Pest Plants

Vine weeds are the biggest threat to our natural landscapes. While ground cover weeds threaten regeneration by growing in dense patches in the shade of forest, and shrub weeds like gorse can smother seedlings,  vine weeds cause the collapse of entire forest canopies.

Three climbing vines that are of particular concern in our native forests are banana passionfruit, old man’s beard and climbing asparagus.

Banana Passionfruit

Banana Passionfruit

What does it do and why is it a problem?

Banana passionfruit grows vigorously in our forest and scrub margins, scrambling through trees to the extent that it can cause collapse and death of native vegetation, reducing native biodiversity.

Banana passionfruit produces distinctive pink flowers, followed by large sweet fruit which attract pest animals. The many seeds are then dispersed by native and introduced birds, as well as pests such as possums, rats and pigs.

How to control Banana Passionfruit

If possible, pull the vines out by hand or dig them out at the roots. Make sure the vines are then kept above ground to prevent them from re-rooting in the soil. The vines can be tied to ensure the roots are above the ground.

Herbicide can be used, but because the plant climbs, those trees and plants that you are seeking to protect can be damaged by contact with sprays. To avoid this, you can cut large stumps at ground level and treat immediately with glyphosate or metsulfuron based products.

If using herbicide, make sure you always follow the instructions, wear protective garments such as gloves, and avoid and avoid spray drift reaching plants other than your target species.

Old Mans Beard

Old Man’s Beard

What does it do and why is it a problem?

Old man’s beard is a vigorously growing vine that can put on 10 metres of growth in a season, and cover an area of 180 square metres! It climbs over trees and shrubs, blocking out the light and eventually causing death and collapse of even mature trees. Known as “Travellers Joy” in Britain, it brings no joy to us here as it has become a major pest.

Old man’s beard is a deciduous plant which means it loses its leaves in winter. It is important not to confuse old man’s beard with native clematis species which are in the same family. Old man’s beard leaves are variable, they can be oval, heart shaped, or serrated and usually have 5 leaflets per leaf. Native clematis have only three leaflets per leaf.

Old man’s beard is particularly distinctive during its flowering and seeding stage from December to around April when it sets seed. The seeds have long, plume tails dispersed by wind or water.

How to control Old Man’s Beard

Cut the thick stems all year round at ground level, and ensure that aerial roots are kept off the ground to prevent them from resprouting. Paint the cut stumps with glyphosate based products. There are a range of other herbicides which are also effective. It is important to dispose of the vines in the transfer station or they can be burnt.

Old man’s beard stumps can re-sprout quickly, and there will likely be seeds that remain viable for several years, so check for seedlings at least every 6 months.

If using herbicide, make sure you always follow the instructions, wear protective garments such as gloves, and avoid spray drift reaching plants other than your target species.

Old man’s beard is a threat to forests, reserves, flood protection and plantings.

Climbing Asparagus

What does it do and why is it a problem?

Climbing asparagus was introduced as a garden or potted plant and is causing serious damage to our native plants. It is a perennial vine that climbs several metres, shading or ringbarking large trees. It is able to grow in semi shade so can easily invade our forest. It is a very difficult plant to eradicate once established.

Climbing asparagus is spread by birds, runners, the movement of soil and the illegal dumping of garden waste.

How to control Climbing Asparagus

Because climbing asparagus wraps itself around host plants, spraying is very difficult without causing damage to surrounding vegetation. It is preferable to physically remove the plant, by first cutting back the leaves and stems then digging out roots and tubers, which should be burned to totally destroy them.

If herbicide control is undertaken, this should be done from spring to early summer for best results. Cut the stems to approximately 50 to 100 cm from the ground and immediately spray the remaining foliage until wet but not dripping with a glyphosate based product.

If using herbicide, make sure you always follow the instructions, wear protective garments such as gloves, and avoid and avoid spray drift reaching plants other than your target species.

For information about a range of other pest plants, go to the Weedbusters website weedbusters.org.nz