The logo for the Silvicast, a podcast hosted by Wisconsin DNR silviculturists Greg Edge and Brad Hutnik and produced by the University of Wisconsin-Stevens Point’s Wisconsin Forestry Center. / Graphic Credit: UW-Stevens Point

By Art Kabelowsky, Wisconsin DNR Outreach and Communications
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167

They talked about pulling it, smothering it, using herbicide on it, making turkey calls and making curtain rods from it.

They even wondered if they should just “kill it with fire.”

But it seems Midwestern foresters’ never-ending battle against buckthorn requires a brainier approach.

That was the conclusion of a recent edition of SilviCast, a podcast hosted by Wisconsin Department of Natural Resources silviculturists Greg Edge and Brad Hutnik and produced by the University of Wisconsin-Stevens Point’s Wisconsin Forestry Center.

The episode, titled “My Buckthorn Chia Pet,” featured Dr. Mike Schuster, a researcher with the Minnesota Invasive Terrestrial Plants and Pests Center inside the University of Minnesota’s Department of Forest Resources.

Buckthorn expert Dr. Mike Schuster, a silviculturist with the University of Minnesota. / Photo Credit: University of Minnesota

Schuster has invested a lot of time, effort and thought into developing and investigating new tools and approaches to slow the progress of fast-growing, invasive plants, which are represented mainly by common buckthorn and glossy buckthorn.

He is also the lead scientist of his university’s “Cover It Up” project, which has been testing, rating and promoting methods of planting various native species to help protect forests from the spread (and re-spread) of buckthorn and other exotic shrubs.

The biggest problem with buckthorn is that it spreads very fast and can often outcompete beneficial, native plants for survival on forest floors. This affects wildlife and tree survival.

“If they (common buckthorn and glossy buckthorn) get out into the natural world, they win. They take over,” Schuster said.

Sure, buckthorn can be pulled, tarped or attacked with herbicide, but none of those solutions are 100 percent effective, especially over time.

“They can regrow quickly … (so that) the next year, you have another forest full of buckthorn,” Schuster said. “And that can be even worse than the previous problem, because for every stem you cut, it could send up 10 new ones.”

Schuster said his team and other colleagues have even found buckthorn that was 60 years old. “It’s not unusual,” he said, “when you’re researching these ‘MOABs’ (Mothers Of All Buckthorns).”

And in reference to the SilviCast’s title, when buckthorn control methods aren’t complete, the ground can be covered the following year by a carpet of short but ever-present buckthorn seedlings. “They call them (Buckthorn) Chia Pets,” he said, referring to the toy that grows grass from holes in a clay vessel shaped like a head or other item.

Rigorous study has shown that while buckthorn becomes all but impervious to competing plants after three years or so, seedlings – especially first-year seedlings – are vulnerable to getting outcompeted for sunlight and struggling to grow in too much shade.

“We found light availability in fall was a major predictor of whether that individual seedling would survive,” Schuster said. “The name of the game is to get in there fast.”

Schuster suggests that after pulling, tarping or otherwise working to control buckthorn, land managers should plant specific grasses, including many wild rye species and bottle brush grasses.

“They produce a thatch layer of grass and grow quickly and densely,” he said. “They can tamp down the growth potential of buckthorn.”