NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

July 29, 1999

NDSU Research Creates Insight for Managing Federally Protected Plant

A group of researchers from North Dakota State University set up a herbicide-demonstration project in the Sheyenne National Grassland earlier this decade, but they eventually stopped applying herbicides because of the reappearance in the treated area of a threatened Midwestern plant, the western prairie fringed orchid, which is protected by the Endangered Species Act. Current federal guidelines do not allow herbicide applications in areas where the plant grows.

A regulatory roadblock? A bureaucratic dead end? Hardly. Instead, the situation produced cooperation.

"What we're doing is really new," says Rodney Lym, an NDSU plant scientist who specializes in invasive weed control research. "As far as we can tell, there has been no research done on herbicides and orchids until now. Our literature search didn't turn up anything."

The season after the spraying ceased on the demonstration plots in the Sheyenne National Grassland, the leafy spurge once again started overtaking the area, and no western prairie fringed orchids appeared, Lym says. Could herbicide applications control leafy spurge without damaging a protected plant?

Lym credits his colleague, Don Kirby, a professor in the animal and range sciences department, for securing the research grant that is providing an answer to that question. Kirby sought funding from the USDA Forest Service, which manages the Sheyenne National Grassland, and the U.S. Fish and Wildlife Service, the agency responsible for helping administer the Endangered Species Act. The U.S. Fish and Wildlife Service also granted the NDSU researchers permission to spray herbicides on up to 100 western prairie fringed orchids.

John Sterling, an NDSU graduate research assistant, is evaluating three herbicides: Landmaster BW (glyphosate and 2,4-D); Plateau (imazapic); and Paramount (quinclorac). Based on preliminary results from Sterling's work, the federal agencies are likely to fund the project for two more years, Kirby says.

"The first-year results are very, very encouraging," Lym says. "We have at least as many orchids in the spray plots as we do in the control, if not more. And there's no sign of any herbicide injury on any of the orchids."

A key botanical difference between leafy spurge and the western prairie fringed orchid may be responsible for the results, Kirby says. Unlike many flowering plants, the western prairie fringed orchid is a monocot, as grasses are. Monocot plants produce only one first leaf (cotyledon). By comparison, leafy spurge is a dicot, producing a pair of initial leaves.

"The herbicides we were putting on those demonstration plots don't hurt grasses, so we assumed they wouldn't hurt another monocot, and it appears they don't," Kirby says. "Plus, we're spraying these herbicides in the fall, after the orchid is dormant. A spring-applied herbicide could damage it."

Timing of the application is just one of the benefits that the herbicides the NDSU researchers are studying appear to provide, says Carolyn Hull Sieg, a research biologist with the Forest Service's Rocky Mountain Research Station who is based in Rapid City, S.D. Another benefit is that all three herbicides have short residual-carryover periods, so a fall application is unlikely to harm orchids the following spring.

"These herbicides are seemingly more selective, although part of it goes back to the application timing. When you spray in the fall, the plants that are actively growing are the most susceptible," Hull Sieg says. "So, I think it's likely that we'll also see less damage on other species that we don't want to target with herbicides."

Because of its role with respect to the Endangered Species Act, the U.S. Fish and Wildlife Service helped the Forest Service establish the guidelines regarding management of the western prairie fringed orchid on the Sheyenne National Grassland, which is one of the few areas in the region where the plant grows on federal land. At present, those guidelines do not allow herbicide use. If the first-year results of the NDSU research are reproduced in years two and three of the study, Hull Sieg is hopeful that revisions to those federal guidelines will provide land managers with more options for protecting the habitat of the western prairie fringed orchid.

Of the roughly 71,0000 acres comprising the Sheyenne National Grassland, about 2,000 to 3,000 acres are considered habitat for the western prairie fringed orchid, says Karen Kreil, a fish and wildlife biologist with the U.S. Fish and Wildlife Service in Bismarck. Overall, 175 sites in six states and the Canadian province of Manitoba serve as the remaining habitat for the orchid, whose apparent historic range extended from the Red River Valley southeast through eastern South Dakota to Iowa and Missouri and west to include portions of Oklahoma, Nebraska and Kansas.

"Even though the orchid habitat on the Sheyenne Grassland represents a small percentage of the total acreage, it's really important to address the issue now, because, as we're finding out, leafy spurge can just completely take over." Kreil concludes. "These herbicides give me some hope that we'll be able to get at this leafy spurge problem and not negatively impact the orchid. I think using biocontrol in conjunction with these new herbicides really holds a lot of promise for the future."

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Sources: Rodney Lym (701) 231-8996
Donald Kirby (701) 231-8386
Editor: Dean Hulse (701) 231-6136

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