Yes, I would say you should be mindful of it.
A seller who misrepresented the presence of Japanese knotweed on their £700,000 London property has been successfully sued for over £200,000.
Of course the facts of the case speak for themselves, worth a read – it’s been in the news recently, but generally speaking when you sell a property, be careful.
When asked to complete a TA6, the answer ‘not known’ is the safest option (unless you are a JK expert or have had treatment done).
Speak to your solicitor if you are unsure what to do. So many lawyers send these forms out with contract packs without checking with the seller, I’m sure of it 
(having acted on hundreds of purchases last year). Don’t leave yourselves open to a potential claim.
(having acted on hundreds of purchases last year). Don’t leave yourselves open to a potential claim.When I act for sellers I always go through the TA6 and check and advise on any issues that sellers may need to reconsider in their replies.
Likewise, when buying, don’t rely on what a seller tells you. Seek specialist advice and have your eyes wide open. Don’t cut corners on what is likely to be your biggest purchase by not taking, good legal advice nor having a survey carried out. Trying to save a few pennies at the outset may cost you greatly in the future.
‘Caveat Emptor’/buyer beware and all that (for what it’s worth!).