Conservation Comment: Dave Scoullar talks tackling weeds in Whanganui

Blue morning glory, seen here close to the Cobham Bridge, can cover trees with a weedy blanket. Photo/ Supplied

Opinion:

It’s been a great season for weeds in Whanganui, particularly the climbing ones which like to take over and smother trees and hedges.

These climbers are like rust — they never sleep. And they have become increasingly prominent this summer in many of our backyards, parks and walkways. With many to choose from, I mention some of the more prominent culprits hoping that property owners will seek to recognise and remove them.

Convolvulus is a genus of 200 to 250 species of flowering plants in the bindweed family. A family member prominent in Whanganui is blue morning glory, a high-climbing vine with tough twining, running stems.

It grows quickly and its longevity, dense smothering habit and ability to climb to the top of high canopies makes it the dominant vine wherever it occurs. Blue morning glory climbs over all other species, ultimately killing them and is the last species in many cases when a bush area succumbs to weeds.

Ivy is a perennial climber with woody stout stems. It clings to and climbs almost any surface, and can grow over the forest floor, sub-canopy and canopy to great heights, forming dense, long-lived masses at a moderate to fast growth rate.

These smother and kill all plants from ground level to canopy, destroy vulnerable epiphyte niches and prevent the establishment of native plant seedlings. The weight of an infestation can bring down branches or whole trees. Invasion into an established forest is slow but relentless through the ground or canopy.

Old man’s beard is a climbing and layering vine up to 20m tall with long, woody stems. It grows rapidly, forming dense, heavy masses that dominate canopies of any height.

It smothers and kills all plants to the highest canopy and prevents the establishment of native plant seedlings. Old man’s beard moves readily into established forests over canopies and by layering. Seed is spread by water or wind, and seed and stem fragments are spread in dumped vegetation.

Banana passionfruit is a large evergreen perennial vine that can grow up to 10m high. A native of South America and originally introduced here as an ornamental plant, it grows in coastal areas lowland and coastal shrub lands and forest margins, light gaps, roadsides, open areas, farm and orchard hedges and domestic gardens.

Mile a minute is an evergreen climbing vine that rapidly smothers low-growing shrubs and regenerates native forest canopy and eventually takes over completely, shading out the plants underneath. It thrives in bare sites.

The climbing dock is a fast-growing, low-climbing perennial with brown kumara or beetroot-like tubers. It invades regenerating habitats, and bare and open sites, replaces low canopy, and prevents the establishment of native plant seedlings. The climbing dock provides support for more aggressive vines and grasses.

These climbing “nasties” (and many others) can take over your property. Go to the internet to find out how to remove them for good.

Dave Scoullar is a tramper, conservationist and member of the Te Araroa Whanganui Trust.