3 minute read
Canopy management
Canopy management in Afourer
mandarins project update
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Department of
Primary Industries and Regional Development
BY RACHELLE JOHNSTONE RESEARCH SCIENTIST, DPIRD
WA growers are taking part in a Horticulture Innovation Australia funded project to develop best practice canopy management techniques in Afourer mandarins that can improve long-term yields and minimise alternate bearing.
The project, which is being led by Steven Falivene at New South Wales Department of Primary Industries, will conduct case studies on Afourer grower properties across Australia. The project commenced in 2020 and will continue until 2024. The studies will explore the numerous management options currently being used including hand thinning, chunk pruning, limb bending, annual limb removal, autumn water shoot removal and mechanical hedging. The Department of Primary Industries and Regional Development (DPIRD) is coordinating activities in WA at three demonstration sites — two in Harvey and the other in Dandaragan — which will assess the effect of different pruning strategies on fruit size and yield.
Each site has 12 trees that were intensively pruned in September and October 2021 using a ‘layering’ technique to optimise light penetration into the canopy at all levels.
The aim of this pruning strategy is to mimic the young tree structure of an Afourer, encouraging fruit across all levels of the canopy. We are aiming to maintain and reinvigorate the middle part of the tree, which tends to be shaded and bare of shoot growth as Afourer trees mature. The first stage will involve pruning the sides of the tree with a little pruning of the centres. First targeting the tree centres will encourage watershoot growth, taking energy away from fruit growth and blocking light to the lower canopy as the branches grow. Next year there should be some leaf growth in the middle parts of the canopy and when the centres are removed this growth will help to suppress some of the watershoot growth. The trees are still relatively young when compared to the 4.5m tall trees in some orchards and do not require excessive pruning. The main strategy is to identify the limbs we want to keep and then prune around them so there is enough space and windows for light to reach most of the way along the limb. Figures 1–3 show an example of an Afourer tree before and after pruning. You can see that pruning has resulted in dappled light throughout the canopy. It is thought that developing a good limb structure and managing regrowth in autumn are important practices. Trees will be monitored in autumn and regrowth pruned if necessary. One of the demonstration sites will also have a row of hedge pruned trees. Pruning treatments will be compared to the grower’s current practice at each site, measuring fruit size, yield and costs of pruning/management. Steven will soon release a series of videos that describe many of the pruning treatments in detail and updates on how the trees responded in the following year.
MORE INFORMATION
Contact: Rachelle Johnstone, rachelle. johnstone@dpird.wa.gov.au or Steven Falivene, steven.falivene@dpi.nsw.gov.au
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FIGURE 1. AFOURER TREE BEFORE PRUNING, SEPTEMBER 2021. FIGURE 2. AFOURER TREE AFTER HAND PRUNING. FIGURE 3. CENTRE OF AFOURER TREE AFTER PRUNING. FIGURE 4. KEVIN LACEY (DPIRD SENIOR TECHNICAL OFFICER) PRUNING AFOURER TREES AT THE DANDARAGAN SITE. CITRUS FUND
This project has been funded by Hort Innovation using the citrus research and development levy and funds from the Australian Government. For more information on the fund and strategic levy investment visit horticulture.com.au
