Often, our most cost-effective method of controlling Japanese knotweed is our  herbicide treatment method. As such, this treatment will involve a schedule of  vigilantly managed Japanese knotweed sprays. This is where the correct use of the chemical sprays will take place over a sustained period of time  (typically 3 years). Due to this, it will exhaust the plant and prevent the spread and growth of Japanese Knotweed. The herbicide treatment is most efficient on a warm day. In fact, we use various chemicals to treat Japanese knotweed. One of which, is 300x stronger than what is available to the general public and one is not available to the public in any form.