1. Tree Structure Project

This project is lead by PFR NZ in collaboration with DAFF Qld and TIA and seeks to improve orchard productivity and fruit quality optimisation by improving crop load management and fruit quality through artificial spur extinction (ASE).

ASE is the regulation of bud number and distribution by selectively thinning spurs at winter pruning and is part of the ongoing drive to develop high density orchard systems. A secondary objective is to understand whether the subsequent changes in canopy management can contribute to more efficient water use. Trials have been established at Stanthorpe, the Goulburn Valley and the Huon Valley.

Some findings were that:

  • Fruit size was generally greatest on terminal buds, closely followed by spurs while fruit from axillary buds is typically inferior
  • Reducing floral bud density increases the fruit set of the remaining buds. Fruit set seems to respond in a predictable pattern to changes in fruit bud density by ASE
  • Crop load decisions can be principally set using spur extinction at pruning, prior to bud break
  • Whilst still early in development, ASE promises to offer new methods for very precise control of the three principal factors for optimising yield and fruit quality:
    • The control of fruit set behaviour
    • The precise setting of crop load (fruit number per tree) from very early in the season
    • Reliable abundant return bloom the following spring.