WHITE PEA VINE

Question We’ve just moved to a place that has this vine growing up a large tree – is it a goodie or a baddie?

J Montgomery, via email

Answer Sorry to say this is a baddie, though it does look quite pretty in your photo. Originally from South Africa, its botanical name is Dipogon lignosus, and it has several common names, including ‘sweet pea vine’, which rather camouflages its true nature, and ‘mile-a-minute’ which, when growing conditions are good, is a very apt description.

It’s an evergreen vine, with leaves consisting of three heart-shaped leaflets (trifoliate leaves). From spring into summer it bears white, pinkish or lavender pea-shaped flowers, followed by pea-like pods that bear viable seeds.

It is the only vine with these pea-like flowers and trifoliate leaves – so is easy to identify.

It’s as tough as old boots and grows almost anywhere, tolerating a wide range of conditions except where subjected to decent frosts. It rapidly climbs up and over shrubs, eventually shading out and killing lower vegetation, so can be a real nuisance in and around the edges of native bush as well as in gardens.

White pea vine is a legume and a member of the Fabaceae family. Like clover, it can fix nitrogen from the atmosphere, which helps enrich fertility in poor soils, but in the end that usually encourages the growth of other weedy species while the vine dominates.

Treating the problem

I checked with Andy Spence, weed control expert and inventor of the Cut’n’paste range of herbicide gels, about which product would be best to use on this particular weed. He says that the glyphosate-based gels, like Cut’n’paste Original or Cut’n’paste Bamboo Buster, should work fine. Other sources suggest using gels containing metsulfuron-methyl (e.g. Cut’n’paste Metgel) but Andy warns that you run the risk of damaging nearby vegetation whose roots may be growing close to the treated vine – a problem you wouldn’t have with glyphosatebased ones.

You can cut the vine off close to the ground and paste the stump or, alternatively, scrape away the bark around the base of the vine and apply gel to the exposed area (the phloem) where it will be readily absorbed into the plant; Andy says this could be a more effective way to deal with multiple stems.

Another tip from Andy – if there are many small vines growing close together, you could tie them together with two ties a few centimetres apart, cut the stems between the ties and paste both cut ends.

You’ll need to check the area regularly for more seedlings arising and either pull them out by hand, making sure to get the roots out, or dab gel on the leaves. Or you can spot spray them carefully with glyphosate plus a penetrant such as Yates Zero Pulse or Yates Sprayfix Wetting Agent.