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In an attempt to combat an ash tree killing-insect, Michigan has added seven counties to the emerald ash borer quarantine list and put a one-year moratorium on the sale and movement of ash nursery stock to, from and within Michigan’s Lower Peninsula.
The U.S. Department of Agriculture estimates that the borers have killed about 6 million of the state’s estimated 700 million ash trees.
The new counties announced are Genesee, Ingham, Jackson, Lapeer, Lenawee, Shiawassee and St. Clair, bringing the number of affected counties to 13. Livingston, Macomb, Monroe, Oakland, Washtenaw and Wayne counties already have been under the state-ordered quarantine.
Under the quarantine, it is illegal to move ash trees, branches, lumber and other materials from the designated counties unless the wood is chipped to one inch in diameter. Firewood from any species within the 13 counties is banned from movement, which means that firewood purchased within the quarantined counties has to stay there.
The state said the beetle also has been detected in small pockets in Eaton, Kent and Saginaw counties. These sites will be treated and managed as isolated infestations unless it’s determined that the beetle is widespread, agriculture officials said.
Beetle larvae live beneath the bark of ash trees, boring into its tissue until water and nutrients can no longer flow up into the branches and leaves. Michigan State University is currently conducting research to determine what can kill the pest. Deb McCullough, professor in the entomology and forestry departments department of forestry at Michigan State, said the beetle problem is exacerbated because it's hard to tell when trees are first infected and there are a lot of unknowns.
Amy Frankmann, executive director of the Michigan Nursery and Landscape Association, said the losses to nurseries and growers will be high. Frankmann says a survey last summer of growers in southeast Michigan showed a loss of about $4 million there.
“The quarantine and moratorium are just devastating to the industry,” Frankmann said. “But we have too many natural stands of ash trees to jeopardize,” Frankmann said.
The state also has established a “core” area including all of Wayne County and parts of five other counties on the original quarantine list, where officials believe the problem is most severe. Ash materials from the core area must stay within that area. Firewood from that area also must stay in the core.
The author is Assistant Editor of Lawn & Landscape magazine and can be reached at lspiers@lawnandlandscape.com.