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<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.

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