Plant Doctor Archive

Woolly nightshade

I'VE just moved into a property that has several large woolly nightshade plants. The previous owner tried to kill them off by chopping them down, but they've just sprouted away again, stronger than ever. A friend tried spraying some at his place with Roundup, but it didn't completely kill them. What is the best way to kill them off?

WOOLLY nightshade (Solanum mauritianum) can be hard to get rid of. The most effective way is to pull out all the young plants before they get established. With older ones it's best to cut them down before they set seed, as birds eat the berries and spread the seed around.

Cut the plants close to the ground and treat the stump with Vigilant, which is available from garden centres and very effective against woolly nightshade and many other woody weeds. It was originally developed by scientists at HortResearch to help Department of Conservation staff control woody weeds like old man's beard. It comes in the form of a gel, which you apply to newly cut stumps and the active ingredient is absorbed into the root system. Make sure you wear gloves and follow the label recommendations. It may pay to wear a dust mask when you cut down large woolly nightshade plants, as their leaves give off fine hairs that can be irritating if breathed in.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.