Japanese knotweed is a large invasive weed of perennial plants. These killer weeds grow in the areas which are used or disturbed by humans which includes Lands, House, Gardens, lawns, etc. It can grow from the smallest crack that may occur on roads, drains, pavements and even on large buildings and bridges. It might destroy the grave yards and classical monuments or architecture. Moreover, the flood defence can also be affected by its growth.
There are several best ways for Japanese knotweed control. Generally, other demands put upon the land in question will define how Japanese knotweed should be controlled. Unfortunately, money as with everything comes into the Japanese knotweed control equation. The cost of Excavation far exceeds that of the chemical control the normal alternative way to remove Japanese knotweed. So other than money what are the deciding factors that need to be considered? Here we have created a simple chart to help those considering how to remove Japanese knotweed.
Chemical Control considerations include the need to be cost-effective, beneficial to the environment, is on-time, as chemical can take 3-4 years to control and even more, years for the plant to fully decompose so the land can be considered re-mediated and/or knotweed eradicated. Also consider changes in future land use are restricted in areas formally impacted with knotweed. The impacted land will always be considered as knotweed contaminated from a waste perspective. It also requires specialist training and certification for professional treatment
There are alternative approaches for Japanese knotweed control which is where specialist advice should be employed. Other methods which fall in the middle of the two options detailed above include; on site relocation, on site burial and partial excavation and capping with root barrier; these options are briefly discussed below.
On site relocation: Excavate and move impacted material from one location where redevelopment is perhaps planned to another location within the same legal piece of land where it can be treated chemically over a longer period. The advantage here is that knotweed can be treated economically over time diverting waste from landfill which is generally more cost effective and better on the environment.
On site burial: Being able to bury Japanese knotweed impacted material on site removes the need for it to go to landfill and is accepted by the Environment Agency as a viable method of Japanese knotweed control. The impacted material must be free from other forms of contamination and the EA do need to be informed.
Partial excavation and capping with root barrier: In some circumstances, it is possible to excavate to formation level and then use a root barrier to cap the knotweed in situ. This is more economical then complete removal and so long a suitable specialist root barrier is used and correctly installed. This method can be an effective and economical solution but might require to be combined with chemical control.
In conclusion, consideration must be given to the site and the demands that will be put on it through future changes in re-development and use. The recommendation is that a proper survey is documented and strategy developed to ensure that proper consideration has been given to the methodology of Japanese knotweed control. Again, it is very important that any such plan contains survey information, risk assessment and proper evaluation of possible control methods.