• Himalayan balsam (Impatiens glandulifera)

Himalayan balsam (Impatiens glandulifera)

Himalayan Balsam originated in the Western Himalayas and was introduced in the British Isles in 1839.  Growing 2-3m in height, it is found mainly along river banks as the silt left by flood water is an ideal habitat resembling that of its native Himalayas. It presents no danger to humans or livestock, but it out-competes native species leaving the ground bare in winter and susceptible to erosion.

When it has set seed in late June or July, being touched by people or animals, blown by the wind, or air gusts from passing traffic, can trigger the seed pods to explode and spread seeds approx 2 – 7 metres, further in water or on feet or car tyres.  Seeds can remain viable for 18 months, so a two year programme is the minimum to control it.

It should be dealt with before it has set seed to avoid a further season’s seeds being dispersed, that is, before July. It can be hand-pulled, especially when it is smaller, although hand-pulling is laborious and time-consuming. It can also be cut off below the bottom node with a scythe or strimmer, and as the more mature cut plants will produce many new roots from each node if the plants are left on the soil, the cut material is best moved elsewhere to dry out. It can be treated with herbicide, but as it is often found near watercourses, Environment Agency permission must be sought before treatment.

As some seeds will remain dormant in the soil, the treatment will need to be repeated again that year and at least for a further year, or longer if any further plants are allowed to set seed.  Even though a treatment programme may be totally effective, new seeds can be brought in to the area just as the original ones were, so the cycle repeats itself.  Ongoing attention is essential.