Dormancy-breaking sprays for low chill in apples

April 2019 | Presented by Camilla Humphries, E.E. Muir and Sons | Future Orchards® presentation

Camilla Humphries reports on a low-chill trial at David Finger’s orchard in Launching Place, Victoria, examining whether dormancy-breaking sprays can compact flowering and improve orchard management. The intended benefits included manipulating harvest timing, improving pollination and fruit set, making thinning sprays easier to manage, increasing ripening uniformity and improving fruit size and quality.

The trial compared dormancy-breaker treatments including Erger® and Waiken™ and placed strong emphasis on application timing relative to green tip and accumulated winter chill. An early treatment was applied on 1 August 2018, around 40 days before green tip, while a later timing was applied on 14 August, about 35 days before green tip.

Assessments included flowering window, BBCH growth stage, fruit set, fruitlet size and harvest fruit size. The presentation shows how the timing of treatment changed the progression of bloom and demonstrates why dormancy-breaking products need to be matched carefully to chill accumulation and the physiological stage of the tree.

The work provides a practical example of how dormancy manipulation may help growers manage low-chill seasons, but also reinforces that timing is critical and that responses need to be evaluated at orchard level.