What is it?

Cotton ash psyllid is an invasive pest to Calgary that attacks black ash and Manchurian ash trees. They like to attack trees that are already stressed.

Symptoms

• Curled or cauliflower-like leaves.
• Premature leaf drop.
• Cottony material found inside the curled leaves.

Damage

• Branches dieback and tree health decline
• Severe infestations can lead to tree death, as the tree cannot recover.

What to do?

• Keep your tree healthy, hydrated,, fertilized and mulched is the most effective way to prevent pests.
• Apply insecticidal soap in early June and again in early July.
• Pesticide treatment can be difficult because the insect in hide inside the curled leaves.

Other resources:

https://www.calgary.ca/parks/pests/cottony-ash-psyllid.html

https://gardening.usask.ca/articles-and-lists/articles-insects/cottony-ash-psyllid.php