R. Paulin
The Western Australian apple industry currently favours free standing trees with single or multiple upright leaders. With greater appreciation of the positive effect of high density on investment amortisation, has come a trend towards higher density of planting and choice of central leader trees.

Orchard productivity is limited by light intensity. This is evidenced by variations in production levels achieved from Northern to Southern Europe. In Northern Europe tree size is small, densities are very high, up to 5000 trees per hectare and yields per hectare are no more than half those achieved on wider spaced larger trees in Southern Europe as well as in other lower latitude regions.

The relevance of high density plantings, greater than 1000 – 1200 trees per hectare under Western Australian conditions are questioned. The associated small tree requirement means that a high percentage of the production is exposed to sunburn from prevailing high temperatures and sunlight levels. This problem would be further increased by the need for low vigour rootstocks. At present only moderate to high vigour rootstocks are used.

Current recommendations favour central leader systems, with spacings appropriate to rootstock scion selection and site conditions. Spacings range from 4.5 × 2.0 to 5.5 × 3.5 mm. It is suggested that with wider spacings, some training and structural pruning is required, otherwise both pruning and training is kept to a minimum during development stages. In the productive phase, pruning increases and it is proposed that the level should reflect fruit quantity and quality in relation to wood age for given varieties.

Paulin, R. (1989). AN APPLE PRODUCTION SYSTEM FOR WESTERN AUSTRALIA. Acta Hortic. 240, 109-114
DOI: 10.17660/ActaHortic.1989.240.17

Acta Horticulturae