How do you kill invasive Oxalis?
Jane McGary via pbs (Mon, 12 Oct 2020 12:31:01 PDT)

I have a similar problem with Oxalis obtusa. I find there is no way to
eliminate it (it got in when the tiny bulblets must have become hidden
in the tunics of desirable bulbs I was moving), but I can keep it down
by waiting until the foliage is fully developed and then reaching into
the sand it's growing in and pulling out handfuls of the roots and
bulbs. At this point I think the new bulblets haven't yet formed on the
stoloniferous roots. It's growing in among plunged pots, so just in pure
sand. If it gets into the pots through the drain holes, I pull it out
and mark the pot for replacing the soil once the bulbs go dormant. I use
color-coded labels for that kind of note. As for using glyphosate
(Round-up), I've read that Oxalis is resistant to it. I've seen a
herbicide at a farm store indicated to be "Oxalis and spurge killer,"
but spotted spurge can be killed with glyphosate.

Jane McGary, Portland, Oregon, USA

On 10/12/2020 11:58 AM, Pamela Slate via pbs wrote:

Thanks much for your input!

The two spp. at O. sternorrhyncha and O. purpurea possibly 'Garnet.' The
latter has purple leaves that lay flat on the ground with a pink flower.

I am still wondering how mature bulbs can be killed effectively. I have
always been an organic gardener, have never applied toxic chemicals and
that is why I asked the solarization question (I've solarized before).

I'd consider a chemical if I could be sure the mature bulbs would not
survive but would prefer another method. There are hundreds of bulbs in
that bed and I have dug up many in the past but now there are too
many.....especially tiny ones.

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