Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)

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ezeiza

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If the stems are cylindrical it is Oxalis pes caprae.

South African oxalises are potential weeds in mediterranean climates. They  can be easily exterminated with glyphosate with the glove method explained before.

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Alisdair

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #1 on: March 17, 2012, 11:32:27 AM »
In much of Greece the single Oxalis pes-caprae ("bermuda clover" or "bermuda buttercup") is widespread and completely out of control, carpeting open spaces and olive groves to the virtual exclusion of wild flowers that bloom at the same time. As Alberto says, glyphosate does eliminate it, but those who rely on non-chemical methods find it virtually impossible to exclude this pest from gardens in areas that are infested with it.
Alisdair Aird
Gardens in SE England (Sussex); also coastal Southern Greece, and (in a very small way) South West France; MGS member (and former president); vice chairman RHS Lily Group, past chairman Cyclamen Society

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Cali

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #2 on: March 17, 2012, 12:08:08 PM »
Alisdair, I am relatively lucky in that I don't have that much, and what I do have I've controled with weeding while the soil is still soft.  (One of my pet peeves is with peolple who exclaim how beautiful it looks as it swarms accross the land sweeping everything in its wake....)
Thank you Pamela, Jorund and ezeiza.
Cali
« Last Edit: March 17, 2012, 12:10:59 PM by Cali »
Cali Doxiadis
Former MGS President
Gardens in Corfu, Greece.

ezeiza

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #3 on: March 18, 2012, 01:28:01 PM »
The problem is that with such terrible pests there is not much to think. And, glyphosate can be very useful and its impact lowest if used the properly. You are solving a highly artificial problem with a natural method and it simply does not work. Pulling the clump while the ground is wet and soft is excellent but how can this be done when hectares of them are involved. Spot treatment now, instead of plane fumigation later.

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anita

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #4 on: March 18, 2012, 01:52:51 PM »
O. Pes-caprae is a menace in southern Australia too. In broadacres glyphosate is the only way to go. However it can be eliminated in smaller gardens by being persistent. When I moved to my current home 11 years ago the garden was yellow in late winter/spring. I now have a patch left in the lawn but the rest have been defeated by persistent hand weeding. There are two key things pull them up early so as to exhaust the bulbs then repeat as the plant regrows. And then repeat again. The other important thing is to burn or very deeply bury the pulled plants. If you leave them on the ground the uprooted plants will form bulbils and you will be back at square one. If you are diligent the yellow peril can be defeated. The first years here I literally pulled out wheel barrow loads. Then it was down to buckets. Now I'm chasing the last little plants hiding in the lawn using just a 2 litre icecream container. The remaining plants are so tiny their stems are threadlike but I can't let them live or they'll recolonise.
Dry mediterranean climate, avg annual rainfall 530mm, little or no frost. Winter minimum 1C, summer max 45C

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Alisdair

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #5 on: March 18, 2012, 02:05:02 PM »
Dear Cali
I, too have this double oxalis in a few places and I love it. I do not pull it out like the single version. It does have a pretty red hue.  Do you have this oxalis problem in Greece as well ?? I spend hours pulling them out. I really do not know how to get rid of them. Someone from SoCal told me you should always CUT them off at ground level rather than pulling them as this starves the bulbs which then die. Have you heard this?  
Pamela, commenting on the red double-flowered version mentioned here by Cali and others, raised the issue of how to deal with the invasive single version. As this can be such a pest, I think it's best to treat is as a separate problem, under Pests and Diseases.
« Last Edit: March 18, 2012, 02:08:31 PM by Alisdair »
Alisdair Aird
Gardens in SE England (Sussex); also coastal Southern Greece, and (in a very small way) South West France; MGS member (and former president); vice chairman RHS Lily Group, past chairman Cyclamen Society

pamela

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #6 on: March 18, 2012, 06:20:45 PM »
Dear ezeiza
Thank you for your ideas.  When you say 'spot treatment' , how do you go about that?

Its impossible for me to use glyphosate as my Oxalis is between shrubs, bulbs and other plants. 
That chemical would kill everything near to it. It's just too risky.

I was interested in how Anita has solved her problem.
Do you start pulling as soon as they appear?  I was told to wait for the flowers......
Jávea, Costa Blanca, Spain
Min temp 5c max temp 38c  Rainfall 550 mm 

"Who passes by sees the leaves;
 Who asks, sees the roots."
     - Charcoal Seller, Madagascar

ezeiza

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #7 on: March 18, 2012, 11:47:13 PM »
"Spot treatment" is very easy: prepare a 10-20% glyphosate solution in a plastic container (can be a half soda bottle, etc.). Now put on latex gloves. Dip the tip of your fingers (or that part of them that face the palm) in the glyphosate solution. Gently grab the plant you want to kill with your herbicide soaked palm/fingers and move your hand towards you. This motion actually paints it with the herbicide and the method is based in the principle that if you apply the herbicide on part of the plant the whole will be affected. Once you get the knack it is very simple and fast to paint many plants in a few hours and this will not affect neighboring plants (if you do not touch them!). One common mistake with glyphosate is to use doses so high that the tissues are actually burnt without the plants absorbing the herbicide. But, this has been mentioned before. Latex gloves must be discarded afterwards or well washed with warm soapy water.

David Bracey

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #8 on: March 19, 2012, 09:34:21 AM »
I use a small/large paintbrush depending on the size of the problem.  Add a squirt of washing up liquid which will help the "sticking" process.  The treated plants wilt quite rapidly, after 24 hours but the full effect will rake the best part of 2 weeks. A 10% solution is ample. .
MGS member.

 I have gardened in sub-tropical Florida, maritime UK, continental Europe and the Mediterranean basin, France. Of the 4 I have found that the most difficult climate for gardening is the latter.

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Alisdair

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #9 on: March 19, 2012, 10:43:40 AM »
Like David, we use a paintbrush too in areas where bermuda clover is invading planted areas, which does work well but is not quick. So I aim to try Alberto's glove method - much as I hate wearing latex gloves! (I'm hoping I can persuade Helena to do it instead as she's quite inured to them.)
Alberto's point about avoiding too high a concentration is important - counter-intuitive but true, that higher concentrations can actually be less effective.
If you have a good sprayer you can spray glyphosate very close to vulnerable plants without damaging them, so long as you keep the spray pressure as low as possible, and spray in cool calm conditions to avoid drift. Also, at least in my own experience glyphosate doesn't damage mature wood.
Alisdair Aird
Gardens in SE England (Sussex); also coastal Southern Greece, and (in a very small way) South West France; MGS member (and former president); vice chairman RHS Lily Group, past chairman Cyclamen Society

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JTh

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #10 on: March 19, 2012, 10:56:15 AM »
I don't like to use these weed-killers, but the few times I have done so, I also preferred the spot treanment. I put a pair of cotton gloves on top of the latex gloves, they are more absorbent and there is less chance of accidental dripping on other plants.
Retired veterinary surgeon by training with a PhD in parasitology,  but worked as a virologist since 1992.
Member of the MGS  since 2004. Gardening in Oslo and to a limited extent in Halkidiki, Greece.

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anita

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #11 on: March 19, 2012, 12:38:26 PM »
I was interested in how Anita has solved her problem.
Do you start pulling as soon as they appear?  I was told to wait for the flowers......
Pamela, I start pulling them out as soon as they appear. I've found that by the time they flower they are already setting new corms. So I weed as soon as they are big enough to grasp. I've used JTh's method with cotton glove liners worn outside latex gloves and it is quick and effective but my garden had been near abandoned for five or more years and when the autumn rains came I had oxalis everywhere and it was risky to use the glove method amongst perennials. It's not the world's easiest solution as you have to repeat the weeding until the corms are exhausted.
Dry mediterranean climate, avg annual rainfall 530mm, little or no frost. Winter minimum 1C, summer max 45C

pamela

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #12 on: March 19, 2012, 03:54:10 PM »
Well, this is all very fascinating.  I have never used weed killer in my garden in fact I don't have any on the property. But, possibly I might brave it and use glyphosate in these very controlled conditions. It could be an answer.  Two more questions:  Can I have a reliable brand name or several brand names please?.  Does the 'painting' of the leaves kill the corms/bulblets as well, meaning that plant won't come up next year?
Jávea, Costa Blanca, Spain
Min temp 5c max temp 38c  Rainfall 550 mm 

"Who passes by sees the leaves;
 Who asks, sees the roots."
     - Charcoal Seller, Madagascar

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Alisdair

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #13 on: March 19, 2012, 04:26:22 PM »
In Europe as in the USA Monsanto, the original developer of this weedkiller, is still the main supplier of glyphosate, even though their patent expired some years ago. They supply it under the brand name Roundup; this includes a surfactant and spreading agent, which help in applying it.
If the glyphosate is applied to the leaves of a bermuda clover plant, all parts of the plant including the attached underground bulbils will die. But any detached bulbils which do not have any above-ground parts will survive (glyphosate is inactivated by contact with the soil).
Glyphosate is not a magic potion (in the UK some weeds of farmland such as willowherb have developed strains that are highly resistant to it, and the same has happened in the USA; there seems also to be some evidence that its use on the same spot year after year, as happens on many arable farms, may in the long run damage soil structure). But as weedkillers go it is remarkably non-toxic - one formulation is even authorised here in the UK for use on wetlands and water plants, although stream and pond creatures are very highly susceptible to almost all other herbicides and pesticides. Used carefully and for specific hard-to-deal-with problems - such as Oxalis pes-caprae - glyphosate can be a real boon.
Alisdair Aird
Gardens in SE England (Sussex); also coastal Southern Greece, and (in a very small way) South West France; MGS member (and former president); vice chairman RHS Lily Group, past chairman Cyclamen Society

ezeiza

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Re: Controlling Oxalis pes-caprae (bermuda clover, bermuda buttercup)
« Reply #14 on: March 19, 2012, 05:54:47 PM »
Well, Alisdair has answered the detached bulbil question. As for formulas, those aimed at gardens are a lot more diluted than the ones used for crops.

As usual, the glove method is criticized without having even tried it. No paintbrush can be more versatile than the fingers.

As for woody plants, glyphosate affects young ones, just by spraying it on the bark. For larger, older trees, a cut (like with a small axe or a machete) that affects the bark and pure glyphosate on it usually kill them.