Looking back to the future: building on 50 years’ gainsTechnology & Data
This article was written by John Wilton of AgFirst for the Autumn edition of Australian Fruitgrower Magazine.
The apple industry is very dynamic with continual change. The last 50 years has seen major developments in new varieties, growing systems, pest and disease management, post-harvest handling, storage technology and shipping.
Of the varieties popular 50 years ago, Granny Smith is the only one still being grown in any significant quantities in Australia, accounting for about 18 per cent of present production. It lies in third place now after Cripps Pink (sold domestically under the name Pink Lady) at 41 per cent, and the Gala group at 23 per cent, with these three varieties making up close to 80 per cent of present Australian production. Varieties which have declined, and in many cases disappeared are Gravenstein, Delicious, Red Delicious, Golden Delicious, Jonathan, Cox’s Orange Pippin, Sturmer Pippin, Lady Williams (one of the parents of Cripps Pink) to name a few. The development of new high-colour strains of standard varieties is a firmly established trend. The development of Red Delicious from Delicious was an early -and possibly the first – example of this trend. More recently we have seen a plethora of high colour strains from Cripps Pink, Gala, and Fuji. Along with Cripps Pink and Gala, Fuji is another variety introduced in the last 30 to 40 years and now sits fourth in terms of production volumes. Although purists claim the original standard variety is a better ‘eat’ in regard to flavour than the ‘improved’ red strains that evolve from it, the market demands high colour and is unwilling to see highflavour as a compensation for less colour and pay the same premiums the high-colour fruit attracts. The message for the grower is that once a high colour strain for a variety is discovered, you have about five years to change from the standard variety.
Another strong trend is the shift to managed varieties and the emergence of a whole raft of new branded varieties seeking to carve a niche in the apple market. A characteristic of these it that they will be managed by a variety owner, and likely to be introduced with tree and production royalties and quality and volume controls designed to protect their value, and thereby maintain healthy returns for all involved. Current examples of new managed varieties include Scilate (marketed as Envy®), Kalei®, Nicoter (Kanzi®), Scifresh (Jazz®) and PremA96 (Rockit®). Many of these managed varieties will remain as small volume “niche” varieties individually, but collectively account for a significant and growing proportion of overall production and new investment. History tells us that only a relatively small proportion of new varieties will become major varieties within the industry. Looking at the world apple scene, Cripps Pink (which is sold domestically under the name Pink Lady and marketed under the Pink Lady® trademark and brand globally) is the only managed variety to make significant volume to date. While both Fuji and Gala and have achieved
significant scale, success for both has been largely due to the development of high colour strains able to meet market demands for fruit colour.
In addition to the emergence of new managed varieties, a recent development has been the branding of high specification commodity varieties enabling them to command a price premium over the non-branded product of the same variety. This is a development we are likely to see more of in the future. The success of branded products will depend on their ability to provide a consistent quality product every season, irrespective of growing conditions. Eve® is an example of a trademarked variety commanding a premium over the generic variety called Mariri Red.
There is a tremendous amount of breeding effort going into new variety development looking for new or improved characteristics. With consumer preferences, environmental concerns and integrated pest management learnings all driving a goal of reduced pesticide use, much of this breeding effort has focused on disease resistance. The challenge for breeders is to develop varieties with enhanced disease resistance without sacrificing the taste and texture characteristics that make for an enjoyable eating experience. After all we do not want the path to resistance to end up with a cultivar that is inedible to us as well as the pests!
Among disease resistant cultivars the Australian variety Kalei® is one of the best when it comes to eating quality. Red flesh is another characteristic apple breeders are striving to perfect. As with the disease resistant varieties, the big challenge with red flesh varieties will be to incorporate the quality characteristics of flavour and texture which are so important in regard to consumer satisfaction. Adaptability to climate change is also a focus of breeding programmes. Here, selection for high temperature tolerance is the main characteristic being sought. In this direction, I believe there is also scope to use root stocks as one of the tools for improving apple adaptability to warming climates. Rootstocks can improve budbreak response to marginal winter chilling.
Over the last 50 years we have seen a number of new varieties come and go. I am sure this will be the same over the next 20 years too. The key for the grower is to do your research, including taking advantage of variety and rootstock trials in your region, consider how the variety will fit in your own production program and spread your risk with a mix of varieties rather than trying to pick winners.
Fifty years ago, most Australian orchards were growing widely spaced multileader vase trees on high vigour rootstocks, which took many years to come into production. Central leader tree training was just getting underway, but still using moderately vigorous rootstocks planted at relatively low tree densities of around 700 to a 1000 trees per hectare. In the last 15 to 20 years the move to intensive plantings on precocious dwarfing rootstocks has progressed to the point where intensive plantings are now the norm. This move has been driven by the need for more labour efficient orchards, shorter non-bearing establishment periods, and the flexibility to change the variety mix as consumer preferences change. Apple production is moving out of the commodity
business, and into the fashion business. At present, there is a very dynamic approach to growing systems with many different system being explored by growers. These include tree densities in the range of 1250 to 3000+ trees per hectare, single leader spindle, bush or central axis tree forms, V-trellis systems and because of the interest in robotics, various 2D forms. For many years, some form of the central leader tree form dominated growing systems. While central leader tree forms still dominate, there is now a move back towards multileader tree forms. This move is being driven by tree and royalty costs, and the development of 2D training systems.
When market returns come under pressure as is happening in Europe at present, there is a tendency for orchardists to adopt lower cost orchard establishment systems. In Europe at present, planting densities are moving back from 3000 trees per hectare towards 2000 trees per hectare. This is because tree costs and their royalties are the major orchard establishment cost.
We are also becoming smarter at making trees grow better and crop sooner.
In recent years, robust tree support has evolved. Fifty years ago, when most orchards were planted on robust vigorous rootstocks little tree support was thought necessary. With the move to intensive plantings on precocious dwarfing rootstocks, good tree support was necessary because the trees often had weak PremA96 (marketed as Rockit®), is an example of “niche” marketing. This is a small, sweet apple, taking on the snack food market. The variety is now being grown in Australia and elsewhere around the world. It is now packaged in an environmentally friendly
There is a tremendous amount of breeding effort going into new variety development looking for new or improved characteristics. With consumer preferences, environmental concerns and integrated pest management learnings all driving a goal of reduced pesticide use, much of this breeding effort has focused on disease resistance. The challenge for breeders is to develop varieties with enhanced disease resistance without sacrificing the taste and texture characteristics that make for an enjoyable eating experience. After all we do not want the path to resistance to end up with a cultivar that is inedible to us as well as the pests! Among disease resistant cultivars the Australian variety Kalei® is one of the best when it comes to eating quality.
Red flesh is another characteristic apple breeders are striving to perfect. As with the disease resistant varieties, the big challenge with red flesh varieties will be to incorporate the quality characteristics of flavour and texture which are so important in regard to consumer satisfaction. Adaptability to climate change is also a focus of breeding programmes. Here, selection for high temperature tolerance is the main characteristic being sought. In this direction, I believe there is also scope to use root stocks as one of the tools for improving apple adaptability to warming climates. Rootstocks can improve budbreak response to marginal winter chilling.
Widely spaced central leader trees on vigorous rootstocks, typical of many orchard plantings made 30 to 50 years ago. Note absence of any tree support. These trees were slow to produce
profitable crops. root systems, or bud unions and had structurally weak leaders incapable of supporting their crop loads.
We have also recognised that with intensification early cropping is possible, even with less precocious stronger rootstocks, provided there is sufficient support structure to enable the tree to carry their crop without collapsing. Cropping is now considered our best vigour control agent. With smart design, tree support structures can be dual purpose and also provide support for netting protection without the added expense of a separate structure to carry orchard protection nets.
In the last 50 years, growth regulators have evolved into major orchard management tools. Fifty years ago, we only had the auxin-based chemical thinners such as NAA and NAD, and the carbamate insecticides, mainly carbaryl, and the beginnings of chemistry for vigour control in the form of Alar ® which was later withdrawn because of residue issues. Intensive research into plant physiology has now led to the development of many growth regulators capable of managing numerous tree growth processes. These include a much wider range of chemical thinning options, particularly in the post fruit set period, such as benzyladenine (BA) and Metamitron, with more to come. Vigour control agents of paclobutrazol, ethephon and prohexadione calcium enable excess tree vigour to be brought under control. There are also gibberellins to stimulate growth, reduce precocity and russet. We also have the harvest management tools of ethephon to advance colour and maturity, as well as AVG (Retain ®) and Harvista , a sprayed form of 1-MCP for harvest delay. AVG can also be used to extend ovule longevity when applied in the blossom period to improve fruit set. Dormancy breakers have been an important development over the last thirty years. Dormancy breakers are anticipated to become more widely used in the future to counter the impact of climate change due to their role in stimulating and compressing bud break as winter chilling levels decline.
Pest and disease control
Growing concern in recent years about the dangers of pesticide residues in food has resulted in a huge change in pest and disease control chemistry away from the persistent toxic broad spectrum pesticides towards more targeted, predator friendly insecticides such as insect growth regulators (IGRs), which target specific insect growth stages, sterile male technology which can even eliminate problem insect pest populations in fruit growing areas, pheromone disruption and insect trapping. This might result in a return to damaging broad spectrum insecticides or maybe adoption of new insect control measures such as insect exclusion nets that are now beginning to be used in parts of Europe. In fungi control, there has been the introduction of new chemistry with systemic and reach back activity which enables better rain fastness and effective control from application after infection periods have begun. Many of these newer fungicides are very site specific in their activity and operate on a single stage in the development of the disease organism consequently resistant management is now a key factor in fungicide choice and use patterns. Apart from the introduction of cultivars and rootstocks with better pest and disease tolerance, I do not expect there to be much change in the next 20 years to pest and disease control measures. The trend toward more environmentally compatible pesticides, many of which may be based on naturally occurring compounds is expected to continue. At present there is a lot of interest in the development of plant activators that stimulate the natural systemic acquired resistance response. There are already several of these being used in fruit growing including prohexadione calcium which has been shown to suppress the development of several diseases including powdery mildew.
As plant performance increases, the demands for better and better nutrition increases. The past 50 years has seen many growers move toward better monitoring and fertilisation including a move to fertigation on the poorer soil types. Within-block variability is a major limiting factor to orchard performance. Variation in nutrient supply across the paddock is a big part of the problem. Plant tissue analysis, and calibration of nutrient levels with leaf condition leading to aerial scanning and mapping of orchards has potential to identify nutrient deficient or surplus zones within orchards so that specific nutrient management programmes can be implemented within blocks to minimise variability. This will also lead to more targeted fertiliser use through fertigation or foliar application replacing broadcast fertiliser ground application. In time, we expect that GPS controlled variable application of fertilisers will become more and more common.
Irrigation and water supply
For virtually all of Australia, irrigation is essential for apple production. Water supplies are scarce, and often unreliable, as well as increasingly expensive. Security of water supply in the future may well determine suitable locations for pomefruit production. Long term climate change on mainland Australia may make some fruit growing locations. more marginal, leading to contraction of pomefruit production in these areas while new areas may emerge. Intensification of growing systems to increase yields relative to water use will be necessary to continue profitable production.
Water use efficiency can be increased through mulching, which also has the benefit of reducing soil temperatures. Partial root zone drying (PRD) which has been shown to give substantial water saving. Buried drip tube to minimise soil surface evaporation losses. Vigour control, early thinning to maximise carbon partitioning to the marketable crop will lift yield relative to water use. In the longer-term climate change may see a resurgence in the Tasmanian pomefruit industry with its milder, wetter climate favourable for pomefruit production. Whether this is alongside a contraction of pomefruit production in the mainland locations currently regarded as more marginal or whether the emergence of new systems, varieties and techniques enables climate change adaptation, we will have to wait and see.
Automation is the buzz word in the industry at the moment. Designing new plantings to be automation compatible is viewed as future proofing the orchard. In my view, fully automated harvesting for instance, is still a long way off for premium quality, fresh market fruit. It could come quite rapidly for process fruit where profit margins are much slimmer and cosmetic appearance less important. Ladders, particularly tall ones, are on the way out, to be replaced by platforms for pruning, thinning and harvest. Platforms and automation will come with their own limiting factors. Their ability to handle undulating ground is rather limited, so a lot of the hillier orchards will probably not lend themselves to automation. With automation in mind, future orchard plantings will need to be on flat, or uniformly gently sloping land. Unless there is significant miniaturisation of robotic equipment, tree rows will need to be much intensively planted. Pickers place the fruit on
conveyor belts, some work on the ground while others travel on the machine. For high quality fresh market fruit, this approach to harvest is more likely than robotic picking. wider than many orchards are being planted at present. As it appears that, initially at least, 2D canopies will be an automation requirement, these canopies will need to be very tall, capture a high proportion of available light, or we can expect yield levels per hectare to drop substantially due to lower canopy light interception. Narrow “V” canopies probably offer the best potential for maintaining yields and machinery access in 2D canopy orchards. In hot climates where sunburn is a significant problem, “V” canopies appear to manage the sunburn issue better than single row vertical 2D canopies. Pursuit of new orchard systems and broader innovation inevitably involves running down a few “blind roads”. Pedestrian orchards planted in bed systems were an example. I am sure there will be many more “blind roads” as we try and adapt orchard systems to automation, but if the rate of change achieved in the past 50 years is anything to go by, there is a good chance that some roads will lead to profitable and productive systems and solutions in the future, the likes of which we can now only imagine.
Future Orchards is funded by Hort Innovation using the apple and pear research and development levy and funds from the Australian Government, and is delivered by APAL and AgFirst.