Why this weed is in your garden and how to beat it
CORKY passion vine, Passiflora suberosa, is a tropical South American vine. Its range stretches from Florida and the Lower Rio Grande Valley of Texas in the United States, south through Mexico, Central America, and the Caribbean to South America.
Corky passion vine is an aggressive climber or ground cover that is widely invasive in northern and eastern Queensland, in the north-western parts of the Northern Territory, and in the coastal districts of northern and central New South Wales.
It is a weed of crops, orchards, closed forests, open woodlands, urban bushland, riparian vegetation, disturbed sites, waste areas and gardens in tropical, sub-tropical and warmer temperate regions.
It is usually mostly found either in the canopy of trees via tendrils, which allows it to climb up to six metres high, where it smothers small trees, and shrubs, or scrambling over the ground cover species smothering native ground plants or tree seedlings. The lower stems are white and corky and the vine roots at nodes where in contact with the ground
In orchards it can climb over trees and smother the trees or reduce their productivity. In agricultural crops it can threaten plants as a ground cover when stems send out roots where in contact with the ground, making it difficult to remove even with agricultural cultivation implements.
The vine climbs over plants smothering the crop plants. While cultivating the crop with implements, the implements break some of vines, leaving some behind. The vines also tangle around tines tearing out crop plants as well.
Agricultural machinery and vehicles can also spread the seeds which are crushed on to tyres, or carry stem fragments to new locations.
It is a threat in the pastoral industry as the leaves, stems, and green fruit are poisonous to human and livestock. The purple to blue berries are readily eaten by birds, aiding in considerable seed dispersal to new locations.
The stems can be spread in flood debris of rivers.
Passiflora suberosa is a perennial vine with extensive, twining tendrils. As the name suggests the stems become white and corky with age. The vine grows to about 6m, variously hairless to hairy.
Stems are commonly purplish. Leaves are dark green and may be three-lobed (with the centre lobe the largest) or entire in shape. They are generally 4 to 8cm long, with a leaf stalk up to 2.5cm long. Flowers are up to 2.5cm wide and appear in solitary arrangement in leaf axils. They are free of petals, but they possess "sepals" that are yellow-green, with a purple inner fringe. Fruit are round berries, blue-black when ripe.
The most reliable method of control for corky passionflower is hand pulling when the soil is moist. Care must be taken not to break the stem above the roots, or the plant will regenerate. The above-ground vegetative parts of the weed can be removed using a brush hook or similar tool. Corky passion flower can be treated with a herbicide but a wetting agent must be used due to the shiny leaves.
Ian Read can be contacted on 4159 9365, or email email@example.com for free weed identification or presentations to landowners and community groups, or for native plants advice, erosion control or landscaping.
Ring Landcare President Michael Johnson on 0422297062 for weed project details and monthly meeting times, or email firstname.lastname@example.org