Timing is everything, especially when dealing with invasive species.
The key to successfully chemically treating Himalayan balsam and Giant hogweed is applying herbicide at the right time. Application needs to be when the plants are young and before they flower and begin to form seed.
Chemical application should be made early in the growing season when the leaves have formed and are fully open (May – June). By treating plants early you can prevent them from setting seed and spreading the infestation further.
The clock is ticking…
As chemical can take a few days to kill individual plants, and the plant can still go onto producing viable seed within this period, mechanical options may be recommended the weeks before seed dispersal.
For example, in mid-summer, Giant hogweed seed heads can be bagged and cut*, and Himalayan balsam can be cut back, or hand pulled (making sure the stems are broken), to prevent the spread of this year’s seeds.
*Giant hogweed should only be dealt with by professional wearing full PPE
Missed the boat…
Once the plants set seed (or are in the process of doing so) chemical treatment and mechanical clearance are no longer an option.
If the areas of Giant hogweed and Himalayan balsam fall within a development footprint, they will require mechanical remediation to remove soils containing the plants and viable propagules prior to development and in accordance with relevant legislation.
If the areas are in a garden, or in an area that is left undisturbed, the plants can be left to die back and rot down naturally over the winter period. Plant seeds can remain viable in the soil (seed bank) for a number of years, for this reason a chemical treatment programme may be recommend to ensure that plants that have not germinated this year can be treated the following year… The cycle continues.
Although you may have missed the window of opportunity this year, don’t miss it the next! Every year that invasive species are left untreated is another year of growth and spread, meaning that a small and manageable infestation can become a bigger (and more expensive) problem.
Don’t leave it another year, contact us today to discuss options for your land.