Author: Barry Rice, Global Invasive Species Team, The Nature Conservancy
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  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 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.Other examples of infestations include sites in Canada ( and Australia .
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.
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).
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