Updated: Jun 8, 2021
Himalayan Balsam, Jac y Neidiwr (Impatiens glandulifera) is native to the Himalayas, and seems to have got its Latin name from the impatiently explosive ejection of its seeds. It is a tall annual, with pink to mauve helmet shaped flowers seen from July to October, the whole plant dies back after the first frost. Detailed information can be found here.
It's quite pretty so what's the problem?
It has invaded our river valleys, damp woodlands and ditches since it was first introduced in 1839. Across the UK it has spread at the rate of 645km2 per year (CABI), a little more than the entire area of the Pembrokeshire Coast National Park. It can grow in the shade and quickly reaches up to 2.5m, forming dense stands that suppress native plants and woodland regeneration, leaving bare soil in winter that is prone to erosion during heavy rains and floods. The ballistic seeds shoot up to 7m on release, and survive through all conditions for about 2 years. They are easily transported further afield; floated on river waters and hitching a lift in mud trapped in hooves, boots or tyres.
It is on Schedule 9 of the Wildlife and Countryside Act 1981, as such, it is an offence to plant or otherwise allow it to grow in the wild. Welsh Government. So cutting it down and moving it without due procedure, or dumping it in a stream would constitute an offence as it re-roots easily, as would taking seeds to plant elsewhere. However there is no obligation to eradicate this species from land or to report its presence to anyone.
But its good for bees isnt it?
They certainly seem to love it, but its like chocolate to them, and you can't eat chocolate all day. (Pers. Comm. Matt Tebbutt) It seems that bees get hooked on its readily available nectar and visit it in preference to native plants nearby. So the local species take a double-barrelled hit of reduced pollination and being out competed. The pollinators themselves have a reduced diversity of nutrients in their diet, which can affect their health and the stability of their populations (Vanbergen et al.).
Some beekeepers comment that honey from areas of high balsam growth is less tasty or even has off tastes.
Well its got to be good for something, can we eat it or feed it to animals?
Yes to both, however harvesting is not encouraged as this can contaminate equipment and the collector, especially with seeds, and you could be committing an offence by removal of schedule 9 plant material off site.
If you do decide to try it then great care must be taken in harvesting it, transporting it and making sure that your clothes are not contaminated with seeds. Foraging is not a method for control and adds to the risk of spreading it.
There are foraging ideas for adding tasty flowers to salads and steaming the young stems to serve like asparagus, as well as eating the "nutty" seeds. Although the stems may be edible they contain high levels of calcium oxalate. This is leached out through cooking, but may accumulate if eaten frequently.
Grazing animals, especially cattle seem to enjoy it without ill effects. To the extent that you won't find it in grazed fields, and this has been used successfully as a method of control on suitable ground. Extra care needs to be taken when moving livestock from areas where balsam is growing to avoid spreading it on hooves or tyres.
But as its usually in woods or on river banks what other ways can we manage it?
There is excellent guidance on methods from the sites below, and a combination of methods is often the most effective.
I add below a few general principles gleaned from a conversation with Matt Tebbutt.
Get the landowners permission before venturing off the public right of way.
Start from the outside at a defendable edge, like the top of river catchment, a road, hard surfaced area, or grazed areas.
Large areas can be cut low when young with scythes, strimmers or flails. Clear brash & bramble the winter before to enable access. Follow up with pulling later in season.
It is important to avoid contaminating new areas by leaving cut/pulled plants on site, and scrubbing boots and tyres before leaving site. Detailed guidance on dealing with the arisings is contained in the links above.