Hazelnut tree issue
Difficult to know from the photos as there are many issues that can can cause chlorotic (yellow) leaves like that. I am assuming this is not from an orchard but from a backyard tree? It looks like potential magnesium deficiency from leaves alone, but there could still be an issue in the roots, trunk or stems that is causing it. Does the tree have adequate drainage? You might inspect for signs of dead wood on the trunk or branches.
Yes, this is a backyard tree, my first year having it. Someone said that they thought it might be blight, but there wasn't any of the bumps on the trunk. It's still pretty spindly. I have it mulched and then of course it rained for weeks. What I thought was strange is that the brown seems to be coming from the center veins of the leaves. Low magnesium is an easy fix. How much Epsom salts should I put on? I have 2 trees, and the second one is unaffected. They are about 4 & 1/2 ft. Tall. Thanks so much!