Application of hydrogen cyanamide to increase bloom uniformity in low-chill peaches: a preliminary report

Abstract

Hydrogen cyanamide (HC) is an important tool for growers of low-chill fruit crops in subtropical production regions. This chemical can help plants break dormancy to enhance the emergence of leaves shortly after bloom and fruit set. Leaf emergence is important for the production of sugars, structural carbohydrates and volatile flavor components in low-chill fruit that often have a compressed fruit developmental period. The objective of this preliminary study was to observe the application of two rates of hydrogen cyanamide (HC; Dormex®) on ‘UFSun’ and ‘UFOne’ peach varieties. Two rates were applied (2% or 3%; v/v + surfactant) in ‘UFSun’ while only 3% was applied in ‘UFOne’. Controls were included in which no chemical was applied. HC was effective at increasing lateral budbreak in both peach varieties, and there was no difference between the 2% and 3% rate in ‘UFSun’. Terminal budbreak was not affected in ‘UFSun’; however application of HC did increase terminal budbreak in ‘UFOne’. Neither variety exhibited phytotoxicity symptoms at either rate when applied three to four weeks before anticipated budbreak. This preliminary study has shown that when applied before bud swell, HC can improve terminal and lateral budbreak in low-chill peaches. However, timing of the application can do severe damage to flower and leaf buds and must be considered to avoid crop loss.