blue periwinkle (Vinca major)
In Taroona, blue periwinkle, blackberry, cape ivy and banana passionfruit are the most common and troublesome ground-covering weeds. Large infestations of blue periwinkle are very difficult to eradicate as they require ongoing attention.
There are two forms of blue periwinkle found in Taroona: the variegated, and the solid green leaved. Blue periwinkle is still sold in some plant nurseries, so beware. Alert friends and neighbours who may be growing this plant.
Blue periwinkle smothers native ground covers by forming a dense mat. A large infestation presently occurs on the Education Department land to the north-east of the Catholic Church in disturbed soil.
Dispersal: The plant can re-shoot from the smallest amount of stem or root fragment. Infected soil, machinery and even flowing water, can also spread blue periwinkle.
Control: Large infestations require repeated efforts of slashing, followed by spraying of the new regrowth. Smaller infestations in your garden can be controlled by very heavy mulching, or by solarisation with black plastic sheeting or old carpet for a month or so to weaken the plants, before digging them out. It is absolutely essential to remove all plant fragments, or the creeper will re-shoot. Persistence is required. Bag and remove all plant material.
Safe alternative: Native clematis (Clematis arista) or bower spinach (Tetragonia implexicoma).
NB: Blue periwinkle is poisonous to sheep, cattle and horses.