The effects of vineyard foliar sprays containing sulfur and nitrogen on wine flavour were studied by AWRI researchers over several seasons. The concentrations of two wine flavour compounds (3-SH, ‘grapefruit’ aroma, and 3-SHA, ‘passionfruit’ aroma) could be boosted through a simple vineyard spray of urea and sulfur, applied late in the growing season. Such sprays also contributed to increased YAN in fruit, supporting healthy fermentations.
This finding was identified, in conjunction with Wine Australia, as a practice change priority for the AWRI’s extension team. A range of practical resources have now been collated to support Australian grape and wine producers to trial and adopt this simple technique to increase wine flavour. Industry trials have also been supported through this practice change project, with case studies provided.
Practical advice and case studies
- A simple fact sheet on foliar spraying for growers interested in applying this technique.
- Case studies were developed with four growers who trialled this technique in vintage 2023. Wines were made from these vineyards (both control and treated) and were analysed for the key tropical thiols. The wines were also presented as part of a series of workshops held in the regions where the trials were conducted. The workshops enabled growers and winemakers to assess what the results looked like in the glass and to discuss the practicalities of the technique. Analytical and sensory differences were seen in the wines from all four vineyards.
- Two podcast episodes on foliar spraying are available – AWRI Senior Scientist Mark Solomon discussing the science behind the practice, and Martin Gransden from Tamburlaine Organic Wines talking about trialling foliar spraying in his vineyard.
- Wines from these trial are available for tasting. If you are interested, please email firstname.lastname@example.org and nominate the region’s wine you would like to try. The wines will be packaged and sent you, with feedback being sought via an electronic survey. Limited stock is available.
The following links provide information about the research that sits behind this practice change project:
- Summary of AWRI research project
- Enhancing tropical fruit flavour in Chardonnay and Shiraz through foliar nutrient sprays (AWRI report published in Wine & Viticulture Journal)
- Cheng et al. 2021. Using foliar nitrogen application during veraison to improve the flavor components of grape and wine (Review article published in J. Sci Food Agric.)
- Perez-Alvarez et al. 2017. Effect of two doses of urea foliar application on leaves and grape nitrogen composition during two vintages (Research article published in J. Sci. Food Agric.)
- AWRI webinar: Influencing tropical thiol concentration in white wine by combining foliar sprays – YouTube
- The science behind boosting tropical fruit flavours (Wine Australia news article)
For more information on foliar sprays, contact the AWRI helpdesk team on email@example.com or 08 8313 6600.
The AWRI’s foliar spraying practice change project is supported by Wine Australia, with levies from Australia’s grapegrowers and winemakers and matching funding from the Australian Government.