The continued discovery of new counties infested with the emerald ash borer may have you thinking about getting your ash tree treated. Iowa State University entomologist, Mark Shour says they don’t recommend any treatments after Labor Day. “It’s a really good time for people to have the opportunity to get bids for tree treatments for next spring. Look at those bids, check on references and decided on which bid they are going to accept and then do the treatment next spring — say mid April to mid-May,” Shour says.
He says you’ll be wasting most of the treatment if it’s put into the trunk of the tree right now. “Really by the end of July the tree has stopped doing active relocating of the resources down to its roots and buds and stuff. And so really, injecting something this time of year — trunk injection — is not going to do as good a job as it would in the spring,” Shour explains.
He says that goes for other types of ash tree treatments as well. “Outside soil treatment or basil bark spray, they’ll just sit there in that environment for that period of time and can be lost off the tree if not careful,” Shour says. Shour says he’s heard the treatments can be a success in healthy trees.
There is work on a non-chemical treatment that uses three wasps from the area in China where the ash borer originated. “It’s been released in centers where EAB has fairly large populations, and they are doing a good job of getting establish,” Shour says. Researchers have also found a wasp in Michigan that can be used to kill the emerald ash borer. “An it’s switched over from its normal host over to EAB, so it’s starting to work too,” Shour says. “But still, when everything is rocking and rolling so to speak, and when we’re ten years down the road where the wasps are catching up to the beetle, we are still only going to be 30 to 40 percent in control of the emerald ash borer.”
The state just recently announced the 13th county infestation from the pest.