Treating Japanese knotweed with Stem Injections

Stem injection is a method whereby herbicide is injected into the lower part of each mature stem of knotweed using a stem injector. Small knotweed plants cannot be treated with this method due to their size. There is some debate as to whether stem injection induces rhizome dormancy - making it look dead but not killing the rhizome system.

We have other preferred methods of treating Japanese knotweed, such as herbicide application by foliar spray. We have worked on many sites which have been stem injected (by others) where it is evident that temporary dormancy had been induced as, after ground disturbance, significant regrowth was experienced.

Advantages of the Stem Injection solution

This isn't to say that stem injection should never be used. The advantage of stem injection is that a measured dose of herbicide can be applied directly into the plant, without the risk of drift prevalent with a foliar spray method of application. It should therefore be used if there are environmentally sensitive factors such as watercourses, protected trees, valuable hedges, etc. which must not be harmed. Bear in mind that it should be considered as a "control" method, so would not be deemed suitable in an area where the ground is likely to be disturbed.

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