Aspen Trees in the Neighborhood Are Dying Off
I noticed last summer that my neighborhood aspen trees are starting to die off. Branch by branch, I've seen three trees in two neighbor's yards die off. The branch will be healthy, then the leaves will change color, the leaves wrinkle and remain on the branch, and finally the branch dies. In early spring, I cut off all the affected branches off of one tree but more branches are dead now that summer is over.
I have two beautiful aspen trees in my yard and they are now showing some signs. There have been a few small patches of dead leaves and the tree closest to the neighbors is also showing cankers with a dark liquid staining downward. Some branches have flaked or bubbled up bark. I'm guessing this is Marssonina leaf spot. Sometime in July I sprayed what I could with a copper sulfate and lime mixture I picked up, but the trees are too tall to spray. Is there a fungicide I can inject to combat this?
Broomfield County Colorado
Thank you for your question concerning your Aspen Trees and other Aspen Trees in your neighborhood. I have attached a couple of links from the Colorado State Extension website. The first link is related the the Marssonina Leaf Blight question you mentioned in your inquiry. I have also included some information on Aspen Leaf Spot. This a Fact Sheet also from the CSU Extension Master Gardeners' website
Please let us know if your have other questions concerning this issue.