Reed sweet grass
Botanical Name
Glyceria maxima
Family
Poaceae (grass)
Also known as
Glyceria, swamp grass, water meadow grass, Poa aquatica
Where is it originally from?
Europe
What does it look like?
Aggressive, perennial, mat-forming grass (<1.9 m tall) with fibrous roots and rhizomes and an erect or lax stem. Soft, light green leaves (30-60 x 2 cm) have a membranous ligule. Much-branched flowerhead has numerous spikelets containing many seeds.
Why is it weedy?
Forms a dense monoculture in nutrient-rich bogs and water. Matures quickly, has a rapid growth rate, and overtops competitors. Sets many long-lived seeds, and rhizomes spread outwards, breaking off and rooting in any damp spot. Tolerates damage, grazing and pollutants, but doesn’t like heavy frost and shade.
How does it spread?
Seed and rhizome fragments spread by flowing water. Contaminated diggers, livestock, soil movement, dumped vegetation, eel nets, boats and trailers all spread seed and rhizome fragments into new catchments, pasture, and drains.
What damage does it do?
Forms dense mats on water and in damp areas, replacing most other species and degrading the habitat for native flora and fauna. Causes silt accumulation and flooding, and attracts cattle into wetlands, causing further degradation of the area.
Which habitats is it likely to invade?
Wetlands, bogs, freshwater margins, lakes, and streams in open frost-free areas.
What can I do to get rid of it?
Begin all control work at the top of the catchment, and minimise site disturbance and the creation of bared areas.
1. Physical removal - Dig out or exxcavate all parts of plant (all year round). Dispose of at refuse transfer station or burn.
3. Foliar spray - Apply 520g/L haloxyfop-P-methyl (12ml/10L + label recommended penetrant). Haloxyfop is selective for grasses and will not harm broadleaf species, however, in store availability may be limited OR apply glyphosate (360g/L active ingredient at 100ml/10L + label recommended penetrant). Note Glyphosate overspray will kill other (desirable) plants. Not for use near water bodies or wetlands - check with your regional council.
4. Weedmat: difficult to apply, need to cover all of infestation to avoid rhizome survival and leave covered 3-4 months. Not suitable where flooding may occur and cause the mat to lift.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and directions for the purchase, use and storage of the product, are followed and adhered to.
What can I do to stop it coming back?
Follow up controlled areas regularly as rhizomes resprout and the seed bank can reinfest bared sites.
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