How to protect Indiana trees from emerald ash borer
by Angie Hicks
Between the destructive emerald ash borer and record dry weather, it’s been a tough summer for trees in central Indiana.
The emerald ash borer – an Asian beetle that feeds on, thereby destroying, ash trees – has made its presence felt in Hamilton and Marion counties, with trees along the Monon Trail and in Sahm Park – among other areas – already showing signs of infestation.
“In Hamilton and Marion County, we’re fully infested,” said Jud Scott a registered consulting arborist with Vine & Branch, Inc. in Carmel, Ind. “If the borer is within 10 miles of you, it’s time to start treating.”
An increase in woodpeckers, dead limbs at the top of the tree, squiggly lines running down the bark and D-shaped holes in the tree are all signs of emerald ash borer activity. Caught early enough and treated, most trees can be saved. Do nothing, though, and the tree will die after several years. By the time most tree owners notice the D-shaped holes at eye level, the tree is likely beyond repair, Scott said.
“The borer starts laying its eggs at the very top in annual cycles,” Scott said. “By the time it gets down to the ground level, it’s been in the tree munching and killing everything under the bark for probably three to four years.”
Michael Webster, a Certified Arborist with Ping’s Tree Service Inc. in Indianapolis, said the most common treatment he uses is an insecticide with emamectin benzoate as the active ingredient, which is injected directly into the trunk wood of the tree.
“We install some plugs that go around the base of tree near the bottom and then we apply the IV system that has a little needle that goes into the plug,” Webster said. “Then, the natural transpiration of the tree just sucks the product up throughout the tree. It has a two-year coverage in the tree and it’s by far the No. 1 university-recommended product available.”
The injection insecticide is classified as a restricted-use pesticide, which means it can only be used by professionals licensed by the Office of the Indiana State Chemist. Cost of a single application varies depending on the diameter of the tree, but on average is between $80-$100.
Homeowners can treat their trees themselves, but only in the spring, by applying a soil drench product that contains the insecticide imidacloprid as its active ingredient. It can take years of annual or biannual treatments to know if a tree being treated for the emerald ash borer can survive.
“If you do it on your own, you really need to make sure you follow directions,” or you can destroy your tree, Scott said. “That’s why you want a reputable company that has certified arborists on staff. You’ll know it’s working over the next five years when you notice your neighbors’ trees are dead and yours are as green as before.”
The dry summer – July was the driest ever recorded in Indianapolis – has made it even harder for trees to thrive.
“We’re seeing just tons of dead and dying spruces, pines and firs,” Scott said.
Trees should get at least an inch of water per week, but just running the hose over the top of the leaves is not enough.
“What we like to tell folks is that if you have a tree that you are wanting to keep healthy during these hot times, you need to have a soaker hose or some kind of a oscillating sprinkler to put underneath the entire drip line of the tree and water it for about 2 to 4 hours maybe every 2 to 4 days during these extreme conditions,” Webster said.
Have your trees inspected by an arborist at least every two years. They can likely spot trouble early on and will offer useful advice on caring for your trees.
Angie Hicks is the founder of Angie’s List, a provider of reviews you can trust on contractors, doctors, dentists and other service professionals. More than 1 million consumers across the U.S. use Angie’s List to help make tough hiring decisions easier.