State Forester Urges City Officials to Prepare for Emerald Ash Borer

    During the regular monthly meeting of the Milbank City Council on Monday, October 14, Jon Livermore, South Dakota community forester, presented information about the emerald ash borer. He urged the city to evaluate the tree population and begin a five- to ten-year plan to reduce the percentage of ash trees in the public areas.
    “The thing we are suggesting is the removal of ash trees before the emerald ash borer infestation hits your area,” Livermore said. The borers were certified in Sioux Falls two years ago. As a result, the Department of Agriculture has begun a state-wide push to decrease the percentage of ash trees in communities likely to develop infestations.
    The emerald ash borer,  a beetle that feeds on all species of North American ash, was first detected in Michigan in July 2002 after it was accidentally shipped in ash crates from China, according to the Department of Agriculture information. Adults are about half an inch long, slender and metallic green color. They normally emerge from ash trees during June or July and leave behind D-shaped exit holes about one-eighth inch in size.
    The larvae are about 1.25 inches long, white and segmented. The larvae feed on the tissues underneath the bark. As they move around to feed, they create tunnels, which inhibit the tree’s ability to transport water and nutrients, leading to the death of the tree. Symptoms in an affected tree include a thinning appearance of the canopy, sprouting from the base and trunk, bark splitting, increased woodpecker activity and the D-shaped exit holes. The adults fly off to feed and lay eggs in another ash tree, thus restarting the life cycle.
    Increasing the effectiveness of the insect’s spread is the fact that the larvae commonly is spread by moving ash firewood from infested areas to non-infested areas. Livermore explained that officials expect the borer to move into areas that are used for outdoor recreation, such as along the lakes. The borer also is adept at hiding under boat covers and in the nooks found on the exteriors of campers and trailers. Livermore cited a study that showed emerald ash borers can cling to a vehicle traveling 65 miles per hour for up to 30 miles.
    “We can’t predict how quickly it will spread, but we expect the emerald ash borer to build new populations along the highway corridors,” Livermore said. “It’s people who move it, and this is a hub for recreation.”
    The city is responsible for the trees in city-owned areas such as the cemetery and parks. Livermore indicated that it is a bigger issue and expense for cities that also own the boulevard trees, but here, those are the responsibility of the homeowners.
    Livermore had previously toured the city-owned areas to determine the extent of the ash trees in the community. “To limit the damage when the emerald ash borer gets here, you need to diversify your tree population. You should only have five to 10 percent of the total tree population any one species,” Livermore advised.
    John Forman, city administrator, told the council members he counted 207 ash trees just in the northern triangle of the Milbank City Cemetery, and there are many more throughout the city property. Livermore estimated that about 70 percent of the trees in the cemetery are ash. “You need to start thinking about removal and come up with a financing plan for it,” Livermore advised.
    In response to questions from council members, Livermore told the group that the emerald ash borer is very cold hardy, surviving as far north as Winnipeg, Canada. “It has to be -15 degrees for three days before you start to see any die-off from temperatures,” he said. He also noted that there are treatments available, but at the cost of $250 to $400 per tree every three years, it’s not a viable option for the cities.  
    Rather than waiting for an infestation to damage and kill the ash trees, the focus is on minimizing the damage and cost, Livermore said. He said that once a tree is infected, the cost of removal skyrockets. “Where the removal of an ash tree that has not been infected might be $800, once it’s infected, the cost goes to $3,000 or so,” Livermore said. The reason is that the infected trees become the equivalent of “standing firewood.” “They become unreliable; they become very brittle, and the nature of the wood is that it is harder to fell them safely,” Livermore explained.
    Forman suggested that in 2020, city employees can begin doing some limited removal of smaller ash trees in the cemetery and start replanting with other species. The council members agreed that it was a reasonable plan and will begin planning for removal and replacement in the next budget cycle.
    Forman also noted that he will try to plan a public informational meeting, but the specifics are not yet available.
~Holli Seehafer