Japanese knotweed herbicide recommendation - Ask Extension
I live in Saint Paul. My neighbors used their backyard to grow produce for farmer's markets. They grew raspberries and Japanese knotweed. My yard has ...
Knowledgebase
Japanese knotweed herbicide recommendation #868601
Asked May 15, 2024, 4:34 PM EDT
I live in Saint Paul. My neighbors used their backyard to grow produce for farmer's markets. They grew raspberries and Japanese knotweed. My yard has been invaded by both. I've had success with cutting back the raspberries, but not the knotweed. The forest service says to break the canes off in spring and then treat regrowing shoots with glyphosphate herbicide in late summer. glyphosphates have an adverse effect on bees. Is there an alternative that would be as effective and not as harmful to pollinators?
Ramsey County Minnesota
Expert Response
This publication lists other chemicals.
https://mnfi.anr.msu.edu/invasive-species/JapaneseKnotweedBCP.pdf
Tricopyr is also listed and is less harmful to bees. See this web page. http://npic.orst.edu/factsheets/triclopyrgen.html#:~:text=Triclopyr
Imazapyr is also apparently safe. See this web page.
https://files.dnr.state.mn.us/forestry/certification/pesticides/dnr-esra-imazapyr.pdf
https://mnfi.anr.msu.edu/invasive-species/JapaneseKnotweedBCP.pdf
Tricopyr is also listed and is less harmful to bees. See this web page. http://npic.orst.edu/factsheets/triclopyrgen.html#:~:text=Triclopyr
Imazapyr is also apparently safe. See this web page.
https://files.dnr.state.mn.us/forestry/certification/pesticides/dnr-esra-imazapyr.pdf
