What was it all about?
High quality almond production is sensitive to weather and climate risks including insufficient chill units, heat waves, drought and untimely rainfall. This project, which ran from 2015 to 2019, sought to identify and rank risks to almond production that can be expected due to climate change as well as adaptations that can be put in place.
The team undertook orchard trials and pot trials to investigate the effects of climate on almond production and also researched current climates in almond production areas as well as future climate predictions.
The project generated an enormous amount of data, including the following key findings…
- Climate analysis of the three main growing regions (Riverland, Sunraysia and Riverina) showed a trend of increasingly warm conditions in all locations, with the Riverina being the warmest but also having the highest summer rainfall. Generally warmer conditions are likely to favour growth but also pests.
- Risks associated with climate change were considered in some detail, and then ranked according to the amount of damage and likelihood. Rain at harvest was considered the most economically damaging risk, followed by heatwaves, non‐synchronous flowering, and rain and humidity leading to disease. The supply of irrigation water was ranked as a moderate risk by the industry as a whole but ranked as a major risk in the Riverland and Sunraysia.
- The researchers note that some climate change predictions such as increased temperature are more certain than others such as changes in rainfall, so these risks will need to be recalculated in time.
- Management options were collated for each risk, including current practices in Australia or overseas that are used to avoid or reduce the impacts of the risk; practices that are currently being trialled and others that need research.
- Comparison of Australian sites with almond growing regions in California showed that even in the coming decades of warming, Australian sites will be cooler than the current conditions in southern California. However, the researchers noted that while comparisons with California are useful in understanding likely future adaptions, California is different from Australian growing regions in that it has a Mediterranean climate which means lower risk of rain at harvest.
- Field trials were carried out to examine the impact of climate and weather on almond tree physiology. The team made use of sites with different climates to simulate the effects of changing climate on crop development and yield. To make sure they could compare development effectively, they developed a photo-standard and assessment protocol to maximise consistency of measurement at the various sites —a world first—that almond growers can use to assess crops.
- Data from field trials allowed the development of an interactive crop calendar that predicts key crop development (phenological) growth stages and associated weather and climate risks. This Australian almond phenology model incorporates predictions of time of flowering, time of fruit maturity and hull‐split and time of harvest. Growers can use it to plan orchard activities in the current year, to assess climate and weather risks in new production areas, or to assess the likely impact of a warmer and more water constrained future on current orchards.
Grower recommendations
- With a gradual rise in mean temperature, and the number and severity of heatwaves very likely to increase, growers can explore the suitability of management options used in other crops such as overhead/within canopy evaporative cooling, altered canopy management for shading, as well as netting or reflective sprays to reduce sunlight. Higher density orchards could also assist, since they were found in this study to have fewer extreme hot days, which can reduce bud development.
- With rain at harvest being the top-rated risk to future production, growers can explore using mechanised shake and catch methods of harvest that would avoid soil moisture. Improved drying practices of nuts and kernels should also be explored. These might include tarpaulin covers and powered driers.
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