New tree training systems for custard apple (CU04004)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

A combination of new varieties and training systems were set to revolutionize the Australian custard apple industry. A new variety, KJ Pinks, sets 50 per cent of its flowers compared with older varieties which set less than 3 per cent. In this study the researcher showed that this new variety was very suitable for higher density training systems such as the Maroochy V trellis and hedgerow systems.

The Maroochy V trellis was planted at 800 trees per hectare compared with about 300 trees with the standard open vase system. Consequently early yields on this system were higher than for vase-trained trees. On a commercial farm, four-year-old trees on Maroochy V trellis produced six trays per tree, or about 5 000 trays per hectare, and at full maturity, the researcher predicted that this system would produce in excess of 6 500 trays per hectare. Regional trials to compare the different training system were set up from north Queensland to northern NSW.

The researcher also investigated the use of mechanical pruning to reduce tree size and labour costs associated with pruning, thinning and harvesting. Early findings appeared promising showing that mechanical pruning during dormancy and mid-late summer was feasible and that tree height could be maintained at less than 3m. Additionally, preliminary studies also showed that growth retardant may have reduced shoot extension growth and increased yields by 20 per cent.