Brown spots on new Oak Tree
I had the city of TP plant a tree in my yard last year and it was growing good. In the last 2 weeks brown spots have developed on the leaves. In img 9625 you can see where a oak tree was cut down about 10 years ago and the roots are rotting. Can you help. Thom Wolf
This looks like feeding damage from sawfly insects. The larvae of these insects etch the surfaces of the leaves when they feed and leave a "skeletonized" appearance to the leaf. Your second photo is very blurry but it looks like there is plenty of good green growth on your tree. Sawflies feed for a brief time and then move on. An otherwise healthy tree can sustain some feeding damage just fine. There are many types of insects that feed on white oak trees so it will not be unusual to see some feeding damage from time to time. No treatment is necessary or recommended.
Since this is a newly planted tree, the best thing you can do to keep it healthy would be to make sure you water regularly during dry weather periods. Also, if there is mulch at the base of the tree, make sure it is not too deep. A mulch layer should be only 2-3" deep and avoid putting it right up against the trunk (which can invite pest/disease problems). https://extension.umd.edu/hgic/topics/after-planting-care