Equisetum control
Roy M. Sachs (Mon, 04 Aug 2003 12:15:14 PDT)

Thanks to Den, Jean and Lauw for advice.

For those interested in herbicides as aids in the control of horsetails:

a) Grammoxone is sold in the US as paraquat.

b) The Oregon State web site refers to a Pacific Northwest weed
control handbook because herbicide permits change frequently and I
suspect that will be the case in CA.

c) I did a web crawl on equisetum control and found most
recommendations for Casoron (dichlobenil is vulgar chemical name),

Of course, the horsetail shoots are right in middle of clumps of good
geophytes (common habit of all weeds, no?) so the herbicide will have
to be painted on the slightly thrashed horsetail shoots.

Firstly, do not treat until the plant is fully grown in late summer because
you need as much growth as you can get to absorb the herbicide. Then thrash
(bruise) the stems and leaves with twigs (this breaks up the waxy surface).
Then mix a systemic herbicide with a mix of light cooking-oil and
white-spirit or turpentine (any light oil will do) until it is thin enough
to spray and use it in place of the recommended water quantity. Finally,
spray the mixture thoroughly over the whole plant. The oil/spirit mix will
ensure that the herbicide is in contact with the plant for a sufficient
period to kill it and it is rain-proof.

There is also a giant, non-invasive form of this plant which looks
absolutely magnificent.

Good luck.

Den.

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