Aspen tree issue

Asked September 5, 2015, 3:32 PM EDT

We have three large aspens surrounding our back deck that each summer give off a sticky sap type substance that covers our porch. The leaves are covered as well and typically die and fall. I've attached photos. Is this normal or could it be some sort of disease?

Polk County Iowa aspen trees

3 Responses

Him Kim,

It is possible that the tree has an insect that is feeding on the leaves and the exudate from the insect feeding is sugary sap that can then grow a sooty mold on the leaves. From the pictures it appears as if the tree might have a little anthracnose as well which we are seeing all over the state this year given the wet growing season. For Aspen in urban areas it is best to keep them with low stress ( fertilize the ground around each tree each spring, give it water if we start to get dry in july and august) . what you can't control is the heat we have here. aspen love cooler temps and the heat can cause stress. lets keep an eye on it and fertilize next spring with granular generic fertilizer , (10,10,10 etc). if you could let me know how big each tree is (circumference ) i could figure out a fertilizer rate.


Any way to identify what insect it might be and how to treat? Diameter of each tree is 10 - 12 diameter. We will proceed to fertilize in the spring. Thanks!

You could contact Dr. Donald Lewis at Iowa State University Extension and Outreach. He is an entomologist at ISU and answers insect questions. You can reach him at