Aspen trees dying from top down

Asked June 30, 2019, 12:54 PM EDT

I have two separate clumps of aspen trees in our yard. The group near the street has died over the past two years, beginning at the top and working down. The tree (two forks) near the house is now beginning to dye at the top. Is there a way to save the one beginning to die? The other group has completely died. I've read, but not sure what the issue is: fungus, beetles, drought, too much water, etc. I also read that if they die they should be removed so the reason they are dying won't spread. One ones that are now dead, have may suckers now grown near these. Any advice or suggestions for say an arborist that may be able to identify the problem?

Jefferson County Colorado

3 Responses

Hi There,


As you noted in your message, there are indeed numerous things which can take down Aspen trees. I would be interested in hearing whether there are any sites on the trunk which are oozing or dripping liquid. Exit holes can also be helpful in diagnosing problems (https://extension.colostate.edu/docs/pubs/insect/05530.pdf ). Leaves can sometimes be good indicators of fungal pathogens (more info here: https://extension.colostate.edu/docs/pubs/garden/02920.pdf) but I do not see any unusual leaf spots in the photos.

In the case that you are in a urban/foothills area of Jeffco, I would like to note that Aspen generally do not fare well down here for extended periods of time. A few years after transplant, the trees tend to decline due to soil, root, cultural, or pathogenic issues.

I agree that it may be helpful to have a certified arborist take a look at your trees.

Here is a link which will help you find an ISA (International Society of Arboriculture) certified arborist near you: https://www.treesaregood.org/findanarborist/findanarborist

If that doesn’t work well, I might also suggest trying an arborist certified with this organization: https://www.asca-consultants.org/search/custom.asp?id=381

Thank you for your response and information. To answer your questions: On the multiple (3) forks that are currently dead I do not see any holes or dripping sap. However, when I pull off some of the bark there are what appears worm lines? I attached a photo of these lines.
Also, the other large (2) fork tree that is beginning to die back from the top: I do not see any holes or dripping. The leaves look very healthy. This tree is located near the house. Possibly not getting enough deep watering. I only water it does get is from our flower bed sprinklers or rain and snow.

Thanks,

Wayne Thompson

1) Oh wow! These are called galleries and are made by some sort of borer insect. The three most likely culprits, to my knowledge are:

The Poplar Borer: https://digitalcommons.usu.edu/cgi/viewcontent.cgi?referer=&httpsredir=1&article=2360&context=extension_curall




2) Watering requirements for trees in urban areas depend a lot on individual landscapes. Do consider giving your trees fall and winter water. A bit of water in the dry season can really help improve tree health throughout the entire year: https://extension.colostate.edu/docs/pubs/garden/07211.pdf

A little more info on watering aspen: https://forestry.usu.edu/files/utah-forest-facts/aspen-how-to-grow-a-good-tree-in-a-bad-situation.pd...