Environment Waikato is having a blitz on the plant pest woolly nightshade this summer.
Woolly nightshade (Solanum mauritianum) is also known as tobacco weed, flannel weed or kerosene plant. It invades pastoral land, native forest margins and urban areas, crowding out and suppressing all other plants. Waikato people are required to destroy it on all land that they own.
Woolly nightshade is a shrub or tree which grows rapidly, up to nine metres. It can form dense stands which stop other plants growing, and get in the way of livestock. It is suspected of poisoning stock and its berries are moderately toxic to humans, especially children. The plant’s leaves shed fine hairs which may irritate the skin, eyes, nose and throat, and give off a strong kerosene- like small when rubbed or crushed. The flowers have five purple petals with a yellow centre which grow in clusters all year round.
Berries are green, ripening to dull yellow and a single plant can produce up to 10,000 seeds with are viable in the soil for 20-30 years. Woolly nightshade thrives throughout the northern parts of the Waikato Region and is very common in other areas. There are dense stands in the Port Waikato area and on the Coromandel Peninsula.
Small plants less than a metre high can be pulled out. Larger plants that are cut down should have the stump treated with herbicide or they will re-grow. In some cases, tree stems need only be painted with herbicide rather than cut. Information and advice on the most suitable chemical to use is available from your Plant Pest Officer.