Effect of hedging and tree removal on productivity of crowding macadamia orchards

Hedging and 25% tree removal were investigated in a 6-year study as strategies to manage tree crowding in mature macadamia orchards. The trial orchard comprised 9-year-old macadamia (Macadamia integrifolia Maiden and Betche) trees, cultivar Kau (HAES 344), planted at 7 × 3.5 m and which had formed a hedgerow. In the hedged treatment, both sides of the hedgerow were lightly pruned annually with a mechanical hedger. In the tree removal treatment, 25% of trees were thinned out by removing every second tree in every second row. Hedging reduced yield in years 5 and 6 after the start of hedging, by 14 and 21%, respectively. Over 6 years, average yield reduction due to hedging was only 4%. Tree removal reduced yield/ha by 17% in the year immediately after thinning and this effect gradually reduced to 11% over the next 5 years as trees grew into the available space. Over 6 years, average yield reduction due to tree removal was 15%. The economic implications of the different patterns of yield reduction are discussed. Nuts dropped earlier in the tree removal treatment but there were no effects of hedging or tree removal on kernel recovery, unsound kernel or grade 1 kernel.