DoC's Helen shows RIBCA members how to tackle a Rhamnus bush

RIBCA members have signed on to the Weedbusters programme to help rid Rangitoto of weeds.

The Weed Problem

Weeds are of real concern on Rangitoto. They over-run native plant species preventing their germination and growth. This has the flow-on effect of reducing food and habitat opportunities for native birds, animals and insects whose numbers decline as they move elsewhere or die off.

Banishing weeds from Rangitoto is part of the Department of Conservations objective of ecological restoration for both Rangitoto and Motutapu.

On Motutapu the Motutapu Restoration Trust has been co-ordinating a successful weeding and replanting programme for many years.

RIBCA families join other volunteers to replant Home Bay, Motutapu

RIBCA's official training started in January when representatives from Weedbusters briefed the Rangitoto Wharf bach families on the programme.

A second session was held at Islington Bay on Labour Weekend.

Training Session

The Islington Bay session started with Mary Stewart, Bio-security officer with the Auckland Regional Authority, giving a very informative power point presentation on the weed problems in Auckland.

Then Steve Benham and Helen from the Department of Conservation zeroed in on the particular weeds most prevalent on Rangitoto. Rhamnus and Maderia Vine are the worst offenders.

Removal

Outside, Helen showed us how to remove a Ramnus bush by cutting it down close to the ground and applying Vigilant herbicide paste to the stump.

It was explained that DoC tries to minimise the use of herbicides on the islands because spray drift and cross-contamination can harm other plants, birds, animals and insects.

DoC prefers Vigilant herbicide paste which can be applied directly to where it is needed.

That said, not all weeds need herbicide. Some can be pulled out by hand, or dug out.

Helen applies Vigilant herbicide paste to the Rhamnus stump

Disposal

However, we were also warned that many weeds can re-root from stem fragments left on the ground.

Therefore, RIBCA families have been asked to carefully gather all fragments and put them in the bags provided for collection by DOC.

Replanting

Normally, replanting is an important step in the process because it reduces the available habitats for invading weed species.

However, because the choice of replacement plant can really matter on Rangitoto replanting MUST NOT to be done without Department of Conservation approval.

Weedbusters Kit

To help get us started, Weedbusters generously supplied each bach with a weed-busters kit that contained a hand saw, composting bags, Vigilant herbicide and WeedBuster's sun hat and T-shirt.

The Problem Weeds on Rangitoto

	Brush Wattle Paraserianthes lophantha A fast growing evergreen tree which produces masses of hard-coated black seeds in long flat green pods. IMPACT Out-competes native species because of its fast growth & long-term seed bank. CONTROL • Hand pull seedlings. Check regularly for new seedlings because of the long life of the seeds. • Cut larger trees near the ground and apply Vigilant herbicide paste to the stump. • For very large trees cut 15mm blazes 30mm apart around the truck near the ground and apply Vigilant herbicide paste to the lower surface.
	Bushy Asparagus Asparagus densiflorus A low, dense, scrambling herb with thin wirey stems, thin leaf and long spines. Small pink-white flowers and bright red berries. IMPACT Forms masses of interlocking branches suppressing other species and preventing regeneration. CONTROL • Dig out small plants carefully removing all tubers which will resprout. • Cut near the ground and apply Vigilant herbicide paste to the stump.
	Cotoneaster Cotoneaster glaucophyllus An arching spreading shrub, 3-4 metres tall. Small pink-white flowers and small glossy red berries in bunches. IMPACT Forms pure stands driving out other species. CONTROL • Hand pull or dig out seedlings. • Cut near the ground and apply Vigilant herbicide paste to the stump. • For large stems cut 15mm blazes 30mm apart around the truck near the ground and apply Vigilant herbicide paste to the lower surface.
	Fairy Crassula, Pitted Crassula Crassula multicava Creeping succulent herb. Leaves fleshy and covered with small pitted dots. Flowers pale pink, star shaped, small, in large clusters on the end of a stalk. Small plantlets develop in these clusters after flowering. Spreads locally by plantlets on flowerheads dropping off and rooting, and elsewhere by carelessly discarded stem fragments. IMPACT Forms a dense carpet replacing other vegetation. CONTROL Stem and root fragments will resprout. • Hand pull or dig out removing all stem and root fragments.
	Japanese honeysuckle Lonicera japonica A vigorous, dense, climbing vine. Paired, fragrant, white or yellow tubular flowers and small black berries. IMPACT Completely smothers small trees and shrubs. Causes canopy collapse opening the ground to invasion by other weeds. CONTROL Stem fragments will resprout if left on the ground. • Cut and dig out roots. • Pull out all minor stems. Cut main stems near the ground and apply Vigilant herbicide paste to the stump.
	Jasmine Jasminum polyanthum A wiry, ground and climbing vine, twining around host. Young leaf reddish, mature leaf dark green. Scented white flowers most of the year, many more in spring. Glossy black berries. IMPACT Forms impenetrable groundcover suppressing regeneration. CONTROL Stem fragments will resprout and grow rapidly if left on the ground. • Pull out all minor stems. Cut main stems near the ground and apply Vigilant herbicide paste to the stump. May need repeat applications.
	Madeira Vine, Mignonette Vine Anredera cordifolia A perennial creeper which forms tubers on the stems and underground. Small fragrant cream flowers in slender spikes. IMPACT Forms dense masses that dominate at mid to high canopy level. Smothers trees and bushes. Weight can topple small trees. CONTROL Tubers will sprout if left on the ground. • Cut main stems near the ground and apply Vigilant herbicide paste to the stump. Rake up all tubers. Find all tubers including those lodged in host trees.
	Pampus Cortaderia selloana, Cortaderia jubata Clump forming grass up to 4 metres tall. Showy seed heads producing large amounts of seed which is dispersed by the wind. IMPACT Competes with and smothers other vegetation. Provides habitats for rats. CONTROL • Dig out entire plant.
	Pinkhead Knotweed Persicaria capitata Trailing herb with redish patterned leaf. Produces numerous pink flowers. Spreads locally by trailing stems that root easily, and elsewhere by carelessly discarded stem fragments. IMPACT Forms a dense carpet replacing other vegetation. CONTROL Stem and root fragments will resprout. • Hand pull or dig out removing all stem and root fragments.
	Rhamnus, Evergreen Buckthorn Rhamnus alaternus Shrub up to 5 metres tall but stunted in exposed sites. Small green petal-less fragrant flowers. Red, ripening to black, berry like dupes. Produces a large amount of seed. Distinguishable from similar native plants by two small holes at the base of each leave with a corresponding bump (buckthorns) on the topside. IMPACT Forms dense stands preventing the regeneration of native plants. Particular threat to pohutukawa and other coastal species. CONTROL • Hand pull or dig out seedlings taking care to remove the total root. The roots are kinked and break easily. • Cut near the ground and apply Vigilant herbicide paste to the stump. • For large stems cut 15mm blazes 30mm apart around the truck near the ground and apply Vigilant herbicide paste to the lower surface.
	Shrub Balsam Impatiens sodenii Perennial shrub up to 2 metres tall. Large leaves arranged in whorls on stem. Pale pink flowers and seed capsules all year round. Spreads readily from explosive seed capsules. IMPACT Forms dense infestations that prevent regeneration of native seedlings. Smothers young plants. CONTROL Stem and fragments will resprout. • Dig out small plants taking care to remove all parts. • Cut near the ground and apply Vigilant herbicide paste to the stump.
	Star of the Veldt Osteospermum ecklonis A squat perennial in the daisy family. It grows in rosettes and sends out trailing stems that root easily and spread quickly. IMPACT Crowds out and prevents the establishment of native plants. CONTROL Stem fragments will resprout if left on the ground. • Hand pull or dig out taking care to remove all parts.
	Sweet Pea Shrub Polygala myrtifolia A many-branched shrub up to 2 metres tall. Pink and white pea-like flowers all year except mid summer. Black seeds inside a winged capsules. IMPACT Produces masses of seeds in winged capsules that are widely dispersed. Crowds out native species. CONTROL • Hand pull or dig out small plants. • Cut near the ground and apply Vigilant herbicide paste to the stump.
	Tuber Ladder Fern Nephrolepis cordifolia Upright rambling fern up to 1 metre tall. The only fern with tubers (round up to 2 cm). Spreads locally by tubers and runners, more widely by numerous spore produced on the leaflets. IMPACT Forms dense masses, crowding out other vegetation. CONTROL Tubers will resprout if left in or on the ground. • Dig out taking care to remove all tubers.
	Wandering Jew Tradescantia fluminensis Succulent creeping vine. Small white star shaped flowers. Spreads easily from stem fragments. IMPACT Smothers ground in light to deep shade, preventing the seedlings of native species from establishing. It causes habitats to open and be invaded by exotic shrubs and vines. CONTROL Stem fragments will resprout if left on the ground. • Weedmat for several months. • Apply Vigilant herbicide paste with a paint roller crushing the vines as you go. Will need to be repeated at least twice 2-3 months apart.

Photographs are from the Auckland Regional Council website, and the National Pest Plant Accord Manual (.pdf) available through the Biosecurity NZ website.

LINKS

Weedbusters is a weeds awareness and education programme that aims to protect New Zealand's environment from the increasing weed problem. "Pest animals and plants (weeds)", say Weedbusters on their website, "are THE greatest threat to New Zealand's biodiversity." All around New Zealand, communities, private individuals, local government, central government, and research organisations are actively involved in Weedbusters work. This includes active control of weeds, as well as education about invasive weeds and pest plants. Weedbusters is overseen by an interagency group with representatives from the Department of Conservation, Biosecurity NZ, Nursery & Garden Industry Association, and Federated Farmers NZ, among others.

The Motutapu Restoration Trust works to protect, maintain and restore the natural and historical features on Motutapu. Since 1994 Motutapu Restoration Trust volunteers have weeded and replanted extensive areas of the island, returning them to native bush and home to a wide range of native species. The Motutapu Restoration Trust's work is ongoing and help is always very much appreciated.

'Weeds cause serious harm to our native environment and threaten economic loss to farmers and horticultural producers', says the Auckland Regional Council. Their website provides a comprehensive list of pest plants and how to control them.