About 21624 Zinc Sulfate: Helps prevent and control Rosette on Pecan trees and provides and excellent source of zinc. Can be applied as a foliage spray or as a soil treatment. For use as foliage spray mix 1 tablespoon per 3 gallons of water and apply after pollination. For soil treatment use, broadcast granules at a rate of 1 3/4 lbs. per inch of tree diameter. About Hi-Yield