Effects of Hydrogen Cyanamide (Dormex) and Ethephon (Ethrel) on Fruiting of `Redhaven' Peach

Abstract

Early flowering of peach in the Southeast can result in annual crop loss as a result of late winter—early spring freezes. It has been shown in peach and other Prunus that a fall application of ethephon delays flowering several days. However, delayed harvest and smaller fruit size of certain varieties may occur. Hydrogen cyanamide replaces lack of chilling in peach but can also advance harvest date and possibly enhance or maintain fruit size. A randomized complete-block experimental design using 12-year-old `Redhaven' trees was used to evaluate whether hydrogen cyanamide could offset the delayed harvest and smaller fruit size disadvantages of using ethephon without advancing bloom dates. Treatment combinations of ethephon (at 20%, 50%, and 90% of required chilling) and hydrogen cyanamide (at 90% to 100% of required chilling) were applied as whole-tree foliar sprays to near point of drip. Although nonsignificant, there were trends toward hydrogen cyanamide overcoming both smaller fruit size and delayed harvest induced by ethephon.