Tide turns against water primrose
20 October 2008
This escapee from garden ponds, which is clogging up Britain's waterways, may be about to join Japanese knotweed, giant hogweed and Himalayan balsam on the government's list of illegal aliens - invasive non-native plant species that can't be introduced to the wild without a licence.
The proposal is one of several possible weapons Defra is considering in its battle against water primrose, Ludwigia hexapetala and the closely-related L. grandiflora. Although the plant is attractive, with dozens of bright yellow flowers, it is very invasive. It grows so quickly that it can double its own weight every few weeks during summer, forming dense, choking mats that clog up ponds and waterways and create a serious flood risk.
“Once this plant gets a foothold outside of garden ponds its effect on the aquatic environment can be devastating,” says Jon Naylor, flood risk expert at the Environment Agency.
Other measures include banning the sale of Ludwigia to the public; despite its invasive nature, the plant is often found in garden centres, sometimes mislabelled as Jussiaea.
Water primrose is a serious problem in France, Belgium and the Netherlands, but has only begun to appear in British waterways over the last two years.
“We are making a concerted effort now to eliminate this plant from UK waterways before it becomes unmanageable and causes us problems in the future,” says Jon.
The Environment Agency has identified six sites infested with water primrose to date, and is treating them by spraying with glyphosate solutions. The treatment will be repeated several times over the next year.
Defra is asking for the public's help in identifying new sites where the weed has established. If you think you have seen water primrose in the wild, call the Environment Agency on 08708 506506 or e-mail enquiries@environment-agency.gov.uk.