Tamar Invasive Plants Project

The Tamar Valley AONB delivers the Tamar Invasive Plants project, on behalf of a partnership of four organisations (Tamar Valley AONB, Environment Agency, Natural England and Cornwall Council – known collectively as the Tamar Invasives Group).

The project continues treatment to control Giant Hogweed on an annual basis. Numbers of plants have shown a progressive decrease in the survey area in recent years. However, the 2021 season showed a slight increase which demonstrates the need for constant vigilance to prevent the spread of this invasive species.

Giant Hogweed Eradication Project survey and control

**The Giant Hogweed Eradication Project Review 2001-2021 is now available to view**

The map below shows the area surveyed for giant hogweed in 2021. Note: survey areas A-E (from Calstock Quay upstream on the River Tamar to the Tamar-Lyd confluence and further upstream on the River Lyd as far as Greenlanes Bridge near Sydenham) have been surveyed annually for a number of years. Survey area F was also surveyed in 2021, but no giant hogweed was located and the area will not be revisited in 2022.

overview map with Area F



Invasives Control in the Tamar Valley

What can be done? – lessons from the past and future action

In May, there was a focus on Invasive Non-Native Species (INNS) in the UK, with Invasive Species Week taking place towards the end of the month. A study in 2021 assessed the economic cost of INNS to the UK economy since 1976 to be between £5.4 and £13.7 billion. A combination of social and environmental problems caused by INNS makes it clear that action to control their spread, while challenging, should be taken if possible.

In advance of Invasive Species Week, the AONB and its partners in the Tamar Invasives Group, with the support of the South West Lakes Trust, held an event on May 12th at the Tamar Valley Centre. We looked at lessons learnt from the Tamar Valley Giant Hogweed Eradication Project and also focussed on Japanese Knotweed and Himalayan Balsam in the AONB and wider catchment.




The Tamar Valley AONB and our partners in the Tamar Invasives Group, are grateful to have been awarded an additional £10,200 funding through the Water Environment Grant (WEG) earlier this year, covering the cost of the 2021 survey and control work. In addition, South West Water generously donated an additional £4,895 in 2021, ring-fenced for future invasives work in the Tamar Valley.

Encouraging better water primrose reporting – August 2021

In August, non-native invasive water primrose (Ludwigia grandiflora) is in full bloom, which makes identification much easier. NNSS has provided a landing page on their website for potential new records.

Please can you look out for water primrose and report any sightings. The Environment Agency have recorded 44 sites, 16 of which have been eradicated. This is a tough plant to kill, so they want to manage sites before water primrose can get too established.

Images are available on the GB NNSS gallery with lots of other information on the species page, too.

Contact us

For more information about the project please contact Valerie Darwall on 01822 835030 or email vdarwall@tamarvalley.org.uk


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