An update on the Yateley Pennywort.
Floating Pennywort is a non-native species of plant, capable of growing as much as 20cm a day. It has escaped into the wild in a number of countries including the UK. It is capable of forming dense and extensive floating mats that can shade out native species, disrupt normal aquatic biological processes, impede angling and boating and also potentially increase flood risk. Large incidences of the plant are challenging and expensive to control.
Floating Pennywort has been found present at four sites around Yateley and efforts are underway to prevent it becoming established in the River Blackwater. A multi organisation group includes input from The Blackwater Valley Partnership, the Environment Agency, Thames Water, the Loddon Catchment Partnership, the Loddon Fisheries Consultative plus the owners of the various affected sites. The sites are all relatively small water bodies but most had a significant growth of Pennywort present.
Efforts to control the plant have been stepped up during 2018 following the concerns raised during the latter part of 2017 over the appearance of significant rafts of the plant in the River Thames downstream of Reading. Fortunately work conducted by the Environment Agency and the Blackwater Valley Partnership over the previous 5-6 years at the closest site to the Blackwater and on the river itself has proved very valuable in keeping the Pennywort under control. We are now however actively trying to eradicate the plant in the Blackwater catchment, rather than simply contain it.
Control efforts have been currently based around a fairly simple strategy:- Identification, manual and / or mechanical removal, followed up by spraying and then further monitoring and manual removal. This approach has so far significantly knocked back the incidence of the plant on 3 sites, and it is hoped to extend these efforts onto the 4th site during 2019. It would appear that there is none currently established in the Blackwater itself, with only a few fragments being removed in the Mill Lane area this year, with checks downstream as far as Swallowfield thankfully proving negative.
The greatest area for concern is dealing with roots that are established in the banks of the water bodies. Current observations suggest that these roots are not particularly deep, but due to the nature of some of the banks cannot always be simply dug out, which is in itself is a particularly time consuming operation. Other methods of dealing with these roots are being investigated, with assistance being sought from a number of other specialist bodies. This part of the Pennywort problem highlights the advantage with tackling the plant when it first appears and hopefully before any drifting rafts or fragments have the opportunity to become more firmly established.
The LFCC would welcome any help in detecting further incidents of the plant which can be reported to the national Environment Agency helpline 0800 80 70 60. PLEASE be as accurate as possible with the location.
https://www.plantlife.org.uk/uk/discover-wild-plants-nature/plant-fungi-species/floating-pennywort
https://www.gov.uk/government/news/cooperation-the-key-to-tackling-pennywort
http://www.nonnativespecies.org/factsheet/factsheet.cfm?speciesId=1766