Woolly nightshade

Woolly nightshade is a threat to native vegetation growing on the edge of forests, and is a pest on farmland and in urban gardens. Groups of woolly nightshade form dense stands that ‘crowd out’ other plants and stop them from growing. Find out how to recognise this plant and check out our tips for control.

On this page:

• Why woolly nightshade is a pest
• Identifying features
• Who is responsible for control?
• How to control woolly nightshade
• Follow-up management
• Summary of herbicides and application methods for control
• Further information
• Related publications

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Woolly nightshade (Solanum mauritianum) is also known as:

• tobacco weed
• flannel weed
• kerosene plant.

Why woolly nightshade is a pest

Woolly nightshade is a major pest in the Waikato region. It invades open areas such as:

• pastoral land
• native forest margins
• urban areas.

Woolly nightshade grows quickly and produces large amounts of seed. For example, a single plant can produce up to 10,000 seeds. The seeds are spread by birds, and can remain alive ‘viable’ in the soil for 20 to 30 years before germinating.

Woolly nightshade can quickly establish large groups (or stands) of plants. It takes over an area by ‘crowding out’ other plants and stopping them from growing.

Woolly nightshade can also affect people and livestock. If you come across woolly nightshade:

• Don’t eat the berries - they are moderately toxic to people, especially children.
• Don’t touch the leaves - they shed fine hairs when touched, which irritate the skin, eyes, nose and throat.
• Keep stock away - berries may also be toxic to livestock.

Woolly nightshade thrives throughout the northern parts of the Waikato region and can be common in other areas. Dense stands occur in the Port Waikato area and on the Coromandel Peninsula.

Identifying features

• Fast growing tree – up to nine metres tall.
• Leaves are large, grey-green, oval-shaped and covered with furry hairs.
• Strong kerosene-like smell, especially when leaves are rubbed or crushed.
• Flowers have five purple petals and a yellow centre.
• Flowers grow in clusters at the ends of branches.
• Can flower almost all year round, but most berries are produced in late spring to summer.
• Berries are initially green and ripen to yellow.

Who is responsible for control?

Woolly nightshade is classed as a ‘containment pest’ in the Waikato region. All landowners/occupiers are responsible for the control of woolly nightshade on their property and are required to work with Environment Waikato in areas where control programmes are in place. Woolly nightshade is also banned from sale, propagation, distribution or commercial display.

How to control woolly nightshade

There are two main ways to control woolly nightshade:

• physical control
• herbicide control.

Physical control

• Pull out small plants less than 60 centimetres tall. Shake all the dirt from the roots and leave the plant to wither and dry out.
• Cut down larger plants higher than 60 centimetres tall. Try not to disturb the soil. Stop the stump from re-sprouting by painting the whole stump with herbicide.

Herbicide control

There are four main methods for herbicide control:

• stump treatment
• cut and inject – for larger trees
• basal treatment of trunk
• overall spray application – for smaller plants.

1. Cut down the tree, leaving a stump no higher than five centimetres above the ground.
2. Paint herbicide over the whole stump surface, including the sides.

1. Use a machete or axe to make shallow downward cuts around the trunk of the tree. Make one set of cuts below the lowest branch and another set near the ground. Cuts should overlap each other all the way around the tree so that they effectively ‘ringbark’ it.
2. Apply herbicide into each cut.

• Liberally paint or spray the trunk with herbicide, from the ground level to a height of 30-50 cm.
• Make sure you cover the entire trunk.
• You may need several applications to kill the plant.

• Totally cover the leaf surfaces with herbicide.
• Pulling out plants by hand may be cheaper and easier.

Follow-up management

After the initial control, it’s important to:

• revisit the site at least annually to control re-growth
• stop weeds invading by replanting with desirable plants (preferably natives) once re-growth is no longer a problem.

Summary of herbicides and application methods for control

When using herbicides:

• Always read the instructions on the manufacturer’s label closely.
• Always wear protective clothing.
• Always minimise the risk to desirable plants.
• Contact the supplier for further advice.

Disclaimer: Although this content has been prepared in good faith from a number of sources believed to be reliable, Environment Waikato does not give any warranty that all information contained is accurate or complete, or that advice given will be appropriate in all circumstances. Mention of product trade names implies neither endorsement of those products nor criticisms of similar products not mentioned.

Further information

For further information and advice contact your local Biosecurity Plant Pest Contractor.

Related publications

Visit our Waikato Regional Pest Management Strategy.

'What makes a pest a pest? - A guide to Waikatos pest management future' download (730 kb, 104 seconds to download, 56k modem) order or pick up for free from our offices.

Pick up or order 'Plant me instead - Plants to use in place of common pest plants' for free from our offices.

Download the National Pest Plant Accord.

Pick up or order 'Poisonous plants and fungi in New Zealand - A guide for parents, schools and child minders' for $15 from our offices.