Weed of the Month: Big Sagebrush
 | Author:
Allison Kosto, MSU Broadwater County Extension Agent
MSU Broadwater County Extension Agent |
Weed of the Month: Big Sagebrush
Allison Kosto
MSU Broadwater County Extension Agent
Although some people don’t like it, the sweet smell of sage immediately gives me a nostalgic feeling of the home we call Montana. Big sagebrush, also called Big Sage, is one of Montana’s most well-known and easily recognized native plants. In moderation, it provides many ecological benefits. However, it can also be invasive by choking out grasses and forbs.
Description & Habitat
Native to the western half of the United States and Canada, big sage had many uses among the American Indians as a laxative, tea substitute, general tonic, hair and eye wash, treating colds and diarrhea, and antiseptic for wounds. It is found in valleys, basins and mountain slopes at elevations between 2,500 to 10,000 feet. It prefers dry, well-drained soils or gravelly soils. It does not tolerate excessive sub-moisture.
Big Sage is easily identifiable. It is an evergreen shrub that can grow 1 to 13 feet tall. Leaves are blue-gray to blue-green in color due to dense gray hairs. Flowers are yellow and often inconspicuous. Plants are very aromatic with the smell being described as bitter to pleasant. Big sage has a unique two-part root system with a deep tap root and a shallow root system. Numerous studies have shown that sagebrush plants create “hydraulic lift” where soil moisture is brought nearer to the surface by the tap root during the day and then released during the night. This makes it very drought-tolerant.
Big sagebrush may be the most important shrub on western rangelands. Sage grouse are the heaviest user of sagebrush which makes up over 70 percent of its diet. Wildlife also feed on the plants, especially during the winter. Sagebrush serves as cover and nesting habitat for over 100 species of birds, rabbits and deer. Some livestock such as sheep and goats are able to forage on big sagebrush. However, it is poor forage for cattle, and overgrazing of the plant understory can decrease plant diversity. This can cause the population growth of big sage to accelerate as well as other invasive plants such as cheatgrass. This can lead to rangeland that is dominated by big sage which may warrant control measures.
Management
Avoiding disturbance or overgrazing and maintaining a healthy population of native or desired species is often effective in keeping big sage at a manageable level. Oftentimes, it is not necessary to remove the entire stand of sagebrush. Simply thinning or controlling in a mosaic pattern is sufficient.
The most cost-effective control option is prescribed burning. Fire can increase the prevalence of some weeds so being aware of your current plant inventory and timing is critical. For example, if there is a lot of cheatgrass, burn when there are ripe seeds on the plant so they will be destroyed. Reseeding with desirable species is sometimes necessary. A variety of mechanical methods can also be effective where practical. This includes anchor chaining, harrowing, brush beating, discing or mowers.
Herbicides are also an option and are often used in combination with mechanical controls. New seedlings can be controlled with a spring application of 2,4-D. For more mature plants use 2,4-D LV ester in the spring when new leaves are forming. Spike is another product that can be highly effective in the fall and is often done with an aerial application. Grasses may be temporarily injured, and it can also kill trees and shrubs. Always read and follow the entire label when applying herbicides. Common chemical names are used for clarity but does not imply endorsement of a product or brand.
For assistance on weed identification and management, contact the MSU Extension Office in Broadwater County at 406-266-9242 or allison.kosto@montana.edu.
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PhotoCredit: Photo Credits: Allison Kosto
Image 1 Caption: Big Sage
Photo Credits: Allison Kosto
