Henry Grabar wrote an excellent piece in Slate on knotweed: “Oh, No, Not Knotweed! What I think is so important about this article is that it lays out the environmental consequences of knotweed – not just the potential for property value losses that are so widely reported about in the United Kingdom. Knotweed is especially devastating to waterways. The article notes the three key problems with knotweed identified by Chad Hammer at the University of New Hampshire:
- In a knotweed stand, virtually no light hits the ground. This prevents other plants and bugs, etc., from living in that patch.
- New trees cannot grow in a knotweed patch. This reduces woody debris, for example, in the stream.
- Erosion! Patches of knotweed have very little organic matter on the ground and the ground can erode easily.
Especially with flood events becoming more common – and water washing live, viable knotweed debris downstream – the problem will only get worse.
Knotweed can be controlled! The above photos show that an aggressive treatment can virtually eliminate it. The key is to keep after the straggler plants that will inevitably persist after the initial treatments. Here is our YouTube video: How to Kill Knotweed: 3 Simple Steps for the Non-Professional.