Des Plaines parks fights to save ash trees
“Trees give you a sense of connection to the past and a sense of community in a neighborhood,” said Steve Krotz, landscape maintenance supervisor, Des Plaines Park District.
The same way our children grow and mature season to season, so, too, do our neighborhood trees.
While offering us shade, reducing cooling costs, and helping to prevent erosion, trees add an intrinsic value to our private and public properties.
Across more than 50 parks and open green spaces, the Des Plaines Park District maintains over 3,500 trees. The plantings are diversified, and many are native to Illinois. Approximately 20 percent of the population is a combination of green and white ash trees.
Over the past several years, ash trees have been under attack from the emerald ash borer. The insect was first detected in Illinois in 2006, and the first confirmed infestation in Des Plaines was on January 27, 2010, in the forest preserves at Devon and River roads.
The borer is an exotic, dark, metallic-green beetle native to Asia, which was accidentally introduced into the United State in the 1990s. It has since spread to trees in over 14 states.
The emerald ash borer has no natural predator. The female lays up to 100 eggs, depositing them on the bark of the ash. Newly hatched larva bore through the bark to the phloem — the living tissue that carries the organic nutrients, particularly sucrose, to all parts of the tree where they are needed during photosynthesis.
The larvae create long serpentine galleries which enlarge in width as they grow. To emerge from ash trees, adults chew D-shaped exit holes through the bark, then fly up into the ash’s canopy and feed on its leaves, doing even more damage to the tree.
The park district has many ash trees lining the drive into the Leisure Center. These ornamental trees have a deep green waxy leaf that changes to yellow, orange, and deep red in the fall. In 2010, a bark window was cut into an ash tree on the east side of the Leisure Center and serpentine galleries were revealed.
In Des Plaines, dozens of ash trees on city-owned parkways and land have been removed to contain the pandemic.
At the Des Plaines Park District, Krotz, landscape maintenance supervisor since 1991, opted to try another approach. A small percentage of older ash trees, especially those planted in parking lots, were removed to contain the infestation, but also to make way for new safety lighting and security cameras. Krotz decided to try to save the rest of the ash trees through treatment.
An insecticide is injected into the trunk that kills the insect. The treatment, applied annually, takes four to six weeks to be distributed through the tree. Krotz is also working to maintain the health of the trees by pruning, creating optimum soil conditions and providing superficial feeding.
“My feeling is if we can slow down the borers’ population within the tree, the tree’s health will improve so that it can recover and continue to grow,” he said. He has treated 156 ash trees to date.
In 2012, The Des Plaines Park District applied for, and received, a Metropolitan Mayoral Caucus Grant, which is administered through the Morton Arboretum. Those grant funds, totaling $10,312, were used to cover the cost of an inventory of the tree population across the district; the creation of a GPS mapping component, accessible on the Des Plaines Park District website, that also includes the location and species of each of the trees in the Tree of Life Program; and the development of the district’s EAB management program.
In the long run, managing the EAB problem is more cost effective than removing and replanting new trees. The treated ash trees, especially those along the entrance to the Leisure Center are showing leafed-out canopies and healthy looking green leaves.
“We will continue to monitor the ash trees throughout this summer. The fact that they survived last summer’s drought, though, is a good sign,” said Krotz.
In 2014, the Des Plaines Park District will apply for a Reforestation Metropolitan Mayoral Caucus Grant to replace lost trees. The grant allows for a 1:1 ratio of lost-to-replaced trees.
“We will look for biodiversity in making our choices for new trees,” said Krotz, “and look to plant more native species as we did in the North Lake Park open space.”