I just put slow release fertilize (1/2 cup per tree) around each of my 2 yr old trees a couple weeks ago. These are oaks as well as fruit trees(apple, crab apple and pears).
In contrast, I have another batch of 4 year old trees(Oaks and Birch) that I planted in a pasture full of fescue and basically walked away from them doing no maintenance at all the 1st couple of years. They are way behind the 2 year old trees. The trees in the pasture have never been fertilized and I let grass grow right up to them. I didn't even have tubes on them the 1st two years. I have to wonder if you have let grass and weeds grow out of control around your trees? Yeah, the drought sure didn't help either but at least killing competing grass/weeds will give your trees whatever little rain that does fall.
I know this won't help trees that are already planted but I give a significant credit to Moisture Mizer granules for the fast growth of my latest bunch of trees. You have to stir it in the dirt around the roots when you plant though. My trees treated with that stuff grew so much faster than the untreated trees that you have to see it to believe it. I wouldn't ever plant a tree out in the field without that stuff again.
Anyhow, I bet you will see a big improvement a year from now if you get some fertilize on them in the next week or so and RoundUp the grass around the trunk.