Autumn Foliage Applications of ZnSO4 Reduced Leaf Nitrogen Remobilization in Peach and Nectarine

Abstract

Premature defoliation of peach and nectarine (Prunus persica L. Batsch) trees resulting from foliar applications of ZnSO 4 reduced N remobilization that typically occurs during leaf senescence. Leaf N remobilization in unsprayed control trees ranged from 45% to 50%, irrespective of tree N status. Leaf N remobilization in trees receiving foliar applications of ZnSO 4 ranged from a positive influx of N into the leaf to ≈30% of the N remobilized, depending on ZnSO 4 application timing and method of expressing leaf N levels. Early ZnSO 4 applications resulted in less N remobilization. Measuring leaf N on an area basis was a more precise indicator of N remobilization than N per unit dry weight, because leaf weight per unit area changes during leaf senescence.