millions of ash trees in southeastern Michigan alone, has spread to 19 states (including Iowa), as well as two Canadian provinces, and is considered the most destructive forest pest ever seen in North America.

Despite precautions such as quarantining counties where EAB has been found, the insect continues to spread and will eventually reach Warren County, putting Indianola’s ash trees at risk.

Taking a proactive approach, the City held one of the first EAB training sessions in Iowa for arborists and other tree professionals in March of 2008, the first step in preparing for the eventual invasion of the insect.

Top Ten Tree Species on City Property | Indianola, Iowa | Fall, 2010Then in 2010 with the help of the Indianola Community Trees Committee and a grant from the Warren County Philanthropic Partnership, an inventory of all the trees on city property was taken.  The inventory maps every tree, showing its location, size, condition and species.  The inventory showed that out of over 3500 trees, 820 are green or white ash trees vulnerable to EAB, nearly one fourth of the total.

Since treating trees with insecticides is very costly and it is unclear how successful that would be, a multi-year plan was created to remove and replace the city’s ashes tree for tree with a diverse mix of trees. By scheduling the replacement of ash trees now instead of waiting until the trees are dying or dead, the cost can be spread over time and the process will be more manageable.  The City Council has approved the plan and its associated costs.

This year the city has removed ash trees in Buxton, Moats and Pickard Parks.  The trees in Moats and Pickard were unhealthy from causes other than EAB and needed to be taken down for safety reasons.  However, the ash trees at Buxton were healthy, and park visitors and neighbors began to ask why living trees had been removed.

In addition to concerns about EAB,  the trees also did not meet the objectives of the park’s function as an arboretum.  Director Glen Cowan explained, “The primary purpose for an arboretum is to be an area with specimen plantings of unique trees and shrubs, to help the public see and compare plants that they might wish to include in their own yards.   With the threat of EAB coming, we wanted to provide residents with alternatives to the ash trees, and to make our collection more diverse.”

City Horticulturist Angie Buchanan recognizes that Buxton Park has a special place in many residents’ hearts.  “We have many people who visit daily, walking through the park on their way to school or work.”

Unfortunately, ash trees are not the only trees currently under attack.  Scotch Pines and Colorado Blue Spruce also are dying due to diseases that specifically target those species.  The majority of the trees removed in Buxton Park this year were dead evergreens.

The questions people asked as she worked in the park showed Buchanan the importance people place on trees. “We love trees, too,” she said.  “We’re trying to maintain the health of our urban forest by planning ahead in this situation.   If you can imagine a quarter of all our trees dying and having to be removed at once, that would be a huge loss. This process allows us to phase it in over time.”

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Emerald ash borer (EAB), is an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002.  On August 1, 2013, the EAB was confirmed in a residential tree in the city of Fairfield, Iowa, just 100 miles southeast of Indianola.

The adult beetles nibble on ash foliage, but cause little damage. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients. Emerald ash borer probably arrived in the United States on solid wood packing material carried in cargo ships or airplanes originating in its native Asia.

EAB has killed tens of millions of ash trees in southeastern Michigan alone, with tens of millions more lost in Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Massachusetts, Maryland, Minnesota, Missouri, New Hampshire, New York, North Carolina, Ohio, Ontario, Pennsylvania, Tennessee, Quebec, Virginia, West Virginia, and Wisconsin.

EAB is now considered the most destructive forest pest ever seen in North America. The scope of this problem will reach the billions of dollars nationwide if not dealt with.  State and federal agencies have made this problem a priority. Homeowners can also help by carefully monitoring their ash trees for signs and symptoms of EAB throughout the year.

For more information,  see http://www.emeraldashborer.info.

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