New campaign to control Floating Pennywort

Environmental groups and government agencies are coming together to help halt the spread of Floating Pennywort, the invasive, non-native plant that presents a major threat to rivers and lakes across Great Britain.

Floating Pennywort was first found in the wild in England in the 1990s. Establishing from tiny fragments, this plant can grow at an incredible 20cm a day forming dense mats that cover the waters surface. These mats block out light, stifling native plants, and make the rivers and lakes unsuitable for insects and fish. These dense rafts can make waters inaccessible to anglers and present a flood risk when plant mats build up around sluices and drains. Floating pennywort can also last for up to 14 days out of water, allowing for unintentional spread of these species between water bodies on damp equipment and clothing which hasn’t been thoroughly cleaned and dried.

Floating Pennywort is notoriously difficult to control because very small fragments of the plant can regrow. As a result, any effort to control this invasive plant needs to be done regularly, at the right scale and for sufficient duration to be effective.

Learning from the success of smaller scale strategic partnerships, in September 2020 the Thames basin project was launched, with the Angling Trust, Environment Agency and British Canoeing working together to coordinate management of Floating Pennywort in the region.

Based on this project, alongside other successful strategic collaborations that have been formed in other parts of the country, a national Great Britain Floating Pennywort Strategy is being launched, uniting recreational users, water companies and government to tackle this invasive plant. Through closer, coordinated action the aim of the strategy is to share best practice and facilitate further partnerships being formed to control this species and prevent the further spread into other areas.

Lord Richard Benyon, Minister for Rural Affairs and Biosecurity said:

“I commend this initiative, which will help inform and transform how we manage this highly damaging invasive species. Invasive non-native species not only challenge the survival of some of our rarest species but cost the economy more than £1.7 billion per year

Floating Pennywort profoundly disrupts aquatic habitats for insects, fish and other wildlife, and disrupts how people interact with Great Britain’s rivers and lakes. Today’s move is a step in the right direction for improving our cherished waterways.”

Trevor Renals, Invasive Species Technical Lead, Environment Agency said:

“Floating Pennywort is a highly-damaging non-native weed, which damages the flora and fauna of our rivers and our ability to enjoy recreation such as angling and boating. It also has the potential to increase flood risk and block flood defence assets. No single organisation has a duty to manage Floating Pennywort, so it is only by working together that we can control this plant. We encourage people to support local partnerships to manage invasive species and use it as an opportunity to enjoy nature and meet people in a socially-distanced environment.’

Later this year, a weevil native to South America will be released into the wild to provide another management tool to halt the spread of this species. This follows extensive research that has been undertaken by CABI to determine the suitability of the species for release and presents one of a number of biological controls that are being used to assist in invasive species management.

Dr Emily Smith, Environment Manager, Angling Trust said:

“We welcome the launch of this national strategy to tackle Floating Pennywort and a movement towards a more coordinated approach to invasive species management. Many anglers are already helping to control invasive species, as highlighted by the fantastic ongoing efforts of the Colne Valley Fisheries Consultative. Through this strategy we hope to be able to facilitate further partnerships such as these, and make strides towards tackling this problematic plant, and protecting the environment and wildlife that we all enjoy”.

Djami Djeddour, Senior Scientific Officer, CABI said:

CABI-UK has already released biocontrol agents against Japanese Knotweed, Himalayan Balsam and Australian Swamp Stonecrop (Crassula) in the UK.

Weevils have a long history of success in the biocontrol of aquatics. Research into the biocontrol of Floating Pennywort using the Argentine weevil, Listronotus elongatus has been funded by Defra since 2011. The weevil has undergone comprehensive screening for safety and efficacy and is now in the last stage of approval for permission to release in the UK.

CABI is hopeful that this agent will reduce Floating Pennywort’s dominance on our waterways, providing long-term and sustainable control. A national strategic approach to Floating Pennywort management provides an excellent opportunity to maximise impact, working closely with partners and stakeholders to integrate this natural solution into conventional management plans”.

How to get involved

The partnership is encouraging everyone to get involved in tackling Floating Pennywort. Find more information and how to get involved on the GBNNSS website.

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