Re: New Potential Weed

Gary Matson wrote:
> 
> One of the most striking things to me about discussions of exotic plant > invasions is just how localized and specific the problems are. What is a  terrible weed one place is not in another despite superficially similar > conditions of climate etc. (snip)
> 
> Is there any alternative other than planting and waiting to see? Should I forgo a beautiful plant because it has become invasive somewhere else?
> 
> This leaves me in somewhat of a quandary, since one of my greatest
> delights is acquiring new kinds of plants and watching them grow
> successfully.  A 'topical' topic for me.
> 
Dear Gary
As you say, this is a difficult problem. In many cases rapid spread is
linked to the ability to easily set viable seed, but this is not always
the case. One of our most seriously invasive weeds locally is
Tradescantia fluvitalis which almost never produces seed in this
country, but gets about by vegetative means because it is such an
incredibly good survivor. (I discovered how good on one occasion when I
tried to use  some I had gathered in a demonstration on flame weeding.
Repeated passes failed to cause the slightest withering of the leaves
and the next morning it appeared totally untouched.)

I am fascinated by regular remarks about the frailty of Pinus radiata in
its native haunts. Not only is it a super-successful crop here, maturing
in little over thirty years, but it has begun to quite seriously invade
native mountain grasslands in the South Island, so parties of volunteers
regularly go out to dig up or chainsaw off these unwanted plants before
they can seed in their turn. One wonders how it can like our climate so
much better than its own. Indeed it seems super-tough  here, if the way
it is usually planted is anything to go by - just a couple of strokes of
a spade to open a crack into which a bare-rooted seedling is dropped and
then a quick step with a boot to firm it in - no fertilizer or
after-care at all and in most areas close to a 100% take.

One thing we do find with many garden ornamentals which tend to become
invasive is that the problem is greatest in our northern (warmer)
regions and becomes rapidly less serious as on gets into cooler
districts. An examples of this would be Pampas grass. In warmer parts
all colour forms from purple through pink to white can be seen scattered
freely along the roadsides and in paddocks where it has sown itself, but
in my area, though it grows perfectly easily in gardens, it rarely
spreads elsewhere without help. I can only remember, in fact, seeing a
single wild clump close to home.

Another factor in invasive spread can be having berries which make good
bird food. Among problem plants which spread this way  around here are
privet, elderberry and blackberry. The method of spread is particularly
easy to pick when these plants start life under one of one's choice
shrubs on which the bird has perched.

 My inclination would be to try any plant one fancies, but keep a close
watch on it if it has a reputation for thuggary elsewhere. 

Moira

-- 
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand
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