Invasive Plant Management

This section of the website contains information on how to plan an effective control programme for a number of invasive plants. While the guidelines focus on Himalayan balsam, Giant hogweed, Japanese knotweed, Rhododendron and Cherry Laurel.

Management quick guide

When considering controlling or eradication of an invasive plant species in a defined area, managers may have to deal with a large number of issues. The following ten point quick guide is provided to help managers begin the planning process and to help ensure they comply with the relevant pieces of legislation as well as good practice in the control of invasive plant species.

1. Confirm species identification. Invasive species can be easily confused with other species. Therefore it is important to confirm whether you have an invasive species on your site that will require to be managed, or a common native species that does not need to be treated. If you suspect that there are invasive species on site and you require help verifying their identification, you should contact a local expert. Alternatively, you can submit images to Invasive Species Ireland for help with identification.
2. Develop and produce a site specific management plan. The plan should consider the management options that are appropriate and available to control or eradicate the invasive species from the site and the timescales that may be involved. A key part of any site specific management plan is to survey and produce a map indicating the species distribution on the site, including the appropriate buffer zones for potential growth. It may also be useful to try to establish the duration of the infestation, as long-standing infestations may be more dense or have larger seed banks, therefore may be more difficult to eradicate. Use the management plan template provided to guide you. Mapping the distribution of the invasive species is an important part of the management process as for some species, such as Japanese knotweed, by year 3 or 4 of a control programme they maybe more difficult to identify.
3. Consider designated sites and protected species on or near to the management area. Actions undertaken at your site could impact on nearby designated sites (i.e. European designated sites such as Special Areas of Conservation) or protected species within the area. Check if there are any designated sites for nature conservation close by and assess whether the planned management work may impact on them. A Habitats Regulation Assessment (HRA) may need to be done under the terms of Article 6 of the Habitats Directive. If protected species, or their resting places, are present (e.g. otters, badgers), you may need to apply for a license under nature conservation legislation in order to proceed.
4. Consider surrounding properties and households. Talk to adjacent land owners and make them aware of the invasive plant species issues and what you plan to do. It may not always be possible, but attempt to get their support. Control programmes will have a higher chance of success with support from the local community. Raise awareness of the issues and ensure alerts are placed in appropriate media e.g. the Invasive Species Ireland website. In addition working in partnership with adjacent landowners will help to protect your site from future re-introductions from adjacent land.
5. Consider whether a specialist contractor is needed. Decide whether you can successfully and safely carry out the management work or if professional contractors, with the relevant training and qualifications, should undertake the work. If appropriate, consider whether the execution of the work programme can be coordinated with voluntary clubs or local societies to gain their help/ support and to increase the understanding of invasive species issues. For example, species such as Himalayan balsam could be hand pulled by volunteers whereas species which require herbicide treatment, such as Japanese knotweed, may require a professional.
6. Safe handling and disposal. To reduce the spread of the invasive species, it may be necessary to set up cordoned off areas/ exclusion zones to stop people entering these areas whilst treatment is ongoing. The following may be appropriate for your site: marking out of contaminated areas; ensuring that vehicles do not work within contaminated areas; ensuring that soils from within infested areas are not spread to other areas; treating contaminated soils carefully; and if works are required within infested areas all machinery and equipment should be thoroughly cleaned to ensure infected soils are not spread to other areas of the site or off site. Works should be planned to avoid double handling of materials as far as possible to reduce the risk of spread. If wastes are being transported off site, ensure that they are appropriately transported by a licensed waste carrier who is informed that the waste material contains an invasive species as part of the waste transfer documentation. It is advisable to contact the licensed landfill site in advance to ensure they will accept the waste material. Failure to inform the landfill site that the material contains an invasive species would be an offence under both wildlife and waste legislation.
7. Health and safety legislation and procedures. All planned works should be carried out in line with relevant health and safety legislation and procedures. In particular, all staff should be aware of the particular health issues related with giant hogweed if working in proximity to this plant.
8. Resourcing. Identify all of the resources that will be required to complete the planned management works in the anticipated timescales. Ensure that all of these resources are available when the works are being carried out; if necessary these should be ‘dedicated’ for the duration in order that the works can be undertaken swiftly and efficiently. This will reduce the risk of spread to other parts of the site. If the works will take more than one year, ensure you have sufficient funds to complete the programme in future years or that efforts will be put in place to obtain appropriate funds.
9. Monitoring. Regular monitoring should be undertaken to identify follow up works required for any missed plants, late germinating seeds, reintroduction or any newly arrived invasive species.
10. Staff awareness of invasive species. All members of staff should be made aware of the presence of invasive species on site; this should include how to identify them, where they are located, how they are being dealt with, how they are spread, any biosecurity measures they should implement and who to report additional sightings to. Also ensure that new members of staff are provided with the same information during site induction.