Managing weeds for biodiversity

● Recorded distribution Periwinkle (Vinca major)

The problem invaded temperate rainforest and has process under the NSW Threatened been identified as a threat to Species Conservation Act 1995 of which Periwinkle, also known as blue endangered and vulnerable periwinkle is one of the species listed. periwinkle (Vinca major) is a creeping species. A dense canopy of periwinkle Periwinkle is spreading in southern Periwinkle plant that is native to Europe and can also alter fauna habitat. at the site level through northern Africa and has been introduced expansion of existing patches, and Weeds such as periwinkle that reproduce to other continents as an ornamental more widely through pieces of plant vegetatively can establish rapidly from plant or medicinal herb. In the higher taking root at new locations. Continued stem fragments at disturbed sites such rainfall regions of southern Australia planting of periwinkle in gardens could – Vinca major as flood zones and areas recently it has escaped from cultivation and is contribute to its further spread. Once cleared of dense weed infestations. In invading native vegetation where its established, periwinkle’s rampant growth a recent experimental study of native broad-leaved runners form a dense is very difficult to control, especially in tree seedlings in riparian zones invaded mat over other . It competes bushland. Restrictions on its sale and by periwinkle in Victoria, survival of with native plants for moisture, light, transport are under consideration in the native manna gum (Eucalyptus viminalis) nutrients and recruitment niches. Its Victorian noxious weeds review. seedlings was greater in plots initially growth is particularly vigorous in riparian cleared of periwinkle to a diameter of and other moist habitats. Invasion of 120 cm. Blackwood (Acacia melanoxylon) Key points riparian habitats by weeds is among seedlings were taller in similar sized a range of factors contributing to • Periwinkle’s broad-leaved runners form plots cleared of periwinkle than in their decline. That is why this is a very a dense mat, shading out native plants uncleared plots. significant issue for biodiversity, and competing for moisture and nutrients. Invasion and establishment of exotic landscapes and river health. In East • It mainly spreads vegetatively but some Gippsland Victoria, periwinkle has vines and scramblers is a key threatening patches also produce seeds. • Very small isolated patches (<1 m2) can be dug out. Stem and root fragments can resprout so all plant material needs to be removed from the site and disposed of appropriately. • Herbicide treatment can be effective if applied when plants are actively growing and followed up. • Along waterways, particular care is needed with physical or chemical treatments to prevent erosion and contamination. There may be restrictions on chemical use. • All treatment needs to be followed up for several years. • Integrated control of periwinkle and other

Blue periwinkle (Vinca major) can form a carpet in native vegetation, NSW. weeds, and perseverance are essential for Photo: Jackie Miles and Max Campbell restoring native vegetation. 2

The weed

Periwinkle has a woody crown bearing runners up to 1 m long with large, stalked, opposite (15–60 mm long, 14–45 mm wide). Each pair is generally at right angles to those above and below. The upper leaf surface is glossy and there are generally very short hairs along the leaf margins. Flowers are large, 30–40 mm across and blue-purple or sometimes white, with Madagascar periwinkle (Catharanthus roseus) Lesser or common periwinkle (Vinca minor) 5 lobes from a basal tube 16–17 mm is a weed of northern Australian coastal areas, flowers are 2.5–3 cm across. These are smaller related to blue periwinkle. t