Planting, pruning, pest strategies for more profitable pears
Pear growers looking to boost profitability were given an insight into the best performing pear-planting systems, how new cultivars are shaping up, thinning and fertilising strategies and better ways of managing pests at the annual Pear Masterclass in Tatura on Tuesday.
A strong line up of Agriculture Victoria and interstate horticulture scientists, and consultants, delivered a packed agenda of research updates highlighting the opportunities to improve pear yields and profitability to around 50 industry attendees.
A strong theme was the benefits to be had from integrated pest and disease management (IPDM), alternatives to chemical thinning, and regenerative agriculture approaches to improving soil structure in reduced chemical usage, better soil health, consequent yield and ultimately profitability.
Profitable Pears
Ian Goodwin, lead researcher for Agriculture Victoria’s Profitable Pears presented an update on ongoing research into blush pears aimed at getting the best yield and fruit quality from new pear cultivars.
The project has looked at yields, light interception and red coverage of three new blush pear cultivars ANP-0131 pears (marketed as Ricó), ANP-0118 (marketed as Lanya®) and ANP-0534, planted on 2D Open Tatura, 3D traditional and 2D vertical systems, across three rootstocks BP1 of South African origin, Pyrus calleryana D6 and Quince A (QA).
Ian presented results showing:
- Yield decreased in Open Tatura systems with an increase in tree-spacing
- Yield across all three systems was highest on the QA rootstock and lowest on the BP1.
- Light interception decreased with an increase in tree spacing
- Light interception was highest on D6 rootstock and lowest on BP1.
- Red coverage was lowest on D6 and highest on BP1 (on 3D traditional and 2D vertical).
- Cumulative yield (3rd to 6th leaf after planting) was significantly higher on ANP-0131, regardless of rootstock.
- Quince rootstocks tended to have the highest yield
- BP1 tended to have the lowest yield.
Presentation: Profitable Pears -Maximising productivity and quality of new pear cultivars, by Ian Goodwin
Ian also presented research showing blush pear cultivars were ‘very responsive’ to exposure to sunlight, with shaded pears rapidly regaining colour and ending with the similar colour to control pears in all but end of season shading trials (a full report on this research is published in the forthcoming Australian Fruitgrower magazine out early September).
Next steps for the project will be to look at reducing biennial bearing through an evaluation of proximal sensing of crop load and fruit size in partnership with Green Atlas and investigating crop regulation; maximising fruit quality in green and bi-coloured pears through
- Determining response of fruit colour to radiation using LiDAR technology
- Exploring management systems to reduce sunburn risk
- Testing DA-meter and inflorescence technology to measure fruit maturity
- Evaluating dynamic controlled atmosphere (DCA) storage to reduce scald; and investigating the long-term effects of tree density, rootstocks and tree training on yield, colour expression, sun damage and packout.
Crop load and yield relationships
Fellow Profitable Pears researcher Lexie McClymont presented work by the project on relationships between light interception, crop load and yield, which would ultimately underpin the development of a crop load model to predict fruit weight and yield and help growers manage crops to match market specifications.
“Using crop load, we can target fruit weight and predict yield to maximise profitability,” she said.
“We are not just managing orchards for maximum yield; we are managing to meet specifications for fruit weight and to optimise packout.”
“Open Tatura trellis and D6 rootstocks gave a higher yield for fruit number,” she said. “But most of this could be explained by light interception.”
Data showing yield tapering off with increasing fruit numbers (due to decreasing fruit size) allowed for the prediction of fruit size and ultimately the identification of an ideal minimum crop load and maximum to achieve fruit size within specification.
Thinning options
Tasmanian Institute for Agriculture researcher Dr Sally Bound reviewed thinning programs for pears, highlighting the increased flexibility of non-chemical approaches.
She presented findings from several chemical thinning studies on ethephon, ammonium thiosulphate (ATS), potassium thiosulphate (KTS) and 6-benzyladenine (BA) on Winter Cole, Nashi and Packham pears which found:
- Full bloom application of ethephon on Winter Cole achieved the best result (opposed to 11 days after full bloom, or two treatments at FB and 11dAFB) with similar fruit number, but much higher mean fruit weight.
- Timing was critical in the application of ATS to Packham. If too early there is no thinning effect on late opening flowers, if too late the fruit was already set.
- increased thinning effect with higher concentrations and number of applications of ATS, the lower the crop load the higher the flesh firmness. Two applications were recommended at 20 per cent and 50 per cent full bloom (at 1 per cent)
- KTS had a slightly milder thinning effect than ATS.
- BA was a consistent post-bloom thinner.
- The best time for BA application in pears differed from apples and could be applied up to 40dAFB.
- BA helps with quality with both sugars and firmness increasing with BA concentration.
- Two applications of BA were no more effective than one, but return bloom the following year was better with two.
- Combining two applications of ATS was an effective thinning program with a good combination of reduced fruit numbers and high mean fruit weight. If further thinning is required BA can be added to the program.
Sally said while there were effective chemical options, they were dependant on conditions being right for the spray window.
“If you rely on one application, particularly if it is a post-bloom thinner and the weather is not conducive, you have lost your window,” she said.
Potential new tools included the recently-registered post-bloom thinner metamitron (marketed as Brevis®) and non-chemical crop load management by artificial bud or spur extinction (ABE/ASE).
Sally said manually removing buds to reduce bud density imitated the natural bud extinction process and allowed control over where and how much fruit set on the tree.
She said spur extinction (ASE) allowed a precise management of the crop load, consistent cropping (no biennial bearing), improved quality, simplified hand-thinning and, once implemented, was cheaper than chemical thinning programs.
“ASE is a paradigm shift, as chemical thinning was when it was first introduced,” Sally said. “My aim is to move away from chemicals altogether.”
Presentation: Chemical thinning programs, by Sally Bound
IPDM program and new website
Agriculture Victoria project officer Emily Crawford provided an overview of new apple and pear levy-funded industry IPDM program and associated website which includes a wealth of practical hands-on tools, case studies, videos and an ‘Ask the expert’ interactive area.
Emily said a series of workshops was planned and the updated IPDM manual would be available online in 2020.
Key features of the new program include the case studies and the expert panel.
“We are aiming to provide a community of practice,” she said. “We are hoping you can learn from the case studies, what is working and what is not.”
Emily said questions and photos could be uploaded to the Ask an Expert area by growers or advisors. Responses would be peer-reviewed.
The well-known Pests of Pome and Stone Fruit and their Predators and Parasitoids pocket guide is now available on the site as an e-book for download to smart phones for easy in-field access.
Facebook users can also keep up with new information added to the site via a Facebook group OzApplePearIPDM
Codling Moth
IK Caldwell horticultural agronomist Russell Fox reviewed options for managing Codling Moth.
He said that while new chemistry was effective, coverage and timing were critical for performance; the use of hand-applied MD ties was labour intensive and costly and if put out late, moths had already flown.
Russell shared data on pheromone mist dispensers, and said they offered a versatile and efficient method of mating disruption of Codling Moth that was as good as or better than hand-applied ties.
Russell also provided an update on the recently-concluded David Williams-led project assessing the effectiveness of the Mastrus ridens wasp as a biological control agent for codling moth and plans for a new project which would include further identification of pesticides impacting on Mastrus, development of pheromone traps for monitoring, introduction of suitable flowers species to orchards to help harbour populations and improved release methods.
The use of sterile insect technology, already being used for Queensland Fruit Fly (Qfly), will be tested for use in regional Codling Moth control in new joint project, led by Sally Bound, and delivered collectively by TIA, SARDI and Biosecurity Tasmania.
Monitoring, mites and CLIDs
Russell stressed the importance of monitoring to understand what is happening in the orchard.
“It is not how many traps you you, but where you put them in the orchard,” he said.
He pointed growers to the cumulative leaf infested days (CLIDs) method of assessing when to treat for mites.
For more information on this method, the efficacy of wetcit and trump oil in management of mites, and biological methods for control of long-tailed mealy bug, see Russell’s Pear IPM Masterclass presentation in the Future Orchards library or visit the new Apple and Pear IPDM website to see how to calculate CLIDs.
Soil health
Horticulture consultant Marcel Veens continued the theme of minimising chemical intervention, highlighting the multiple uses of organic material in not only providing nutrients, but improving soil structure and water holding capacity in addition to increasing the abundance of natural predators.
Organic matter could be improved in orchards by surface mulching, or establishing cover crops in winter and either spraying them off or mowing them in spring. Rows should be mowed alternately to leave cover for beneficial insects. “We need to work with nature, not against it,” he said. “Mowing every row is not a clever idea in the orchard.”
Marcel urged the use of leaf and soil sampling (at least every three years), to assess nutrient requirements.
He said the timing of nitrogen application was soil dependent and should be applied earlier to heavier soils and later to lighter soils to ensure availability to the tree.
He said pears required more potassium than apples and a 40t crop of pears would take about 200kg of potassium from the soil. For every 10t pears, an application of 50kg of potassium was advised.
“On pears we would like to see good initial growth, which means that we apply approximately 40kg pure Nitrogen to the tree line,” he advised.
It if stays dry, fertigation is always an option.
Marcel led a pruning demonstration in the Demonstration Orchard at the Horticulture Centre of Excellence and at Silvers Orchard.
Acknowledgements: Many thanks to all presenters and to the Bo and Maurice Silverstein for hosting the pruning demonstration.
Further information
Pear Masterclass presentations – all presentations are available in the Future Orchards library.
Apple and Pears IPDM website – The new Apple and Pear IPDM website is now live and contains a wealth of information on identifying and managing pests, including tools, case studies and the opportunity to ‘Ask an expert’.
Blush Pears research – check out the Agriculture Victoria blush pears research online
Artificial spur extinction – Precision crop load management without chemicals
Watch a video of Sally Bound demonstrating artificial spur extinction
