Ron Klataske has never seen his beloved Flint Hills in more peril.
America’s last stand of tallgrass prairie — primarily located in the Flint Hills of eastern Kansas and extending to the north and south — is being overgrown by non-native plants. The worst are Old World bluestem grasses and sericea lespedeza, robbing ranchers like Klataske of prime grazing lands and wildlife of special habitat.
It’s bad now and may get much worse. A 2019 Kansas Department of Agriculture Department survey shows more than 550,000 acres of Kansas grasslands infested with sericea lespedeza, even with several key Flint Hills counties not reporting. K.C. Olson, Kansas State University professor of animal sciences, estimates the number is closer to 900,000 acres of sericea lespedeza infestation just within the 3.5 million acres of the Flint Hills.
“Old World bluestems have the potential, over the next 50 to 100 years, to eliminate native grasslands as we know them,” said Klataske, who is also the Audubon of Kansas executive director. He fears the invasives may form a monoculture on his grasslands where 200 or 300 different native prairie plants currently thrive.
The Flint Hills hold hundreds of non-native plant species. Many — like a patch of daffodils that mark where a prairie homestead once stood — cause no problems. Old World bluestems and sericea lespedeza are as bad as it gets, says Brian Obermeyer of Chase County, director of protection and stewardship at the Nature Conservancy of Kansas.
Old World bluestems encompass several species of grasses native to Europe and Asia. Caucasian and yellow plants are the most problematic species in Kansas. Sericea lespedeza is native to Asia. It is a forb, a herbaceous flowering plant that some would just call a weed.
All three species of plants outcompete native prairie plants for space, nutrients and moisture. They also produce a toxin that doesn’t allow other plants to grow nearby. Since cattle won’t often graze the invasives, that usually means less income for ranchers.
Displacing native forbs and legumes makes life difficult for Flint Hills’ wildlife, especially such ground-nesting birds as greater prairie chickens and many songbird species. Klataske said grassland birds have declined more in the past 50 years than birds of any other habitat.
Problem created by man
Old World bluestems and sericea lespedeza were imported over a century ago at the encouragement of county, state and federal agencies. Sericea lespedeza was billed a “poor man’s alfalfa” and touted as a better-than-nature forage crop for livestock. It was also said to create great habitat for quail. It first came to Kansas to grow on open dirt left by strip-mining.
Old World bluestems were imported to the U.S. with hopes of creating livestock forage where native plants struggle. It’s still planted as close as Oklahoma and Texas. Their ability to grow fast and thrive in drought conditions made them popular plants for seeding in road and highway ditches.
Some governmental and agricultural groups have been slow to see the problems the plants can bring. Olson, the Kansas State professor, said the U.S. Department of Agriculture still recognizes Old World bluestems as a viable forage crop, so the agency doesn’t help fund the battle in Kansas.
The USDA’s Conservation Reserve Program also accelerated the problem when seeds of the invasives were accidentally included in approved seed mixtures designed to revert marginal croplands to native grasslands. Over a period of 35 years, millions of Kansas acres were enrolled in the program to reduce crop surpluses, curtail erosion and improve wildlife habitat. Klataske can trace some infestations on his pastures to nearby fields being enrolled in CRP.
The plants can also be quickly spread by those who eventually spend thousands of dollars fighting them.
“There are a lot of places on a pick-up or four-wheeler for seeds to collect as they drive through a pasture,” said Keith Harmony, Kansas State University range research scientist. “When they drive through another pasture, those seeds get dropped off.”
Solution A: Start small
Experts have been working over 30 years to stem the spread of the plants brought to the region with innocent intent. For Old World bluestems, experts encourage early detection and diligent plant removal. Removing sericea lespedeza has recently become easier, but ranchers will need to adjust how they manage grasslands.
Harmony has been researching Old World bluestems since 2000, when many ranchers couldn’t identify the plants or see the disaster they’d bring. It looks enough like native grasses to be tough to spot when it first appears in a pasture, but early detection is critical: Harmony’s research shows a patch spreads at about 16% per year.
“That’s a really nice growth rate for a retirement account,” he said, “but not when you’re talking about an invasive plant that’s taking over your pasture.”
So far, non-selective herbicides like Round-Up have been the most effective against Old World bluestems. But that can come with environmental and financial costs. Klataske describes places in Oklahoma where decades of sprays intended for invasives have left no habitat for prairie chickens.
“It’s especially hard on plants like the native legumes and forbs that are essential for so many kinds of wildlife,” Klataske said. “You keep spraying and eventually you’ve lost all of the food for many birds.”
Harmony said it often takes several annual applications since seeds can remain viable several years. Large patches require blanket spraying, often many acres at a time. That’s expensive: Glyphosate usage costs up to $40 an acre, a huge amount for ranchers to pay if the patches have any size.
“It’s far better to detect it early and get aggressive with it,” Obermeyer said. “It’s not hard to spray when it’s in small patches.”
Solution B: Follow nature’s plan
Landowners have been fighting sericea lespedeza in the southern Flint Hills for decades as it’s expanded. Olson quoted a report that said Kansas’ sericea lespedeza infestations increased nearly 60-fold from 1988 to 2001. While it was mostly found in the southern U.S., climate change has helped it expand northward. For years it’s been sprayed with strong herbicides like glyphosate with limited results.
About 10 years ago, Olson and others began researching alternative controls. One idea was to stock pastures with sheep and goats, which readily eat sericea. It wasn’t cost-effective because it warranted expensive fencing and could attract predation by coyotes.
Eventually, researchers, like Olson, experimented with a common grassland management tool – controlled burning. Rather than in the spring, which is customary, they tried summer and fall burns in hopes to destroy plants before they had a chance to drop seeds.
“It was a smashing success,” said Olson. “Not only did we control sericea reproduction, … when wildflowers came back, it enhanced the bird populations as well.”
Josh Hoy is the fifth generation of his family to ranch in the Flint Hills in Chase County, far from Klataske in Manhattan. He became one of the first ranchers to try late summer and fall burning. He has seen an 80% sericea reduction in pastures that are burned in the late-summer. The same burns also took out problematic trees and brush. His research shows nobody should be suprised.
“Historically 90% of the wildfires were in the summertime,” Hoy said. “It’s when conditions are best. The grass is tall and dry and it’s a time when thunderstorms would be most likely to cause fires. Sometimes we just need to do things Mother Nature’s way.”
