Downy brome, commonly known as cheatgrass, is an invasive, winter annual that occupies over 76 million acres of land throughout the Western United States. This grass drives many treatment decisions as it creates monocultures by overpowering native rangeland species, causes an increased risk of wildfires, and decreases diversity and warm-season grass and forage production.
Why is cheatgrass predatory?
Cheatgrass germinates, in a semi-dormant state, from late summer through the fall and into the winter and reaches full maturity in late spring or early summer of the following year. Each plant can have multiple upright stems that grow up to two feet tall and flowers as an open panicle with each having five to eight florets tipped with a short awn. Cheatgrass grows rapidly, forms thick stands, and develops a dense root system. These characteristics enable it to rob early-season moisture and nutrients from desirable native plant communities.
With self-pollinating flowers and the ability to produce thousands of seeds that can live in the soil for up to five years, cheatgrass can invade grazing spaces and rid pastures and rangelands of quality forage.
What management techniques can be used on cheatgrass?
Management strategies can include grazing, mechanical, and chemical control. Each can be effective independently or used as a program approach.
- Grazing can be an effective treatment when used as an intensive flash grazing to prevent flowering and remove biomass. Timing is critical as cheatgrass is only palatable early in the season while green and quickly becomes unpalatable and even harmful as it matures.
- Mechanical methods include mowing, tilling, or disking the ground to reduce seed production. Cheatgrass often grows in rugged terrain which makes mechanical control impossible. Furthermore, this technique lacks an economic benefit when controlling large numbers of acres and may encourage a resurgence of cheatgrass by exposing buried seeds.
- Chemical control is the most common type of treatment and is applied to large numbers of acres annually. Timing is crucial as herbicides should be sprayed on cheatgrass as a pre-emergent or early post-emergent application to receive the highest level of control.
How can Alligare help you protect your grazing spaces?
Alligare’s Panoramic herbicide (active ingredient: imazapic) can be applied in the late summer or early fall as a post or pre-emergent treatment. The recommended rate for cheatgrass control with Panoramic is 2-12 ounces per acre, however; eight ounces per acre is commonly used.
This treatment is effective and can be used in all states except California where Panoramic is not registered. For cheatgrass and control of other winter annual grasses in California, Alligare’s product Laramie (active ingredient: rimsulfuron) can be used as an effective fall treatment when applied at four ounces per acre. In many areas, it has become a common practice to tank mix with additional herbicides to add extended years of control. However, if reseeding is in the treatment area’s future it is safer to only use Panoramic or Laramie to allow for seed germination.
Will these herbicides help control any other unwanted species?
Panoramic and Laramie are also effective treatment methods for other annual invasive grasses such as medusahead and ventenata (African wiregrass) which are also common in the northwestern United States.
In a study conducted by UC Davis in Northern California, Alligare’s Laramie (active ingredient: rimsulfuron) applied in the fall had excellent medusahead control when applied for two consecutive years. This treatment also had less injury to desirable forbs and grasses than other commonly used herbicides.
Treatment in the fall allows for minimal injury of the warm-season grasses, however, injury can still occur. Read all label recommendations prior to use.
Give desirable forage the opportunity to thrive by spraying challenging and invasive species in the fall. Alligare's portfolio of Range & Pasture products, including Panoramic and Laramie herbicides, offers solutions to increase the growth of quality native vegetation while decreasing unwanted weeds and plants. Use the fall to treat cheat, and other nuisance species, and ensure you are growing grass, pounds, and profit in the spring.
Cover Photo by Jennifer Strickland, U.S. Fish and Wildlife Service
