Could be too wet, too dry, shaded out, low nitrogen, or possibly a foliar disease. Any chance of a picture?

16 DAYS W/O RAIN. I have 6 IN. OF WOOD CHIPS AROUND all trees. plums,apricots.nectrine and peaches. have had dry spells for 20 and 25 days over the last 4 yeas. no yellowing. but that seems to be the problem?

Trees under a small amount of stress can drop the interior leaves. I am losing interior leaves on a few peach trees now which got some bacterial spot damage. I would give them some water and then stop worrying unless they drop a bunch more.

Scott