Perennial Ryegrass

Description

Perennial ryegrass is a bunch-type grass that is used for winter overseeding on sites where high quality and winter color are needed. The texture, color, and density of perennial ryegrass are very similar to those of Kentucky bluegrass. Perennial ryegrass is often utilized for winter overseeding on golf course fairways and teeboxes, athletic fields, and high profile home lawns. Perennial ryegrass is often confused with tall fescue and / or Kentucky bluegrass. However, Kentucky bluegrass has a boat-shaped leaf tip and distinctive light-colored lines on both sides of the midrib. Tall fescue has rough leaf blade margins whereas perennial ryegrass has smooth ones. Also, tall fescue has rolled vernation in the leaf bud and perennial ryegrass has folded vernation.

Perennial Ryegrass as a Weed

Cultural Control

Perennial ryegrass is often overseeded to provide winter color in warm climates where turf is utilized in winter months. When warm weather prevails in late spring or early summer, this species usually will not survive. However, in the transition zone, especially during cool summers, wet summers, or both, perennial ryegrass can survive the summer and often becomes clumpy. This very attractive turf species becomes a difficult-to-control weed in these conditions. Control strategies should concentrate on controlling perennial ryegrass before it becomes clumpy.

Chemical Control

Herbicide and Formulation Amount of Formulation per 1,000 sq ft Amount of Formulation per Acre Pounds Active Ingredient per Acre
Postemergence Control
flazasulfuron, MOA 2 (25 DG) (Katana) 0.011 to 0.069 oz 0.5 to 3 oz 0.0078 to 0.0469
Precaution and Remarks: For use on well established bermudagrass, zoysiagrass, centipedegrass, and seashore paspalum grown turf including golf courses (including fairways, roughs, greens (bermudagrass and seashore paspalum only), tees, collars and approaches), industrial parks, tank-sod- and seed farms, cemeteries, athletic field and commercial lawns. Residential turf applications are limited to spot applications. Apply a maximum of 1.5 ounces per acre on fully green centipedegrass and seashore paspalum. 3 ounces per acre needed for annual bluegrass control and best if applied in spring. 0.5 to 1.5 ounces per acre will control perennial and Italian ryegrass. For clumpy ryegrass, use 1.5 to 3 ounces per acre. 1.5 ounces per acre needed for tall fescue control. 2.25 to 3 ounces per acre needed for poa trivialis control. Include a nonionic surfactant at 0.25% by volume.​
foramsulfuron, MOA 2 (0.19 SC) (Revolver) 0.2 to 0.6 fl oz 8.8 to 26.2 fl oz 0.013 to 0.039
Precaution and Remarks: For use on bermudagrass and zoysiagrass grown on home lawns, golf courses and sod farms. Do not use on warm season turfgrass collars surrounding bentgrass greens. May be applied up to 1 week prior to overseeding. Do not apply within 2 weeks of bermudagrass sprigging. Apply in 25 to 60 gallons water per acre. Rainfast after 2 hours. Surfactant not required.​
rimsulfuron, MOA 2 (25 DF) (various brands) 0.011 to 0.092 oz 0.5 to 4 oz 0.0078 to 0.0625
Precaution and Remarks: May be applied to bermudagrass, zoysiagrass and centipedegrass on professionally managed sports facilities at professional and collegiate levels, golf courses, sod farms, roadsides, industrial and commercial lawns. For annual bluegrass control, apply November through December and again February through March if needed at 2 ounces per acre. May be applied 10 to 14 days prior to overseeding. For overseeded removal, apply 2 ounces per acre 3 to 4 weeks before desired removal date, and repeat 3 weeks later if needed. For weed control along roadsides, apply 4 ounces per acre if single application only. A nonionic surfactant at 0.25% by volume or an oil adjuvant such as crop oil concentrate and modified seed oil at 1% by volume are required. Do not apply to cool-season turfgrasses, residential lawns or newly sprigged/sodded bermudagrass.
[metsulfuron + rimsulfuron], MOA 2 + 2 (37 WG) (Negate) 0.0344352 oz 1.5 oz 0.0346875
Precaution and Remarks: Use on well established bermudagrass and zoysiagrass grown on nonresidential turf including golf courses, sod farms, industrial and commercial lawns, and professionally managed college and professional sports fields. Overseeding can occur 2 months after application. Include a nonionic surfactant at 0.25% by volume.​
sulfosulfuron, MOA 2 (75 DG) (various brands) 0.017 to 0.046 oz 0.75 to 2 oz 0.035 to 0.09375
Precaution and Remarks: May be applied to certain ornamental native grasses and also bermudagrass species, zoysiagrass, centipedegrass, St. Augustinegrass, and kikuyugrass grown on sod farms, golf courses (excluding greens), commercial and residential turf that is highly managed, and other noncrop areas. Use 1.5 to 2 ounces per acre for fall annual bluegrass control 7 to 10 days before overseeding. Use 0.75 to 1.25 ounces per acre for fall or winter control in nonoverseeded bermudagrass, and reapply if needed but not before 21 days after initial application. For tall fescue control, two applications may be required at 4- to 10-week intervals. Perennial ryegrass control not as complete as with foramsulfuron, rimsulfuron, or trifloxysulfuron. Use a nonionic surfactant at 0.25% by volume. Do not exceed 2.66 ounces per acre per year.​
trifloxysulfuron, MOA 2 (75 WG) (Monument) 0.0023 to 0.0129 oz 0.1 to 0.56 oz 0.0047 to 0.0263
Precaution and Remarks: May be applied to residential bermudagrass and zoysiagrass and also on golf courses, sod farms, and other nonresidential turf areas. A nonionic surfactant at 0.25 to 0.5% by volume is recommended. Temporary discoloration may occur if used with MSO or COC. May be applied 3 weeks prior to overseeding. Use rates of 0.1 to 0.3 ounces per acre to remove overseeded perennial ryegrass and Poa trivialis to aid bermudagrass spring transition. Labeled turf species can be seeded or sprigged into treated areas 4 weeks after application. ​
metsulfuron, MOA 2 (60 DF) (various brands) 0.003 to 0.02 oz 0.125 to 1 oz 0.005 to 0.038
Precaution and Remarks: May be applied to established bermudagrass, zoysiagrass (Meyer or Emerald), St. Augustinegrass, Kentucky bluegrass or fine fescue. Do not apply to turf less than 1 year old. Do not exceed 0.5 ounces per acre on centipedegrass, fine fescue, or Kentucky bluegrass. See label for a complete list of weeds controlled. The addition of 0.25% nonionic surfactant will enhance control. May be used for removal of perennial ryegrass from overseeded warm-season turf species. For bahiagrass control, use 0.25 to 0.75 ounces per acre after spring greenup but before seedhead development. A repeat treatment may be necessary in 4 to 6 weeks.​
metsulfuron, MOA 2 (60 WDG) (Patriot) 0.007 to 0.046 oz 0.33 to 2 oz 0.012 to 0.075
Precaution and Remarks: Apply to unimproved industrial turf only. Use maximum of 0.5 ounce per acre for fescue and bluegrass and 2 ounces per acre for bermudagrass.​
[thiencarbazone-methyl + foramsulfuron + halosulfuron], MOA 14 + 2 + 2 (60.5 WG) (Tribute Total) 0.0735 oz 3.2 oz 0.121
Precaution and Remarks: Apply to well-established residential and commercial bermudagrass and zoysiagrass (Emerald, Meyer, Zeon) lawns, golf courses (excluding greens), athletic fields, sod farms, roadsides, parks, cemeteries and recreational areas. Do not exceed 3.2 ounces per acre per application or 6.4 ounces per acre yearly. Use 0.25 to 0.5% by volume nonionic surfactant or 0.5 to 1% by volume methylated seed oil. After application, wait 12 weeks to overseed ryegrass or bermudagrass. Wait 1 month after bermudagrass seedling emergence and 2 weeks after sprigging or sodding bermudagrass before treating. Temporary stunting and yellowing may last up to 2 weeks but turf will recover. Crabgrass and goosegrass are controlled up to 2 tiller stage.​

Species Data

  • SEEDHEAD / FLOWER
    • a spike, with flattened spikelets along each stem
  • VERNATION TYPE
  • LIGULE TYPE
    • membranous; collar-like to blunt, may be toothed near top, 0.02 - 0.06 inches (0.5 - 1.5 mm) long
      Figure 3, Figure 4
  • GROWTH SEASON / LIFE CYCLE
    • cool season turf or perennial weed
  • AURICLE TYPE
  • LEAF BLADE TIP SHAPE
    • sharp-pointed; bright green, sharply creased, deeply ridged upper surface, lower surface smooth and glossy, edges slightly rough
      Figure 8
  • LEAF BLADE WIDTH
    • 0.08 - 0.2 inches (2 - 5 mm) wide
  • STOLON PRESENCE
    • absent
  • RHIZOME PRESENCE
    • absent
  • COLLAR TYPE
    • divided by midrib, not hairy, distinct
  • SHEATH TYPE
    • sheath is usually flattened, reddish at base
Perennial Ryegrass VernationFigure 1. Perennial ryegrass vernation.Perennial ryegrass vernationFigure 2. Perennial ryegrass vernation.Perennial ryegrass liguleFigure 3. Perennial ryegrass ligule.Perennial ryegrass liguleFigure 4. Perennial ryegrass ligulePerennial ryegrass auricleFigure 5. Perennial ryegrass auricle.Perennial ryegrass auricleFigure 6. Perennial ryegrass auricle.Perennial ryegrass auricleFigure 7. Perennial ryegrass auricle.Perennial ryegrass leaf bladeFigure 8. Perennial ryegrass leaf blade.

Written By

Photo of Charles Peacock, N.C. Cooperative ExtensionDr. Charles PeacockProfessor and Extension Turfgrass Specialist (919) 515-7615 charles_peacock@ncsu.eduCrop & Soil Sciences - NC State University
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This Extension factsheet can also be viewed at:
https://content.ces.ncsu.edu/perennial-ryegrass