Current control methods

Traditional control methods are currently inadequate in controlling Himalayan balsam in the UK. This is often because the plant grows in inaccessible areas or sites of high conservation status where chemical and/or manual control is not an option. Land managers often give up when faced with controlling Himalayan balsam over a large area due to the inaccessible places where the plant grows.

Himalayan balsam monoculture on the river Camel, Cornwall, UK
Himalayan balsam monoculture on the river Camel, Cornwall, UK

Chemical control
Users must be aware of the risks involved when using chemicals to control any plant especially as it tends to grows near water. Consent to use specific herbicides near UK waterways must be sought from the Environment Agency.

Chemicals that are persistent in the soil may delay the planting of replacement species. Herbicides are usually sprayed but can also be applied directly to target plants using a weed-wiper or herbicide glove. Commonly used glyphosate-based herbicides are most effective in late summer however specialist advice for the most appropriate treatment should be sought (link to Useful Resources). Some herbicides can also be injected into the hollow stems of the plant immediately after cutting, however this is time consuming and costly.

Repeated herbicide treatments over several years are normally recommended for complete control of Himalayan balsam. Continued monitoring of the treated areas should also be carried out to ensure that no new shoots appear.

Physical removal
For short term control, Himalayan balsam can be pulled but this is not a long-term solution. Seeds are often carried down the river, so control needs to be undertaken on a catchment scale. Also access is often impeded making physical removal unworkable.