Banana passionfruit
What is it?
Passiflora mollissima and its close relative Passiflora mixta are vigorous climbers, often growing several metres in height. The leaves are a shiny green with clearly defined veins, the flower is large, pink and green petalled with a yellow and white centre. The fruit is yellow-orange when ripe and contains a sweet edible orange-coloured pulp with black seeds.
Why is it a problem?
The banana passionfruit is capable of smothering forest margins and forest regrowth with its dense growth of leafy vines. It is a particular problem in parts of Nelson and Marlborough.
Methods of control
Manual Control: Small banana passionfruit plants can be hand pulled - be careful to ensure you get all the roots.
Chemical Control: Common herbicides that are suitable include Roundup and Escort. They can be applied using a knapsack, brush gun or by the cut stump method. Take care to spray only in still conditions to avoid wind drift to non-target plants and don't spray when rain is expected. During spraying, non-target plants can be shielded with cardboard, plastic sheets or a large plastic container. The use of a marker dye helps to avoid double spraying and wastage, and a foaming agent can be added to the spray to help prevent spray drift. As with all spraying you should read the instructions on the manufacturer's label closely and always wear protective clothing.
Controlling the vines
The best method of control is to cut the vines back as much as possible in winter or early spring, and then spray the regrowth later in spring with herbicide. When the vines are cut and only the regrowth sprayed you will not affect surrounding plants along with the banana passionfruit. Leave the vines in the tree to dry out before removing, to prevent damage to the host tree.
For larger specimens, the cut stump method can be used. Remove the vines to access the base of the plant. Cut the base of the plant close to the ground with a straight flat cut. Apply herbicide immediately to the cut stump, as the sap ceases to flow once the tissues are severed. There are several convenient ways the application can be made, with a paintbrush, eye dropper or a small squeeze bottle. For very large specimens it is only necessary to wipe the herbicide around the outer rim of the cut. Make sure you leave the plants in the ground until the roots have died off. Do not re-apply herbicide too soon after the initial treatment. Wait until the plant actively begins growing again.