What is wrong with this Oak Tree?

Asked August 8, 2019, 4:02 PM EDT

Our client brought in these Oak leaves to see what is wrong with them. They are covered in spots as you can see and he said it's almost like there are larvae in them. The trees are about 20ft tall and in their front yard. There are about 6 trees affected and this is the first year it started. Thanks for your help

Alpena County Michigan trees and shrubs insect issues oak leaf miner

1 Response

Hello,

This looks like oak leaf miner damage. The insect larvae are inbetween the leaf upper and lower layers. Insect populations vary year to year, and typically there is no chemical control required. At least 14 species of parasitoid wasps help keep populations in control.

What your client can do is rake up leaves and bag and discard, or otherwise destroy. Insects overwinter inside the leaves. The most important thing to do is give the trees good care. Never prune oaks in the growing season- wait until after the first hard frost. Provide deep slow watering when we have droughts in summer and fall( up to the first hard frost- don’t stop watering in September if we have a dry fall). Soil should be moist 6-10 inches down after watering. Mulch the root zone no deeper than 3-4 inches, with mulch pulled back from the trunk so it does not touch it. When weeding around the tree, do not nick or damage the bark. A healthy tree is able to recover more easily from leaf loss.

Here is a reference- scroll down to see oak leaf miner.

https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/oak/leavesbrownspots.html

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