Some of our clients have contacted us about trees dripping sap on their paths and cars, making an unpleasant sticky mess. The usual cause is tree aphids. These insect pests can also put your trees under serious stress and lead to disease. Tree aphids are soft-bodied, pear-shaped insects can be almost any colour. Aphids on tree foliage and shoots feed by sucking fluid from the tree through a slender mouthpart called a proboscis. They feed in clusters, usually on the undersides of leaves near the point where the leaf attaches to the stem, or on tender young shoots and buds. As they feed, they secrete a sticky fluid called honeydew. When enough aphids are feeding on the tree, this honeydew will begin dripping from the leaves.
Some tree diseases are spread by aphids, especially fungal diseases. Tree disease is much more serious than aphid infestations, and can kill or seriously damage a tree. To prevent the spread of aphid tree disease, keep the tree as healthy as possible to support its natural defence against disease and control the aphids as much as possible.
One of the best ways to treat these infestations is to ask your tree surgeons to prune the young shoots from the tree, eliminating the insects and the cause of the infestation in one go and giving your tree a trim at the same time.