Now the Japanese Knotweed growing season is well underway we have been very busy across the UK conducting surveys for homeowners and property developers. Knotweed has again been in the news for various reasons due to a recent experiment conducted by Swansea University. Professor Dan Eastwood conducted a 3-year experiment applying various herbicides & techniques to a large stand of Japanese Knotweed at Taffs well. His conclusion that “Japanese Knotweed cannot be eradicated” has had many of us in the industry baffled. Having witnessed this experiment first-hand fundamental issues were noted in 2016. The Japanese Knotweed was sprayed with a variety of chemicals (many not recommended for Japanese Knotweed anyway) in differing sections. What wasn’t highlighted in the press was that the stands of Japanese Knotweed are linked via rhizome. So, if you’re applying one herbicide to one area of the same stand & another chemical (with differing active ingredients) you’re bound to get differing results. Some of these results could be resistance, dormancy or shift. The study did state that Glyphosate is the most successful product to tackle Japanese Knotweed. This is the only product we have ever used in the fight against this invasive species. It also failed to state that the recommended amount of time for a Japanese Knotweed programme is 4 years & for an area, the size of taffs well would most likely be 5-6 years.
The industry has and will continue to respond to these “findings” and will hopefully help calm clients concerns by the potential nightmare this may generate. Like any living organism on the planet, Japanese Knotweed is not indestructible. Links to the articles from both sides are here: