The most common and preferred treatment method is herbicide treatment. The best time for Japanese knotweed to be sprayed is when the plant is actively growing as the herbicide we use is a systemic translocating herbicide. The herbicide treatment is most efficient on a warm, sunny day.
We use various chemicals to eradicate Japanese knotweed. The chemicals we use are 300 times stronger than what is available to the public and some of the chemicals we use are simply dangerous to be available in any form to the public.
- If the herbicide treatment is used it would be a glyphosate-based product as this is a systemic translocating herbicide which kills the top of the plant as well as the rhizome or root.
- The chemicals we use are 300 times stronger than what you, as a member of the public, can buy.
- In year one, we treat the invasive weed by spraying it four to six times over the growing season. If there are other plants in the area that need to be protected then stem injection can be used for Japanese knotweed.
- Monitoring is carried out in year two. If no growth is seen, we monitor for a second year and then declare the site free of any invasive plants. A completion certificate is then issued.
- Soil should not be moved off-site – it may still be classed as controlled waste as it could still be contaminated with dormant rhizome. It should instead be used in landscaping areas where it can be monitored.
- Your 10-year guarantee starts once your certificate of completion is issued.