Japanese knotweed
A herbicide log has two visits and then stops. Has the survey decided the treatment programme is finished?
No. The survey has not decided the treatment programme is finished. The herbicide log has two visits and then stops, which is an incomplete record, not a completion certificate. Two attendances do not show that a plan ran its course or that the knotweed is gone. The visit saw a log that ends. It did not watch the treatment, did not dig for rhizome and has not declared the programme closed. Finish is unproved.
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?
Knotweed treatment is a sequence managed by a specialist, often with several visits and a record of what was applied. A log that stops may mean the rest is missing, the work ceased, or the later pages were not in the pack. The survey cannot choose among those. It can say the paper in hand is two visits and no close. Stems, crowns and disturbed ground, if seen, are separate from a claim that treatment is complete. The mechanism is a file that does not show an end.
Give the log to the solicitor and ask the seller for the full management plan, any guarantee and the later visit sheets. A knotweed specialist can say whether the programme is unfinished. The survey has not made that decision and has not told a lender the plant is clear. Do not describe two lines in a log as a completed treatment when you write to the lender or the insurer.
What should you ask your surveyor?
- What dates do the two visits show, and who wrote them?
- Is there a guarantee or a later page that was not in the pack?
- Did the survey itself see live stems, or only the incomplete log?
What are the typical next steps?
- Send the incomplete log to the solicitor and ask for the rest of the programme.
- Do not describe the treatment as finished.
- Ask a knotweed specialist if you need the programme judged.
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
Do two herbicide visits prove the crown is dead?
No. Two visits are two entries. They do not prove a crown is dead and they do not prove rhizome has been killed. The survey did not excavate and did not decide the programme was finished. Dead-looking ground on one day is not a completion test. The log stops, so the record itself does not close the question.
Should the lender be told the knotweed has gone?
No. The survey has not decided the knotweed has gone, and an incomplete log is not that decision. Tell the lender, if you must tell them anything, that treatment papers stop after two visits and that finish is unproved. A specialist conclusion, if you obtain one, is the later document. Do not upgrade the gap into an all-clear.