Q: We’ve just moved on to this property and have two weed questions. At one end of the section we’re clearing weeds from under tea tree and native bush and want to know if this delicate-looking climbing plant is a native or a weed. Other parts of the garden are rampant with a succulent with prickly leaves and a thick creeping stem, which goes under concrete steps and pops out through cracks in the retaining walls. Can you tell what it is and how we can control it? We’ve dug up some of it, but it’s everywhere.
Question from D. Spencer, Coromandel Peninsula
A: Your climbing plant is Asparagus asparagoides, and is a weed. Given half a chance it will climb two metres or more, flower and produce seeds in reddish berries which will be eaten by birds and spread around. It is a listed pest plant so you should make an effort to control it. Other asparagus weeds have ferny foliage, but this one has shiny oval leaves tapering to a point, and it does look cute when young and can sometimes be mistaken for young native clematis.
It has underground tubers, which sprout if left in the soil so if you dig it out try to get all the tubers out. Spraying the foliage with 20ml glyphosate in 1 litre of water (this is double the normal rate recommended for most garden weeds) should be effective at killing both the plant and tubers. Now that you can recognise this weed you’ll be able to spot it sooner and dig out seedlings or spot spray them as soon as they appear.
Your weedy succulent is an interesting challenge; it looks like Aloe maculata, previously named A. saponaria, and has the common name of soap plant because the juice from its leaves is used as soap by the people of South Africa from where it originates. It’s a variable species with slight differences in foliage and flower colour which are further affected by the environment in which it’s growing. It’s tough, tolerates drought and blazing hot sun, yet can take full advantage of decent soil and rainfall, which it seems to be doing at your place.
I have no experience of controlling this plant when it gets weedy and can find little information that might help, though it is listed in a booklet Weeds of the Surf Coast Shire published by the Department of Primary Industries, Victoria, Australia, so it is clearly a weed there. The brochure says this plant “can cover extensive areas of land forming large clumps of vegetation which, because of their dense nature, smother the small ground-covering indigenous species”. Unfortunately the only control measures they suggest are pulling or digging it out.
If digging out the plants and rhizomes is too laborious or impractical for your situation I’d try using loppers or a pruning saw to cut off the leafy top growth leaving a horizontal cut on the rhizome and apply a glyphosate-based herbicide gel such as Cut’n’Paste to the cut, following the label recommendations. The top portions you cut off will simply grow again if left lying around so take them or send them to the local landfill and make sure they get buried, or you could put them in black plastic rubbish bags, tie the tops and leave them in the sun to ‘cook’ until they’re fully rotted down.
If any reader has experience of controlling this weed we’d love to hear from you.
Answer by Andrew Maloy (The Plant Doctor)