- Himalayan Balsam is an annual plant that reproduces from seed.
- Plants can grow up to 2-3m tall.
- Each plant can produce hundreds of seeds which explode from ripe seeds pods up to 7m away.
- Can form a dense monoculture which smoothers out native vegetation.
- Plants have very shallow roots and when plants die back in winter the banks are left exposed and susceptible to erosion.
- It is an offence under the Wildlife and Natural Environment Act 2011 to plant or otherwise cause Himalayan balsam to grow in the wild.
Recommended methods of control.
- Manual pulling. Pulling should be performed prior to the formation of seed pods. HB has a very shallow root making uprooting by hand easy. Uprooted plants can be left to air dry and decompose. This method is highly suited to dealing with initial outbreaks of the species and in areas where balsam plants are mixed in with sensitive native species.
- Strimming and mowing of HB is effective but only prior to the seed pods developing. Any attempt to cut this plant once the seeds have developed will cause the seed pods to burst, spreading the plant. Strimming must severe the stem below the lowest node as a plant can regrow from anything longer being left in the soil.
- Spraying using knapsack sprayer and systemic, glyphosate based herbicide is widely accepted as the most effective chemical suitable for use near watercourses. The main disadvantage to using herbicides to control any invasive weed is the unavoidable application to native plants growing in the immediate vicinity of the target species. Consequently, spraying is only recommended where HB forms large dense stands and prior to flowering.
As HB is an annual and its seed viability is thought to be around two years, it can be eradicated in a relatively short period of time with sufficient effort. Strategic control from the upstream limit is required to achieve this goal.
Download Poster here (pdf): Himalayan Balsam Poster