One chapter closes, another opens in citrus postharvest research

One chapter closes, another opens in citrus postharvest research

26 June 2020

By John Golding, Research Horticulturist, NSW DPI 

Postharvest is the crucial link between the orchard and the consumer. To consistently and efficiently deliver high quality, safe and nutritious fruit to domestic and export markets there are many significant challenges for postharvest to overcome.

The recently completed Hort Innovation ‘Citrus Postharvest Science Program’ (CT15010) addressed these major challenges by focussing on two key components; (1) postharvest decay control, (2) managing fruit quality through the supply chain and postharvest treatments to reduce MRLs.

The aim of the research-based program was controlling postharvest decay and maintaining fruit quality through the supply chain where MRLs are not a barrier to market access.

Managing Postharvest Decay. The results of the Project showed there are significant opportunities for the effective use of new postharvest fungicides and new alternative methods for the control of postharvest decay (green and blue mould).

New fungicide chemistries and new formulations were assessed and showed significant potential for the control postharvest decay (see articles in Australian Citrus News Spring 2017, Winter 2019, Summer 2019/20). The results also showed there may be opportunities for the postharvest control of anthracnose, which can contribute to significant out-turn problems in wetter growing regions, such as Queensland.

The results of two seasons of packinghouse surveys of postharvest fungicide technical resistance showed there could be significant issues with poor postharvest sanitation and the development of technical resistance to common postharvest fungicides.

Extension articles in Australian Citrus News (Summer 2017/18, Summer 2018/19) and presentations at the Technical Forum in Adelaide and numerous regional forums / meetings were given to highlight this issue and provide recommendations for effective management.

Improving Fruit Quality. While decay is the primary cause of postharvest losses, it can be successfully managed with good postharvest practices and fungicides.

However, there are a range of other fruit quality issues which impact the ability to successfully market fruit into both domestic and export markets. These include; (1) chilling injury, (2) development of off-flavours, (3) and adoption of new technologies to improve fruit quality management during storage.

These issues were addressed with a series of postharvest storage trials. Results showed that reduced chilling injury could be achieved through greater understanding of relevant preharvest factors and the application of postharvest treatments (Australian Citrus News, Winter 2019 ).

These insights need more research to assess their efficacies over different growing seasons. A review of the potential postharvest quality effects of low dose irradiation as a market access treatment for export was also conducted. It showed low dose irradiation has a place in the market access toolbox, where high value export markets allow this treatment.

Improving Postharvest Outcomes. A range of extension materials were developed and extended to industry through regular contributions to industry newsletters (such as Australian Citrus News), citrus postharvest web pages, and with regular presentations and workshops in all major growing regions around Australia.

The ‘Packer Newsletter’ was continued through this Project is now hosted by Citrus Australia here. The newsletter provides industry with updates of research outcomes from the Program with practical and up-to-date postharvest information for Australian growers and packers.

The ‘Packer Newsletter’ was written and successfully run by Peter Taverner (SARDI) for many years and is now searchable and contains a wealth of valuable postharvest information. More articles from this Project will be appearing in the coming editions of Australian Citrus News.

Where to next for improving citrus fruit quality?

A new citrus postharvest project is being funded by Hort Innovation to continue meeting the needs of the industry around fruit quality management. NSW Department of Primary Industries is co-investing in this work and is leading the new Hort Innovation project – ‘Citrus Postharvest Program’ (CT19003).

This Program will build on the success of the previous project through the development and extension of a new ‘Postharvest Best Practice Manual’ and increased research focus in to postharvest decay control and fruit quality.

For more information on the outcomes of the previous project and new project R&D, please contact John Golding. NSW Department of Primary Industries. Email: john.golding@dpi.nsw.gov.au, or phone (02) 4348 1926.

This is a contribution from the ‘Citrus Postharvest Science Program’ (CT15010) and ‘Citrus Postharvest Program’ (CT19003) and funded by Horticulture Innovation and NSW Department of Primary Industries. Levies from Australian citrus growers are managed by Horticulture Innovation and contributed to funding this project. The Australian Government provides matched funding for all Horticulture Innovation’s research and development activities.