A RIVER is to have its banks cleared of destructive invasive species that harm the natural environment.

Tees Rivers Trust, which was given £179,000 at the start of this year from the Green Recovery Challenge Fund, has begun the first set of biocontrol releases for invasive non-native species Himalayan balsam and Japanese knotweed.

Jennifer Grant, Tees Rivers Trust Project Coordinator, said: “Both the natural and cultural heritage of the River Tees and its tributaries are at risk due to the presence of invasive non-native species. 

“A typical 100m transect of a stretch of the Tees in its middle and lower reaches contains approximately 60-100 species of flora and fauna, whereas a similar sized stretch colonised by invasive plants comprises little else other than invasive species such as Japanese knotweed and Himalayan Balsam. 

“The aim of this project is to create a long-term self-sustaining biological control system for two of the most abundant and problematic invasive non-native plants within the Tees catchment. 

"It will form the beginnings of a more sustainable, cost effective and efficient method of controlling them.” 

The project is using government approved biological control agents produced by the Centre for Agriculture and Biosciences International (CABI). 

There are 11 Himalayan balsam and five Japanese knotweed biological control sites in various locations throughout the Tees catchment, which will be managed and monitored for the long-term establishment of self-sustaining biological control agents.

The highly specific biological control agents to be released include a rust fungus that exclusively attacks Himalayan balsam plants, and a psyllid, a tiny, sap-sucking insect that is a Japanese knotweed specialist. 

The creation of these sites and release of the biological control agents will facilitate the re-establishment of native flora, increasing biodiversity in the natural environment, improving access, and restoring a safer amenity. 

Once established, the biological control agents from the initial sites will naturally spread over time to other areas affected by Himalayan balsam and Japanese knotweed.

They may also be used as sources to transfer and introduce plant material carrying the biological control agents to other problem sites. 

Funding came from Defra and was distributed by the National Lottery Heritage Fund.