A number of different species of Cotoneaster are grown in South African gardens, five of which have been declared as invasive aliens. Existing plants may be retained in one’s garden providing they do not grow within 30 m from the 1:50 year flood line of watercourses or wetlands, and that all reasonable steps are taken to keep the plant from spreading. They used to be popular hedging plants and we were advised to plant them as such in our Pietermaritzburg garden. They have been planted in some gardens specifically for their attractive clusters of red berries.
These trees originated from Asia and are spread by birds feeding on the berries – as we have discovered to our cost in our present garden. While this plant is a particular problem in the Western Cape, our experience is that we ignore a seedling at our peril because before long there will be a forest of fully-fledged trees. Unless removed, they can form dense stands which shade out indigenous plants. They can reduce available grazing land and, when eaten in quantity, the berries are toxic to animals.
Cape White-eyes have a predilection for the berries. Black-eyed Bulbuls, Black-headed orioles, Red-winged Starlings, Speckled Mousebirds and Olive Thrushes feast on them too.
We have severely pruned some impossibly large Cotoneaster trees and actually removed others to little avail: seedlings continue to pop up all over the garden.