ENTERPRISE, Ore. — A variety of invasive plant species are threatening the West’s livestock grazing land. Through a variety of methods, Wallowa County land managers are searching for new ways to slow their rapid takeover of bunchgrass prairie.
The Zumwalt Prairie in the northeast corner of Oregon is the last intact short grassland in the West. Unfortunately, a long list of invasive species, including Medusahead rye and Ventenata, is choking out the native grasses on which deer, elk, cattle and sheep thrive.
On a morning roughly 20 miles northeast of Enterprise, Kelly Birkmaier, a private rangeland consultant, and Ryan Oberhelman, Wallowa County weed manager, a, traverse a hillside carpeted with Ventenata dubia, an invasive weed from a grass family native to Europe, North Africa, central and southwest Asia. Without natural predators, the grass has grown unchecked over an entire pasture.
Underneath the thick mat of Ventenata remnant bunchgrass can be found — much of it looks sickly and starved for nutrients. Birkmaier and Oberhelman hike across the field looking for another noxious weed within the carpet of Ventenata — Medusahead rye that is not as pervasive, but just as deadly to healthy rangeland.
As Oberhelman scanned the Ventenata-choked ground under his feet looking for Medusahead, he said, “It’s like looking for a needle in a stack of needles.”
Birkmaier holds up a stalk of each Ventenata and Medusahead to show the differences. Ventenata Medusahead looks a lot like its namesake, with a head of spikey hairs. Ventenata has small, whispy seed heads on a stalk. Small patches are marked with red flags, prioritizing the areas Birkmaier and Oberhelman will come back to spray later in the morning.
Controlling the spread is no easy task. Lindsay Jones of Wallowa Resources, a natural resource nonprofit in Enterprise that partners with agencies and landowners to combat noxious weeds.
Jones said, “Weeds are a symptom of land management and we need to talk about their control as part of long-term management.”
Jones said Medusahead and Ventenata grow unchecked on the prairie for several reasons — high silica content makes it unpalatable for livestock and game animals, it grows on bare ground and needs few nutrients, a weed primarily transported in the fur of animals. It also causes problems during wildfire season, growing across natural fuel breaks like swales, creating a continuous fuel supply across otherwise bare ground and wetlands.
“Managing the weed successfully is a huge challenge,” Jones said, and is pretty good at excluding other species,” Jones said.
Many different approaches have been deployed to combat the spread of Medusahead — biological agents, chemicals, prescribed fire and different grazing strategies, Jones said. Grazing has met with limited success, because of the high silica content, but she said there has been some success keeping Medusahead at bay with sheep grazing.
Reseeding the range with a mix of perennial grasses like Intermediate and Siberian wheat grass is another attempt to take back the rangeland from the noxious weeds. While these grasses are also non-native, they are more desirable than the Medusahead and Ventenata, Jones said.
A recent concerted effort to fight the two invasive weeds with bacteria ran from 2009 to 2014, Jones said. In 2015 Intermediate wheat grass was planted in hopes it would outcompete. She showed photos of a pasture show grass coming back to an area once overrun with weeds.
“We are in it for the long haul,” Jones said. “Using all the tools is what is going to lead to success — we can’t just spray it and hope for the best.”
The effort is expensive. Cost shares help the private landowner with investments between 25 and 50 percent of the cost. Many landowners contribute labor as part of their percentage, Jones said. To help the effort, Wallowa Resources seasonally hires 10 local contractors who do a majority of the chemical treatment.
“All of our contractors are great to work with and want to know they are having a positive impact,” Jones said. “They help Wallowa Resource’s mission — to help support local economy through natural resource stewardship.”