Beating back the alien invasion

Despite an awkward start to the 2020 INNS control work programme, the Invasive Non-Native Species (INNS) team at the Bannau Brycheiniog National Park Authority had a very successful season in tackling Japanese knotweed (Fallopia Japonica) along the banks of the River Usk. Japanese knotweed is a non-native species that has negative impacts on our habitats and species, it is also a significant problem in urban environments where its strong growth allows it to push through weaknesses in concrete and asphalt even damaging properties.

The River Usk is designated a Site of Special Site of Scientific Interest (SSSI) and a Special Area of Conservation (SAC) for its special habitats and wildlife. Surveys in 2018 & 2019 revealed some nasty infestations of Japanese knotweed lurking on both banks of the river in and around the county town of Brecon (Aberhonddu), 71 records of Japanese knotweed to be precise! Being in the upper reaches of the Usk catchment the Brecon area was a clear target for control. Working with the ethos of ‘source to sea’ in mind and controlling these infestations in the upper Usk catchment would limit the potential for invasive plant material being washed downstream and infesting new areas.

In 2020, we were grateful to be awarded a grant from the Welsh Government’s ‘Local Places for Nature’ fund.  This was for the control of an invasive non-native species, helping the restoration and enhancement of freshwater habitat on the River Usk SAC & SSSI, benefitting biodiversity and people’s enjoyment of the river.

The grant enabled us to employ a specialist contractor to herbicide treat the Japanese knotweed along an 11km stretch of river centred on the town of Brecon. We had an extremely positive response from all 25 landowners along this stretch of the river many of whom were unaware of the problems Japanese knotweed pose or even that there were invasive species in the area.

The glorious summer weather was not to last all the way into optimal Japanese knotweed control season alas but despite this and also the moving feast that was Covid 19 restrictions the contractors were able to spray in September & October 2020 treating all 71 knotweed sites and even finding a few new ones too!

A follow up survey in autumn was not able to be carried out in full due to flooding and further Covid lockdowns, however those sites that were able to be reached on a walk from home by the INNS staff showed a good die back rate of the plant.

The spring and summer seasons of 2021 will show us the effectiveness of the 2020 treatment, the hope being that a high control rate will enable follow up treatments to be far less time consuming and costly, fingers crossed! We are searching for further funding for these follow-up treatments in 2021 & 2022 and once the infestations are under control  a much less intensive monitoring programme can be carried out periodically.

The INNS team and the Bannau Brycheiniog National Park Authority would like to take this opportunity to thank the funder (Local Places for Nature), Natural Resources Wales (for help with herbicide permissions), the contractor (Phlorum) and most especially the 25 landowners  along the Usk who without exception were all pleased to work with us on this project. Roll on 2021!

For further information please contact:

Beverley Lewis – Invasive Non-Native Species Co-ordinator, Bannau Brycheiniog National Park Authority, 07854 997 508.