Black leaf aspen trees - Ask Extension
Is there a basal bark banding fungicide for aspen trees? Our aspen leaves turned black and dropped prematurely last fall.
Knowledgebase
Black leaf aspen trees #924603
Asked February 15, 2026, 11:27 AM EST
Is there a basal bark banding fungicide for aspen trees? Our aspen leaves turned black and dropped prematurely last fall.
Larimer County Colorado
Expert Response
Hi Jeannie,
It's hard to recommend a specific fungicide or control option without knowing exactly what disease the aspen had. There are a few foliar issues that aspen get at lower elevations (mostly due to stress) - they are explained in this publication: https://extension.colostate.edu/resource/aspen-and-poplar-leaf-spots/
As you read through the publication, is there one that seems similar to what you saw on your tree last summer? Many of these diseases are determined by the type of spring we have - a lot of cool, wet conditions tend to lead to more fungal issues. Since it's been dry, we may not have as many issues.
Other things to do is to rake up infected leaves in the fall and throw in the trash (do not compost) and alleviate stress by proper watering and pruning.
It's hard to recommend a specific fungicide or control option without knowing exactly what disease the aspen had. There are a few foliar issues that aspen get at lower elevations (mostly due to stress) - they are explained in this publication: https://extension.colostate.edu/resource/aspen-and-poplar-leaf-spots/
As you read through the publication, is there one that seems similar to what you saw on your tree last summer? Many of these diseases are determined by the type of spring we have - a lot of cool, wet conditions tend to lead to more fungal issues. Since it's been dry, we may not have as many issues.
Other things to do is to rake up infected leaves in the fall and throw in the trash (do not compost) and alleviate stress by proper watering and pruning.
I have read through your publication. We did rake up infected leaves last fall. It appears from your publication that our trees have Marssonina fungus. Our arborist recommends a basal bark banding. What do you know about this process for ridding this fungus?
Thank you,
Jeannie
Hi again,
What is the product (fungicide) your arborist wants to use?
--Alison
What is the product (fungicide) your arborist wants to use?
--Alison
