Effects of hydrogen cyanamide, paclobutrazol and pruning date on dormancy release of the low chill peach cultivar Flordaprince in subtropical Australia

The growth regulator hydrogen cyanamide (Dormex, 50% a.i.) was tested for its effectiveness in promoting earlier and more even budbreak, flowering, and fruit maturity of the low chill peach cv. Flordaprince at 2 sites in subtropical Australia. The influence of the growth retardant paclobutrazol was also tested at 1 site, and at the other, the effect of altering pruning date.

At 1 site only, hydrogen cyanamide applied early-mid June, during endodormancy, advanced mean harvest time by 10 days. At the other site, there were no consistent trends between harvest time and date of application of cyanamide. Dormex at the lowest concentration applied (10 mL/L) caused severe yield reductions (40.8%). Flowering and fruit maturity were advanced by about 6 days with dormant pruning in early winter, compared with pruning at later dates, and by 13 days with the application of the growth retardant paclobutrazol, compared with no application.