Q: Which is best for mature pecan trees, broadcasting zinc sulfate or spraying leaves with liquid zinc?
A: It’s far better to spray the leaves. Pecans need sufficient levels of zinc in their leaves to produce good nuts. Zinc applied to the soil will be bound up by soil particles and will take at least two years to become available to the tree.
Three to six foliar sprays per season are needed, with the first spray being applied two weeks after budbreak. Make subsequent applications at two week intervals while shoots are elongating, typically through late May.