Future Orchards wrap – winter 2016
Research & ExtensionFrom 13 to 17 June the Southern Loop Future Orchards® walks took place throughout Australia, starting in Manjimup, then moving onto the Adelaide Hills, Hobart and finishing in Southern Victoria.
A similar program was run two weeks later for the northern growing districts. The quality of the orchard venues presented to the 200 odd growers and industry personnel that attended were of a very high standard.
APAL Technical Manager Angus Crawford, Horticultural Advisor Marcel Veens and I gave indoor presentations that are available on the APAL website along with other notes from the Northern Loop:
- Designing labour efficient canopies, Ross Wilson, AgFirst, June 2016
- Platforms for increased labour efficiency, Steve Spark, AgFirst, June 2016
- Precision management of apple nutrition in poor and variable soil, Tienie du Preez, June 2016
- Labour efficient canopies, Marcel Veens, June 2016
This article follows on from these presentations and summarises some of the interesting in-orchard demonstrations, trials and discussions we saw while on the Southern Loop.
Long pruning
Early in the Futures Orchard program, AgFirst introduced long pruning techniques and this has progressed to such an extent that the majority of growers are using long pruning principles today.
Long pruning has enabled the establishment of simple pruning rules and easy adoption by growers and staff. Simple pruning rules along with some tree training have seen the transition from low yielding orchards into modern high yielding orchards capable of producing world class yields. Also, long pruning is easily adopted into the newer high density plantings.
Marcel Veens and I presented and demonstrated long pruning, and discussed with growers the reasons behind the minor differences in our individual pruning styles. The common theme we both expressed was that trees should have no more than 18-22 branches per tree (depending on tree height and spacing).
Well-pruned Gala apple trees at Ian Armour’s orchard, Victoria.
Branches should be evenly spaced up and around the leader of the tree. Branches near the top of the trees should be smaller in diameter and stronger branches should be removed in order to maintain optimum light penetration into the lower canopy. Without good light penetration into the lower canopy, buds can be shaded and lose fruitfulness quickly.
As newer, high density plantings become more mature, there is a need to remove the stronger branches in the top of the trees systematically as the trees age, making sure sufficient branch and bud numbers are left in the tree to meet cropping targets.
All orchards visited on this loop were pruned to a very good standard and required only minor pruning changes to maintain or increase tree performance. Some of the changes were as simple as removing 1-3 of the biggest branches from the tops of the trees, and removing shoots longer than your snips in the top of the tree (approximately 160mm).
We continually encouraged pruners to look up the tree to remove branches causing shading and not to concentrate on the branches in the bottom of the tree that were affected by shade. Look for the cause of the shading and not the result.
The other point we stressed was to keep the trees narrow in the tops to allow good light penetration into the lower branches otherwise the crop will migrate to the top of the tree.
Optimising tree uniformity
Achieving a standardised/uniform orchard early on is very important, especially in the newer SNAP (simple, narrow, accessible and productive) high density orchards. Although a pruning strategy is important, often ensuring young trees are not over cropped is equally as important.
It can be easy to overlook tree growth variation and treat every tree the same. However, experience has taught us that this isn’t always the best approach. Some trees are smaller and have a reduced trunk circumference and therefore should not carry the same crop load as the larger better growing trees.
Identifying these weaker trees can be as simple as painting the trunks of the trees with a band of cheap household acrylic paint. At hand thinning time, staff can be instructed to remove the fruit from these weaker, marked trees easily, therefore giving the trees a better chance to grow and catch up with the stronger, higher-cropping trees.
Often painting two grades of trees is beneficial. Some trees that are just too small to crop early on in the orchard’s life should be painted with another colour to avoid fruit stopping these trees from reaching their true potential. We saw a good example of this and how easy a potential future problem could be averted. Be observant in your orchard.
Of course the best plan would be to grade the trees prior to planting and plant trees of the same size and quality together, finishing up with the weaker-graded trees in rows by themselves. They can receive different chemical thinning strategies and would be easier to look after, rather than having them spread among the bigger and better trees.
Good grafting with new twin stems achieved.
There were also some very good examples of reworking older less profitable varieties over to newer varieties. It was also evident that because of the wide tree spacings, growers are utilising twin stems more to reduce future tree vigour. These young grafts had grown very well. If good tree training and support are provided, these trees will be very productive in the near future and provide a quick turnaround in production to a more profitable variety.
The true rewards from undertaking this type of grafting can only be fully realised if the follow up is done correctly (correct pruning, crop load, tree support, training etc.), otherwise this good result may be wasted. Every district has this type of redevelopment occurring and there are some very good results to date.
Often the cheapest way to increase production is to increase tree height. In Tasmania, there was a good example at Hansen Orchards where, by adding simple post extensions, Jazz™ crop loads have increased from 42 t/Ha to 60 t/Ha or more for a very small cost.
Burr knots
Burr knots are becoming more prevalent in orchards throughout Australia. They are tumour-like swellings on the trunk of the tree that grow overtime and have a significant effect on the tree’s health and vigour. They can also harbour pests such as woolly apple aphid and can swell to such an extent that tree growth is affected and fruit yield compromised.
Some rootstocks, such as M9, M26, MM106 and MM111 are more prone to developing burr knots than others. Burr knot development is promoted on these sensitive rootstocks by low light intensity, warm temperatures and high humidity. Ensuring good weed control under the tree and avoid using tight fitting spray guards will help minimise the development of burr knots.
Control can prove difficult and usually the best practise is to prevent burr knots establishing in the first place. One method we saw that was having some success at maintaining tree vigour when severe burr knots were present was to use a chainsaw (or hand grinder) to put a 6-8mm wide vertical cut through the burr knot. We were told that the sap can flow more easily up the vertical saw cut once calloused and local experience indicated this method was having some success at keeping the trees healthy. More research is needed on this potential problem.
Burr knot at base of tree with vertical saw cut forming a new callous that allows easy sap movement past the burr knot.
WA Community Orchard Group trials
Local Front Line Advisor Susie Murphy White and the WA Community Orchard Group have two exciting trials lined up.
The first involves the West Australian Focus Orchard of Trevor, Carmel and Jo Fontanini of Manjimup. They have several rows of older cordon style trees. Worldwide there is a trend to reduce the number of trees planted per hectare by growing more stems per tree – much like the cordon style trees.
The WA Community Orchard Group decided to use these older cordon trees to implement newer tree training techniques to promote SNAP trees (simple, narrow, accessible and productive). The existing trees will be reworked in the next few years to see if it is possible to achieve higher yields of better quality fruit. Although the row spacing is wider than desired for a modern orchard, valuable lessons will be learnt in this orchard demonstration.
The other trial Susie and group are working on is on soil fumigation. This involves reviewing a range of soil and biological treatments to assess if any are effective at reducing the impact of tree replant stress in this area.
Results for both trials will become available at Future Orchards walks and more information on these trails will be presented in future articles.
Acknowledgements
Thanks to the growers who hosted the orchard walks and freely shared their information for everyone to learn from. These included Terry, Carmel and Jo Fonatanini (WA), Joel Brockhoff (SA), Howard Hansen and Ryan Hankin (Tas), Thom Fillips and Ian Armour (Vic). Also I would like to acknowledge the Front Line Advisors in each region that assisted with such a good turnout of growers and industry people: Susie Murphy White, Paul James, Sophie Folder and Angus Crawford.
APAL’s Future Orchards® program is funded by Hort Innovation using the apple and pear industry levy funds from growers and funds from the Australian Government. AgFirst is a key Future Orchards partner.
