Effect of Fall Ethephon Applications on Bloom Delay, Flowering, and Fruiting of Peach and Prune

Abstract

Studies in the use of fall ethephon to delay bloom in peach and prune were carried out during 1985-87. In `Italian' prune, ethephon at 250 and 500 mg·liter-l at 10% leaf-drop stage delayed bloom 13 and 16 days, respectively. Only a 5- and 7-day bloom delay occurred when applied at 50% leaf-drop stage. Fruit set and yield were not reduced in `Italian' prune when ethephon was applied at the 50% leaf-drop stage. Early applications, from vegetative maturity to the 10% leaf-drop stage, did not reduce yield in prone when trees had been previously defoliated with 3.0% urea. Early leaf removal, before vegetative maturity, caused reduction in peach flower and fruit number. In several peach cultivars, all the ethephon treatments were detrimental to flower density, fruit set, and yield, in spite of bloom delay. The ethephon-treated prune trees yielded more than the untreated trees in 1987 as a result of frost avoidance.