Ash leaf aphid

Systematic position: The ash leaf aphid (Prociphilus fraxinifolii) belongs to the order Hemiptera and the family Aphididae. It is a specialized pest that specifically targets trees of the genus Fraxinus, playing a significant role in the health decline of ash populations in various landscapes.

Crops damaged: This aphid primarily infests different species of ash, such as the European ash and the green ash. They predominantly settle on the undersides of young leaves and tender terminal shoots, where they can feed undisturbed by environmental factors.

Biology and life cycle: The lifecycle involves overwintering as eggs within the bark crevices of the host tree. In spring, stem mothers hatch and begin feeding on succulent tissues. Throughout the summer, several generations are produced, including winged morphs that enable the spread of the infestation to adjacent trees in the vicinity.

Damage and economic significance: The aphid’s feeding causes leaves to curl tightly and form characteristic galls or distorted clusters, often covered in a white, waxy, woolly substance. Heavy infestations lead to premature leaf drop, stunting of shoot growth, and a significant reduction in the aesthetic and physiological value of the host tree.

Control measures: Management involves a combination of cultural and chemical tactics. Integrated pest management (IPM) is recommended, focusing on the application of systemic insecticides early in the season before the leaves curl, as the waxy covering protects the aphids from contact sprays later on.

• Pruning and removal of heavily infested terminals.
• Encouraging natural predators like lady beetles and lacewings.
• Application of horticultural oils or systemic insecticides at the bud-break stage.