Japanese knotweed
Old canes show what look like injection marks and this year's growth was not seen. What treatment record has a mark on a cane not replaced?
A mark on a cane has not replaced a treatment record. Old canes show what look like injection marks, and this year's growth was not seen. A hole that resembles an injection is a mark on dead or old stem. It is not a document naming a contractor, a date, or a herbicide programme. The survey has recorded the look of the marks and the growth it did not see. It has not adopted those marks as proof that treatment was done, finished, or successful.
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?
Stem injection is one way contractors treat knotweed, and old canes can carry the scars. Scars are not the file. A treatment record would set out what was done, when, and with what follow-up. The surveyor saw marks that look like injections and did not see this year's growth, so they cannot report whether the plant is active now. Looking like a treated cane is not a guarantee, and it is not a management plan. The home survey has not converted a mark into paperwork that was never produced.
Ask the solicitor for the actual treatment record, and do not let injection-like marks stand in for it. Tell them this year's growth was not seen, so the survey has not reported current growth. If you need the status of the plant, that is a specialist look at the right season. Keep any later letter from a contractor separate from a hole in an old cane.
What should you ask your surveyor?
- What do the marks on the old canes look like?
- Was this year's growth present to be recorded?
- What treatment record was missing?
What are the typical next steps?
- Ask the solicitor for the actual treatment record, not the marks on the canes.
- Tell them this year's growth was not seen.
- If the plant's status matters, arrange a specialist look in the growing season.
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 the old canes look dead, has this year's growth been reported?
No. Dead-looking canes do not report this year's growth, which was not seen. They also do not replace a treatment record. A mark that looks like injection remains a mark. Dormancy, or death, of the stems you can see is not a certificate that treatment happened or that it worked.
Does a mark on a cane name the contractor or the date of treatment?
No. A hole in a cane does not name the contractor or the date. It does not say what was injected, or whether a programme was finished. The treatment record is the paper those facts would live on. The mark has not replaced it, and this year's growth was not there to be described.