Japanese knotweed
A herbicide schedule lists visits and the last date has passed on the face of the page. What visit has the survey not confirmed took place?
The survey has not confirmed that the last listed herbicide visit took place. The schedule names visits, and the last date has already passed on the face of the page. A date on a programme is not proof the contractor attended, that herbicide was applied, or that the knotweed responded. The survey has read the paper. It has not stood on site for those visits, and it has not matched the schedule to what is growing.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Herbicide work on Japanese knotweed is a sequence of visits, not a single spray that ends the matter. When the last date on the page is already past, the question is whether that visit happened and what was found. A schedule can be a plan that was never completed. The survey does not turn a timetable into evidence. It has not named the chemical, and it has not said the stand is dead because the dates have run.
Ask the solicitor for the contractor's records of those visits and for any letter saying the programme is finished. Do not treat the schedule in the pack as confirmation the last visit occurred. If stems are still there, say so to whoever is managing the treatment. The survey has not certified eradication and it has not extended the programme. Keep the paper and the plants as two separate facts.
What should you ask your surveyor?
- Which visit date on the schedule has already passed?
- Has the survey confirmed that last visit actually took place?
- Was any comparison made between the schedule and the stems on site?
What are the typical next steps?
- Treat the passed date as an unverified visit, not as completed treatment.
- Ask the solicitor for the contractor's record of that visit.
- Do not read the schedule as a certificate that the knotweed is dead.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If no stems show in winter, did the last visit succeed?
Dormant ground is not proof of a visit, and it is not proof the plant has gone. Japanese knotweed dies back above ground and can return from rhizome. The survey has not confirmed the last listed visit took place, and it has not certified eradication. A bare bed out of season does not complete the schedule.
Can you add the next visit yourself and call the schedule current?
No. Writing a new date on the page would not be a contractor's visit, and the survey would still not have confirmed the visit that has already passed. Treatment records have to come from the firm that did the work. The report has not extended the programme and it has not identified a chemical.