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. This species is penetrating well into the headwater with some particularly dense patches found up upstream of Selkirk on the Ettrick water. 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 subcatchment is heartening with a steady decrease in the presence of this species. Along stretches of the river Till there was complete coverage of Himalayan Balsam, leaving the sandy soils of the Till at a very high risk of erosion during higher waters because of the bare ground and shallow root system of the plant. 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 to eradicate large dense patches in order to be more cost effective and provide a more viable control option. A clear reduction in infestation has shown that this Himalayan Balsam does respond relatively quickly to coordinated control.
Elimination of emerging invasive species during each control season means that native plants are less adversely affected and the further spread of these invasive species is halted. As Giant Hogweed is also a public nuisance (contact with its sap results in chemical burns) removal of this species ensures public access to the Tweed’s rivers and burns is safe and enjoyable. (Feb 2013)