Eradication of Japanese Knotweed on a large site in South Wales
Client: Site owner
Contract period: 130 weeks
This large manufacturing site in South Wales was extensively infested with large stands of Japanese knotweed. An options appraisal was carried out which identified various potential approaches for knotweed eradication. Since site redevelopment in the affected areas was not scheduled to start for at least two years, herbicidal treatment was considered the most cost effective option.
A proposal was submitted to our Client to treat the knotweed stands present within the whole site boundary, but also incorporating a 5m buffer zone on adjacent sites. A pre-works survey was undertaken to determine the locations and extent of the knotweed stands. A large number of knotweed stands were identified, varying in size from 2m x 2m up to 25m x 30m, covering an estimated area of 9,500 m2 on this 44 hectare site.
Application of the systemic herbicide, glyphosate, was undertaken using knapsack sprayers with extendable lances. A coarse droplet nozzle was used to keep drift to a minimum and to avoid migration of herbicide from the target plant. Stem injections were undertaken in sensitive locations such as close to the nearby river and in the vicinity of other sensitive non-target plants such as trees and ornamental shrubs.
More than 90% of the Japanese knotweed was eradicated during the first season of treatment, with more than 99% removal after the second season. The remaining dwarf, stunted regrowth was eliminated during the third season.
- Options appraisal taking into account time available and budget
- Discussions with Environment Agency
- Risk assessment in connection with nearby river, water feature, wildlife, ornamental plants and site workers
- Treatment of knotweed stands by qualified staff holding National Proficiency Test Council (NPTC) Certificates of Competence for Pesticide Use
- Validation and reporting
Our solution was very cost effective and allowed our Client to redevelop areas of the site previously heavily infested with Japanese knotweed.
A pdf version of this Japanese knotweed eradication case study is available here.