Author: Barry Rice, Global Invasive Species Team, The Nature Conservancy
Latin Names: Agrostis stolonifera L.
Common Names: Creeping bentgrass
There is some controversy about the range of Agrostis stolonifera as an invader because it is notoriously difficult for non-experts to distinguish it from closely related plants such as Agrostis capillaris and A. tenuis. The fact that these species can hybridize (Belanger et al. 2003) complicates the identification process!
Where it occurs as a non-native invasive, it can form dense mats that exclude native species. In grasslands, Agrostis stolonifera fills in openings among native bunchgrass, apparently competing with native forbs that require this microhabitat. Staff of The Nature Conservancy have observed it (and closely related species) damaging wildland sites in New York (M. Jordan, pers. comm. 2001), Oregon (N. Rudd, pers. comm. 2001), and Washington (P. Dunwiddie, pers. comm. 2006).
Outside the USA it has been documented invading many different habitats. On Marion Island--a sub-Antarctic speck of land of great conservation value in the Southern Ocean--it is forming thick infestations in otherwise undisturbed habitats (Gremmen et al. 1998). Other examples of infestations include sites in Canada (Cody, et al. 2000) and Australia (Randall 2003).
There is interest by industry to market a genetically engineered form of Agrostis stolonifera that is tolerant to the herbicide glyphosate. Since Agrostis stolonifera is wind pollinated, it is possible that this herbicide resistance could be transferred from sites where the engineered form is used, to invading Agrostis stolonifera plants in wildland sites. Furthermore, there are other species of invasive Agrostis which can hybridize with Agrostis stolonifera, so the herbicide tolerance could be carried into hybrids. The modified gene has already been found in wild Agrostis outside of test plots in Oregon (Watrud et al. 2004; Reichmann et al. 2006).
Because of its rapid degradation in the environment, glyphosate is the most commonly used herbicide in natural area management. An herbicide resistant form of Agrostis would make this challenging invasive even harder to manage in the wild.
The best way to control Agrostis species is to prevent new invasions. Existing invasions are best handled by manual removal (if the population is extremely small) or by careful applications of glyphosate-based herbicides. Low mowing of Agrostis stoloniferashould not be done, as this will result in the plant forming a dense, lawn-like turf (M. Jordan, pers. comm. 2006).
Belanger, F.C., Meagher, T.R., Day, P.R., Plumley, K., and Meyer, W.A. 2003. Crop Science 43:240-246.
Cody, W.J., MacInnes, K.L., Cayouette, J., and Darbyshire, S. 2000. Alien and invasive native vascular plants along the Norman Wells Pipeline, District of Mackenzie, Northwest Territories. JT Canadian Field-Naturalist 114 (1): 126-137.
Esser, L.L. 1994. FIES summary, www.fs.fed.us (accessed 10/2006)
Gremmen, N.J.M., Chown, S.L., and Marshall, D.J. 1998. Biological Conservation 85: 223-231.
Randall, J., Jordan, M.J., and Wolfe, B. 2001. References documenting the widespread presence of bentgrass and bluegrass (Agrostis species, Poa pratensis) in natural ecosystems. Unpublished document provided to USDA APHIS.
Randall, R. 2003. Rod Randall's Global Weed List, (dated 11/2003). On line at: www.invasive.org/gist/biglist.html
Reichman, J.R., Watrud, L.S., Lee, E.H., Burdick, C.A., Bollman, M.A., Storm, M.J., King, G.A. and Mallory-Smith, C. 2006. Establishment of transgenic herbicide-resistant creeping bentgrass (Agrostis stolonifera L.) in non-agronomic habitats. Molecular Ecology, 15: 4243-4255.
Watrud, L.S., Lee, E.H., Fairbrother, A., Burdick, C., Reichman, J.R., Bollman, M., Storm, M., King, G., and Van de Water, P.K. 2004. Evidence for landscape-level, pollen-mediated gene flow from genetically modified creeping bentgrass with CP4 EPSPS as a marker. Proc. National Acad. Sciences, 101(40): 14533-14538.