For some years, we’ve been trying to eradicate the Himalayan Balsam on the lower reaches of Bourn Brook. Although a pretty plant, it is highly invasive, so crowds out everything else. However, our problem has been that reeds and nettles have made it very hard to remove the Himalayan Balsam from the lower reaches of Bourn Brook, so its been quietly spreading… But we’ve now got help!
Pembrokeshire have a very useful advice leaflet, which includes the suggestion of using contractors to brush cut an area in early summer. They point out that this very substantially reduces the amount that needs to be hand pulled by volunteers, and “on a flood free site can get rid of most plants within a season”.
We’re excited about this idea, so earlier this year we raised the funds to engage contractors to help us by cutting back the reeds and nettles in advance of the main volunteer working parties.
We’d realised that we needed to start by cutting back the reeds, before the reed warblers arrive in mid April. The plan is that this will encourage them to make their nests a few hundred yards downstream, where they won’t be disturbed while we deal with the Balsam. They can then return next year (or the year after)
We started with a little preparation work in March 26, when volunteers cut back a bramble bush and piled up some fallen branches.
Trumpington Farm Company then kindly used their flail mower to cut what they could.
Then in late March 2026, our contractor (Gary, from MLP) worked hard for 2 days cutting back the more fiddly bits along the banks of the brook.
This created a delightfully clear meadow, all the way to the bank of the brook
By mid April we could see tiny Balsam plants plants starting to emerge, ahead of the nettles. It was very satisfying pulling them out by the handful!…
We will be repeating the cut in late May, aiming to once again, remove all the nettles, reeds and Himalayan Balsam plants on the south bank of the brook. This should substantially reduce the amount that we need to do by hand. It should also make it much easier to see new Himalayan Balsam plants when they start to emerge from remaining seeds.
To “finish” the job, we plan to run volunteer working parties roughly monthly from June – October to pull up any newly emerging Himalayan Balsam plants…. With your help and persistence, this should go a long way towards eradicating Himalayan Balsam from this beautiful spot, just upstream of Cambridge.
If you would like to help by spending a few hours pulling Himalayan Balsam in this beautiful spot this summer, do signup here, or email us on info@camvalleyforum.uk