Invasive species survey & control: Himalayan Balsam

The client: Affinity Water

The site: The River Mimram is approximately 20km in length. The Mimram is classified as a chalk stream, a rare and valuable habitat in England.

The brief: As part of Affinity Water’s aim to restore biodiversity along the Mimram, Maydencroft was commissioned to undertake a programme of Himalayan Balsam control in the Spring/Summer of 2017 and 2018.

Our solution: Over 13km of river was surveyed to confirm the presence or absence of Himalayan Balsam. Detailed maps were produced for each site highlighting zones for trained operatives to carry out management (hand pulling, strimming or flailing). An ecologist was always on hand to provide advice and supervise works where necessary.

The result: Of the 13km of river surveyed in 2017, 7km was confirmed to be free from Himalayan Balsam and control was implemented on the remaining 6km. In 2018 control continued and access was agreed on more land, a further 5km of river was confirmed to be free from Himalayan Balsam. As the seeds can survive in the soil for up to three years, the project will continue for a number of years with the ultimate goal of eradicating Himalayan Balsam from the River Mimram.

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