A critical time for orchard managementResearch & Extension
To help growers in this busy time of year, AgFirst’s Jesse Reader gives a run-down on the important orchard management activities that need to be done now to help optimise orchard productivity.
2014 is all but over and it’s around this time we often hit the panic button and fear that the ship has sailed on important tasks in the orchard. However, to the contrary, the current list of jobs to do is extensive and worthy of your time and attention. Whilst fruit set has occurred, trees are planted and chemical thinning is more than likely done, several key areas are begging for your attention. With the platform for the season set, it is often a nice time to take stock, make a list and look at your obligations as a business owner/manager going forward. Furthermore, both timeliness and efficiency of execution in the following areas is critical and often the difference between ‘the best and the rest’ – where do you sit?
Soil moisture monitoring and irrigation management
With a dry start to the season in many growing regions across Australia, irrigation and soil moisture management will be front of mind. It is likely that several growing regions of Australia are experiencing up to 1.5 to 2 inches of evaporation/week. To put that in perspective, that’s up to 500,000L/ha/week in evaporation! If needed, are you equipped to replace 40-50 per cent of that? The scientists refer to this stage of irrigation demand as stage three, where rapid fruit growth is occurring and can last between four to eight weeks prior to harvest. Shoot and root growth is slow and bud formation for the following season’s fruit begins. Irrigation is critical at this stage and soil moisture should be readily available. Furthermore we know varieties such as ‘Royal Gala’ respond positively to water right up to harvest. Conversely, it’s not too late to use soil moisture management and deficit irrigation as a tool to your advantage in managing vigour, colour and fruit size in varieties such as ‘Cripps Pink’ and ‘Cripps Red’. See the APAL website for further details on deficit irrigation in the ‘Guidelines for irrigation management for apple & pear growers’ document.
By now, productive young blocks of trees will have put on two thirds of their season’s annual growth and will likely require some support, training and essentially growth optimisation. Begin by ensuring all central leaders are straight to maximise the apical dominance and ensure the trees don’t have an excuse to terminate earlier than desired. This will require the use of either a good tree clip, a flexible rubber tree tie or in some cases the attachment to a ‘guide string’ with a MaxTape gun. This process of tree support goes hand in hand with ensuring the tree is carrying the appropriate crop load for the tree’s size, the system adopted and the climatic conditions. Wires should be in place for the attachment of future growth and leaders should remain free of fruit unless secured to the wire.
For early season varieties such as ‘Royal Gala’, summer pruning is often undertaken prior to Christmas to optimise light distribution in blocks where the inherent vigour is excessive, crop load is light or simply where the crop’s final outturn will benefit from the activity. Summer pruning (when required) plays a crucial role in allowing light to penetrate the canopy and assist in the development of next year’s buds whilst maximising colour development at the same time. In addition, the technique of summer pruning for the creation of short fruiting shoots and subsequent buds for next year is becoming widely used. This technique was explained in detail by Alberto Dorigoni during a Future Orchards event in June 2013 and his presentation is well worth revisiting on the APAL website for a refresher.
Hand thinning should be well and truly underway by now for early season varieties that have had their secondary shed and are now being groomed for optimal fruit distribution and size maximisation. For most varieties, it’s not too late to begin hand thinning and in some instances such as ‘Cripps Pink’ blocks it may well be too early for you to thin due to the lighter crop load and potential for large, unmarketable fruit. Whatever your scenario, hand thinning is a significant part of achieving an optimum crop load and needs to be seen as an integral part of setting up a high quality crop and maximising potential block profit. Furthermore, timely hand thinning is directly linked to return bloom as total seed number per tree is a key driver in biennial bearing. Things to consider when developing a hand thinning and crop loading strategy include available water to see the crop through to harvest and current level of vigour in the tree. Do you need to be mindful of carrying a larger crop and ‘pulling up the tree’ too much or is vigour out of control and will that influence where you place the remaining fruit to optimise the capture of light? What is the desired fruit size for your chosen market, how many days until harvest and will bunchy fruit expose you to pest and disease pressure? Be thorough and think about the flow-on effects of your hand thinning decisions.
Ordering planting material
It’s not too late and it’s never too late to start talking with your preferred nursery to assess your future requirements. This could include grafting material for re-working existing blocks or it may be ordering new rootstocks/varieties.
This is a discussion that should be ongoing to avoid surprises and ensure your next block is primed for take-off. There are some handy templates in the Future Orchards archived library on the APAL website that will help you provide, and commit to paper, a description/picture of what you desire, which you can then give to your nursery.
Vigour control/return bloom sprays
Early December is an ideal time to be introducing low rate applications of certain plant growth regulators into the system for return bloom benefit and mild vigour control. As is well documented, flower initiation is inhibited in the bourse shoot by gibberellins (GA) produced in the seeds and shoots and then transported down the stem and shoots. Studies have shown that NAA and Ethrel® applied in early summer can counteract the effect of seed – and shoot – produced GAs and stimulate more flower bud initiation. It is likely that a temporary reduction in shoot growth rate is the mechanism at play. There is some fantastic information around this topic in the Future Orchards library by Steve McArtney and also some applied trial results from these spray applications to counteract biennial bearing in the Adelaide Hills. Applying Ethrel in this situation will also assist with terminating annual shoot growth, thus providing some bonus vigour control in the process. This is a complicated topic and one which you should seek advice about before applying in your orchard.
Fertigation will be well underway on young trees and continuing into the new year, however supplementary fertigation to heavily cropped, mature blocks is equally important. It is vital to remember, big crops need feeding and many of our emerging varieties are inherently big feeders regardless of crop load. Monitor your leaf and soil nitrogen levels to ensure fruit quality and colour are maximised but revisit your phosphorus, potassium and calcium requirements and get a soil and leaf test done if needed, it’s not too late!
Throw over nets are a cost effective solution – but get them out now![/caption]
Overhead netting in hail prone areas (in whichever form) will be out by now no doubt, but if you are one of the many Australian orchardists who use a ‘throw over’ style net for bird control, sunburn protection and simply improved pack out, then make it a priority to get it out now. Too often these type of jobs are the last to be done and can have the biggest consequences. Furthermore, begin looking at your winter requirements if moving to a permanent set, I know it seems early, but risk mitigation needs to be a priority in your business.
By the time you read this, several regions will be rolling out reflective mulch under ‘Gala’ to optimise colour consistency and maturity throughout the canopy. It’s not too late to ensure your equipment is serviced and all the associated attachments are in stock and of working order. Be prepared.
Fruit sizing and monitoring
Finally, the Future Orchards favourite, the orchard steering wheel as I like to call it – fruit size monitoring. It should have begun by now but it’s not too late to start, particularly on mid-late season varieties. The data that can be gained between now and harvest is extremely valuable in maximising this season’s crop and laying a road map for next year’s crop. There are webinars on APAL’s website guiding you through the process and I strongly encourage you to watch them.