The Weed Wire: European Beach Grass
History and Native Range:
Originating from the coasts of Europe and North Africa, European beach grass (Ammophila arenaria) was introduced to the West Coast of the United States in the mid-1800s for the purpose of sand dune stabilization; a task it accomplishes exceedingly well due to its thick rhizomes which allow it to rapidly grow both laterally and upwards through accumulating sand.
Highly adapted to the wind-exposed, nutrient-poor, high-disturbance environment of outer dunes, European beach grass is an extremely hardy plant that has asserted itself as the most dominant species out of any dune flora on the West Coast. Aside from protected pockets of habitat, most sand dune ecosystems of the Pacific Coast have been converted into dense, single-species stands of Ammophila.
Identification:
European beach grass grows in stiff clumps reaching up to 4 feet in height with thin, needle-like blades with sharp tips. Fresh growth is pale green in color, but dries to a golden brown.
Another Ammophila species, Ammophila breviligulata, originates from the East Coast of North America but has also been established as an invasive on the West Coast. A. breviligulata is visually very similar to A. arenaria, and the two species are known to have hybridized in many places. In contrast, most native dune grasses are sedges (Carex macrocephala, Leymus mollis) and therefore have wider, flat blades.
The Problem Here:
As stated previously, European beach grass has overtaken the dune systems of the Pacific Coast to such an extent that it is now the default species of more foredune habitats. Besides crowding out native dune flora, European beach grass monocultures lead to reduced diversity of native arthropods and destroy nesting habitat for the threatened Snowy Plover, which relies on open stretches of sand to lay its eggs.
Manual Control:
As European beach grass propagates via rhizomes, complete eradication by manual removal can prove difficult, especially in long-established stands. However, manual removal by hand-digging or use of heavy equipment is a common way to prevent the spread of Ammophila or eradicate small infestations. The hand-digging is particularly favorable if any native plants are still present nearby.
Cultural Control:
Though not an effective eradication on its own, prescribed burning can be used in tandem with manual removal or herbicide control to reduce the mass of surface growth, making it easier to reach roots for digging or reduce the necessary amount of herbicide to be applied. The U.S. Army Corps of Engineers has also found some success in killing off Ammophila infestations through saltwater irrigation.
Herbicides:
Multiple studies have shown that applications of solutions containing 2% glyphosate, 1% imazapyr, and a non-ionic surfactant to be the most effective form of herbicide treatment for European beach grass, with fall being a preferable time of application (both in terms of effectiveness and in avoiding the nesting and rearing seasons for Snowy Plover). Dead vegetation will require removal before re-planting can begin. Only licensed pesticide applicators should conduct herbicide treatments
Links to Information and Studies:
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