Dealing with that pesky annual ryegrass

Annual ryegrass is typically seen as a high-quality, cool-season forage and is utilized by many livestock producers for winter grazing. However, the annual forage can also become a weed issue in warm-season perennials.

Vanessa Corriher-Olsen, a Texas A&M AgriLife Extension forage specialist, explains in a recent Forage Fax that seed survives for multiple years in the soil, and winter rainfall promotes seed germination. Allowing the annual ryegrass to mature in the spring delays and prevents warm-season perennial forages like bermudagrass and bahiagrass from breaking dormancy in April or May, which can push back the initial hay cutting.

There are, however, several options for managing the unwanted ryegrass in spring hay meadows.

Graze it: Grazing is an excellent way to utilize the high-quality forage while also removing it, but it requires that the meadow be fenced in and that a good source of water is available for livestock.

Bale it: Corriher-Olson also suggests harvesting the ryegrass for baleage or dry hay. For baleage, harvest at 50% to 60% moisture and preserve in air-tight plastic wrap. Making dry hay can be a challenge during wet springs.

Kill it: The most common management option is using herbicides to control the annual ryegrass. Prowl H2O (pendimethalin) is a pre-emergent herbicide for dormant bermudagrass or bahiagrass pastures and hay meadows. Apply before rainfall to enhance incorporation into the soil and improve herbicide activation.

Glyphosate or Pastora (nicosulfuron + metsulfuron) are two postemergence herbicide options. Corriher-Olson notes that timing is critical for an effective ryegrass kill. Ryegrass needs to be sprayed when the plant is under 6 inches in the fall.

“Annual ryegrass is generally susceptible to postemergence herbicides in early winter prior to freezing temperatures and before seedhead emergence,” Corriher-Olson says. “Unfortunately for bahiagrass growers, there are no selective herbicides available for postemergence control of annual ryegrass. Spot treatments of glyphosate are recommended in bahiagrass for control."

Beat it: The last option is to just out compete it. Corriher-Olson suggests maintaining a substantial stubble height of the bermudagrass and bahiagrass to provide shade and reduce ryegrass seed germination. This doesn’t provide full control, but competition helps reduce unwanted plant growth. Higher stubble height also promotes a better root system, which captures deeper soil moisture and nutrients and improves growth during the next growing season.

Michaela King

Michaela King served as the 2019 Hay & Forage Grower summer editorial intern. She currently attends the University of Minnesota-Twin Cities and is majoring in professional journalism and photography. King grew up on a beef farm in Big Bend, Wis., where her 4-H experiences included showing both beef and dairy cattle.