Apples, nectarines, and peaches to no closer than 4 inches apart. Deep water trees. If you haven't watered your mature trees they may be suffering from drought stress. Water established drought tolerant trees once per month. Pick up dropped fruit daily.
Citrus is a heavy consumer of nitrogen and needs phosphoric acid to set flowers.
If the foliage is yellow with green veins, the soil is iron deficient. Add iron chelate. Cut brambles back to ground after harvest. You might have done this last month. Prune suckers around base of trees.