Dear Graham, 

It appears that your tree has multiple problems, both a fungal disease and a bacterial infection. It is difficult to determine the lesion detail from your photo.  If you send a photo of a closeup of just some leaves with the lesions I might be better able to tell for sure. However, taking your description of blisters into account, there is a fungal disease called Oak Leaf Blister and the conditions we've recently had would certainly have favored development of this disease. The symptoms include raised circular areas of up to 2 inches in diameter scattered on the upper surface of the leaf with corresponding depressions on the underside. The top of the lesions are yellowish white while the underside is a yellow-brown color. The disease is favored by cool wet weather in the spring. Trees that lose leaves early in the season will often leaf out again later in the season. Usually, the disease is not fatal and an established tree should survive with proper care.

The best treatment is to keep the plant from becoming overly stressed by making sure that it is watered properly with about 1 inch per week (less rain water) and making sure that there is proper drainage during heavy precipitation. There are fungicides (chlorothalonil/Daconil) that can be applied but it is usually not necessary. Well-established trees will generally leaf out later in the season and when they emerge the conditions should not favor redevelopment of the disease. In addition, the fungicide must be applied at the proper time early in the spring before the buds open to be effective so the window for treatment this year has passed.

I think that you may have  second problem, Slime Flux caused by bacteria. This is the dark seepage shown on the trunk in your photo.  This disease occurs on many types of trees in North Carolina. Bacteria have entered the tree through a wound. The bacteria ferment the tree’s sap producing methane and carbon dioxide gases as a byproduct. The internal pressure builds up in the wood and the fermented sap seeps out. The oozing should stop after a few weeks.  Fortunately, this is another disease that is not likely to be highly damaging to the tree. Slime flux can also be triggered by drought or other stress so the same strategy of making sure your tree is properly watered should help with this as well.

Here are some links if you would like additional information:

https://content.ces.ncsu.edu/common-disease-pests-of-oak-in-north-carolina

https://union.ces.ncsu.edu/2022/06/slime-flux/#:~:text=The%20underlying%20cause%20of%20Slime,upon%20exposure%20to%20the%20air.

Good luck!