oxalis, lawns

I've been away two days having my hernia repaired.  I came back to over 50
messages from this group, alone.  We're cookin.  Since I'm in
post-operative pain no one is allowed to yell at me about how unnecessarily
long this post is.

These streams give me a chance to make a confession.  I lurk in this group
feeling consistently guilty because my interests are in the practicalities
of horticulture:  fertilizers, pesticides, lawns, etc.  I know that I'm
supposed to be commenting on Medit plants, their care and appreciation.
The trouble is I don't know much about that.  I know a lavender from a
rosemary but I'm in awe when I read the delineations of variations within a
genus or even among cultivars.  My strategy has been to keep quiet within
the group as much as possible and then to quickly cram in a post from my
perspective hoping that no one will notice that I'm always violating what I
believe to be the tacit rules of the discussion.

I'm doubly conflicted because I'm trying to write a book about products
commonly sold in California nurseries so I'm filled with this kind of
minutiae and its hard for me to resist boring others with it.

Re recent posts:
Botanical names vs. common names:
I love the fact that I'm taking part in a discussion amongst members from
Tasmania, Australia, New Zealand, Hawaii, North Carolina, Florida, England,
Scotland, Italy, Greece.  I don't want California to dominate the
discussion.  I'll gladly try my best to include botanical names in order to
avoid any implication that we're excluding other areas.  I like to
occasionally boast to the customers at the nursery where I work:  'Ah, we
were just discussing Monterey Pines on my internet group.  Yes, Moira in
New Zealand, told us.....'  It's my best chance to be snooty.


Oxalis:  (Sorry, here comes the herbicide stuff)  You think *we've* got
problems with Oxalis names.  Try researching herbicide treatments and
you'll find some of the following:

The University of Florida, USA, lists O.corniculata and O.pes-caprae on
it's weed list.  But when the same university cross-references with
herbicide treatments they suddenly drop any mention of O. and  begin
talking about 'Smallflower Buttercup'!  Is that an Oxalis?  Who the heck
knows????  And these guys are scientists.

The University of California specifies O.corniculata as a common weed.  OK.
Then they say that the herbicides that control O.corniculata do not
control the common weed O.stricta.  But they never specify which herbicides
control which weed.  A fat lot of good that does me.

Ohio State University lists 'red sorrel' and 'wood sorrel'(Oxalis).  Is red
sorrel an oxalis?  Some of my books list 'Sorrel' as *Rumex scutatus*, a
totally different weed.

The University of Maryland eschews botanical names altogether!  They list:
Oxalis, creeping
Oxalis, common
Red Sorrel (*Rumex*?)
Each of these gets a different herbicide treatment.  How am I supposed to
decipher this???

And trying to do a search for Oxalis revealed that different universities
in the US list Oxalis as:

Sorrel, red
Wood sorrel
Common yellow wood sorrel
Creeping woodsorrel(Oxalis spp.)!!

A few even list it under, tadah, Oxalis, except that they mention(without
much explanation) the following species:

corniculata
stricta(southern US says the U.Cal)
pes-caprae
forida(U.Fla)
dillenii
adenophylla(is this the pink petalled variety mentioned on this group?)
triangularis
oregana(an ornamental, is it a weed some places?)

Now from a practical point of view all the above has much significance.  I
could ramble on about this for pages but I think I can summarize:

pre-emergent herbicides prevent O. from growing.  But they don't work on
the bulbous forms nearly as well as the others.  And their effectiveness
varies according to soil texture and climate.  Failure to be clear on the
*botanical* name makes most of the university literature useless to me.

post-emergent herbicides kill the growing plant.  Some of the universities
recommend the world's most common herbicide, 2-4-D and its relatives,
mecoprop and dicamba.  Others(U.Cal) adamantly maintain that O.is resistant
to these herbicides.  But 2-4-D comes in at least 3 distinct forms.  Could
this be the area of disagreement?  Who knows, the universities don't
specify the species *or* the kind of 2-4- D they are talking about.  Again,
*this makes the info useless to me*.

One of the 'trick' ways of controlling O. is to adjust soil pH.  Pes-caprae
hates a low pH soil.  Oregana loves a low pH.  Better know what species
you have before you try this one.

Other trivia:
Oxalis is from the Greek word for sour, according to the U.Florida

Post-emergent you can kill it *non-selectively* with glyphosate(aka Roundup
and lots of other names).
*Selectively* you can kill it in a lawn with a material called triclopyr
which can be bought from two companies, Monterey and Ortho(in California,
that is).
Ammonium thiosulfate is another post-emergent which someone perseptively
mentioned on this group.  But AT works best only when aerial temperatures
are above 80 degrees.
All of the above require repeated treatments.  Don't expect one spraying to
do the job.  The herbicides don't always translocate into the bulblets of
the bulbous forms and the others reseed every 6 days or so in spring and
fall.

You can partially control corniculata *pre-emergently* with materials
called pendamethalin and isoxaben, both widely available in California
retail nurseries.

Rod Randall, if you can correct any mistakes I've made here I'd love it.
Jerry Heverly, Oakland, CA
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