Effects of early tree training on macadamia production

Abstract

The current industry recommendation for the training of young macadamia (Macadamia integrifolia, Macadamia tetraphylla, and hybrids) trees is to prune the trees to a central leader, but there is little science to support this recommendation. We planted an orchard to assess the merits of central leader training relative to a minimally pruned control. We used two cultivars, 246 and 816, representing spreading and upright growth habits, respectively. Training to a central leader reduced cumulative yields per tree over the first 3 years of production by 16% in ‘246’ and 23% in ‘816’. The reduction in yield was correlated with a reduction in the number of racemes per tree. The early training of the upright cultivar 816 appeared to improve its resistance to storm damage, but no such effect was seen in the more spreading cultivar 246. The yield penalty in training young trees to a central leader is such that industry should reconsider its early tree training recommendation.