D.W. McKenzie
In New Zealand, mild climate and fertile soils are ideal for exploitation of the heavy fruit-induction produced by Malling-Merton 106 rootstocks. On less fertile soils, similar results can be obtained with Merton 793 rootstocks. Some semi-intensive commercial orchards are already producing very heavy yields at 3, 000–4,000 bushels per acre (130–170 tonnes per hectare), on trees that require no support and without summer pruning.

The ideal tree unit has been planned as a centre-leader pyramid having a height of 4 metres and maximum spread at the widest point of 4 metres. Trees of these dimensions need to be trained to a multi-canopy pattern with a very open texture in order to avoid problems with spray penetration, shading-out of fruit-bud formation, poor fruit colour and difficulties with harvesting, fruit thinning etc. This branching pattern can be achieved with a very light pruning programme in the early years, which also provides very precocious cropping from young trees. Economic studies, since 1970, have shown that semi-intensive orchards provide the most profitable returns in New Zealand. Observations of fruit-setting and fruit colour have been used to determine the ideal branch arrangement for the pyramid trees. In considering cost of harvesting it is important to remember that factors other than height above ground level may be important. Density of fruit per unit tree volume and fruit-size can both affect harvesting costs. Total profit per carton is the deciding factor when comparing different orchard management methods.

McKenzie, D.W. (1981). THE IDEAL APPLE TREE UNIT IN NEW ZEALAND. Acta Hortic. 114, 343-345
DOI: 10.17660/ActaHortic.1981.114.48

Acta Horticulturae