Following large-scale herbicide spraying and burning on Assateague Island, a barrier bar island located in Maryland and Virginia, the invasive common reed (Phragmites australis) was largely reduced from vast monocultures to less dense patches interspersed within maritime shrublands. To improve the control of these remnant/reemerging infestations and limit further nontarget damage, we tested three new treatments: mechanical cutting followed by dripping imazapyr onto stems, cutting followed 2 wk later by the foliar spraying of regrowth, and simple cutting with and without the removal of Phragmites litter. All herbicide treatments and cutting paired with litter removal significantly reduced Phragmites coverage (P ≤ 0.01) when compared with untreated controls. Native plant coverage was significantly greater after the cut-stem treatment than after traditional foliar spraying (P ≤ 0.01) because of the former's reduced herbicide use and more direct contact limited to Phragmites stems; native coverage was also greater after litter removal than when litter remained (P ≤ 0.001). Cutting followed by stem applications of herbicide is an effective means of treating scattered common reed stands in sensitive habitats, and litter removal after cutting can provide native vegetation with an advantage at recolonization.

Common reed [Phragmites australis (Cav.) Trin. ex Steud.] is an invasive plant that reproduces poorly by seed but regenerates vigorously by rhizomes. Because Phragmites australis propagates well through rhizome growth, invasion often occurs from transported rhizome tissue. We investigated both rhizome-fragment biomass and seasonal effects on survival and growth of ramets. Rhizomes were collected along roadside ditches during the fall of 2009 and 2010 and during the summer of 2010 and 2011. Fall and summer were chosen because the plants were either dormant or actively growing, respectively. Rhizomes were cut into fragments then grown in a greenhouse for 60 d in vermiculite with no added nutrients. Rhizomes collected in the fall had a survival rate of 71.1%, whereas only 15.6% of those collected in the summer survived. Within season, rhizomes with low initial biomass had lower survival rates and growth than did large rhizomes. There was no seasonal difference in the total biomass produced by the surviving plants; however, allocation of biomass did differ. Summer-collected rhizomes showed a higher belowground to aboveground biomass ratio than did those collected in the fall. Understanding the viability of Phragmites australis rhizome fragments provides land managers a greater awareness of the high-establishment risks of Phragmites australis. This information should be included in an integrated weed management program, and actions should be taken to reduce the spread of this weed during roadside maintenance. Although the risk of survival is lower during the summer, soil contaminated with Phragmites australis should not be transported or must be sifted with a screen to ensure all rhizome fragments are removed.