Annual ryegrass (Festuca perennis), also referred to as Italian ryegrass, is a bunch-type grass that can be used as a nurse crop for quick cover or for winter overseeding of bermudagrass on low maintenance athletic fields or golf courses. It does not possess the quality of perennial ryegrass and is not recommended for sites where high quality turf is desired. However, it is very inexpensive and can be used on low profile fields such as school, park or recreation sites where winter color is desirable. Its seedhead can be confused with that of quackgrass. Annual ryegrass does not have rhizomes, whereas quackgrass does. Annual ryegrass can be easily confused with tall fescue. However, tall fescue has rough leaf blade margins on the lower 1 ⁄3 – 1 ⁄2 of the leaf whereas annual ryegrass has smooth ones. Tall fescue has non-clasping auricles, whereas annual ryegrass has clasping auricles. The backside of the tall fescue leaf blade is less glossy than that of annual ryegrass.
Annual Ryegrass as a Weed
Annual ryegrass is a common weed problem in turfgrasses on roadsides in the southeastern United States. Maintaining a dense, vigorous turf is the first step in effective weed control. Cultural and management practices that enhance turfgrass growth generally reduce weed competition and encroachment. First, select adapted turfgrass cultivars for your area and then properly fertilize, mow, and water to encourage dense growth.
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Overseeding should be done when the days are warm enough for the seed to grow, and the nights are cool enough to reduce the incidence of disease. Thirty days before the first frost, when daytime highs are near 70 °F and nighttime lows are usually above 50 °F, is generally a good time to overseed. This usually corresponds to early October in the Upstate and late October in the Midlands and Coastal regions.
In the spring, mow the ryegrass down to one inch height, which will weaken it and allow the permanent grass to rejuvenate. Be sure to not scalp the permanent lawn as this could also cause a delay in transition (i.e., green up in the spring). When the permanent grass resumes growth, begin regular maintenance, especially fertilization.
Perennial ryegrass (Lolium perenne) and annual ryegrass (Lolium multiflorum) may be used to overseed dormant bermudagrass lawns in South Carolina. They provide a green cover during the winter when this warm-season grass goes dormant and turns brown after frost. Alternatively, they can be used as a winter cover to help prevent erosion on new lawn areas where the permanent grass has not yet been planted. Keep in mind that overseeding may even retard the bermudagrass, unless it is managed correctly in the spring, because the ryegrass competes for moisture, sunlight, and nutrients.
After the second mowing, apply one-half pound of nitrogen per 1000 square feet using a fertilizer, such as 16-4-8 or 15-0-15 (this would be 3 pounds of fertilizer per 1000 square feet of lawn). Apply another one-half pound of nitrogen during mid-winter, if needed to maintain ryegrass color and growth. Pythium blight disease can be a problem on over-watered, over-fertilized ryegrass, especially during warm, humid weather; therefore, it is important to monitor the nitrogen applications and to not over-fertilize or over-water.
It is not generally recommended to overseed home lawns, but if it is performed, it should only be on a bermudagrass lawn. The extra irrigation, fertilization, and shading effects of the overseeding will severely retard or damage centipedegrass, zoysiagrass, and St. Augustinegrass in the spring and early summer and cause undesirable competition on the permanent turfgrass.
Excerpted from Southern Lawns, Bert McCarty (editor) and the University of Florida Extension publication Florida Lawn Handbook.