Aspen limbs and sometimes whole trees dying

Asked September 11, 2017, 2:16 PM EDT

I have a grove of about 30 small aspen trees on the north side of my house north of Boulder. Most of the trees look pretty healthy, but for the past 2-3 years a few branches on many trees seem to die, and sometimes an entire tree will wither and die. The progression of the dieback is that the green leaves wither on the limb and then gradually turn brown. Generally the dead leaves stay on the branch until winter winds blow them off. We water the grove with a well water sprinkler system, so the trees get wet a lot, even during dry summers. Based on this description can you diagnose the problem and suggest a solution? I have attached a couple of photographs, one showing the early stage of the disease (green withered leaves) and another showing a more advanced stage.

Boulder County Colorado trees and shrubs

2 Responses

Here is a link to a fact sheet on aspen trees. Without seeing the whole tree, it is impossible to diagnose the exact problem, but the black on the leaves looks like a fungus. We would suggest calling a certified arborist to come to your home to help you diagnose what is going on. You can also request a visit from one of our Master Gardener Tree Teams for $25.

http://extension.colostate.edu/topic-areas/yard-garden/aspen-and-poplar-leaf-spots-2-920/

Thanks for your reply. Yes, I think you're right. The problem is probably aggravated by the well sprinkler system, which sprays the trees to at least 10 feet above the ground 2-3 times per week. I would definitely like to schedule a visit from a master gardener... should I just reach out to the email address you've linked, or will you set the visit up?

Deane Little
720-839-9718