Terrestrial plants

The following provides an indication of the most effective forms of treatment for the key invasive plant species. Treatment and management methods must always be tailored to the species and level of infestation at your site. This guidance should not act as a replacement for undertaking a site survey and developing a site specific management plan. Treatment should include all stands and buffer zones appropriate to the species.

Recommended method Biological Physical Chemical (herbicide) Other methods
Japanese

knotweed

Herbicide control unless site is needed for development. In these circumstances follow a combination of chemical and physical methods. None generally recommended at present. Deep excavation and deep burial. Hand cutting will not achieve control and may promote growth / spread. Do not use a strimmer as this will spread the plant. Various residual and non-residual herbicides are suitable. Please see the Invasive Plant Management Section summary table for more info. If your site is near water, you must ensure your chosen product is licensed for use. Read the label for more information. Root barrier membranes can also be used to contain the species and/or stop spread to your site. Other patented methods of treatment have been developed by commercial contractors. Ensure biosecurity measures are in place to prevent further spread off site of plant / rhizome material.
Giant hogweed Herbicide control. Spot treatment of isolated plants (March – June) prior to flowering head forming. Planned treatment of larger infestations. Monthly checks should be undertaken throughout growing season for any late germinating seeds. Not generally recommended at present. Removal of top ½ metre of soil which contains seeds and deep burial at a metre in depth with follow up checks for any missed seeds. Isolated plants may be dug out with a spade at a 45 degree angle during the early stages of growth wearing protective clothing. Various herbicides. Please see the Invasive Plant Management section summary table for more information. Health & Safety issues regarding handling/ contact with vegetation.

If your site is near water, you must ensure your chosen product is licensed for use. Read the label for more information.

Integrated management using a combination of methods may be required on your site. Other methods of treatment may be available through contractors. Ensure biosecurity measures are in place to prevent further spread off site of seeds.
Himalayan balsam Regular and planned hand pulling (Mid May – Mid June) prior to seed pods forming.  Monthly checks should be undertaken throughout growing season for any late germinating seeds. Grazing by cattle and sheep can be effective Not appropriate on all sites and must be part of a plan.

Research is currently ongoing in GB looking at classic biological control options.

Hand pulling individual plants prior to seeding is most appropriate.‘Balsam bashing’ is a popular form of control for voluntary groups to assist with. Strimming in mid May – to Mid June is also an option but should not be undertaken any earlier as it may promote regeneration with more seeds. Glyphosate and various other residual and non-residual herbicides.

If your site is near water, you must ensure your chosen product is licensed for use. Read the label for more information.

Not generally required for this species.
Rhododendron

Cherry laurel

Physical removal and/or herbicide treatment of stumps. Combination of both may be required. Can take many years to eradicate from a site. Grazing of young Rhododendron growth can be achieved using pigs. Must be part of a management plan. Due to the thick waxy leaves of Cherry laurel it is typically not grazed by animals. In addition it is known to be poisonous to some animals. Physical control of both Rhododendron and Laurel typical involves a combination of physical methods and herbicide treatment. Physical treatment typically involves the cutting of the plant close to ground level. The stump is then treated with herbicide or the young growth which emerges from the stump is spot treated by a foliar herbicide application.  ‘Rhody bashing’ is a popular form of control for voluntary groups to assist with. Mechanical removal can be effective if the entire root system can be removed. Herbicide treatment of stumps after vegetation has been removed. Combination of physical and chemical methods will usually be required.