You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
<strong>Cover</strong> <strong>story</strong><br />
20<br />
worst<br />
WEEDS<br />
Our experts have joined forces with the national<br />
Weedbusters programme to name and shame<br />
20 of the worst weeds in the nation – most of<br />
which were introduced as popular garden plants.<br />
Find out how to stop these noxious nasties now<br />
12<br />
INTRODUCTION: RUUD KLEINPASTE<br />
PHOTOS: WERNER BOLLMANN/STOCKCENTRAL, WEEDBUSTERS<br />
ost gardeners are familiar with<br />
our strict quarantine regulations.<br />
Over the years we’ve opened our<br />
borders to enough exotic pest<br />
species to keep us scientifi cally employed for<br />
the next millennium… or three. Although<br />
quarantine offi cers now do a magnifi cent job<br />
keeping the nasties out, in the past there was<br />
no such thing as “biosecurity”. As a result, our<br />
gardens and native bush ended up playing<br />
host to wattles, ginger, hawthorn, gorse,<br />
blackberries, broom, selaginella – and a heap<br />
of small herbaceous buggers.<br />
Of course, we’re not the only country with<br />
weeds. Travel through Europe, the US or Asia<br />
and expect to see the world’s great leveller:<br />
eucalyptus. It’s hideous outside of Australia.<br />
So, what about New Zealand native trees?<br />
Are there any species that have become a<br />
weed elsewhere? The answer is yes – and<br />
there are some surprisingly spectacular ones.<br />
The islands of Hawaii tend to have quite<br />
specifi c and fragile ecological systems, which<br />
are open to invasion by interlopers. In the<br />
late 1800s, someone there thought it would<br />
be a “good idea” to introduce our karaka<br />
(Corynocarpus laevigatus) to Kaua’i. Thanks<br />
to pigs and birds eating and spreading the<br />
nutritious seeds, it is now considered an<br />
“aggressive coloniser”. It grows in shade<br />
and forms even deeper shade underneath its<br />
glossy green leaves, suppressing the growth<br />
of one of Hawaii’s rarest plants, the heau.<br />
In Hawaii, our tea trees (Leptospermum<br />
and Kunzea) are also regarded as weeds. They<br />
behave – just like at home – as very competent<br />
pioneer species. Any bare patch of soil is<br />
colonised immediately, thereby excluding<br />
Hawaii’s native pioneer species.<br />
Other islands bothered by our tangata fl ora<br />
include St Helena and Tristan da Cunha in<br />
the south Atlantic. Flax (Phormium tenax) was<br />
planted there as a crop for the fi bre industry.<br />
But when the market collapsed in the 1960s,<br />
St Helena was left overrun with the stuff and,<br />
as a result, its endemic plants are threatened.<br />
Even our most beautiful native trees,<br />
like pohutukawa, can become a nuisance.<br />
Metrosideros excelsa was introduced to South<br />
Africa as an eye-catching ornamental and<br />
you can see magnifi cent specimens in the<br />
streets of Cape Town. But our metrosideros<br />
didn’t confi ne itself to a life in the city: aided<br />
by its small, windblown seeds, it invaded the<br />
local ecosystems, or “fi jnbos”, and its status is<br />
now “invasive alien”. In the global war of the<br />
weeds, nature’s proving a tough opponent. <br />
Moth plant<br />
Araujia sericifera<br />
This banned plant is also known as kapok<br />
vine, moth vine, cruel plant and wild choko<br />
vine. The poisonous, rampant, evergreen<br />
vines form large, heavy, tangled masses<br />
that smother trees and bushes. When cut,<br />
the vines bleed milky sap – hence the<br />
common name of milk vine or milk weed.<br />
The choko-like green pods split open to<br />
release thousands of airborne seeds that<br />
spread long distances.<br />
HOW TO KILL IT<br />
Moth plant is poisonous and can cause skin<br />
irritations so always wear gloves to protect<br />
against contact with sap. Seedlings can be<br />
pulled out year round. For large vines, always<br />
remove and destroy (burn) the ripe pods fi rst<br />
to minimise seeding and seed contamination<br />
of clothing. Chop down the vines (this is best<br />
done summer/autumn) and coat the stump<br />
with Tordon Brushkiller, Banvine, Yates<br />
Woody Weedkiller or McGregror’s Weed Out<br />
for Woody and Scrub Weeds. Stumps can<br />
resprout, so follow up six-monthly and<br />
replant bare spots to stop seeding.<br />
1 2 3<br />
Montbretia<br />
Crocosmia x crocosmiifl ora<br />
Although this once popular garden plant<br />
fl owers profusely in summer, it produces<br />
few seeds. The real problem is caused by<br />
its corms and rhizomes – they multiply<br />
rapidly and even a small fragment will<br />
sprout into a sturdy plant. The strappy,<br />
sword-shaped leaves rise from the base<br />
and the tall, zig zag-shaped orange fl owers<br />
appear from January to February. It tolerates<br />
frost and heat, damage and grazing, damp,<br />
and moderate shade. Montbretia competes<br />
mainly with groundcovers and small shrubs<br />
and it will invade low-growing habitats and<br />
roadsides. If you love crocosmia fl owers,<br />
plant the named variety ‘Lucifer’ instead.<br />
HOW TO KILL IT<br />
Dig out small infestations and burn any<br />
corms you collect. However, this approach<br />
can prove futile when tackling big areas as<br />
any corms left in the ground will resprout.<br />
Cut back and coat stumps with Roundup.<br />
For large spots, spray the foliage with<br />
Roundup or Escort after fl owering. Add<br />
some spraying oil so the weedkiller sticks.<br />
4perennial, mat-forming groundcover has<br />
Artillery plant<br />
Galeobdolon luteum<br />
Also known as aluminium plant, this<br />
square, purplish stems and stolons that<br />
are densely hairy and smell mint-like.<br />
HOW TO KILL IT<br />
Dig out small patches and burn. For larger<br />
infestations, wipe leaves with Roundup,<br />
Escort or McGregor’s Weed out General<br />
Purpose spray. You’ll need to follow up<br />
with another spray every three months<br />
until eradication is achieved.<br />
Blue morning glory<br />
Ipomoea indica<br />
Its very fast growth rate, longevity, dense<br />
smothering habit and ability to climb to the<br />
top of high canopies makes blue morning<br />
glory a dominant vine wherever it occurs.<br />
It can smother forest growth with a low<br />
weedy blanket, with tough, hairy, twining,<br />
running stems and tough fi brous roots<br />
without rhizomes. Creeping stems spread<br />
this plant locally, and stem fragments are<br />
accidentally moved in dumped vegetation.<br />
In New Zealand it rarely seeds.<br />
HOW TO KILL IT<br />
Where it is not too far advanced, hand pull<br />
and dig out the roots before burning.<br />
Otherwise, cut the vines down and paint<br />
the stumps with Roundup, Escort or<br />
McGregor’s Weed Out General Purpose. In<br />
summer and autumn you can cut the vines<br />
at waist height and spray the remaining<br />
foliage. A good trick to limit any potential<br />
spray drift is to pour systemic weedkiller<br />
into a container, place inside a plastic bag<br />
and tie around part of the vine so the stems<br />
slowly soak up the weedkiller.<br />
WAR AGAINST WEEDS<br />
This article focuses on noxious and nasty<br />
weeds that, largely, were once loved garden<br />
plants. In our March 2007 issue, we featured<br />
20 common lawn and soil weeds including:<br />
onion weed, dandelions, wild carrot, oxalis,<br />
lawn daisies, groundsel, bristly ox-tongue,<br />
plantain, fathen, thistles, buttercup, puha,<br />
milkweed, clover wall fumitory, cleavers,<br />
hawksbeared, dock and assorted grasses.<br />
To fi nd out how to control these weeds,<br />
visit our website (www.nzgardener.co.nz)<br />
to download a PDF copy of the article.<br />
13
Monkey apple<br />
Acmena smithii<br />
Also known as lilly pilly and acmena, this<br />
banned Australian import eventually grows<br />
into a smooth-barked tree up to 15m tall<br />
with oval, leathery leaves that are very<br />
aromatic when crushed. Monkey apples<br />
can live for a century or more and were<br />
once a very popular option for hedging and<br />
shelterbelts. However, when left unpruned,<br />
whitish fl owers appear from October to<br />
January, followed by bunches of pink or<br />
white berry-like fruit with large seeds that<br />
are greedily scoffed and then spread widely<br />
by birds – including our native wood pigeon.<br />
In bush, monkey apple seedlings can form<br />
dense carpets under the canopy and they<br />
quickly claim any gaps created by windfall<br />
or possum damage.<br />
HOW TO KILL IT<br />
This one’s a toughie. You can pull or dig<br />
seedlings and leave on site to rot down,<br />
but, be warned, bare areas reseed quickly.<br />
For mature trees, drill a hole every 10cm<br />
around the trunk and apply a slurry of a<br />
metsulfuron-based weedkiller (Escort,<br />
Meturon or Mustang) to each hole. Or cut<br />
down and paint the stump with the above.<br />
14<br />
5 6 7<br />
Darwin’s barberry<br />
Berberis darwinii<br />
Originally from Chile and Argentina, this<br />
spiny, evergreen, yellow-wooded shrub has<br />
hairy stems with tough, needle-sharp spines.<br />
It tolerates moderate to cold temperatures,<br />
damp and dry conditions, high wind, salt,<br />
shade, damage and a range of soils. From<br />
July until February, the plants produce<br />
hanging clusters of deep orange-yellow<br />
fl owers, followed by oval purplish-black<br />
berries with a bluish-white surface. The<br />
fruit of Darwin’s barberry is eaten by birds<br />
who spread the seed into native bush. The<br />
plants (occasionally dense stands) replace<br />
shrubland and regenerating forest,<br />
sometimes permanently in open habitats.<br />
HOW TO KILL IT<br />
Grub out young plants (although be careful<br />
of the sharp spines) and leave to rot down.<br />
For larger specimens, cut down and coat<br />
the stump with Roundup, Escort, Vigilant<br />
gel or Tordon Brushkiller. From spring until<br />
autumn, when the plants are actively<br />
growing, spray with Escort or Tordon<br />
Brushkiller. Cut stumps resprout quickly<br />
and are hard to kill, so follow up every six<br />
months and keep an eye out for seedlings.<br />
8forest fl oor and heads up into the canopy,<br />
Jasmine<br />
Jasminum polyanthum<br />
This evergreen climber grows rapidly over<br />
forming dense, long-lived masses. The<br />
runners spread long distances – even under<br />
buildings and over rocks – and because it’s<br />
highly shade-tolerant, it’s extremely hard to<br />
kill. The white fl owers (pink in bud) appear<br />
year round and are very fragrant, hence its<br />
initial popularity.<br />
Mexican daisy<br />
Erigeron karvinskianus<br />
This sprawling perennial daisy has long,<br />
thin stems, small leaves and masses of<br />
white-to-pink fl owers from January to<br />
December, followed by fl uffy seeds. Seed<br />
sources can include contaminated topsoil<br />
and potting mix. In the bush, dense mats of<br />
Mexican daisies are crowding out native<br />
plants and opening the way for invasion by<br />
vines and other weeds. They are also<br />
pushing aside vulnerable plants on bluffs,<br />
coastal zones, islands and herb fi elds.<br />
HOW TO KILL IT<br />
Convince your fellow gardeners to stop<br />
growing it, for starters. Their well-travelled<br />
seeds are constantly creating new colonies<br />
in bush many miles away. Tell them they’re<br />
harbouring terrorists! (It is illegal to sell,<br />
propagate or distribute Mexican daisy<br />
under the Biosecurity Act 1993.) Dig out<br />
small plants, avoiding unnecessary soil<br />
disturbance, and leave to rot or, if seed is<br />
present, burn. A range of herbicides is<br />
suitable for controlling Mexican daisy,<br />
including glyphosate-based sprays such<br />
as Roundup Renew, McGregor’s Weed out<br />
and Watkins Weedkiller.<br />
HOW TO KILL IT<br />
Cut down the snaking vines (always dry<br />
and burn the cut vines or take them to your<br />
local refuse transfer station) and swab the<br />
stump with Escort, Banvine or Yates Woody<br />
Weedkiller. Add a penetrant (such as<br />
Sprayfi x) to ensure the weedkiller sticks to<br />
the glossy foliage. Spray any regrowth with<br />
Roundup Renew, Escort, Banvine, McGregor’s<br />
Weed Out for Woody and Scrub Weeds or<br />
Yates Woody Weedkiller.<br />
Ivy<br />
Hedera helix<br />
About 75 per cent of New Zealand’s weeds<br />
are garden escapees. Ivy, which can cling<br />
to and climb almost any surface, forming<br />
dense, long-lived masses and completely<br />
smothering tree trunks and branches, is<br />
right up there as one of the worst threats<br />
to native bush. Ivy especially destroys<br />
vulnerable epiphyte niches. The sheer<br />
weight of an infestation can bring down<br />
branches or whole trees.<br />
How to kill it<br />
Be aware that ivy can cause skin irritations<br />
so avoid contact. Small infestations can be<br />
controlled by removing all stems in contact<br />
with the ground, and digging up the roots.<br />
Burn or bury deeply. When ivy has climbed<br />
into the canopy, or around a favourite tree,<br />
the cut stump method is best. Cut vines to<br />
ground level and apply herbicide to the cut<br />
stump. Suitable herbicides include Vigilant,<br />
Grazon, Escort and glyphosate-based<br />
herbicides such as Roundup and McGregor’s<br />
Weed Out for Woody and Scrub Weeds.<br />
Because of the way ivy clings to host trees,<br />
it is best to leave the remaining stems on to<br />
die. Pulling them off can damage the tree.<br />
NO<br />
Spray, NO Mess, NO Weeds<br />
• WWoolly<br />
nightshade • Cotoneaster • Gorse<br />
• OOld<br />
man’s beard • Kahili ginger • Agapanthus<br />
• WWandering<br />
Jew (Willie)<br />
Ask for Vigilant Herbicide Gel at your<br />
local garden centre or rural supply outlet.<br />
9 10 11<br />
Japanese honeysuckle<br />
Lonicera japonica<br />
A vigorous evergreen (semi-evergreen in<br />
cold regions) climber with long, tough, wiry<br />
stems that twine clockwise, Japanese<br />
honeysuckle has sweetly scented, tubular,<br />
white flowers that turn yellow as they age.<br />
It flowers from September until May. The<br />
dense, long-lived plants climb over and<br />
smother most plants from the ground up to<br />
the mid-canopy, even causing canopy<br />
collapse and subsequent invasion of grasses<br />
or ground vines. Japanese honeysuckle also<br />
provides support for faster growing weedy<br />
vines such as morning glory and moth plant.<br />
How to kill it<br />
Small sites can be cleared by removing the<br />
stems and digging out the roots. Because<br />
Japanese honeysuckle is a light seeder,<br />
sites usually remain clear after treatment.<br />
A number of chemical controls can be<br />
used, including Vigilant gel, Grazon, Escort,<br />
and glyphosate-based herbicides such as<br />
Roundup Renew and McGregor’s Weed Out<br />
General Purpose. The best method of<br />
control is the cut stump method: cut vines<br />
to ground level and apply herbicide to the<br />
cut stump immediately.<br />
Herbicide Gel<br />
www.hortresearch.co.nz/bet/products/vigilant 0800 VIGILANT (0800 8444 526)<br />
Agapanthus<br />
Agapanthus praecox<br />
This prolific seeder is long-lived and<br />
tolerates heat, damp, drought, wind, salt...<br />
even a dip in the sea. Although not a<br />
problem in frosty climates, it’s an invasive<br />
beast in northern regions. Seeds blow short<br />
distances, cover banks and are also carried<br />
in flowing water. Seed and root fragments<br />
are spread in contaminated soil, dumped<br />
vegetation and deliberate planting in our<br />
gardens. Agapanthus is commonly found in<br />
gardens, roadsides and banks and seems<br />
capable of growing in no soil at all. If you<br />
love agapanthus, there are a number of<br />
sterile varieties to choose from.<br />
How to kill it<br />
First, cut off the flower heads before any<br />
seeds can form. Because agapanthus does<br />
not respond well to herbicide, hard labour’s<br />
pretty much the only option – dig out the<br />
plants, getting as much of the roots as you<br />
can, and burn or take to your local refuse<br />
transfer station for disposal. An application<br />
of Vigilant gel may also help. Prune all the<br />
shoots off just above ground level and<br />
apply a 3mm-5mm layer of Vigilant gel<br />
across the cut surface.<br />
<br />
15
You get back to enjoying life.<br />
We’ll take care of the lawn.<br />
Irene is fl at-out. Netball champion, TV adverts, magazine shoots,<br />
pick up the kids from school, weed the lawn and fi nd time to relax<br />
(if she gets a chance).<br />
We can’t pick the kids up from school, but we can certainly help you<br />
with weeding the lawn. It no longer has to be hard or time consuming.<br />
Simply connect the hose to the sprayer and we’ll mix the water &<br />
concentrate as you spray, ensuring exactly the right proportions of<br />
liquid fertiliser and weedkiller is distributed onto the lawn.*<br />
Yates Weed ‘n’ Feed kills broadleaf weeds and promotes a lush green<br />
lawn in one application.<br />
We’ll take care of the garden stuff. You get back to enjoying life.<br />
*Always read the product label before using.<br />
16<br />
More information?<br />
DPP34857<br />
12<br />
Wild ginger<br />
Hedychium gardnerianum and Hedychium flavescens<br />
Don’t let its good looks fool you. Wild ginger threatens to<br />
smother our native forests. Introduced to New Zealand from<br />
India in the 1890s, it rapidly spread throughout Auckland, the<br />
Coromandel and Northland. It is now a problem in parts of the<br />
top of the South Island, and on the West Coast.<br />
There are two types of wild ginger. Kahili ginger (Hedychium<br />
gardnerianum, above) grows up to 2m, has large cream flowers<br />
with long red stamens, is strongly perfumed and produces up to<br />
100 seeds per flower head. Of the two types of wild ginger, this<br />
is the worst, because of its ability to successfully spread by<br />
seed. The roots also spread outwards to sprout new plants.<br />
Yellow ginger (Hedychium flavescens) has cream flowers in<br />
late autumn/early winter but doesn’t set seed or multiply as<br />
fast as Kahili ginger. Make its removal a second priority.<br />
Both wild gingers produce massive branching rhizomes.<br />
These horizontal underground stems produce new buds and<br />
form a dense layer up to a metre thick, which invades forest<br />
remnants and which other plants cannot penetrate. Extremely<br />
shade-tolerant, wild ginger tolerates most soil types and is<br />
drought and frost-tolerant once established. The dense rhizome<br />
beds replace all other species and are shallow rooted, so when<br />
they become heavy with rain they can slip on steep sites and<br />
streambanks, causing erosion.<br />
How to kill it<br />
Pull out small seedlings by hand. Isolated plants can be grubbed<br />
out, but you must get all the rhizomes. The stalks and roots are<br />
hard to burn and should not be composted. Take them to your<br />
council dump or transfer station. If in doubt, check with your<br />
council. Spray with Amitrole, Escort, Roundup or McGregor’s<br />
Weed Out General Purpose spray from spring to late autumn.<br />
Spray lightly on the leaves and roots. Do not remove the leaves<br />
or stalks until they have gone brown and dried out. This takes up<br />
to four months. For larger plants, the cut-stump method can be<br />
used. Cut the plant close to the ground with a straight, flat cut.<br />
The cut must be horizontal so the herbicide will stay on the cut<br />
area and be absorbed. Apply any of the above herbicides or<br />
Vigilant gel immediately, as the sap ceases to flow once the<br />
tissues are severed. This method uses less spray and reduces<br />
the risk to non-target plants.<br />
13 14 15<br />
Wandering Jew<br />
Tradescantia fl uminensis<br />
Named for John Tradescant – gardener to<br />
King Charles I – this South American nasty<br />
produces no fruit or seed in New Zealand,<br />
but that doesn’t hold it back a bit. It creeps<br />
and rapidly forms dense mats from even<br />
the tiniest fragments and is also very<br />
tolerant to dense shade. It has dark green,<br />
shiny, oval leaves with pointed tips and<br />
white fl owers in summer. Wandering jew,<br />
also known as wandering willie, smothers<br />
bare ground, preventing the seedlings of<br />
native species from establishing.<br />
HOW TO KILL IT<br />
In small spots simply rake, roll up, burn and<br />
dispose of at your local refuse transfer<br />
station. But be very careful as any dropped<br />
fragments will simply spread infestation.<br />
Usually a follow-up spray is needed. Use a<br />
triclopyr-based spray (Grazon, Victory or<br />
Brush Off) or a glyphosate spray such as<br />
Roundup. Spray raked-up piles of the plant<br />
to ensure you fi nish them off. Spray in spring<br />
when dry. The paint-roller technique is also<br />
effective: put a capful of Vigilant gel in a<br />
roller tray and use a paint roller to apply<br />
over the weed (a capful covers 1-sqm.)<br />
Chilean fl ame creeper<br />
Tropaeolum speciosum<br />
This climbing perennial, often found in the<br />
high canopy in the bush, is a banned beauty.<br />
Related to the common nasturtium, it has<br />
a thick rootstock and slender stems with<br />
curling tendrils and watery sap. The dull,<br />
soft, light green leaves have fi ve leafl ets.<br />
The solitary, tubular, scarlet fl owers have<br />
fi ve irregular petals with the bottom three<br />
having a very slender claw. Flowers appear<br />
from November to April followed by a thin,<br />
fl eshy, deep blue seed capsule made up of<br />
three round parts. Birds spread the seed.<br />
The Chilean fl ame creeper climbs up into<br />
native bush canopy, alters light levels and<br />
prevents the establishment of regenerating<br />
native species.<br />
HOW TO KILL IT<br />
If you have it growing in your garden,<br />
admire it for the last time, then pull this<br />
pest plant out and dispose of the vines.<br />
Check every few months for new seedlings.<br />
No fully effective herbicide treatment is<br />
known, however you could try cutting it back<br />
in spring and summer and coating the base<br />
with Roundup, Escort, Tordon Brushkiller or<br />
McGregor’s Weed Out General Purpose.<br />
16fern,<br />
this ground-dwelling or epiphytic fern<br />
Tuber ladder fern<br />
Nephrolepis cordifolia<br />
Also known as the sword fern and Boston<br />
grows to 1m tall with small, erect, scaly<br />
rhizomes producing many long runners and<br />
hundreds of round, 1cm-3cm, potato-like<br />
tubers. (The rare native ladder fern –<br />
Nephrolepis novae-zelandii – is similar, but<br />
it doesn’t have tubers.) The pesky tuber<br />
ladder fern spreads by spores, runners and<br />
Periwinkle<br />
Vinca major<br />
This scrambling groundcover has short<br />
rhizomes and trailing stems that take root<br />
when they come in contact with the soil.<br />
The blue fl owers don’t seem to produce<br />
much seed – this plant spreads through<br />
rhizome and stem fragments instead.<br />
Sources of infestation include many old<br />
homestead gardens, cemeteries, woodlots<br />
and farms. Periwinkle prevents seedlings of<br />
native species establishing and opens up<br />
habitats so that they are more vulnerable<br />
to weedy vines and grasses.<br />
HOW TO KILL IT<br />
Vinca major is extremely diffi cult to kill. For<br />
very small sites, dig it out and burn. Check<br />
for regrowth. Mow with your lawnmower’s<br />
blades set low and then, as it regrows, grub<br />
out the obvious roots. On other sites that<br />
are steep or lack access, try smothering it<br />
with black plastic or weedmat. Or spray<br />
with a glyphosate-based herbicide<br />
(Roundup Renew or McGregor’s Weed Out<br />
General Purpose) and follow up as required<br />
to eventually win the battle. Periwinkle<br />
takes a few years to eradicate, so spray<br />
twice a year, in spring and in autumn.<br />
tubers to form dense, long-lived patches<br />
that are often large. It crowds out<br />
groundcovers, shrubs and other ferns, and<br />
can contribute to streamside erosion.<br />
HOW TO KILL IT<br />
This one’s easy – well, if you don’t mind a<br />
little hard slog. Pull it out, and burn the<br />
tubers and runners. If you spray, use Escort<br />
and leave for three to four months to allow<br />
the herbicide to translocate to the tubers<br />
before clearing or replanting.<br />
17
Pampas Grass<br />
18<br />
17 18 19<br />
Cortaderia selloana<br />
Also known as cutty grass, Prince-of-Wales<br />
feathers and – incorrectly – toetoe. Our<br />
native toetoe species do look similar,<br />
however the exotic imposter has a number<br />
of recognisable differences. Its fl uffy fl owers<br />
are more upright and dense and appear<br />
from February to June (whereas the native<br />
species fl owers from September until<br />
January). Native toetoe leaves also don’t<br />
snap readily and have distinct secondary<br />
leaf veins and the dead leaves don’t spiral.<br />
Pampas grass grows up to 6m tall, produces<br />
massive amounts of wind-borne seed and<br />
colonises sprayed, burnt and eroded sites.<br />
HOW TO KILL IT<br />
Dig or grub out seedlings or small plants.<br />
Take a chainsaw to small plants and leave<br />
to compost or rot down on site. Burn any<br />
fl owerheads. Chainsawing and slashing can<br />
be combined with chemical spraying. Spray<br />
with Gallant, Roundup Renew or Touchdown<br />
from spring to autumn. Make sure you leave<br />
the plants in the ground until the roots have<br />
died off. Do not re-apply herbicide too soon<br />
after the initial treatment. Wait until the<br />
plant actively begins growing again.<br />
20<br />
Arum Lily<br />
Zantedeschia aethiopica<br />
The so-called death lily is a common sight<br />
in farm paddocks and old homestead<br />
gardens. This evergreen, clump-forming,<br />
tuberous plant is long-lived and persists<br />
under regenerating canopy, forming dense<br />
patches excluding other vegetation. Arum<br />
lilies can tolerate damp, windy and coastal<br />
sites and, once established, they’re also<br />
drought-resistant. Because arum lilies are<br />
poisonous, the clumps are left to their<br />
own devices by stock in grazing areas and<br />
slowly expand by producing new shoots.<br />
The seed is spread by dumped vegetation<br />
and soil movement.<br />
HOW TO KILL IT<br />
Mowing gives no control and digging out<br />
can leave root fragments and small pieces<br />
of tubers to resprout. So be prepared for<br />
a physical battle. Slash down the tops and<br />
leave on site to rot down. Dig out tubers,<br />
dry and burn or bury deeply. Repeat for any<br />
regrowth. Cutting down and painting the<br />
stumps with Escort may also work. Exclude<br />
all livestock from the area when treating.<br />
White-veined Italian arum (Arum italicum)<br />
is similarly weedy. Kill it this way too.<br />
Blue passion fl ower<br />
Passifl ora caerulea<br />
This vigorous, evergreen, high-climbing<br />
vine has long stems with spiralling tendrils.<br />
The leaves are very thin. Hanging whitish<br />
purple fl owers with purple fi laments appear<br />
from December to April, followed by hanging<br />
round fruit that ripens to yellow. The large<br />
masses smother native bush and the blue<br />
passion fl ower can also strangle host plants<br />
and stop native seedlings from establishing.<br />
Old man’s beard<br />
Clematis vitalba<br />
Made famous by David Bellamy’s “Old<br />
man’s beard must go” TV advertisements,<br />
this deciduous, layering vine can grow up<br />
to 20m long. It grows rapidly, forming a<br />
dense, heavy, permanent, tangled mass<br />
that smothers its host. It produces many<br />
long-lived seeds that are spread by water<br />
and wind. It kills all plants to the highest<br />
canopy and prevents the establishment<br />
of native plant seedlings.<br />
HOW DO I KILL IT<br />
The best method of control is to cut vines<br />
to ground level or waist level in winter or<br />
spring. Then spray the regrowth in March<br />
with Roundup, Escort or McGregor’s<br />
Weedout General Purpose. For larger<br />
specimens, chop down and immediately<br />
apply herbicide (Vigilant gel is especially<br />
suitable) to the stump. Burn all cutaway<br />
segments. Old man’s beard will not be<br />
eradicated in one season.<br />
For more information<br />
about weed control, visit<br />
the informative website<br />
www.weedbusters.org.nz.<br />
HOW TO KILL IT<br />
Pull up the roots and cut off the vines<br />
above ground or tie their stems together in<br />
the air to prevent them coming in contact<br />
with the ground and taking new roots.<br />
Otherwise cut down and paint the stump<br />
with Roundup, Escort, Tordon Brushkiller,<br />
Banvine, Woody Weedkiller or McGregor’s<br />
Weed Out for Woody and Scrub Weeds. Use<br />
herbicide only when roots cannot be pulled<br />
out. The stumps may resprout.