Reducing the impact of late season rainfall (CY12000)
This now-completed Tasmanian project has generated important results regarding cherry cracking that are directly applicable within current orchard management practises. The project shifts the thinking of cracking management from a reactive approach when rain is imminent to a holistic year-round approach, providing information with which to improve fruit integrity, and consequently fruit quality.
The broad aims of the project were to reduce crop damage, and the impact of late-season rainfall specifically, by preventing rapid and excess water uptake to fruit following rainfall events and building fruit resilience before a rainfall event.
A number of trials were undertaken, building on results of earlier project Improving marketable yield of premium quality cherries (CY09002). The results show building resilience in fruit early in the season helps reduce the impact of rainfall late in the season when fruit is most susceptible to cracking. However, no practical options to reduce the rapid uptake of rainfall late in the season were revealed – ground covers will slow uptake but are not suited to current systems, vascular tissue stays connected and functional throughout fruit maturation, and root pruning late in the season is not viable.
Methods shown for building early resilience included maintaining cuticular and skin integrity and strength, enhanced by a comprehensive calcium program to allow calcium uptake early in fruit development. Maintaining irrigation was key to reduce excessive diurnal shrinking and swelling of fruit during development, and to avoid trees being water stressed coming into a rainfall event. Managing crop load, and considering the growth rate of fruit early in fruit development, is also a recommendation of the project.
The work is to be presented as part of an upcoming user-friendly manual about cherry cracking.
Improving fruit quality and consistency in cherries through maximised nutrient availability (CY12002)
The aim of this project is to investigate whether soil microbiology to can be utilised to maximise the availability and uptake of plant nutrients, to in turn boost crop yields and fruit quality.
The Tasmanian project is progressing on target and is providing interesting information on annual changes under alternative and conventional nutrient management. A Derwent Valley site has now been established for four seasons and a Nicholls Rivulet site for three seasons. Although they have different soil types and cultivars, the two sites have shown similar trends to date, with a higher percentage of A-grade fruit and a reduction in cracking in fruit from the alternative treatments. All sampling and assessments have been completed for the 2015/16 season and data analysis is in progress.
The alternative treatments involve humates with combined minerals, and with ‘effective microbes’ (a mix of about 80 different species of co-existing beneficial microorganisms).
Optimal management of pre-harvest rot in sweet cherry (CY13001)
This project aims to improve knowledge of cherry-rot pathogens. Its final field season activities have now been completed, including assessments of latent infection and rot for orchards in Tasmania and New South Wales.
A weather-based infection risk tool has been developed and is being tested with new infection models derived from this project. The remaining six months of the project will focus on data analysis, reporting and communication. A fact sheet will also be created and distributed.
Evaluating the sugar floatation method testing cherries for Qfly (CY14009)
This now-complete project investigated whether the brown sugar flotation (BSF) procedure could be used for detecting the eggs and larvae of Queensland fruit fly (Qfly) and Mediterranean fruit fly (Medfly) in Australian cherries.
Sugar flotation procedures have been used for many years to separate insects from other substrates. With recent restrictions on chemicals that have been successfully used to manage fruit fly pests over many decades, and increasing demand for pest freedom from importing states and countries, BSF was seen as a potential quick and robust test for validating the risk of Qfly and Medfly infestation along the supply chain.
From the experiments, it was determined that the BSF procedure is an effective tool in detecting Qfly and Medfly insect in cherry fruit and should be incorporated, together with the existing sampling practice, as part of the system approach protocol for detecting fruit fly infestation in Australian cherry fruits.