Nobody likes a cheater. But what if the cheater happens to be an invasive winter annual weed?
Cheatgrass or downy brome is an aggressive grass species from Asia and is one of the most problematic weeds in the west. Due to the lifecycle of cheatgrass, it robs native plants of resources, including sun, space, and water, necessary for their survival. It also cheats land owners and managers out of needed forage for domestic grazers and wildlife alike.
Cheatgrass germinates in late summer or early fall. The plants grow rapidly with growth continuing throughout the winter in the roots of the plants. When warmer temperatures and precipitation arrive in the spring, the plants are already established and continue flowering, setting seed and ultimately dying. Seed production takes place during the spring when plenty of moisture is usually available. Native plants don’t complete this stage until later in the season when moisture is less available and new seedlings may struggle to survive.
Once established, productivity of the land decreases as the plants continue to occupy more area each year, altering native landscapes and increasing the potential for fires. The forage value is low due to the narrow time frame that it may be grazed by livestock or wildlife.
Once seed heads emerge, grazing is reduced to zero due to the dangerous awns on the seeds. In addition, stands of this invader may have several growth stages from newly germinated seedlings, to those that may already be heading out, reducing the likelihood that domestic animals may graze on the species. Cheatgrass seeds can cause problems for animals when those seeds get lodged in the mouths and digestive tracts of grazing animals as well as various medical problems for dogs when they get into the nose, ears or between toes.
And then there’s the human factor. Treking across any lands infested with this species is sure to spread the weed even farther as any seeds that haven’t yet fractured and fallen out are sure to get imbedded in shoes, clothing, equipment and the fur of any animal.
The best strategy for managing cheatgrass is an integrated approach. Key components include reducing seed production through mechanical means such as pulling, continually mowing or tillage, combined with proper grazing practices, limiting disturbances, use of specific herbicides at the correct time, replanting desirable species if necessary and generally managing for desirable species. There are several herbicides available for controlling cheatgrass depending on the situation or areas of infestations. Common ones include:
Pre-emergent (applied before germination)
Plateau and generics (Imazipic) 4-8 oz. per acre. May use as early post-emergent with the addition of adjuvant with mixed results. May suppress other desirable brome grasses.
Prodiamine, many generics 1-2.5 per acre. Timing before germination, late August, early September. Moisture required to move into germination zone. Controls most winter annuals – both grasses and broadleaf weeds. Safe in perennial landscape areas.
Matrix and generics (Rimsulfuron) 3 oz. per acre. Some agriculture use. Early spring (post-emergent) applications suppression is only 2 oz. per acre.
Esplanade 200SC Indaziflam (pre-emergent). Use rate varies. Not for range and pasture. Needs moisture event after application for pre-emergent control.
Roundup and generics (Glyphosate) 8-16 oz. per acre. Plants must be green and growing. For best results, treatment should coincide with early seed head emergence of the most mature plants. Avoid off target damage to any desirable plants with any green showing in early spring or late fall.
Esplanade EZ- Indaziflam, Glyphosate, Diquat (pre/post emergent) herbicide. Use rate varies. Not for range and pasture. Needs moisture event after application for pre-emergent control. Will harm any desirable plants that are green and growing.
Gaining back lost acreage from this cheater is possible. It does however require surveillance, on the ground monitoring, use of special tools like mowers, plow, herbicides and more, and keeping desirable plants happy.
For more information contact Park County Weed and Pest at (307) 754-4521.