Fungi to the rescue: South African scientists use innovative approach to protect apple trees

Gardeners the world over dread the appearance of aphids on their plants. There are around 4,000 species of these sap-sucking insects and about 250 are pests that can wreak havoc on crops in a garden or orchard. One of them is the woolly apple aphid (Eriosoma lanigerum). As its name suggests, this aphid attacks apple trees and is recognisable by the white, waxy excretions that cover and protect the insects. The aphid is native to the US and can be found throughout the world wherever apples are cultivated. It was first identified in South Africa in 1895 and has, over time, become a serious pest of apples. The aphids infest apple trees through the plants' root systems and above-ground growth. The colonies cause abnormally large swellings on apple roots, impeding the flow of nutrients and water throughout the plant. If the infestation is not controlled, a tree's buds, shoots and fruit-bearing wood can be entirely destroyed. The mother insect on the roots produces live young called ...