Several insecticides tested against the emerald ash borer have proven to be somewhat effective, MSU researchers said.
About six different products have worked fairly well, said David Smitley, a professor of entomology and an MSU Extension specialist. Effectiveness varies by product, Smitley said, adding that out of about 15 products tested, the percentage of ash borers found in the trees varied from 33 percent to 90 percent.
The types of insecticides tested were injected into the soil and absorbed by the tree, injected directly into the trunk, or sprayed onto the leaves and branches.
How well a certain insecticide works depends on how early homeowners start treatment, Smitley said.
"You have to start early, before the trees become heavily infested," he said. "That's the message we're trying to get out to people. It's especially important for people in Lansing right now because we're on the edge of the infestation."
Ingham County is among 13 counties in Michigan - the majority of which fall in the southeastern part of the state - that are considered quarantined, meaning no ash materials can be transported out of the area.
Eight million ash trees have been destroyed by the beetle, Smitley said.
None of the insecticides tested have been 100 percent effective, and some that were tested did not work at all, said forestry and entomology Professor Deb McCullough.
"Every tree that we've treated still ends up with some larvae in it," McCullough said, adding that the insecticides are being tested in the most heavily infected area of the quarantine, known as the core.
Pockets of infestation outside of the area are relying on tree removal in order to prevent further population development, rather than using insecticides, McCullough said.
Studies will continue to show which products work best in certain situations, so researchers can give recommendations on insecticides to homeowners and landscapers in the core, as well as looking at what insecticides do while inside the tree, she said.
In addition to testing insecticides, there are other attempts to control the emerald ash borer. The United States Department of Agriculture Forest Service is asking hunters not to transport firewood from their homes with them as they go north during the hunting season.
If people transport wood outside of the quarantined area, they would be in violation of the quarantine and can be fined by the state, said Kenneth Arbogast, a public affairs officer with the Huron-Manistee National Forest, part of the Forest Service. He added that the three national forests in Michigan recently signed orders that include a $5,000 fine for people caught bringing in firewood from the quarantined area.
"We've had no reports of the ash borer in the Upper Peninsula, so we know that if it crosses the bridge, it's because people took it there," Arbogast said, adding that there are a lot of ash trees in the U.P.
"The insect could be just devastating in those areas."
