GIANT Giant Hogweed

Our staff have once again been out along the Wye and Usk continuing the control treatment of Giant Hogweed (Heracleum mantegazzianum) as part of the Giving Up The Weed project. This project, established in 2007, sought to eradicate the invasive plant within the catchments of both rivers. Year on year, the infestation of Giant Hogweed has been reduced, but each seed head can produce 100,000 new plants, so it is imperative that no flowers survive.

To prevent the likely re-infestation, our staff use a combination of different methods to further reduce the existence of this invasive species along our rivers’ banks. Each year, a Knapsack walkover of the two rivers is carried out, spraying any plants which are found before they flower and seed. Later in the year, a boat survey is completed to remove any flowering plants which were missed or were inaccessible from the bankside.

Giant Hogweeds threaten surrounding biodiversity, cause river bank erosion and also pose a severe risk to human health. The sap of a Giant Hogweed contains phytotoxins, which if in contact with skin and in the presence of sunlight, cause a rash which is often followed by severe burns and scarring. These burns may recur for several years following exposure, making the work done in this project even more important.

Don’t touch it, report it!

If you come across a plant that looks like a huge cow parsley, please do not under any circumstances touch it. If it is on a riverbank in the Wye or Usk catchments, please take a photo and email it to us with as close a description as possible of its location. The What3words app is especially good for recording and reporting the location of Giant hogweed and other invasive plants.

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