Hi Alternety: fellow Washingtonian and horsetail obsessed gardener! I have been struggling with horsetail in my front yard (terraced hillside and adjacent gardens at level) for years. Lots of water issues given that we live on a hillside in Washington, so this doesn't help. The front yard is huge and fully landscaped (more every year). I have pulled out probably HUNDREDS of spores from the a spall rock covered portion of a bank. They come up fully grown under the rocks- they are absolutely not deterred by complete lack of light. We already have probably a thousand plants that have emerged into the yard. We have tried digging up, spraying the beds with extra strength roundup (killed a bunch of the nearby plants), and this year digging combined with 50% glyphosate painted on several test beds. This only turned the really small lacy plants brown (same as always), but the bigger shoots just laugh and emerge green anyway. Right under the soil is a defiant vibrant green.
I am dying to know how your eradication project has turned out. Can you share?
This is a great source of info- tons online if you do different searches on horsetail eradication.
Glyphosate products are often used to suppress horsetail; however, you should expect
regrowth. To eradicate a horsetail stand you may have to make several applications over
several years. In many cases, control of horsetail with glyphosate is inconsistent. Casoron
(dichlobenil) has also been reported to have activity on horsetail. MCPA has been used in
small grains to suppress horsetail. Richardson and Zandstra of Michigan State University
reported control ranging from 77% to 92% with Curtail M®
(MCPA + clopyralid) at 3.5 pts/A.
is not labled in the state of Indiana and has a 30-day rotation to ﬁeld corn, and a
12- to 18-month rotation, depending on organic matter, to soybean.
Peter Sikkema of the University of Guelph, Ontario, has reported more than 80% control (and
as high as 95% control) with combinations of glyphosate and ﬂumetsulam. Flumetsulam can
be found in the product Python.
Best of luck!!!