The damage in your pictures looks more like Oak Leaf Miner than Tubakia Leaf Spot. The larvae feed off the surface of the leaf between the margins. The best cultural control is to pick up all leaf debries in the fall and dispose of in the garbage. If the tree continues to display symptoms in the next season I would recommend contacting a local tree care company for chemical care options. http://labs.russell.wisc.edu/insectid/2014/05/08/oak-leafminer/