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RE: Oxalis pes-caprae and climate

Ahhh OK here goes,

Oxalis pes-caprae would have to be one of the most difficult to kill
weeds commonly found in gardens in in crops to for that matter.  In
crops though there are some very good herbicides based on sulphoyl urea
chemistry that are extremely effective but somewhat residual and not to
suited for the garden. I have used them on lawns with great success but
don't overspray!!!  These herbicides would be better known as GLEAN
(Chlorsulfuron) or ALLY (Metsulfuron-methyl).  I mention the active
ingredients because you may not recognise the trade names (bit like
latin and common names eh?) These herbicides are very very low on the
mammalian and insect toxicity scale and the application rates are also
very low, ie 5-10 grams per Hectare, they will only affect broadleaf
plants (mostly smaller spp. and annuals) but are generally safe on lawns
(some tender varieties may get a bit clobbered)
Anyway these group herbicides are very effective against Oxalis spp. in
general and if used to treat large infestations will do a very good job.
You need to be sure of an effective an even cover though otherwise
you'll need to retreat the plants missed.  The biology of the spp. is
very intersting as it produces bulbs that as the plant dies back
actually retract themselves deeper under group like an anchored elastic
band that has been released from the top.  An interesting survival
technique.  These bulbs and smaller bulbils produced by the plants are
what make them so hard to control, digging them out is NOT an option!
Don't bother trying to mulch them out as I have seen them grow through
several feet of rubbish dumped onto them, bricks, concrete etc, they are
tough!
Another herbicide that works well but needs care in application is good
old Roundup (Glyphosate)
Not selective at all and has to be used at higher concentrations to be
effective against Oxalis but it is useful if you can spot spray in the
garden as it is not residual.
The main thing to remember is don't disturb the soil or absolute minimum
disturbance. Even the smaller fragments of the roots can develop a new
plant and the bulbils are quite tiny as well, 2-4 mm in length.

Hope this helps, don't give up I've eradicated several patches over the
years usually with an initial Chlorsulfuron application and followed up
with Glyphosate spotsprays.

On Seans other note about Climate parameters I have a Macintosh Program
written by our group that we use to determine wether or not a species
would be able to grow in Australia by comparing that species climatic
variables from its native and introduced range with Australian climatic
conditions.
The output is a nice coloured map and a text screen showing the climatic
variables of the basic 16 parameters we use for the analysis, based on
rainfall and temperature.

I have used it on many occasions for people asking wether or not they
could grow a certain crop here and where?  And I can also back analysis,
for example where would this species of Acacia grow elsewhere in the
world?

The program is available for anyone with a MAC to download for free from
the site address below.
It will run any on ANY Macintosh although it looks nicer with a colour
monitor.

Here is a sample output of the climatice parameters for Perth Western
Australia Sean.


                                    CLIMATE
                           Climate prediction system

                          Analysis results for Predict


                     Summarizing prediction for statistics


16  variables in analysis.
2   location records analysed. (Perth and Belmont,  about 10 Km apart)

Cummulative method used. Closest Euclidian match used.

________________________________________________________________________
______
                                         Statistics
                               Mean   St. Dev.  Skew  Kurtosis   Min
Max
_________________________________________________________________________
_____
 1   Mean annual temp.         18.27    0.35    0.00    1.00   18.03
18.52
 2   Min temp. cool month       8.55    0.92    0.00    1.00    7.90
9.20
 3   Max temp. warm month      31.00    0.85    0.00    1.00   30.40
31.60
 4   Average temp range        22.45    1.77    0.00    1.00   21.20
23.70
 5   Mean temp. cool quarter   13.58    0.45   -0.00    1.00   13.27
13.90
 6   Mean temp. warm quarter   23.76    0.11   -0.00    1.00   23.68
23.83
 7   Mean temp. wet quarter    13.58    0.45   -0.00    1.00   13.27
13.90
 8   Mean temp. dry quarter    23.44    0.13    0.00    1.00   23.35
23.53
 9   Average annual rainfall  835.50   47.38    0.00    1.00  802.00
869.00
10   Rainfall wet month       180.50    3.54    0.00    1.00  178.00
183.00
11   Rainfall dry month         7.50    0.71    0.00    1.00    7.00
8.00
12   CV monthly rainfall       90.83    0.89   -0.00    1.00   90.20
91.46
13   Rainfall wet quarter     477.00   22.63    0.00    1.00  461.00
493.00
14   Rainfall dry quarter      33.50    0.71    0.00    1.00   33.00
34.00
15   Rainfall cool quarter    477.00   22.63    0.00    1.00  461.00
493.00
16   Rainfall warm quarter     37.00    2.83    0.00    1.00   35.00
39.00
_________________________________________________________________________
_____

Australian prediction:
Data point     Match
  


                 Summary of Prediction 
(This shows how many locations match this particular output in
Australia)


7      locations within 40 % of the mean.
8      locations within 30 % of the mean.
1      locations within 20 % of the mean.
1      locations within 10 % of the mean.

17 matching locations from 2798 comparisons.

The output location file is 'Predict.loc' and possesses the following
format:
latitude longitude code - where code is a number proportional to climate
similarity.

Cheers, Rod

Rod Randall
Weed Risk Assessment
Weed Science Group, Agriculture Western Australia
Home Page  http://www.agric.wa.gov.au/progserv/plants/weeds/Weedsci.htm

             "I weed..."

> ----------
> From: 	Marina & Anthony Green
> Reply To: 	green@pangeanet.it
> Sent: 	Wednesday, 31 December 1997 9:59 AM
> To: 	SAOUC@UCCMVSA.UCOP.EDU
> Cc: 	medit-plants@ucdavis.edu
> Subject: 	Oxalis pes-caprae
> 
> Sean's mail on his garden throws up the problem of Oxalis pes-caprae.
> I
> would be interested to know if anyone has managed to defeat this
> beautiful but obnoxious weed. My garden is becoming a monoculture!! I
> am
> thinking of a systemic herbicide to be applied very carefully so as
> not
> to throw the baby out with the bathwater...
> 
> Anthony
> 
>
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