Himalayan Balsam – Adair Walk
If you visited the Norfolk and Suffolk Aviation Musem on Tuesday 31st July you may have seen some activity by the boardwalk close the River Waveney. A small working party consisting of four volunteers from the River Waveney Trust (RWT) worked hard and long despite the hot weather to physically remove the heavy infestation of Himalayan balsam that was nestling deep in swathes of nettles, encroaching on the river banks and the surrounding land.
How did we do this?
Removal was done by hand pulling as these plants have very shallow roots. Flower heads were bagged and removed and then the stems were laid out to dry and die on the river bank or in the open area (see photos)
Description
It has large ‘policeman’s helmet’ pink-purple flowers. Leaves have small red teeth at the edge and are in whorls of 3 or opposite. The stem is reddish and hollow (see photos)
Local names include Nuns and Jumping Jack, as well as Policeman’s Helmet, Bobby Tops and Gnome’s Hatstand which refer to the fact that the flower is decidedly hat-shaped. Himalayan Balsam and Kiss-me-on-the-mountain arise from the fact that the plant originates in the Himalayan mountains.
Why do this?
Himalayan balsam (Impatiens glandulifera) is a highly invasive annual weed, which has spread rapidly throughout the UK since its introduction in 1839. Native to the Himalayas, this vigorous growing annual has the ability to reduce biological diversity by out competing native plants for space, light and resources. It is the largest annual plant in Britain, growing up to 2.5m high from seed in a single season (see photo). Himalayan balsam spreads quickly as it can project its seeds for more than four metres. Many seeds drop into the water and contaminate land and riverbanks downstream, but the explosive nature of its seed release means it can spread upstream too.
What impact does it have?
During the summer months, Himalayan balsam attracts pollinators away from native species with its high sugar nectar content and extended flowering period. This form of indirect competition can reduce the genetic diversity of native species and lessen their fitness by reducing seed set. Then in the autumn when the plant dies back it can leave the bank bare of supporting vegetation and prone to erosion, dead plant material can enter the water body thereby increasing the risk of flooding.
Economic status
It is currently estimated it would cost between £150-300 million to eradicate Himalayan balsam from the UK.
Official status
This species is listed in Schedule 9 of the Wildlife and Countryside Act in England and Wales, it is also an offence to plant or otherwise cause to grow these species in the wild.
For further details or comments please contact Gillian Allard, RWT Trustee: gillianallard2013@gmail.com
Well done all Waveney River Trust volunteers.