Like any living organism it can be destroyed, It just takes time. Japanese Knotweed is particularly strong and can grow from very small fragments into a fully established plant. Our advice is to choose a company that has experience in this field, do not get duped by an intimidating sales pitch or anecdotes, simply be aware of the facts to make an informed decision. There is plenty of information on the internet and many specialists like us have a good level of content on their websites. For a standard herbicide programme you should expect multiple visits by the contractor plus a period of monitoring once the treatment has been completed. If the contractor states they can eliminate Japanese Knotweed in a year avoid them no matter how cheap they are!