Cut and Stem Fill
The "cut and stem fill" method has been developed as an alternative technique for treating Japanese Knotweed in certain situations, as well as being the treatment of choice for Himalayan Knotweed. In the case of Japanese Knotweed, there are many sites where the risk of spread of the plant by human activity or environmental conditions are such that the time required for a stem injection treatment to take effect becomes too long and a risk in itself. Examples include roadside conditions where the plants are encroaching on the vehicle carriageway or along riverbanks where the plants are already encroaching onto the waterbody. In such circumstances it is often better to remove the viable plant material immediately and to then treat the lower plant and rhizome in situ. In the case of very mature Japanese Knotweed, this technique may also be necessary if the stem itself has become too woody and cannot be pierced by a needle. Himalayan Knotweed, on the other hand, has a very narrow hollow stem which, even when fully mature, is not practically suitable for treatment by stem injection. The "cut and stem fill" technique is therefore a more practical option for its control.
The "cut and stem fill" method requires the stems to be cut off low down on the plant, and a calibrated dose of neat or diluted systemic herbicide delivered directly into the hollow core of the remaining stem. The objective is the same as in stem injection, which is to deliver a dose of herbicide as close as possible to the plant's rhizome. For very mature Japanese Knotweed, the success rate of this method can be improved by using long spear needles to deliver the herbicide dose closer to the plant's root crown and rhizome system. It is important to note that when deploying the "cut and stem fill" technique, all cut plant material must be very carefully managed and safely disposed of.