Dealing with Japanese knotweed in a let property

Why it matters

Untreated knotweed can block a remortgage and produce a private nuisance claim from a neighbour.

Legal requirements

• Knotweed is controlled waste and must be disposed of at a licensed facility.
• Allowing spread onto neighbouring land can amount to private nuisance.
• Local authorities can issue community protection notices for failure to control it.
• Sellers and lenders expect disclosure and a documented treatment plan.

Common mistakes

• Cutting or strimming it, which spreads fragments and worsens the problem.
• Putting the arisings in the garden waste bin.
• Asking the tenant to deal with it as garden maintenance.
• Leaving it untreated because it is at the back of the plot.

Practical guidance

• Get a specialist survey and a written identification before acting.
• Commission a treatment plan with an insurance backed guarantee.
• Tell the tenant what is happening, and mark the treatment area.
• Keep the plan and guarantee with the deeds for future lending and sale.

Identifying it correctly

Look for bamboo like hollow stems with purple speckling, shovel shaped leaves in a zig zag pattern along the stem, and creamy white flower clusters in late summer. Several harmless plants resemble it, including bindweed and dogwood, so pay for identification before spending on treatment. Photograph the growth with a scale item and note the date.

Treatment and lending

Herbicide programmes run over three to five years with periodic monitoring, and are the usual route where there is no development pressure. Excavation is faster and far more expensive. Lenders generally want a professional plan with an insurance backed guarantee rather than eradication before completion, so getting the paperwork right matters as much as the chemistry.