28 September 2026
‘Resting’ any blocks this season by removing yield and reducing water, nutrition and spray inputs?
Find out how, when and where you can apply ethephon for best results and permit compliance.
This ebulletin adds to previous information relating to vineyard resting (AWRI eBulletin 7 October 2025) and includes information relating to water quality, agrochemical compatibility and government rebates available for South Australian businesses.
What is ethephon and how does it work?
Ethephon is a plant growth regulator. It can be sprayed on to grapevines in spring to significantly reduce grape yield by causing undeveloped berries to detach from the rachis.
Application details
Ethephon for bunch removal must be applied in strict accordance with APVMA Permit PER94008 which allows use in all Australian states and territories. The following sections summarise the requirements and expectations from use −
WHEN TO APPLY
- Apply ethephon between E-L 25 (80% capfall) and E-L 27 (fruit set: young berries enlarging (>2 mm diameter), bunch at right angles to stem).
- Results of research trials completed by the South Australian Research and Development Institute (SARDI) on one block of Shiraz in the Riverland across the 2023 and 2025 vintages indicated that the most effective fruit removal resulted from ethephon application at E-L 27.
HOW MANY APPLICATIONS
- Apply 1 or 2 applications of ethephon between E-L 25 and E-L 27, at least 7 days apart. In most circumstances, one application is sufficient.
WHAT PART OF THE CANOPY TO TREAT
- Apply ethephon to the entire canopy unless there is a defined bunch zone where spray application can be targeted to saturate the bunches.
IMPORTANCE OF WATER QUALITY
- Ethephon is naturally acidic and decomposes more rapidly as the pH of the final spray solution increases. DO NOT mix ethephon with alkaline water as it can reduce its efficacy. Follow the product label’s water quality requirements and seek advice from your ethephon supplier before adding an acidifier.
CAN ETHEPHON BE TANK-MIXED WITH OTHER PRODUCTS?
- Check with the manufacturer before mixing ethephon with fungicides or fertilisers. While a jar test can help identify physical mixing problems, it does not confirm vine safety or effectiveness. For example, acidic spray mixtures less than pH 6.5 can increase the risk of vine damage by copper fungicides. Therefore, tank-mixing ethephon with copper fungicides is risky.
WHAT LABEL RATE SHOULD BE APPLIED?
- 32-104 mL/100 L for 900 g/L ethephon products
- 40-130 mL/100 L for 720 g/L ethephon products
- 63-190 mL/100 L for 480 g/L ethephon products
WHAT WATER RATE SHOULD BE USED?
- Apply ethephon at a dilute spray rate to the point of run-off with a non-ionic wetting agent at label rate.
WHAT WEATHER CONDITIONS SHOULD BE AVOIDED?
- DO NOT apply unless the wind speed is between 3 and 20 kilometres per hour during the time of application, to minimise spray drift.
- DO NOT apply if heavy rains or storms are forecast within 3 days.
EQUIPMENT USE
- Apply ethephon using an air-blast sprayer.
- Thoroughly clean spray unit after applying ethephon to ensure all residue is removed.
- Ethephon is corrosive to acrylic plastics, certain paints and metals. Flush and rinse all exposed equipment with detergent and water after use.
GRAZING RESTRICTIONS
- DO NOT graze any treated plants or cut for stock food.
IS THERE A CARRYOVER EFFECT OF ETHEPHON?
- Research trials completed by SARDI on one block of Shiraz in the Riverland, South Australia, indicated minimal carryover effects on yield in the year after one or two ethephon applications were applied.
Government Support
- The South Australian Government is currently offering commercial wine grape growers in the state, a Vineyard Resting Rebate to reimburse eligible growers $40 (GST exclusive) per hectare for the cost of ethephon that is purchased between 1 July 2026 to 31 January 2027 to rest up to 1,000 hectares of vineyard per ABN.
- Refer here for the Vineyard Resting Rebate Guidelines, and here for eligibility criteria and how to apply.
More information
- APVMA Permit PER94008 is in force from 21 July 2025 to 31 July 2030
- SARDI Fact sheet: ‘Resting Vineyards using Ethephon: A Cost-Saving Strategy when Grapes are in Oversupply’
- AWRI Webinar delivered by Paul Petrie (SARDI): Vineyard Resting – Webinar
- AWRI helpdesk – call 08 8313 6600, or email helpdesk@awri.com.au
This eBulletin is funded by Wine Australia with levies from Australia’s grapegrowers and winemakers and matching funds from the Australian Government. AWRI is a member of the Wine Innovation Cluster in Adelaide, SA.
