Poa bulbosa L. var. vivipara Koeler

http://plants.usda.gov/ Hitchcock, 1971; Gaines & Swan, 1972; Cronquist, 1977). However, it is believed to reproduce primarily through sexual means in its native habitat of Europe and mid East Asia (Youngner & McKell, 1972). This phenomenon may be explained by differences in climate. Youngner (1960) conducted a study to determine the effects of day length and temperature on reproductive structures of bulbous bluegrass, and found high temperatures (70-80ºF) and long days (16 hrs.) following inflorescence initiation promoted seed production, whereas cool temperatures (68ºF or less) and short days (8 hrs.) promoted bulblet production. Long days and cool temperatures or short days and high temperatures produced panicles with both seeds and bulblets. Sexual reproduction of bulbous bluegrass may occur more frequently in North America than originally expected. Novak & Welfley (1997) used bulbous bluegrass to evaluate genetic diversity within and among populations of an introduced, vegetatively reproductive species, and found the diversity to be surprisingly high at both the species and population levels. They concluded the diversity likely resulted from a combination of sexual reproduction, the autopolyploid nature of the species, and multiple introduction events. Bulbous bluegrass was introduced to North America accidentally, as a contaminant of alfalfa and clover seed. The grass was also introduced intentionally, for research purposes. In 1906 the USDA Office of Foreign Plant Introduction received bulblets of bulbous bluegrass from Russia (Vinall & Westover, 1928). The bulblets were grown by the Arlington, VA Experimental Farm in 1907, 1908 and 1909, and at Pullman, WA in 1907. At that time the grass was reported as having no particular promise, and the investigations soon ended. Bulbous bluegrass was re-evaluated in 1915 after the groundskeepers at the state capitol in Richmond, VA asked the USDA for assistance identifying the grass and determining methods to eradicate it. The groundskeepers considered the grass to be undesirable since it performed poorly in the summer months. The USDA grew the grass in a greenhouse and determined the grass to be Poa bulbosa. They advised the groundskeepers not to eradicate it, but instead manage it as winter grass in combination with Bermuda grass for the summer months (Vinall & Westover, 1928). In 1916 bulblets of the grass were distributed by the USDA to several experiment stations. Commercial production of the grass followed, and in 1928, Medford, OR was considered the center of production (Vinall & Westover, 1928). During this time, bulbous bluegrass was used to compliment Bermuda grass in pastures and turf, but new evaluations were beginning to demonstrate the grass did not tolerate frequent clipping, and actually outcompeted Bermuda grass when both were grown together. Bulbous bluegrass was still thought to have value in 1948, when it was recommended to replace cheatgrass on poor condition sites and as an understory species in seed mixtures in southern Idaho (Hull & Stewart, 1948). The Pullman Plant Materials Center (PMC) evaluated bulbous bluegrass for use in critical area plantings in the 1950's. In 1956, P-4784 was released but the bulblets failed to retain acceptable levels of germination. Consequently, P-4784 was not distributed to growers. As recently as 1997, the merits of bulbous bluegrass were still being considered, when it was included in a study to determine optimal species for low-input sustainable turf grass in the upper Midwest. The grass performed poorly and was not recommended for this use (Diesburg, 1997). Distribution: Bulbous bluegrass grows in nearly all temperate and subtropical regions throughout the world. In North America, it inhabits roadsides and hay and crop fields. It tends to be more common in western states than eastern states.

Adaptation

Bulbous bluegrass is best adapted to areas that have dry summers, mild winters, and winter rainfall. It is typically found within the 12" – 40" precipitation zones.

Establishment

This species is not recommended for seeding.

Mechanical Control

Control

Control

Spring tillage is very effective in controlling bulbous bluegrass. Fall tillage is less effective. Haying and mowing are not effective because the seed heads are frequently shorter than the cutting height. Burning is not effective because it rarely reduces the number of bulblets in the soil. Environmental/Cultural Control Infestations can be prevented by using crop seed, hay and straw that is free of bulbous bluegrass bulblets or seed. In addition, cleaning equipment before moving from a site infested with bulbous bluegrass and controlling weeds along fence rows and roadsides will prevent its spread. Within crop fields where bulbous bluegrass has established, it can be controlled by rotation with a spring crop or to permanent pasture or alfalfa. In uncropped areas, bulbous bluegrass can be managed by establishing a stand of competitive perennial grass. Intensive spring grazing can reduce bulbous bluegrass populations providing that intensive grazing is applied over a period of several growing seasons. Consult with the NRCS or a Certified Rangeland Management Specialist to determine if this practice could adversely impact other grazing plants and/or soil conditions.

Chemical Control

There is a wide range of chemicals available to control bulbous bluegrass. Contact your local agricultural extension agent or county weed specialist to learn what products work best in your area and how to use them properly. Always read and follow label and safety instructions.

Biological Control

No biological controls are known. Cultivars, Improved and Selected Materials Including Area of Origin The Pullman Plant Materials Center (PMC) evaluated bulbous bluegrass for several years in the 1950's. P-4784, an ecotype collected near the Washington-Idaho state line exhibited very robust late maturing growth. It was released in 1956 in cooperation with the Idaho Agricultural Experiment Station. The Pullman PMC grew P-4784 for several years but the bulblets failed to retain acceptable levels of germination. Consequently, P-4784 was not distributed to growers. All seed stock of P-4784 was destroyed in 1976 based on its poor seed storage characteristic and its weedy nature. Currently no seed is commercially available. Illustrations and Photographs Burrill, L. C., et al. 1996. Weeds of the West, 5th ed., T.D. Whitson, editor. University of Wyoming. Larimie, WY. pp. 482-483. Cronquist, A., A.H. Holmgren, N.H. Holmgren, J.L. Revcal, P.K. Holmgren. 1977. Intermountain Flora, vol. 6. Columbia University Press, New York. p. 235. Gaines, X.M. and D.G. Swan. 1972. Weeds of Eastern Washington and Adjacent Areas. C.W. Hill, Spokane, WA. pp. 54-55.

Plant Traits

Growth Requirements

Temperature, Minimum (°F)	-33
Adapted to Coarse Textured Soils	Yes
Adapted to Fine Textured Soils	Yes
Adapted to Medium Textured Soils	Yes
Anaerobic Tolerance	Low
CaCO3 Tolerance	Medium
Cold Stratification Required	No
Drought Tolerance	Medium
Fertility Requirement	Medium
Fire Tolerance	High
Frost Free Days, Minimum	100
Hedge Tolerance	None
Moisture Use	Medium
pH, Maximum	7.2
pH, Minimum	5.0
Precipitation, Maximum	40
Precipitation, Minimum	12
Root Depth, Minimum (inches)	8
Salinity Tolerance	Low
Shade Tolerance	Intermediate

Morphology/Physiology

After Harvest Regrowth Rate	Slow
Toxicity	None
Shape and Orientation	Decumbent
Nitrogen Fixation	None
Resprout Ability	No
Active Growth Period	Spring and Fall
Bloat	None
C:N Ratio	Low
Coppice Potential	No
Fall Conspicuous	No
Fire Resistant	No
Flower Color	Yellow
Flower Conspicuous	No
Foliage Color	Green
Foliage Porosity Summer	Moderate
Foliage Texture	Fine
Low Growing Grass	Yes
Lifespan	Long
Leaf Retention	No
Known Allelopath	No
Height, Mature (feet)	1.5
Growth Rate	Moderate
Growth Form	Bunch
Fruit/Seed Conspicuous	No
Fruit/Seed Color	Brown
Foliage Porosity Winter	Porous

Reproduction

Vegetative Spread Rate	None
Small Grain	No
Seedling Vigor	Low
Seed Spread Rate	Moderate
Seed per Pound	266240
Fruit/Seed Persistence	Yes
Propagated by Tubers	No
Propagated by Sprigs	No
Propagated by Sod	No
Propagated by Seed	Yes
Propagated by Corm	No
Propagated by Container	No
Propagated by Bulb	No
Propagated by Bare Root	No
Fruit/Seed Period End	Summer
Fruit/Seed Period Begin	Summer
Fruit/Seed Abundance	Medium
Commercial Availability	Routinely Available
Bloom Period	Late Spring
Propagated by Cuttings	No

Suitability/Use

Veneer Product	No
Pulpwood Product	No
Protein Potential	Medium
Post Product	No
Palatable Human	No
Palatable Graze Animal	Medium
Palatable Browse Animal	Low
Nursery Stock Product	No
Naval Store Product	No
Lumber Product	No
Fodder Product	Yes
Christmas Tree Product	No
Berry/Nut/Seed Product	No

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler

Poa bulbosa L. var. vivipara Koeler