By Travis Legleiter
Annual ryegrass has become a popular cover crop choice for growers in Indiana and many other states. Annual ryegrass has many attributes that make it a favorable cover crop including quick establishment across a wide range of environments, the ability to survive Midwest winters, a vigorous and aggressive vegetative growth habit, and a high biomass potential both above and below the soil line. Annual ryegrass is also valued for its ability to sequester and release nitrogen for corn production.
Successfully terminated cereal rye cover crop.
Unfortunately, its adaptability, quick establishment, and aggressive growth are also considered to be characteristics of a weed. The annual ryegrass we know as a cover crop is the same species (Lolium multiflorum) as Italian ryegrass, which has become a major pest in both the southern Mississippi Delta and Pacific Northwest. Italian ryegrass is not only tough to control, it also has been confirmed resistant to four herbicide sites of action in the United States: ACCase inhibitors (Group
1), ALS inhibitors (Group 2), glyphosate (Group 9), and glufosinate (Group 10). This species’ aggressive growth aspects and its ability to adapt to herbicides has made many weed scientists cautious about recommending it as a cover crop. While annual ryegrass has shown to be an excellent cover crop it is also the most difficult grass cover crop to terminate, so should only be grown by experienced cover crop users.