Featured Weed: Bulbous Bluegrass

Bulbous bluegrass is a perennial that has the capacity to regenerate from its root system each year.

by Jane Mangold MSU LAVIN, PHOTOS BY MATT Extension Invasive Specialist, Montana State University FIGURE 1. Bulbous bluegrass .

Bulbous bluegrass ( bulbosa) was very prevalent from late dormancy; in essence, each bulblet is a mini-plant that can form spring through early summer in 2014 around Montana. This article roots and grow once it falls to the soil surface. The viability provides a brief overview of the species, including management of bulblets is believed to be relatively short (2 years). Bulblets recommendations, so that if 2015 proves to be another good year can be moved via livestock, wildlife, infested hay, vehicles, for bulbous bluegrass, you can be better prepared. and caching by small mammals. Interestingly, while bulbous bluegrass mainly reproduces by bulblets in its introduced range, Bulbous bluegrass identification, biology and in its native range it primarily reproduces sexually by seed. The impacts name bulbous bluegrass can also be attributed to the stems Bulbous bluegrass is a relatively small, shallow-rooted, cool- which are thickened and bulblike at the base (Figure 3). season perennial bunchgrass native to Eurasia and northern Bulbous bluegrass was accidentally introduced to North Africa (Figure 1). Because it grows new roots each season and America as a contaminant in and clover seed. It was has a relatively short life span, it is sometimes described as an discovered in Oregon in the early 1900s. Because of its vigorous annual with “perennial tendencies.” However, it is a perennial growth and tendency to form a solid mat, its use as a pasture that has the capacity to regenerate from its root system each and turf grass was repeatedly researched in the first half of the year. This is in contrast to some other invasive grasses that you 20th century. The growth characteristics that sparked interest may be familiar with like cheatgrass (Bromus tectorum) and in bulbous bluegrass as a turfgrass are the same characteristics Japanese brome (B. japonicus). These species are annuals and that make it weedy! Bulbous bluegrass tolerates a wide range

must regrow from seed each year. PHOTOS BY MATT LAVIN (L) AND JANE MANGOLD (R), MSU of environmental conditions, but is best adapted to disturbed, The leaves of bulbous bluegrass are mostly located at the base shallow soils that are moist during winter and early spring. It of the plant and have a membranous ligule (thin membrane on typically does not grow very well in soils that are continually the inside of the leaf blade at the junction of the leaf sheath moist. It has been reported in nearly every state in the U.S., but and leaf blade). The lower stems are flattened, while the upper is most common in the West. It is not listed as a noxious weed stems are wiry and round in cross-section. Bulbous bluegrass in Montana or any neighboring states. ranges in height from eight to 24 inches. Bulbous bluegrass produces very little biomass for grazing, and The panicle (, or flowering and seed producing its palatability is confined to early to mid-spring before the grass portion of the plant) is usually dense and has a plume-like dries out. The bulblets, however, contain high levels of starch and appearance. The name bulbous bluegrasss arises from bulblets fat that are sought after by a variety of birds and small mammals. with purple bases that form on the panicle (Figure 2). Bulblets Bulbous bluegrass competes with more desirable vegetation on provide the primary means of reproduction (asexual). These rangelands. It can also invade cropland and hayfields. structures can germinate immediately without a period of

8 | big sky small acres FIGURE 1.Bulbousbluegrassplants.

PHOTOS BY MATT LAVIN, MSU PHOTOS BY MATT LAVIN (L) AND JANE MANGOLD (R), MSU (R), MANGOLD JANE AND (L) LAVIN MATT BY PHOTOS they aremorelikelytosurviveprescribedfire. on theplant.Astheyfalltosoilsurfaceorbecomeburied, intensity. Bulbletsaremostlikelytobekilledbyfireifthey the fire(i.e.,onplant,atsoilsurface,orburied)and survival ofbulbletswilldependontheirlocationatthetime well known,butindividualplantscanbetop-killedbyfire.The The effectsofprescribedfireonbulbousbluegrassarenot perennial grasses. bulbous bluegrassgenerallygrowsearlierandfasterthanother used, itmustbeappliedearlyinthegrowingseasonbecause reduce bulbousbluegrassinfestations.Ifgrazingisgoingtobe Intensive earlyseasongrazingforseveralgrowingseasonscan Fall tillageislesseffective. if usedinconjunctionwithre-seedingduringpasturerenovation. bluegrass andmaybeappropriateinsomesituations,especially by scatteringbulblets.Springtillagecanreducebulbous considered tobeeffectiveandmayevenproliferatetheproblem it isdifficulttoremoveallofthebasalbulbs.Mowingnot bluegrass becausetheplantisshallowlyrooted;however, Hand pullinganddiggingcanbeusedtomanagebulbous desirable vegetationorcreatebaresoil. so avoidovergrazingandotherdisturbancesthatreducevigorof existing infestations.Disturbancepromotesbulbousbluegrass, preventing invasionbybulbousbluegrassorforreducing desirable competitivevegetationcanbeveryeffectivefor of perennialcropslikealfalfaorpasture.Therefore,maintaining Bulbous bluegrassistypicallynotcompetitiveindensestands Bulbous bluegrassmanagement FIGURE 3.Above,stemswith thickened,bulb-likebases. FIGURE 2.Left,paniclewithpurple-basedbulblets. be suretointegratere-seedingwithherbicideapplications. infestations areverydenseandlittledesiredvegetationremains, information/natural%20areas/wr_P/Poa_bulbosa.pdf. When by researchersandlandmanagers:http://wric.ucdavis.edu/ a listofherbicidesthatmaybeeffectivebasedonreports emergent fromfalltoearlyspring.Thefollowinglinkprovides are moreselectivethanglyphosateandcanbeappliedpost- perennial grasses.Theotheractiveingredientslistedabove should beappliedearlyspringpriortoactivegrowthofdesired selective (willkillorstressanyactivelygrowingvegetation),it sulfosulfuron (e.g.,Outrider®).Becauseglyphosateisnon- (e.g., Matrix®),sulfometuronmethylLandmarkXP®),or the activeingredientglyphosate(e.g.,Roundup®),rimsulfuron rangeland andinpastures.Theyincludeherbicidesthatcontain Several herbicidesarelabeledforbulbousbluegrasscontrolon for moredetailedinformationandalwaysfollowlabeldirections. season. Whenusinganyherbicide,besuretoconsultthelabel herbicide andapplyingitatthecorrecttimeofgrowing while notdamagingdesiredgrassesrequiresselectingtheright Using herbicidesthatwillselectivelyreducebulbousbluegrass Many landownerswishtoconserveandpromotegrassgrowth. org/publications/AgandNaturalResources/MT201402AG.pdf.  MontGuide grass identificationterminology, checkouttheMSUExtension cropland, pasture,andrangelandinMontana.Forhelpwith app includes105grassandgrass-likespeciescommonto Grasses” appatwww.highcountryapps.com ($4.99).The Do youneedhelpidentifyinggrasses?Checkoutthe“Montana Grass IdentificationBasicsathttp://msuextension. Spring Summer 2015 | 9