A new natural treatment – a rust fungus, has been discovered, which will, it is hoped, see the eradication of one of the most invasive weeds in England and Wales, the Himalayan Balsam (Impatiens glandulifera).
After an eight year research programme with the help of funding from Defra and the Environment Agency, with contributions from Network Rail, the Scottish Government and Westcountry Rivers Trust, researchers at CABI are to proceed with a series of controlled releases of rust fungus at locations in Berkshire, Cornwall and Middlesex, as part of field trials to control the weed.
"Many anglers know the problems of Himalayan balsam on the river banks, not only taking over from our native flora, but also creating unstable mud banks, which easily erode, causing siltration issues in rivers and waterways,” commented Mark Owen, Angling Trust Head of Freshwater.
"This is a great step forwards in tackling Himalayan Balsam. This invasive weed prevents our native plants from flourishing, can increase flood risk, and costs the British economy £1m per year to clean up,” added Lord de Mauley, The Minister for the Natural Environment.
"The release of the rust fungus against Himalayan Balsam is a result of over eight years of research evaluating the safety of its use against the target species,” explained Dr Robert Tanner, senior scientist at CABI, “Over time, we should see a decline in the Himalayan Balsam populations along our rivers, with native plant species recolonising these degraded sites."
Himalayan Balsam has rapidly become one of the UK's most widespread invasive weeds: colonising riverbanks, wasteland, damp woodlands, roadways and railways. The Environment Agency estimates that the weed occupies over 13 per cent of riverbanks in England and Wales. It can reach over three metres in height, and competes with native plants, reducing biodiversity. Large-scale chemical and manual control is often not feasible or economically viable.
Using existing measures, the Environment Agency estimates it would cost up to £300 million to eradicate Himalayan balsam from the UK.