Annual Bluegrass

Description

Annual bluegrass is a light green bunch-type to slightly spreading winter annual weedy grass. Some subspecies exist which are classified as short-lived perennials (Poa annua ssp. reptans). These perennial types are particularly evident in bentgrass golf greens. One reason annual bluegrass is so unsightly is its ability to produce a light colored seedhead even at very low mowing heights.

Cultural Control

Management practices that encourage annual bluegrass persistence include: 1) excessively close mowing; 2) shallow, frequent irrigation; 3) poor soil drainage; 4) improperly timed fertilization; 5) aerifying or dethatching during primary periods of germination; 6) use of heavy equipment causing compaction; and 7) shade.

Chemical Control

Herbicide and Formulation Amount of Formulation per 1,000 sq ft Amount of Formulation per Acre Pounds Active Ingredient per Acre
Preemergence Control
[benefin + trifluralin], MOA 3 + 3 (0.86 G) (Fertilizer with Team Pro 0.86%) 4 to 8 lb 174 to 349 lb 1.5 to 3
Precaution and Remarks: Apply during late summer before Poa annua germinates. Do not apply to turf areas that are to be overseeded. See section on preemergence control of crabgrass and goosegrass or product labels for turfgrass tolerance, precautions and remarks for the listed preemergence annual bluegrass herbicides.
bensulide, MOA 8 (4 EC, 8.5 G, 12.5 G) several concentrations available 12.5
Precaution and Remarks: Apply during late summer before Poa annua germinates. Do not apply to turf areas that are to be overseeded. See section on preemergence control of crabgrass and goosegrass or product labels for turfgrass tolerance, precautions and remarks for the listed preemergence annual bluegrass herbicides.
dithiopyr, MOA 4 (various brands) 2 EW, 2 L 0.75 fl oz 1 qt 0.5
40 WP 0.46 oz 20 oz 0.5
Precaution and Remarks: Timely irrigation or rainfall is critical for activation.
indaziflam, MOA 21 (various brands) 20 WSP 0.057 to 0.115 oz 2.5 to 5 oz 0.031 to 0.063
0.622F 0.138 to 0.23 fl oz 6 to 10 fl oz 0.029 to 0.049
0.0224 G 2.9 to 4.6 lb 125 to 200 lb 0.028 to 0.045
Precaution and Remarks:
metolachlor, MOA 15 (7.62 EC) (Pennant Magnum) 0.48 to 0.96 fl oz 1.3 to 2.6 pt 1.24 to 2.48
Precaution and Remarks:
napropamide, MOA 15 (50 DF) (Devrinol 50 DF) 1.5 to 2.25 oz 4 to 6 lb 2 to 3
Precaution and Remarks:
oryzalin, MOA 3 (various brands) 4 AS 1.1 fl oz 1.5 qt 1.5
85 WDG 0.64 to 0.88 oz 1.75 to 2.4 lb 1.4875 to 2.04
Precaution and Remarks: Apply full rate unless potentially thin turfgrass cover is a problem caused by dense poa infestation.​
oxadiazon, MOA 14 (2 G) (various brands) 2.3 to 4.6 lb 100 to 200 lb 2 to 4
Precaution and Remarks:
pendimethalin, MOA 3 (various brands) 2 G 1.72 to 3.44 lb 75 to 150 lb 1.5 to 3
0.086 G 2.67 to 5.34 lb 116 to 232 lb 1 to 2
1.29 G 2.67 lb 116 lb 1.5
3.8 CS 1.15 to 1.55 fl oz 3.1 to 4.2 pt 1.5 to 2
Precaution and Remarks:
[pendimethalin + dimethemamid], MOA 3 + 15 (1.75 G) 2.3 to 4.6 lb 100 to 200 1.75 to 3.5
Precaution and Remarks:
prodiamine, MOA 3 (various brands) 65 WDG 0.185 to 0.83 oz 0.5 to .3 lb 0.325 to 1.5
4 FL 0.23 to 1.1 fl oz 0.625 to 3 pt 0.3125 to 1.5
Precaution and Remarks:
pronamide, MOA 3 (3.3 SC) (various brands) 0.46 to 1.29 fl oz 1.25 to 3.5 pt 0.5 to 1.5
Precaution and Remarks: Not for home use. Can be applied from Sept. 15 to Feb. 1 for preemergence or postemergence annual bluegrass control in bermudagrass, zoysiagrass, centipedegrass, and St. Augustinegrass grown for sod, nonresidential or industrial sites, golf course turf, and stadium or professional athletic fields. 1.25 to 2.5 pints per acre provides preemergence to pre tiller stage control. 2 to 2.5 pints per acre provides postemergence control from early tiller to early seedhead stage. 2.5 to 3.5 pints per acre needed for postemergence control at seedhead stage. Henbit and chickweed species controlled at preemergence timings. Can be used for removal of overseeded grasses; therefore, do not overseed if it is desired to maintain a stand. Do not overseed treated area within 90 days of treatment. Injury symptoms from postemergence applications can take up to 5 weeks to develop.
benefin, MOA 3 (2.5 G) (various brands) 2.75 lb 120 lb 3
Precaution and Remarks: Apply in late summer before Poa annua germinates. Perennial ryegrass can be overseeded 6 weeks after benefin is applied.​
dithiopyr, MOA 4 (various brands) 2 EW, 2 L 0.75 fl oz 1 qt 0.5
40 WP 0.46 oz 20 oz 0.5
Precaution and Remarks: Apply in late summer before Poa annua germinates. Perennial ryegrass can be overseeded 6 to 8 weeks after application. Apply only on well-established bermudagrass. Do not reapply in fall or winter after overseeding unless injury can be tolerated.
prodiamine, MOA 3 (65 WG) (various brands) 0.213 to 0.367 oz 0.58 to 1 lb 0.37 to 0.65
Precaution and Remarks: Use on golf courses (excluding putting greens) when overseeding with perennial ryegrass at a minimum seeding rate of 350 pounds per acre. Apply 8 to 10 weeks before overseeding and expect 70% or greater control. For best potential control, use higher rate and shorter time interval before overseeding. However, this could increase ryegrass seedling mortality or temporarily reduce root growth.​
ethofumesate, MOA 8 (1.5 EC) (Prograss) 2 fl oz 2.67 qt 1
Precaution and Remarks: For control of annual bluegrass in dormant bermudagrass overseeded with perennial ryegrass or in established perennial ryegrass turf. Rates are per application. The first application should be 30 to 45 days after overseeding with perennial ryegrass. The second application should be 21 to 28 days later. Do not apply ethofumesate to overseeded bermudagrass after Jan. 1 in N.C.​
ethofumesate, MOA 8 (4 SC) (various brands) 0.55 to 1.47 fl oz 1.5 to 4 pt 0.75 to 2
Precaution and Remarks: Must be professionally applied to residential and nonresidential turf including golf courses and sod farms. May be applied to established perennial ryegrass, Kentucky bluegrass, creeping bentgrass, tall fescue, St. Augustinegrass, and dormant bermudagrass. Do not apply to putting greens. Delay application at least 8 weeks after a pgr application. Fall annual bluegrass control best during period of maximum germination. Spring appliclations most effective following fall applications. For overseeded bermudagrass, apply 1 to 2 weeks after perennial ryegrass emergence and repeat at 21- to 28-day intervals. Do not apply to bermudagrass 4 weeks prior to breaking winter dormancy.​
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. ​
atrazine, MOA 5 (various brands) 4 L 0.75 to 1.5 fl oz 1 to 2 qt 1 to 2
90 DF, 90 WDG 0.025 to 0.05 lb 1.1 to 2.2 lb 1 to 2
Precaution and Remarks: Use on centipedegrass, St. Augustinegrass, and dormant bermudagrass. Apply Nov. 15 to Dec. 31. Follow label directions.
simazine, MOA 5 (various brands) 90 DF, 90 WDG 0.4 to 0.8 oz 1.1 to 2.2 lb 1 to 2
4 L 0.75 to 1.5 fl oz 1 to 2 qt 1 to 2
Precaution and Remarks: Use on bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass. See label for instructions on newly sprigged turfgrass or on hybrid bermudagrass. Apply Nov. 15 to Dec. 15. Follow label directions.
Postemergence Control
bispyribac-sodium, MOA 2 (17.6 SG) (Velocity) 0.046 to 0.138 oz 2 to 6 oz 0.021875 to 0.065625
Precaution and Remarks: Do not apply to putting greens, ryegrass mowed to less than 0.375 inch, or non-overseeded bermudagrass. Apply between Feb. 1 and March 15. Make first application when annual bluegrass begins flowering. If actively flowering, use the low rate and re-treat in 28 to 35 days. If not actively flowering, use the low rate and retreat in 14 to 21 days with the low rate. Do not apply if air temperature is less than 50 degrees F within 3 days after application. Check label for further special instructions.​
amicarbazone, MOA 5 (70 WG) (Xonerate) 0.023 to 0.23 oz 1 to 10 oz 0.044 to 0.44
Precaution and Remarks: Also tolerant to 6 month established turfgrasses such as bahiagrass, centipedegrass, seashore paspalum, St. Augustinegrass, zoysiagrass, bentgrass, Kentucky bluegrass, perennial ryegrass, fine and tall fescue. Labeled for use on golf course, sod farm, residential, commercial, athletic field and roadside turf. Bentgrass tees: 1 ounce/acre at 7 day intervals for 4 applications. Bentgrass roughs and fairways: 2 to 3 ounces/acre for 14 to 21 day intervals for 2 applications. Cool season turf: 2 to 4 ounces/acre for 14 to 21 day intervals for 2 applications. Warm season turf: 3 to 10 ounces/acre for 14 to 21 day intervals for 2 applications not to exceed 10 ounces/acre per year. Allow 4 weeks before cutting or lifting sod. Allow 1 week before overseeding winter grasses.
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.

Species Data

  • SEEDHEAD / FLOWER
  • VERNATION TYPE
  • LIGULE TYPE
    • membranous; sharp pointed entire, 0.04 - 0.12 inches (1 - 3 mm) long
      Figure 8
  • GROWTH SEASON / LIFE CYCLE
    • winter annual weed
  • AURICLE TYPE
    • absent
  • LEAF BLADE TIP SHAPE
    • boat shaped; smooth above and below, not glossy, light green; two distinct, clear lines, one on each side of the midrib
      Figure 9
  • LEAF BLADE WIDTH
    • 0.08 - 0.1 inches (2 - 3 mm) wide
  • STOLON PRESENCE
    • absent
  • RHIZOME PRESENCE
    • absent
  • COLLAR TYPE
    • divided; distinct, not hairy, V-shaped
      Figure 10
  • SHEATH MARGIN
    • open part way only
  • SHEATH TYPE
    • flattened; slightly sharply creased
Annual bluegrass seedheadFigure 1. Annual bluegrass seedhead.Annual bluegrass seedheadFigure 2. Annual bluegrass seedhead.Annual bluegrass seedheadFigure 3. Annual bluegrass seedhead.Annual bluegrass seedheadFigure 4. Annual bluegrass seedhead.Annual bluegrass seedheadFigure 5. Annual bluegrass seedhead.Annual bluegrass seedheadFigure 6. Annual bluegrass seedhead.Annual bluegrass vernationFigure 7. Annual bluegrass vernation.Annual bluegrass liguleFigure 8. Annual bluegrass liguleAnnual bluegrass leaf blade shapeFigure 9. Annual bluegrass leaf blade shape.Annual bluegrass collarFigure 10. Annual bluegrass collar.

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/annual-bluegrass