Bur Oak Leaf Spots - Ask Extension
My family and I planted this Bur Oak tree eight years ago, in honor of my late father. It was approximately seven years old when we planted it. Has be...
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Bur Oak Leaf Spots #838332
Asked June 29, 2023, 6:33 PM EDT
My family and I planted this Bur Oak tree eight years ago, in honor of my late father. It was approximately seven years old when we planted it. Has been very healthy, other than gall wasp larvae. The past few weeks, the leaves started getting yellow and brown spots. Is it leaf blight?
We don't want to lose this tree, as it has significant meaning to our family. Picture of leaf spots attached. Thank you in advance!
Larimer County Colorado
Expert Response
Hi Mandy,
This is oak leaf blister, which is a fungal disease. However it's an aesthetic issue and rarely causes any harm or damage to the tree. It just makes the leaves look bad for the season. Those lighter green patches will turn brown, so the leaves will look unattractive later this summer.
We see it in springs that are cool and wet (sums up this year perfectly) and there is no curative treatments - it would need to be sprayed with a fungicide as prevention very early in the spring prior to budbreak. If this is something you want to consider next year, the fungicides labeled for use include copper-based products and mancozeb. They are best applied by an arborist/tree care company.
This publication from UMass Extension covers the disease well: https://ag.umass.edu/landscape/fact-sheets/oak-leaf-blister
This is oak leaf blister, which is a fungal disease. However it's an aesthetic issue and rarely causes any harm or damage to the tree. It just makes the leaves look bad for the season. Those lighter green patches will turn brown, so the leaves will look unattractive later this summer.
We see it in springs that are cool and wet (sums up this year perfectly) and there is no curative treatments - it would need to be sprayed with a fungicide as prevention very early in the spring prior to budbreak. If this is something you want to consider next year, the fungicides labeled for use include copper-based products and mancozeb. They are best applied by an arborist/tree care company.
This publication from UMass Extension covers the disease well: https://ag.umass.edu/landscape/fact-sheets/oak-leaf-blister
