Treatment for aspen - Ask Extension
I live on acreage in the Ochoco foothills. We have a small stand of native quaking aspen. We have the same looking disease that has hit residential st...
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Treatment for aspen #629995
Asked May 01, 2020, 8:33 PM EDT
I live on acreage in the Ochoco foothills. We have a small stand of native quaking aspen. We have the same looking disease that has hit residential stands in Bend. Leaves become black and fall during the summer. We have cut down our oldest trees (one had died over 3 years or so). We left several smaller ones that are spaced quite a way from one another. I realize their roots are connected. Is this disease a fungus? Is there a successful treatment? Organic? At this point, the new leaves are healthy and trees are leafed out to the top. Can’t change county below but I’m in Crook Co.
Crook County Oregon
Expert Response
Hi, There are several factors that can cause aspen leaves to turn black, the most common being and insect called Aspen Leaf Blotch miner. This type of damage does not typically kill the tree and is just aesthetic damage. Only if you have consistent (every year) and severe damage would it actually kill a tree. Chemical control is rarely warranted for this pest. https://extension.oregonstate.edu/pests-weeds-diseases/insects/common-insects-found-central-oregon See attached photo, I pulled the larva out from between the top and bottom leaf tissue where they mine. The second photo of the entire tree is one with aspen leaf blotch miner. The third photo is of Marssonina leaf spot. There is also Marssonina leaf spot which can cause some blackening of the leaf tissue, management for that can be found here: https://pnwhandbooks.org/plantdisease/host-disease/aspen-populus-tremuloides-marssonina-leaf-spot I am not aware of any organic pesticides that are effective if it is this disease.
