Himalayan Balsam (Impatiens glandulifera)

Species

Distribution

Himalayan balsam (Impatiens glandulifera)

Photo courtesy of GB Non Native Species Secretariat

To view NBN location data click here

Impacts

Pathways

• Thick monospecific stands, shade out low level native plants reducing diversity and denuding riverbanks of understory vegetation.
• Winter dieback exposes soil to erosion.
• Greater nectar production makes flowers more attractive to bumblebees resulting in less pollination of native species.

• Escape from gardens.
• Natural dispersal.
• Contaminated soil

Management

Prevention

Correct disposal of garden waste. Do not discard plants with developed seed heads. Control of movement of soils contaminated with seed.

Physical Control

By hand pulling is an effective way of removing adult plants in small areas and is more environmentally friendly than chemical control. Care should be taken to remove the whole plant as plants can regrow within the same season if cut and not fully removed.

Cutting or grazing can also achieve control but cutting should not be attempted once the seed heads have formed, as this would effectively spread the plant. Continual monitoring should be undertaken to prevent reseeding as cut plants can regrow. The first monitoring visit should be timed shortly after cutting, as Himalayan Balsam has been known to re-grow within weeks of control.

Chemical Control

Can be used for high density large populations but the use of herbicides near a watercourse is restricted and requires prior written permission from SEPA. Chemical control can take up to two years to eradicate the plant (with additional monitoring following this).

Biological Control

None known.

Important Note

Himalayan Balsam is an annual plant and therefore the key objective for control of Himalayan Balsam is to exhaust the plants seed bank. This is done by repeatedly removing adults before they set seed.  Seed bank longevity is about two years and control programmes should be undertaken for the whole of this period followed by a 5 year monitoring programme.  It may also be necessary to consider a bankside rehabilitation programme to prevent erosion.

Links

Non Native Species Secretariat Fact Sheet

SNH SAF Identification Guide

SRDP-eligible methods of control

NetRegs Guidelines

SNH SAF Training Manual

Invasive Species Ireland Fact Sheet and Best Practice Document