Canopy management strategies for macadamia ('Macadamia integrifolia', 'M. integrifolia' x 'M. tetraphylla')

Abstract

Macadamia is a subtropical evergreen tree native to the east coast of Australia and grown around the world for its edible kernel. The trees are tall with dense canopies and at maturity orchards are heavily shaded and crowded unless tree size is controlled. This shading has been associated with yield decline but the evidence for this is limited to one site. The shading also limits ground-cover growth leading to increased soil erosion; slows orchard floor drying after rain resulting in harvest delays and reduced nut quality; and increases pest and disease pressure. Crowded orchards are also more difficult to spray effectively. The aims of this study were to further investigate the evidence for yield decline, assess canopy management methods adopted by industry, and investigate the effect of pruning on fruit set to improve outcomes from some of these methods. A yield survey in mature orchards confirmed earlier conclusions that yield decline occurred at high levels of light interception but that it was small compared with inter-seasonal yield variation.