Controlling Himalayan Balsam
The initial objective for effective control is to develop a strategy for a treatment schedule, usually in the form of a Management Plan, with the prevention of Himalayan balsam seed formation and spread as its primary purpose. This can be achieved in a number of ways, so consideration has to be given as to the most appropriate option. Environmentally sound options are preferable; although sadly not always the most cost-effective or achievable, these options should be first on the list. Firstly, consider whether control can be achieved using non-chemical means such as digging out or suppressing with mulch. Where these methods are not feasible, chemical controls may need to be used.
On a garden scale, appropriate measures include pulling up young plants by hand when the soil is moist. The best time for this is in May/June when the Himalayan balsam has reached a reasonable height, but before it has produced flowers. For large infestations on more open sites, mowing, strimming or even grazing (if you have a few goats or cattle handy) may be more appropriate.
If the flower spike has already formed, remove it before the seed pod can develop. This is also a good time to trim the plant, as it less likely to survive trimming than earlier in the year. If you are cutting or strimming, make sure you wear suitable protective clothing.
Larger scale areas should really be dealt with by professionals. Manual techniques may not be suitable in these circumstances. Using appropriate machinery, the infestation can be cut, pulled, mulched, dug or stripped out. Control of the infestation, including the seed bank will, under most circumstances, take a number of years, with repeated visits to the site.
Himalayan balsam prefers moist fertile areas often near waterways. It is essential that weed-killer is not allowed to enter waterways. Environment Agency permission must be sought and given before undertaking spraying near rivers, streams and ponds.
Controlling the growth of new Himalayan balsam plants and the seed bank can be achieved through repetitive herbicide treatments of the live plants prior to seed formation. With this process, three or four years will normally be needed before the seed bank is sufficiently depleted. Consideration has to be given to treating all plants in a location rather than those growing on a single property since seed can be transported in from neighbouring infestations. Using a selective herbicide may be most appropriate as it is desirable to limit the amount of other plants killed or damaged by the treatments.
Disposing of Himalayan Balsam
Himalayan balsam material is classed as a controlled waste so, if it is taken off site, it can only be disposed of in licensed landfill sites with the required documentation.
Bees, and wasps, love Himalayan balsam and large infestation will be well frequented. Sting relief spray at the ready…
How PBA can help…
PBA have many years experience and are accredited to deal with all aspects of giant hogweed management and control. We work with private property owners, estate agents and management, developers and public sector organisations in the remediation of land impacted by giant hogweed and provide Management Plans that enable effective control solutions to be developed and actioned.
For more information, call PBA on 0203 174 2187 or 01202 816134.
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