A native of the Himalayas and related to the popular “Busy Lizzy” houseplant, the Himalayan Balsam (Impatiens glandulifera) was introduced into the UK in 1839 as a cheap alternative to expensive treehouse-grown orchids and spread quickly into the wild. Also known as “Indian balsam”, “jumping jack”, “Policeman's Helmet”, “Bobby Tops”, “Copper Tops”, and “Gnome's Hatstand”, this rather striking plant can reach up to 6.6ft in height with succulent stems and attractive orchid-like flowers.
Thriving in the UK climate, it is found mainly in damp woodland and along the banks of rivers and with no native pests or diseases to slow its advance; this rapidly growing annual has become an unwelcome invader across most of the UK.
Himalayan Balsam is deemed so damaging to the environment that is listed in Schedule 9 of the Wildlife and Countryside Act in England and Wales which makes it an offence to plant or allow it to grow in the wild.
Himalayan Balsam produces clusters of pink and sometimes white orchid-like flowers from June to October. Providing a plentiful supply of nectar the plant attracts bees and other pollinating insects to the detriment of our native plant species. Without the essential pollination by bees, our native flora struggles to reproduce.
Along riverbanks where it flourishes, the Himalayan Balsam out-competes and smothers local plant species causing them to struggle to survive or even die out altogether. In the autumn and winter months, Himalayan Balsam dies back leaving large areas of bare ground along riverbanks. Without any native plants with permanent roots in the soil to hold the riverbanks together, they weaken and become prone to erosion and eventual collapse.
Even though Himalayan Balsam is an annual species and reproduces only through seed, it is difficult to control once it becomes established because it often thrives in inaccessible places and its means of reproduction and spread is so very effective.
The ripe seed pods burst open when triggered by movement catapulting the seeds up to 20ft. Even the slightest movement is sometimes enough to cause the pods to pop open and eject the contents. Remaining fertile for up to 18-24 months the seeds are carried down streams and rivers and can be spread on the soles of shoes to previously unaffected areas.
In recent years this invasive plant has become such a widespread problem that in some areas ‘Balsam Bashing’ events are organised in an attempt to arrest its rapid spread. If the infestation is not too significant, this can be effective as Himalayan Balsam can be easily pulled up for disposal as the roots do not reach deep into the ground.
If the plants are cut down rather than pulled up it essential that it is done very low on the stem, close to the ground and below the first pair of leaves to ensure that more shoots and consequently, even more, flowers do not appear.
Any plants that have been pulled up or cut down in this manner should ideally be removed from the area for proper disposal.
With seeds surviving for up to two years, it is essential that the areas tackled in this manner are regularly inspected to ensure that no new plants are allowed to grow the following season.
‘Balsam Bashing’ at the wrong time can often make matters much worse, and it is essential to ensure that any efforts to manually pull up and remove Himalayan Balsam take place before the plants begin to set seed in late June. Disturbing the plants during the flowering season when the seed pods have ripened will only assist in catapulting the seeds further and exacerbate the problem.
With perseverance and a little luck, Himalayan Balsam can be brought under control quickly or even completely eradicated from an area in around three years.
With no natural pests or diseases in the British Isles, the UK Government tasked CABI (Centre for Agriculture and Biosciences International) to develop a safe and natural method of controlling Himalayan Balsam.
After years of research, CABI scientists discovered a rust fungus which affects only the Himalayan Balsam and not our native plant species. The hope is that by introducing a disease that will weaken the plant sufficiently, it will become more manageable and much less invasive.
The results so far have been promising, and if the trials are deemed successful the fungus will be released across the UK, and our native plants and habitats will have a better chance of competing.
If you would like to know more about CABI’s research into developing a biological solution to the Himalayan Balsam problem you can read in-depth about their progress at their dedicated website listed in our ‘Links’ section below.
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Field Guide to Invasive Plants and Animals in Britain
by Olaf Booy, Max Wade, and Helen Roy
Alien Plants (Collins New Naturalist Library, Book 129)
by Clive A. Stace and Michael J. Crawley