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2008/7/4 Staden, Richard <Richard.Staden@xxxxxxxxxxxxxx.gov.uk>:
Err. Here's the missing link!
http://pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-ziram/triclopyr-ext
.html<http://pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-ziram/triclopyr-ext.html>
Richard - thanks very much for that, a useful site for future reference.
Useful also to read that while the half-life of triclopyr in soil averages
46 days [while in water it is only 10 hours], one of the products of it's
rapid conversion through an acid to a salt, trichlor-pyrinidol has a half
life of 279 days in one of the 15 soils tested, while in 12 soils it is less
than 90 days
Trouble is, it gives no idea of the effect of this breakdown product, as
opposed to triclopyr itself, on the plant roots it may come in contact
with. Though it does seem to be *relatively* harmless to other organisms
especially aquatics [I'm just waiting for the storm of abuse...].
And to refer to the original question, the use of chemicals has to be
weighed against the drawbacks of alternative methods of controlling
vegetation in an RPA, where the possibility of physical damage from grubbing
or digging may be worse, and may still leave [depending on the shrub or
plant species present] potential problems for a no-dig surface from
residual roots suckering, especially if there is a reservoir of the plants
nearby. I've seen couch, bindweed and rhododendron, coming through
polyester resin gravel over a concrete base... Which would be difficult to
deal with by anything but herbicides. Or a mower... Cut-stump application is
very localised, and if the half-life in drying foliage is anything to go by
this stuff [triclopyr] locks into dead plant tissue with little leaching.
I guess it would depend on the assessment of the vulnerability of the tree
and the other stresses on it, and whether alternative methods of removal of
the offending vegetation would be successful enough, without damage.
Regards
Anthony Mills
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