If Japanese knotweed is present at the property, the valuer must confirm what category/stage the knotweed is at and the following rules must be applied; 

Category A and B – The property may be considered as acceptable for mortgage purposes, subject to an inspection by a suitably qualified remediation specialist and commitment shown to the commencement of any recommended works under an insurance backed Japanese Knotweed Management Plan 
Category C and D – Acceptable to lend 

If the valuer identifies a heavy stand of Japanese knotweed on neighbouring land (eg very close to the boundary) that may present a threat, the subject property should be declined.