EFFECTS OF WAIKEN ON FLOWERING AND SPRING GROWTH IN APPLE

A series of six trials, commencing in 1995, was conducted over three years to determine the effect of late winter/early spring applications of the experimental rest breaker Waiken (an emulsified vegetable oil compound, SST Australia Pty Ltd) on flowering and spring growth of several apple cultivars. In year 1, Waiken was applied to drip point to ‘Granny Smith’ and ‘Imperial Gala’ trees at three rates (2, 4 or 6 % v/v). While there was some bud swell, the trees were essentially still dormant. Waiken extended the dormant period of both cultivars and resulted in a more concentrated flowering period. There was a gradation in response, with the 6% rate having the most effect and 2% having the least effect. The treated trees grew rapidly out of dormancy and caught up to untreated trees with regard to canopy development. In the second year, Waiken applied at 4% concentrated the flowering of ‘Pink Lady’ and ‘Fuji’ apple trees. Treatment also advanced flowering in ‘Fuji’. On both apple varieties, Waiken resulted in greater leaf canopy development in spring, appearing to counteract apical dominance, and cause much more uniform bud burst and leaf development throughout the trees. In the third year Waiken was applied at two times to ‘Fuji’ and ‘Sundowner’. On ‘Fuji’ both applications advanced and concentrated the development of flowering and accelerated leaf canopy development. An early application of Waiken to ‘Sundowner’ apple trees slowed and concentrated the development of flowering, but the later application had no effect on flowering.