In my limited experience growing fruit trees ( 5 1/2 years ), the only trees I've lost are a couple I had growing in pots at home. The bark on the limbs and twigs got dry and wrinkly - it wasn't tight and smooth. And any bending caused immediate breakage.
I wouldn't be quick to write off any trees that haven't leafed out yet, or are pushing growth out of the trunks only. It takes new (-er ) planted trees a couple years to get their permanent root systems established. Local climate conditions ( rain, heat, cold ) may hinder that process, resulting in slower green-up. Scratch a tiny section of bark on a limb tip and if you see green cambium - have a cold one and wait !!!