Weed Control
One of the most resilient weeds is Periwinkle, a shade tolerant creeper with long lasting
seeds and it is hard to kill with herbicide. Another weed, Mexican Devil, is widespread,
with prolific windborne seeds that colonise broken ground. We expect it to increase
in extent with our change to blanket spraying of grass for planting site preparation.
It must be controlled until canopy closure at which point it should only be found at
margins where there is plentiful light. Another nasty is mothplant, which climbs up
trees and readily smothers. It produces prolific seeds which are windborne, and again
seeds appear to last a good number of years in the ground. It is difficult to control
as it breaks at ground level readily and fragments easily regrow. Vigilance is required
and luckily, the number of mothplant sites on the island is limited.
Of lesser concern are blackberry, pampas, tobacco weed, privet, cotoneaster, Mexican
daisy and wattle. Blackberry is widespread but controlled to the extent where there
are no un-walkable clumps. Blackberry will eventually disappear under the canopy of
trees. The odd pampas and tobacco weed turns up but is relatively easy to control with
herbicide or hand pulling if small enough.
Cotoneaster and privet are widespread but not numerous, vigilance is required as these
two appear to be able to establish from seed (bird dispersed) through thick grass. Long
lasting wattle seed continue to sprout in confined areas and are hand-pulled each year.
Limited in number and extent, Mexican daisy is present on some exposed bluffs and perched
on parts of the cement mill ruins.
Of little concern, but still requiring attention, German Ivy and Nasturtium are present
in isolated spots. Nasturtium has been hand-pulled for three years and the seed bank
in the soil is almost exhausted. German Ivy is very susceptible to spray and easily
killed. Fortunately the wind borne seeds are not particularly viable and do not last
very long in the soil.
Several Taiwanese Cherry has been found on the island and hand pulled before reaching
a size where they could seed. Two found at the back of the navigation beacon were about head
height before being discovered. The odd 15cm high ginger plant and palm-tree species has also been hand-pulled around
island. Having fairly large seeds, these species have probably been bought across by visiting
native wood pigeons. More of these can be expected as the forest matures on the island and
becomes more attractive to pigeon.
Australian sedge is present over the whole island, mostly in the main paddock. Though
not surveyed, it appears not be spreading at a great rate. There is no active control
of this weed. Stock might in the future be used to graze the main paddock, in which
case, control of the sedge would be made easier and in fact may become necessary.
Of interest, walnuts are washed up on the island each year and a few grow at the high
tide mark. These are hand-pulled and indicate there is a ready source of seed somewhere
up harbour – probably washed down in floods from one of the stream tributaries.
Mats of alligator weed are washed up as well, though to date these dry out and die at
the high tide mark.
The small island towards Portland (Rabbit Island) has, with a predominant westerly wind, been a
continual source of weed seed for moth-plant, pampas, mexican-devil and mexican daisy. It also
has others but they do not have wind-bourne seed like those mentioned. Funding was provided by DOC Biodiversity Condition and Advice Fund,
and with the agreement of the owner (the island is privately owned), a weed control programme
was started on the island in 2005. Still in its knock-down phase, the programme is led by weed expert and committee member,
Ken Massey, and to 2008 all of the weeds have been significantly reduced in area.
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| Rushing along now, island restoration was
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| Goals now remain the same as when island
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