Radical tree spacings and training configurations are being trialled for other Prunus crops such as peaches and plums.
While the drivers for those trials in those crops are different to the drivers the almond industry contends with, some of the issues that need to be solved or managed are the same — viz. maximising reproductive capacity and managing tree shape — although harvesting methods are likely to be very different. Irrespective of the way nuts are removed from the tree, the industry’s aim to avoid dropping the nuts on the ground will probably necessitate some form of catching system, most likely catcher plates deflecting around tree trunks. Minimising the number of times that those plates need to be deflected would improve the efficiency of detached nut capture. An added benefit would be that fewer nuts would be left on the orchard floor, and so less over-winter food for insect pests. So, the goal here then is to try to reconcile the need to maximise yield potential with the need to minimise potential inefficiencies in the nut catching system. The aim is to have the same number of vertical shoots per metre of row to maximise the number of potential fruiting sites, but to vary the number of leaders. This means that each vertical shoot may arise from a single tree (i.e. a central leader), or from a horizontally trained shoot. The ability of each rootstock to supply enough water and mineral nutrients will be critical here because demand for water and nutrients will increase as the number of vertical shoots each root system is trying to support increases. It goes without saying that row and tree shape will be maintained by hedging. The natural tendency of each variety to throw new shoots following pruning, and for those shoots to produce spurs or terminal flowers will be important responses.
Video: Dr Micheal Treeby introduces nut tree training research that will take place at the Nut research orchard
This project (RnD4Profit-15-02-011 ‘Advanced production systems for temperate nut crops’) is supported by Horticulture Innovation Australia Limited, through funding from the Australian Government Department of Agriculture and Water Resources as part of its Rural R&D for Profit programme and Agriculture Victoria (Victorian Government), the South Australian Research and Development Institute (SARDI), the Almond Board of Australia (ABA), and New South Wales Department of Primary Industries.