Future Orchards: Managing vigour and variability to achieve crop targets

Published on November 23, 2022

Business Management

The Future Orchards® Spring Orchard Walks took place around all apple and pear growing regions from 14–18 November.

Jonathan Brookes and Nic Finger from the AgFirst team led discussions around knowing your numbers for each block to make decisions to achieve harvest crop targets. Guest presenters Dr Lee Kalcsits from Washington State University, Jorika Cronje, Horticultural Consultant from South Africa, and Dr Nigel Swarts from the Tasmanian Institute of Agriculture shared their latest research outcomes and knowledge about crop nutrition to manage nutrient inputs to achieve high quality.

Common themes across the regions were the wet, cold start and the impact on flowering and pollination, managing vigour and variability in crop load.

Vigour management to achieve tree targets

A very green orchard greeted us when we kicked off the spring walks at Savio Orchards in Stanthorpe, a far cry from 2019 when growers had to truck water into the drought-hit region. Stanthorpe has, like many growing regions, had one of the wettest starts to the season in a very long time. As in other regions, this has affected flowering and pollination and, while it is still early days, the crop in the region is expected to be a little lighter as a result, particularly for varieties sold as Pink Lady, Gala and Red Delicious.

With the recent rains, vigour is also presenting challenges in some varieties. At Savio’s we looked at Ambrosia™, Jazz™ and Kanzi™ blocks and Jonathan Brookes led discussion around ‘What is the crop response I want from my tree and how can I achieve that?’ as well as addressing other regionally relevant topics.

In this orchard, vigour was largely managed by application of Regalis®. Other options discussed both here and in other regions, included irrigation management, summer pruning, root pruning and nutrition. While it’s getting a bit late now for Regalis or where purchasing products is not an option, Jonathan suggested snapping off branches or twigs in January which can help to get some leaf off and act as a ‘brake’ on the tree. Lee Kalcsits, APAL’s guest from Washington State University, mentioned that growers in Washington thin during bloom, a practice which is less common in Australia.

Jonathan’s rule: “Leaves are an accelerator; removing them puts the brakes on vigour. Removing fruit will promote tree growth.”

Root pruning to manage vigour was not commonly practised by growers present at the orchard walk in Stanthorpe because of concerns that it promotes suckers from some rootstocks as well as a greater risk of soilborne diseases such as Phytophthora.

Being a wet season, growers are also aware of the greater risk of Glomerella and Alternaria. These diseases were also a concern in some other regions in the eastern states.

Stanthorpe growers report that fruit colours well in the region and the orchard does not use leaf blowers or hedgers, but reflective matting is used to help with colour development on some varieties closer to harvest. This helps to achieve the target packouts.

Managing tree and orchard variability

Achieving crop targets also dominated discussions at Orange, NSW, where the walk was hosted by Bernard and Fiona Hall at BiteRiot. The impact of a very wet winter and spring season was evident in the recent earth works to manage water flowing through the orchard.

Following the presentations from Jonathan and Lee, we looked at two blocks where rootstocks were variable, mixed or unknown. We discussed the challenges of obtaining quality nursery stock and subsequently working with tree variability. Consistency in trees (including in the depth at which they are planted) within a row and across the block makes it simpler to manage the tree, the crop and achieve targets because it is less likely that there will be differences in maturity dates, vigour, colour development, disorders, thinning requirements and other impacts on management practices.

In one of the blocks in this orchard, achieving tree height and filling the canopy has been particularly challenging due to variable rootstocks and other unknown factors. We discussed options on how to improve this through crop load management (e.g. take off fruit to increase growth and drive height – fruit being the brake) to fill the canopy. Jonathan suggested when plant material is received from nurseries it is a good idea to sort them into groups of similar size/traits when planting to make managing the trees easier in the orchard as trees with similar ‘characteristics’ are grouped together.

Linear systems and filling the canopy

Variation in trees and orchard architecture was also discussed in Batlow at Nightingale Bros. orchard.

Jonathan showed how uniform 2D systems made it easier to set simple rules for pruning teams, improving efficiency and crop load consistency.

Jonathan gave an example of an orchard in New Zealand where trees vary from top to bottom. In that orchard, fruit from the top of trees is harvested using platforms, and the fruit from lower in the tree is harvested using bags and bins (pedestrian). This type of top versus bottom management of trees may be a practical option for blocks in which rows are wide – in this case there is an option to grow branches in the lower part of the tree out into the row, while managing the upper part of the tree as a more 2D or planar system.

At Nightingale’s, the orchard has recently step-grafted Fuji as a three-leader system onto M9. Different techniques of grafting and benefits of keeping a ‘bleeder’ branch when step grafting were discussed. Owner Don Nightingale and manager Billy Brennan had also found that grafting on the western side of the tree was better suited for their weather conditions to ensure the grafts took.

In an older Fuji block in the orchard, the goal was to better fill the canopy while managing vigour. Options to do this included tying down the branches along wires to increase the fruiting area, which would also help to calm the tree.

The final walk on the ‘northern loop’ was hosted by McNab Orchards at Ardmona in Victoria’s Goulburn Valley.

Fruit drop was an issue and Jonathan said this could be caused by poor drainage – drainage being an issue in many regions this season. However, if fruit drop is limited to only certain parts of the canopy (e.g. the top or bottom), then other factors may be at play, such as chemical thinning, light or pollination.

Lee said light could also be a contributing issue: “Light is an issue particularly in older trees – for flower induction and for keeping fruit on tree,” he said.

Knowing your numbers

A key theme of the walks was the importance of knowing the numbers for each block to inform decisions on setting and achieving harvest crop targets. Consistency in the block can make things simpler and more efficient.

Do you know how many apples you have on your tree? If you don’t maybe give it a try on one of your blocks.

At each of the orchard walks, Jonathan and Lee discussed different ways to determine and manage crop load including trunk cross sectional area (TCA/TSCA) or branch cross sectional area (BSA) crop load management.

This essentially involves measuring trunk or branch diameter using calipers or wheels, calculating the area and multiplying it by the target fruit load. As the tree gets older, you can start looking at the BSA or leader (target number of fruit per leader). A tree with a bigger trunk diameter can make a difference in achieving the target crop load. For example, a tree with a 3cm trunk or branch may carry 28 fruit and one with a 4cm trunk or branch can carry 48 fruit – a 1cm difference in trunk diameter, but a difference of 20 fruit. This can result in large variation in crop loads and subsequent effects on fruit size and quality across a block.

As Jonathan said: “You want every tree performing as a winner.”

More information about crop load management can be found in the Future Orchards library.

Read:

• Good thinning for orchard performance
• Review Crop Loading with Ross Wilson and John Wilton
• Setting the crop up for a successful harvest with the right hand-thinning

Watch:

• Ross Wilson from AgFirst discusses how to manage vigour and crop load to increase profit
• Visit Waima Orchards with Ross Wilson to see how Mark Ericksen and Warren Grant achieve their optimum crop load targets using girdling to manage vigour and chemical and hand thinning
• Review last year’s Future Orchards November Talk with Nic Finger and Jonathan Brooks to prepare for summer

Many thanks to John Savio and Rosie Savio (Savio Orchards), Bernard and Fiona Hall (BiteRiot), Billy Brennan, Keith Nightingale and Don Nightingale (Nightingale Bros.), Mitch McNab (McNab Orchards) and  Thom Phillips and Ian Armour (Armours Apples).

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