Ash curl leaf aphids

Severe damage from the ash curl leaf aphid, but is rarely a health concern for the tree.

Severe damage from the ash curl leaf aphid, but is rarely a health concern for the tree.

This summer, like last summer, will be a bad year for the ash curl leaf aphid in Sioux Falls. The cool wet spring, along with another mild winter will likely lead to the large populations of the insects.

The Damage:
The damage to the trees is mostly cosmetic and rarely harmful to the trees unless the trees are already predisposed to stresses or other health related issues. The damage to the leaves is unsightly and really bad infestations can distort the twigs of the trees.
The insects suck out the “juices” out of the leaves and as a result, the leaves curl up. That curling then makes perfect cover for the aphids to reproduce and thrive. It protects them from insecticides and predatory insects.

The Problems:
The aphids can be a problem in our lawns and backyards in two ways. One is the look of the tree. Not a great reason for control, but that decision is up to the individual tree owner.
The second, is the honeydew or sticky substance that the aphids exude. Honmeydew is often confused as tree sap, but it as actually the feces of the aphids. This can make decks, patios, and driveways a pain during high aphid activity with the sticky covering of the honeydew. Additionally, sooty mold then feeds off the honeydew making surfaces black.

The Control:
Aphids are best controlled in trees by a good integrated pest management program. Providing a healthy tree to fight off the pests naturally and also making your landscape friendly to other predatory insects such as lady beetles.
Spraying of insecticides is not a good option as it kills non-target insects. Plus, when you see the damage from the aphids, it’s often too late for good control due to the curling of the leaves and the protections the leaves provide.
There are systemic insecticide control options, although care must be taken with application so the chemical is not in the trees when the tree is flowering so as not to kil or harm pollinators.

If you have more questions with ash leaf curl aphids or other problems with your trees, contact me today for a consultation. 605.759.6020 or