Winter and Sour sobs in AU!!!

Well Aussies, it's been a bit quiet on the Australian Forum - We must be into winter now! Time for electric blankets, lots of hot cuppas - AND Soursobs!!!! So has anyone figured a full-proof way of getting rid of them?? I say this with a bit o' tongue in cheek because there are as many theories as there are soursobs in my garden!!! I'm just pulling them up as they grow - no flowers yet thank goodness!

Duh ! Please tell an ignorant Kiwi -what are Soursobs ?
Emelle.

Soursob is Oxalis pes-caprae: http://davesgarden.com/pf/go/55661/index.html
look at all the negative comments on the PlantFiles page. Like many Oxalis, it creates enormous numbers of tiny bulbils which keeps it spreading rapidly and makes it very hard to eliminate.

Surely someone out there had a bit of luck ridding their gardens!! Anyone???

Ah ! Oxalis !- I've tried ! O how I've tried! Lots of muttering about the previous owner who brought it into a garden that was free of it.! I am normally a nice polite lady .
I found I was unable to grow my flowers in the contaminated area -tried for 4 years -it always looked a mess ,so I took out the flowers ,and planted shrubs such as hebes ,coprosma,and flaxes etc.I dug a hole out for each one,and put new soil in ,then planted. I kept the surrounding soil sprayed regularly for weeds -it was reasonably easy as there is a gap between plants.
3 months ago I put a really thick layer of newspaper down ,then covered it with a thick mulch of finely shredded bark -ex calf shed. I have rarely seen a weed since .I remove it pronto if I do.Photo is recent of the area.
Emelle.

I agree with Emelle....Don't dig...they just get worse.you have to smother them.I garden on red clay and all of the gardens are no dig ...it kills the weeds and after a season the soil is workable and I find that I can grow almost anything (in the right micro climate)...the other thing you might want to try is lime ...I think that they like acid soil...so if you sweeten the soil with a dressing of lime that may save you a lot of trouble.Good luck!

Can't agree with the acidic soil theory. Adelaide is primarily very alkaline (mine is 8+ !). They love the plains and the hills (some have clay and some are acidic) equally. There's no way I would add lime to my garden. As for newspapers - yep, good idea. How thick (how many sheets) is recommended?? I'm concerned that I may be blocking out the rain. Thought about weedblock but have so much to cover that it isn't very economical.
Emelle - thanks for the photo, very tidy!!

ok so much for the lime....when I moved here about 16 years ago there was no lawn only sour sob....looked pretty good!.After I was told that it was not clover I just set about "sweetening the soil "as told by someone who was an experienced gardener.I used lime and dolomite.Also chook poo.I was not trying to kill anything just help the grass to grow.My lawnmower is a mulch mower so that may have helped....after two summers the sour sobs had just about gone.The only thing I can think of is that they may enjoy lousy soil and /or the light mulching smothered them.In the no dig garden beds they have never come back......good luck

I got the newspaper idea from a friend -really thick -6 thicknesses or more.After putting it down,I hose it thoroughly to get it really wet ,then put the sawdust down .My friend says the worms absolutely love it and there is a lot of worm activity under it all.
The SSs we had in the lawn have just about gone with mowing too.I like the name soursobs -I wonder how it came to be called that ?
Emelle

Hi Hi to Everyone, and to Emelle I say this, try pulling off a flower stem and chewing on the broken end - then you will KNOW why they are called SOURsobs! We did this every winter when I was a kid, and it is actually quite a refreshing taste when you get used to it, but don't eat too many as the oxalic acid which gives the plants their generic name is toxic in large doses. Also ,you can eat the bulbs after you peel the black or brown layers from them, but it is really tedious to do as even the biggest ones are not so large when regarded as a food source. The bulbs do taste really good though, I always have a few of the biggest ones to eat whenever I pull any up.

On to the more serious matter of control, ahem! They do grow very well in poor, compacted and undisturbed soils - hence their love of lawns! I have heard that you can fertilise them to death, but I am not sure if I am brave enough to try it! I have visions of metre high soursobs using Adelaide as a base to take over the world (grin). I wonder if the combination of the chook poo AND mowing is what did for the ones in chrissy100's lawn?

I will have a chance to try out a few new techniques on the darn things in my new garden - the so called "rockery" out the back under the pear tree is a sea of the darn things and the area is completely undiggable and very hard to weed, thanks to the random chunks of buried concrete and rocks layered over each other!

My previous garden had a lot of them when I started there, but we had them mostly under control four and a half years later when I moved out, but they certainly weren't eradicated. We did a lot of the newspaper/mulch at that house, it was weedy beyond belief when I moved there, Paper and mulch IS a great technique for a lot of weeds, especially annuals, but alone it won't do much for soursobs as they will just keep going until they find a way through the layers.

Anyway, here are my best tips to date -

1/ DON'T DIG if you don't have to - you will spread the bulbs.

2/ Pull them up as soon and as much as you can - this will weaken the bulbs, and slow down the production of new bulbils later in the season.

3/ Don't add what you pull up to your compost bin or to your green waste stream - no one will thank you! These guys can regenerate new cormlets at any time if they feel threatened by drying out and this is a great way to get them into areas of your garden where they don't exist already, AND into you potting compost as well. I have a big yard, so I have a plastic rubbish bin down the back which is half full of water. I throw any weeds which have gone to seed or are capable of regenerating into this bin each week and put the lid on. It gets slightly fermented and smelly, but it helps the weeds rot very quickly and kills pretty much anything - even buffalo grass runners! The bonus is that the liquid from the bin makes a fantastic fertiliser - even if you have to hold your nose while applying it!

4/ The main key to soursob control is to understand the life cycle of the plant which is as follows -

A: Dormancy - last seasons corms rest out the dry season as much as 30 cm down in the soil.

B: Dormancy breaks when winter rains reach the corms. Corms which do not "waken" due to depth or lack of rain may persist in the soil for quite a few years only to spring into life when you dig them up and distribute them.

C: The corm is used up by the growing plant as it pushes through the soil or attempts to find a way into the light. Note that the underground stem from a large corm may extend to well over a metre as it tries to find a way into the light! This is the first point of attack for a gardener as each corm can only sprout once. Pulling the plants up when they are about 2 to 4 inches high WILL kill THAT corm and plant - any regrowth in the following year will be from dormant corms left behind in the soil and any regrowth in the current year comes from other, lower corms as they take advantage of the moisture the plant you pulled up was blocking from them! Cutting the plants off at a low level also helps, but it's not quite as good as pulling because decapitated stems can regenarate during the season. It does work to some extent in lawns though, because the frequent cutting makes it hard for the plants to keep going.

D: Once the yellow flowers appear, the plant will already be starting to make new cormlets, so attack early and attack often. Glyphosphate herbicides (Zero or Roundup) can help at this stage as this is when the plant is most biologically active and likely to take up the chemical, though of course this solution will only work where there are no other plants, or where you can use a weed wand or paint brush to get at individual plants, the benefit of using it at this stage is that you get not only the parent plant but any offspring it might be incubating. For non chemical control or for plants in difficult spots try pouring boiling water on them!

E: In the spring, any remaining oxalis plants will die, leaving their corms behind them, and that will be that; at least until next year!

5: Be PERSISTENT, and as thorough as possible. The tiny little ones you miss this year will come roaring back next year if you give them a chance to make new corms. One of my techniques is to sit on the ground and stay there without moving until every last visible leaf and stem is gone from within my reach. The next session I move on to a different square metre or so. It is amazing what a difference yau can make to a garden by simply looking intesively at one small patch at a time.

Don't you just LOVE gardening! By for now, Kaelkitty.

KK-I really loved your story-I forgot I was reading about the big Ox.
Actually our Ox flowers are pale pink.
I also tried marking off a square metre at a time and sieving it -wearing my reading glasses,I went right down to the clay base ,and really thought I'd made a difference,but back they all arrived.
Your rockery area makes me wince -once they are among all that it would be so discouraging for you ,and seems like a heavy job if you are going to shift it all.
I am going to try to print your story off so that I can keep it.
Best wishes,
Emelle
PS-I have recently found that most of my favourite DG forums-mostly 'cottage gardens have been closed to me as a non-subscriber-very disappointing.However I am glad that the Aussie forum is still available.-OzzyOzzyOzzy!

Ah-hah, another night owl! There are a couple of pink flowered weedy Oxalis species here in Australia. Here is a good link to identify them http://members.iinet.net.au/~weeds/western_weeds/oxalidaceae.htm
if you WANT to! My guess is that your dormant corms are actually down in the clay you mention. Try digging one up when it first appears in the autumn and follow how far down the roots go. KK.

The stems break off when I am following the trail down down down-Dash ! However the garden is all covered up now for winter ,so I am trying not to think about it.A NZ woman has produced a potion'Death to Oxalis' spray made of the oxalic acid she gets from boiling the bulbs together(I 'm not sure how exactly) It is good in that it does not affect other plants in the garden,as poisonous chemicals do.
Emelle
We are getting some wonderful publicity advertisements on TV about Adelaide-it seems a lovely place to live.Do you get enough rain?

No, not really enough rain. It seems every year the climate gets a bit more extreme - It rains less and then only in flash flood proportions, with long gaps in between. Having said this, we seem to have reverted to "normal" winter rain so far this year, fingers crossed it will continue right through to spring, top up the reservoirs, and flush out the river systems. We have been on water restrictions for about 6 months - no sprinklers, hand held hoses before 8 am and after 8 pm only etc. etc.- it's no fun at all.

KK - thanks so much for all the soursob advice. I knew a bit about them from asking around. Instinctively (I guess) I just sat in the garden yesterday and started pulling. I let them get big enough so it's easy to get them out but not so mature that they are in flower. I agree that it's the best bet for a permanent solution and I will try and be diligent about grabbing them when they look their healthiest. I am hoping the over-all result will be less and less weeding as the years go on. There's no way I could use Round Up because so many of them seem to come up right underneath one of my plantings (sneaky devils!!). I too will print out your advice to remind me every Autumn!!! Thanks again and pray for more rain!!! kh

Perhaps we're more downunder than you are,because I am a bit puzzled about your season there -the NZ oxalis has now died down in early winter and won't appear now till mid-summer-is your little pests a winter crop?(the reason I didn't know our new home had the stuff till after we got here ! it was dormant when we looked)
Thank you for everythingyou have written.A great help and encouragement.
emelle

Hey there is someone here ...whew what a relief...what a lot of work has gone into this saga of the soursobs...I think you are wonderful
after just visiting the beginners forum and saying the ozzy site was lonely! Well there may not be a lot here but how good are you all ..I am a reasonably good gardener but one plant sulks and I don't know why...see new thread....perhaps you can help me :) Chrissy100

Emelle - Yep soursobs start popping up in late autumn and stick around all winter til they disappear in early spring. As a weed, it's not the worse thing to happen since they do go away but it can take over an entire area in no time at all. Some people with hillsides actually don't mind them because they help keep the hill soil stable during the winter rains. I just would rather look at the plants that I've spent money on!!! PS - spent three hours yesterday carefully pulling up four buckets worth of the little buggers!!!! Woke up to frost on the lawn this morning burrrrrrrr!!

Kaelkitty that was fantstic posting on sour sobs, I was going to leave a posting but you've covered it nicely.
the temptation to pull or mow them is very strong and I always have a mental race to beat hubby too them. neighbours can be friendly too and pull them out as they come up close to flower! this year with extra rainfall we have heaps and im just bidding my time to get out there and let them have it!! garden4grace

Here are some Soursobs photographed the other day in Traralgon near here in Victoria:

and here is a close-up of the leaves:

Well, I'm quite flabbergasted! After enlarging your photos and gazing at them,I think we've been writing about completely different plants!! But it has been a jolly interesting conversation though.Next summer I'll take a photo of mine !
Emelle.

Kill em with fresh horse manure:

I am in Adelaide, Australia. I mulched my garden beds with an inch thick fresh horse manure (keeping manure away from bush and rose stems) and the sour sobs did not break through (so far).

I guess as the manure was fresh and very rich it rotten the stems of the sobs - also because horse manure knits well into a blanket so sobs cant get through without spending a lot of energy. The sobs were close to flowering when I applied manure, so it maybe the sobs did not have enough stored energy in the bulb to grow again. If you try this maybe wait till the sobs are just about to flower.

Also you need to fork the manure into the soil in early spring (after sour sobs are gone) otherwise 1 inch of horse manure might form a waterproof mat. Even if it doesnt work any manure - even horse - is great for the soil and worms love the manure.

All the best fellow wannabe sob killers

Rob / Adelaide

Thanks for your input Rob! Lots of horse poo available throughout the hills so I'll experiment next year since I already pulled out all my soursobs for this year!