Glyceria maxima

Mass growths of reed sweetgrass (Glyceria maxima) on the riparian zones of lakes and ditches displace original species, particularly shore vegetation. By replacing natural shore vegetation, it modifies the habitats of fish and crayfish negatively. As extensive stands are difficult to move, they impede recreational use such as fishing, swimming and boating.

In places, the plant is even useful as waterfowl can nest in the stands and its vegetation protects the shore from erosion. The plant is not recommended as a form of animal nutrition because of its common parasite, a smut fungus.

The most economical and easiest control method is to prevent reed sweetgrass from spreading to new locations and to remove growth before it has spread extensively. Large stands are arduous to eradicate and may prove costly. Control is often limited by the fact that reed sweetgrass is not recognised as an alien species.

If dredging is planned in the water body, it should be targeted at reed sweetgrass in particular. Restoring spring floods in regulated water systems favours natural vegetation and restricts the spread of reed sweetgrass. No chemical control methods have been identified that are safe for aquatic environments.

Be aware of the fact that reed sweetgrass spreads easily. The seeds may travel in mud clinging to boots, for example. Birds and cattle may also spread the seeds. If a shore is being used as pasture, it must be ensured that grazing animals do not spread reed sweetgrass to other shores.

Small stands can be mowed, preferably several times each summer, but this is subject to the landowner’s permission. The first mowing should take place before the plant flowers in late June. Mowing should then be repeated at three to four week intervals and cut vegetation should be collected immediately after mowing.

Locations where the reed sweetgrass grows can be reported via the Invasive Alien Species Portal, for example. You can monitor the spread of growths by photographing them every year.