Some of the feedback is definitely worth sharing. Two separate correspondents recommend Aeroguard! Yes that's right the mozzie repellent. Apparently it will kill Oxalis and not the surrounding plants. I thought this was an expensive approach but for spot spraying around plants you want to keep it's cheaper and easier than selective herbicides. At least it should help Laurie:
Peter . Your solution is off target .My Oxalis grows with my daffodils –camelias and other flowers . There I cannot use roundup or cover with paper . We need a another solution . I use your (grand) father`s solution.
By the way I haven't tried this so please trial carefully before spraying liberally.
As usual the best practical advice comes from John, king of the Knox Garden Plotters:
Anyway the recurring theme is do whatever you can to keep knocking down the top growth which will over time starve the bulbs. If you can, dig the bulbs out and destroy them.
These plotters are students at Chelsea Heights Primary School. This whole area had been invaded by a Banana Passion fruit root stock that had escaped but the kids and their families have done a great job building a really successful vegie garden.