Waiken: an effective dormancy breaker in 'Sylvia'and 'Vista' sweet cherry

Trials were conducted over two seasons to determine the effect of late winter applications of the rest breaker Waiken (an emulsified vegetable oil compound, SST Australia Pty Ltd) on flowering and spring growth of sweet cherry cultivars ‘Vista’ and ‘Sylvia. Trial design in all trials was a randomised complete block with 10 single tree replicates. An untreated control was included in all trials and Waiken was applied to dormant trees. In the first season, Waiken was applied at 4% by volume to drip point to ‘Vista’ trees on 4th August (approx. 7 weeks before budburst). Treatment advanced and concentrated the flowering and harvest maturity and also reduced apical dominance and increased leaf canopy development in spring. The following season trials were established on ‘Vista and ‘Sylvia. In the ‘Vista’trial, 4% Waiken was applied as a single application at four different times - the earliest on 2 August (54 days before budburst (dBBB)) and the latest application on 27 August (30 dBBB). In the ‘Sylvia’trial, 4% Waiken was applied at either 73 dBBB (2 August) or 60 dBBB (15 August). In both cultivars, earlier applications of Waiken advanced bud break, flowering and fruit maturity. Later application of Waiken at 30d BBB delayed bud development and flower opening, reduced the length of the flowering period and concentrated fruit maturity. For the second season, Waiken again increased early canopy development, this occurred at all timings but to a greater degree with earlier applications. This work has demonstrated that Waiken is effective in manipulating budbreak and flowering ain sweet cherry and has potential to delay bud and flower development to help avoid frost in frosty areas. However further work is needed to determine how late it can be applied to delay bud break in cherries.