Large-scale chemical control of smooth cordgrass (Spartina alterniflora) in Willapa Bay, WA: towards eradication and ecological restoration

  • Published source details Patten K., O’Casey C. & Metzger C. (2017) Large-scale chemical control of smooth cordgrass (Spartina alterniflora) in Willapa Bay, WA: towards eradication and ecological restoration. Invasive Plant Science and Management, 10, 284-292.


This study is summarised as evidence for the following.

Action Category

Use herbicide to control problematic plants: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Use herbicide to control problematic plants: brackish/salt marshes

    One study in 2003–2015 of an intertidal area invaded by smooth cordgrass Spartina alterniflora in Washington, USA (Patten et al. 2017) reported that after treating smooth cordgrass with herbicide, native salt marsh vegetation developed. One year after herbicide treatment began, three salt marsh plant species were present: glasswort Salicornia pacifica, Canadian sandspurry Spergularia canadensis and arrowgrass Triglochin maritimum (see original paper for frequency and cover data). After 12 years, three additional species were present. Saltgrass Distichlis spicata was the most abundant species (both frequency and cover) at high elevations, next to an existing salt marsh. Total native species cover reached 100% at these high elevations. Methods: Smooth cordgrass was controlled in a 300-ha cordgrass meadow that had developed on intertidal mudflats. Between 2003 and 2005, the meadow was sprayed with herbicide (1.7 kg/ha imazapyr). In subsequent years, remaining cordgrass plants were spot-treated (2% glyphosate, 0.75% imazapyr). Vegetation was surveyed between 2004 and 2015: approximately 300 quadrats/year, along sixteen 600-m transects extending seawards from the edge of an existing salt marsh.

    (Summarised by: Nigel Taylor)

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