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Freeway flowers, weeds & arboricides

I'll not rabbit on to long folks

Nick asked if Oxalis pes-caprae is weedy is South Africa,  YES
It is one of four spp. considered weedy enough to be listed in a neat
little book called "Problem Plants of South Africa"  There are roughly
243 native Oxalis spp. in South Africa with two natives and two
introductions treated as weeds.

There are roughly 1100 introduced species in Western Australia that have
naturalised and many of these are considered serious weeds.  Liz was
right, I could spent hours going on about it or if you are really
interested you could buy a copy of our book "Western Weeds, a guide to
the weeds of Western Australia" 
Or if you want to wait a while I am converting the book into a web site,
I'm about 1/3 rd finished and have yet to get the search engine working
but what I've done so far looks very nice.  I have included all the
photos and drawings from the book (600+) and all the text.  Its a slow
process as I want it to look like the book, not some auto generated
database site.

On the issue of arboricides Tim, many herbicides you could use would
leave residues in the plant tissue.  Something that could be tested for
easily, especially if some of this herbicide was found by the plant
police on your property.
On the other hand testing for residues is specific and if the testing
lab isn't told what to test for, then they can't test. Testing is
expensive and sometimes the results can be open to interpretation, some
herbicides have quite innocuous breakdown products, others leave
distinctive chemical residues.  
We commonly have people bringing in their prize plants all withered and
dieing quite obviously afflicted by herbicide but we can do nothing as
in most cases the culprit cannot be linked to the resultant damage, it
is your tree however and you have asked previously to remove it? Talk
about establishing a motive   :-( 
I have used picloram based herbicides to kill large trees, but these
herbicides are quite residual and I could not grow anything on the spot
where the tree was for several years (no real problem, a few square
meters in over 1200).  Any form of stem injection will leave marks
easily spotted.  Its a problem Tim   

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..."
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