Protected Cropping in Cherry Orchards – 2022-2023 Growing Season (Year 1)
Disclaimer: The outcomes presented relate to the first year of our trial which are based on a limited sample size. We strongly recommend seeking guidance from a qualified industry expert before installing any protective covers.
Protective rain covers provide a way for growers to protect their crop against unfavourable climatic conditions. However, questions remain in terms of the impact of the covers on microclimate, such as temperature, humidity and wind, in cherry orchards in NSW. It is also unclear how the covers might affect the quality and yield of cherries.
To answer these questions and inform growers of decisions on adopting covers, NSW Department of Primary Industries are working with local NSW growers to better understand the use of protective rain covers in cherry orchards. The NSW DPI’s Digital Agriculture team ran a two-month trial using rain covers in two blocks of Lapins and Sweet Georgia in a commercial cherry orchard at Nashdale (near Orange NSW) over summer in 2022-23. Conducting field trials allows meaningful data that is relevant to growers operating in NSW. Using a suite of digital technology, we monitored temperature, relative humidity and wind speed in areas with and without the cover.
Preliminary trial results on microclimate variables
The data captured over the two months prior to harvest showed that, in both blocks:
- The average daily maximum and minimum temperatures under cover were higher than those without cover.
- The average daily maximum humidity under cover was lower than without cover whereas the minimum humidity under cover was higher than without cover.
- The wind speed was lower under cover than without cover.
Note that field trials are influenced by seasonal conditions and so the data should be interpreted with the weather conditions of the season. During this pilot trial, the weather was cooler and wetter than general seasons. Specifically, growers in Orange experienced above average rainfall during November (232.2 mm) and below average temperatures in November up until the end of December. These conditions likely resulted in a delayed harvest for each variety up to 3-4 weeks.
Climate Variable | October | November | December | |||
Historical | 2022 (Nashdale AWS) | Historical | 2022 (Nashdale AWS) | Historical | 2022 (Nashdale AWS) | |
Average minimum temperature | 6.7oC | 9.2°C | 9.2oC | 8°C | 11.3oC | 9.6°C |
Average maximum temperature | 18.0oC | 15.8°C | 21.3oC | 16.2°C | 24.6oC | 20.6°C |
Average rainfall | 79.2 mm | 158.3 (total) | 81.7 mm | 180.2mm (total) | 79.0 mm | 42.3mm (total) |
Further investigation is needed to understand the impact of protective covers on microclimate in orchards under different seasonal conditions.
Cherry Quality
As a result of the covers being used during the growth and harvest period, initial harvest results indicate that the quality of the cherry was increased under the covers, with larger, firmer cherries being picked under the nets than outside the nets. A larger volume of cherries were picked under the covers, as less were culled.
A higher percentage (69%) of fruit graded in the covered lapin blocks was determined to be Class 1 packout (premium, often export quality), whilst only 49% of fruit in the uncovered block was graded at Class 1. A higher percentage (27%) of fruit in the uncovered lapin box went to juice (quality not good enough for fresh market consumption), compared to 17% in the covered lapin block. Fruit was larger and firmer in both covered blocks, compared to the uncovered blocks (Figure 2 and 3).
Cherry Splitting
Each block was sampled (100 pieces each block) for splitting incidence. There was no splitting found in either of the covered blocks, whilst splitting was observed in every rep in the uncovered blocks (Figure 4).
Pest and disease
A higher incidence of cherry slug was observed in the uncovered blocks compared to the covered blocks. Covered cherries also had a higher incidence of shot hole in early in the season, potentially due to the higher humidity causing more favourable conditions.
It is important to note that this trial was at one orchard for one season, but it does make clear that running longer and more geographically diverse trials of covers (both rain and shade) and their impacts on mitigating important climate variables such as wind speed and maximum temperature in cherry growing areas will be of value to the industry. Further research is also needed to investigate the modified farming practices that will need to operate in conjunction with the covers to optimise their performance.
Being able to make an informed decision, based on data and local research will increase the adoption of protective covers in the NSW cherry industry. Further work into the economic viability to combine with the results of our trial will make this more effective. We hope to continue this trial, with the addition of new locations and types of net to create more datasets for industry to use to make more decisions.
The focus of season 2023-24
NSW DPI are committed to providing reliable and relevant information and decision support tools for NSW cherry growers to make informed decisions about protective covers for their orchards. During an in-orchard discussion, we discussed with local growers what they would like to see investigated in subsequent years of the trial. Questions the growers noted about using covers included its impacts on irrigation requirements and on pest and disease. These questions are being addressed by the trial in the growing season 2023-24. Additionally, while continuing with the trial of plastic cover, we are trailing another cover option of netting and will collect data to:
- Provide an economic analysis tool for growers to compare and the benefit: cost of different cover options.
- Explore how the future climate might impact the feasibility of these adaptation options.
As we start to understand the impacts of climate change more, research into adaptation practices to improve growing conditions in certain scenarios can be explored.