Himalayan balsam (Impatiens glandulifera) is a terrestrial botanical species. The native home range for this plant is the Himalayas of which it is named after. It is known to be a high-impact invasive species in countries that it is alien to, hence the plant holding the status of ‘alien invasive species’ within Ireland.
Himalayan Balsam is thought to have been first introduced to Ireland during the late 1830s. This species was introduced for the purpose of being an ornamental garden plant. This reason is pretty much the same for the majority of botanical non-native species in Ireland, as having exotic plant species in your garden at the time was considered a sign of grandeur. For this reason, many non-native botanical species in Ireland can be found in large estates and beautiful old public gardens across the country.
Since its introduction in the 1800s, this species has reached the majority of parts across the entire island. This plant is very adaptive and for this reason it has thrived in our climate and nutrient-rich soils. This ability to adapt has allowed the plant to become widespread and highly invasive across our country as well as parts of Europe.
This plant is highly problematic for our island because it is thought to be the tallest annual plant in Ireland, growing more than 10 feet high. The term annual refers to the fact that this plant completes its entire life cycle in just one year!
Himalayan Balsam grows higher than our native plant species and out-competes them all for light availability and many other resources. The plants that grow underneath this plant die off quickly because of the lack of light and nutrients that are available due to the presence of this invasive species.
This plant can be found commonly across Ireland in areas that have damp soils such as river banks and alluvial woodlands and its flowers can be observed during June to October.
There are various management options that can be used when controlling this alien invasive species in Ireland. For small-scale infestations, such as in domestic gardens, this plant can be removed by just pulling them up out of the ground. This species have very shallow roots so removal by this method is very easy!
For more larger-scale operations of removal, chemical or biological controls can be put in place. Chemical control involves the use of herbicides, foliar sprays or Glyphosate. Chemical control should be the absolute last resort due to the impacts these chemicals have on our environment, but in many difficult large cases they are often the most appropriate methods of removal!
Biological methods include the use of livestock such as cattle or sheep from the months of April right through until winter. The livestock keep vegetation levels at an appropriate level throughout these seasons and greatly help with the control of invasive plant species as they can easily remove them by consuming them throughout the day.
There are a few limitations to using grazing as a management technique, as poaching can happen. Additionally the grazing of riparian areas can have a negative impact whereby our native vegetation that act as a buffer zone become removed and its function is demolished in that area, causing environmental problems.
For this reason, it is important to correctly assess the impact grazing will have as a management control for Himalayan Balsam in riparian areas, as this is a common area that this species can be seen throughout Ireland.