Invasive species such as Giant Hogweed, Japanese Knotweed and Himalayan Balsam, pose a serious threat to our natural heritage by out-competing native species. They can out-compete because the natural checks and balances (e.g. predation) which native species are subject to do not affect non-native species.
The Project uses various elimination methods, including spraying (with certified herbicides) and hand-pulling, to ensure that these damaging invasive species are prevented from flowering each year. For plants such as Giant Hogweed, with a seed-life of up to 12 years, this is vital in ensuring the eventual eradication of the species from the Tweed catchment.
The Project is a close collaboration between Tweed Forum staff and local landowners, farmers, ghillies, fishermen and volunteers. This means that the control work is carried out in partnership, a key factor in the success and longevity of our work.
After 10 years of catchment-wide control, Giant Hogweed coverage is greatly reduced and all plants have been prevented from flowering. This means that the seedbank for this species should be decreasing year on year making eventual eradication more likely.
Japanese Knotweed has proved more challenging to control, however, it is more widespread than previously thought. A number of control methods have been trialled but the method of manually chopping the Japanese Knotweed down and then spraying down the stems appeared the most successful, with patches treated in this manor vastly reduced in density and abundance.
The status of Himalayan Balsam control in the Till sub-catchment is heartening with a steady decrease in the presence of this species.
During the initial years of control, hand pulling was the method of control adopted, however, this proved to be very slow and costly, making it impossible to cover the whole river. In 2007, the decision was taken to use chemical control and a clear reduction in infestation has shown that this Himalayan Balsam does respond relatively quickly to coordinated control.