Description

Annual bluegrass (Poa annua)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.

Species Data

• SEEDHEAD / FLOWER
  • light-colored panicle seedhead
    Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6
• VERNATION TYPE
  • leaves folded in the bud
    Figure 7
• 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