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Kentucky Bluegrass

Poa pratensis

Summary 7

Poa pratensis, commonly known as Kentucky bluegrass, smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to Europe, Asia, North America, and northern Africa. Poa pratensis forms a valuable pasture plant, characteristic of well-drained, fertile soil. It is also used for making lawns in parks and gardens and is common in cool moist climates like the northeastern United States.

Range and habitat in illinois 8

Kentucky Bluegrass occurs in every county of Illinois and it is quite common (see Distribution Map). It was introduced from Europe as a lawn grass and pasture grass. Habitats include lawns, parks, pastures, roadsides, degraded prairies, weedy meadows, vacant lots, waste areas, open woodlands, savannas, limestone glades, and gravelly seeps. This grass is usually found in areas with a history of human-related disturbance. While it is not considered a major invasive species (at least in Illinois), it is often found in some native habitats as described above. Its capacity to recover from wildfires is poor. Faunal Associations

Description 9

Kentucky bluegrass is an introduced, perennial, short to medium-tall,
cool-season, sod-forming grass.  The leaves are primarily basally
attached and are usually 4 to 12 inches (10-30 cm) long [100].  Stems
are numerous in a tuft and grow 12 to 36 inches (30-91 cm) high.  The
inflorescence is an open panicle.  Kentucky bluegrass is shallow rooted
and is intolerant of drought.  Most roots and rhizomes are found within
3 inches (7.5 cm) of the soil surface [40].

Diagnostic description 10

The genus Poa is distinguished by its flat leaf blades, 2-6 flowered panicles, 1-3 nerved glumes and tuft of cobwebby hairs at the base of the 5-nerved lemmas (Gleason 1957, Mohlenbrock 1972, Hitchcock 1950).

Range and habitat in illinois 11

Kentucky Bluegrass occurs in every county of Illinois and it is quite common (see Distribution Map). It was introduced from Europe as a lawn grass and pasture grass. Habitats include lawns, parks, pastures, roadsides, degraded prairies, weedy meadows, vacant lots, waste areas, open woodlands, savannas, limestone glades, and gravelly seeps. This grass is usually found in areas with a history of human-related disturbance. While it is not considered a major invasive species (at least in Illinois), it is often found in some native habitats as described above. Its capacity to recover from wildfires is poor. Faunal Associations

Fire management considerations 12

More info for the terms: cool-season, cover, prescribed fire, warm-season

Burning for bluegrass control:  Frequent (annual or biennial) late
spring burning can be used to control Kentucky bluegrass and promote the
growth of warm-season grasses in the Midwest.  The timing of burning is
critical and should take place just prior to the resumption of
warm-season grass growth.  Such burning favors warm-season grasses
because they are dormant at the time of burning.  Conversely,
cool-season species like Kentucky bluegrass are harmed by late spring
fire because they resume growth in the early spring and are thus
actively growing at the time of burning.

In mixed-grass prairie, mid-May has proven to be the most effective time
to burn for Kentucky bluegrass control and has resulted in concomitant
increases in warm-season grasses [31,83].  In native bluestem prairie in
eastern Kansas, Kentucky bluegrass has been nearly eliminated from sites
annually spring burned for decades [112].  In aspen parkland in
northwestern Minnesota, 13 years of annual spring burning in late April,
when bluegrass was 4 to 6 inches high (10-15 cm), reduced Kentucky
bluegrass to about half its original percent composition [107].  After
10 years of biennial spring burning on the Curtis Prairie on the
University of Wisconsin Arboretum, Kentucky bluegrass frequency
decreased from 60 to 13 percent [6].

Burning to promote bluegrass growth:  When using prescribed fire to
promote the growth of cool-season species in the Northern Great Plains,
Kentucky bluegrass will probably respond best to very early spring
(March-April) or late summer (August-September) fires [130].

Disease control:  In Kentucky bluegrass commercial seed fields, burning
after harvest successfully controls several diseases.  It is effective
in controlling ergot (Claviceps purpurea); silver top, caused by the
fungus Fusarium trianctum; and the mite, Siteroptes cerealium.  Burning
also helps control leaf rust (Puccinia poae-nemoralis) and other fungi
harbored in crop residue [48].

Wildlife considerations:  Succulent new grass shoots arising from burned
mountain grasslands are highly palatable to wildlife.  On the Front
Range in Colorado, mule deer and bighorn sheep ate considerably more
Kentucky bluegrass on areas burned in late September than on nearby
unburned areas [102].  Following late October and early November fires
in aspen stands in Colorado, Kentucky bluegrass cover increased and thus
provided more forage to wildlife [99].

Where Kentucky bluegrass is desired for providing ruffed grouse drumming
ground cover, it can be burned when the soil is damp and plants are
dormant [122].

Burning under aspen:  Powell [90] reported that in south-central
Colorado, aspen/Kentucky bluegrass communities have only a moderate
probability of carrying a prescribed fire and only if livestock grazing
is deferred for at least one season.  For fall prescribed burning, the
likelihood of a relatively uniform burning treatment may be increased by
burning after aspen leaf fall [99].

National nature serve conservation status 13

Canada
Rounded National Status Rank: N5 - Secure
United States
Rounded National Status Rank: NNR - Unranked

Pests and potential problems 14

White grubs, billbugs and sod webworms can destroy plantings of bluegrass. Insect populations should be monitored so that timely insecticide applications can be made. Pest management in this manner is much more cost effective than routine insecticide applications or replanting large areas.

Kentucky bluegrass is sometimes vulnerable to fungal infections including Fusarium, Helminthosporium, leaf spot, rust and powdery mildew. Mixing bluegrass seed with ryegrass will prevent Fusarium blight.

Taxonomy 15

Comments: When broadly treated as by Kartesz (1999), includes plants native in North America as well as plants introduced to North America from Eurasia ("Kentucky Bluegrass"). If narrowly treated as in Kartesz (1994), Poa pratensis is primarily if not exclusively Eurasian, widely cultivated worldwide and often persisting or escaping, although considered by some to be native in the more northern portions of North America.

Comments 16

This grass has been introduced everywhere and it has become ubiquitous. It is undoubtedly the most common bluegrass in Illinois. Distinguishing different bluegrass species (Poa spp.) can be difficult; this task often requires a 10x hand lens or a 30x field microscope while examining the lemmas of the spikelets. Because many different cultivars have been developed, Kentucky Bluegrass (Poa pratensis) is both genetically and morphologically diverse. Unlike some species in this genus, Kentucky Bluegrass forms a turf from long rhizomes. Its lemmas have 5 visible veins; the midvein and marginal veins are finely hairy on the lower half of each lemma, while the intermediate veins are hairless. Other bluegrass species are finely hairy along the intermediate veins as well, or they may lack fine hairs along the veins of their lemmas altogether. As a group, bluegrass species differ from many other grasses by the small tufts of webby hair that are usually found at the bottom of their lemmas.

Sources and Credits

  1. (c) Matt Lavin, some rights reserved (CC BY-SA), http://www.flickr.com/photos/35478170@N08/3884600006
  2. (c) Biopix, some rights reserved (CC BY-NC), http://www.biopix.com/photos/JCS-Poa-humilis-62705.JPG
  3. (c) Biopix, some rights reserved (CC BY-NC), http://www.biopix.com/photos/JCS-Poa-pratensis-65944.JPG
  4. (c) Biopix, some rights reserved (CC BY-NC), http://www.biopix.com/photos/JCS-Poa-humilis-62719.JPG
  5. (c) Biopix, some rights reserved (CC BY-NC), http://www.biopix.com/PhotosMedium/JCS%20Poa%20pratensis%2025687.jpg
  6. (c) Biopix, some rights reserved (CC BY-NC), http://www.biopix.com/photos/JCS-Poa-humilis-62707.JPG
  7. (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Poa_pratensis
  8. (c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29449261
  9. Public Domain, http://eol.org/data_objects/24633096
  10. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/29113505
  11. (c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29449262
  12. Public Domain, http://eol.org/data_objects/24633107
  13. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/29113501
  14. Public Domain, http://eol.org/data_objects/1391200
  15. (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/29113499
  16. (c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29449263

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