Managing Smooth Brome in Mixed Grass Prairie: A Long-term Commitment

Smooth brome (Bromus inermis) is a sod-forming, invasive perennial grass that negatively impacts rangelands throughout the Northern Great Plains. Smooth brome is difficult to control and outcompetes native species, degrading habitat for wildlife and potentially impacting livestock performance. Smooth brome is productive and has moderate forage quality, but it can alter the forage cycle and reduce quality through its effects on native plants.

• Excellent competitor! Smooth brome takes up soil nitrogen very quickly and decomposes rapidly, limiting nitrogen availability for surrounding native species and changing local nutrient dynamics.
• Early spring growth! Smooth brome resumes growth earlier in spring than many native species, taking advantage of spring moisture and high light availability, eventually shading out native species.
• Extensive belowground reserves and growing points! Smooth brome forms extensive buds and below-ground rhizomes that are protected and spread rapidly when resources become available.

Various management techniques, including grazing, prescribed fire, mowing (especially when grazing and prescribed fire are not feasible) and herbicides have been employed to target smooth brome in the mixed grass prairies of the Northern Great Plains. Properly managed grazing and prescribed fire can be used to improve desirable species in areas invaded by smooth brome. When designing a management plan, two key considerations are how to 1) reduce smooth brome and 2) promote native species. Fostering native species can help reduce smooth brome!

It can be challenging to target smooth brome without stressing desirable cool-season plants, due to similar growing patterns. However, smooth brome’s characteristic early spring growth and late fall regrowth may provide a window in which smooth brome can be targeted while avoiding impacts to desirable species. Management to promote native species can be achieved by integrating prescribed burns into properly managed grazing. However, regular monitoring will be necessary to make adjustments in response to observations.

Managed grazing and prescribed fire can be effective to reduce smooth brome and enhance desirable species, especially when used in combination. It is important to time grazing and/or prescribed burning to target smooth brome and mitigate stress to native species. In areas where grazing is impractical, consider mowing multiple times in a single growing season rather than leaving a smooth brome-dominated area idle for an entire growing season. Using management to target smooth brome is a long-term commitment — a single prescribed burn will not be enough to dramatically reduce smooth brome over the long term. Plan to keep an eye on desirable species and adjust your management plans to promote desirable plants while reducing smooth brome.

For more information, contact:

• Natural Resources Conservation Service
• North Dakota State University Extension
• North Dakota Prescribed Fire Cooperative