Phosphorous acid is a registered fungicide with post-infection capabilities, but residues in wine are to be expected if it is used at any time during the growing season. For this reason, some exporting wineries have no tolerance for fruit that has been treated with this active ingredient. The ‘Dog book’ recommendation states that phosphorous acid should not be applied to fruit destined for export wines. Growers should contact their winery or grape purchaser prior to any phosphorous acid application. See the AWRI’s agrochemicals resources for information on other fungicides.
The lists below separate Australia’s major export markets into those that have a tolerance for phosphorous acid residues and those that do not. In doing so, it highlights the potential for ‘batching’ grapes and wine according to market. This will not be an option for wine companies that export to markets that do not have any tolerance for phosphorous acid residues in wine. The AWRI’s agrochemical online search facility provides the latest information on MRLs in different markets.
EXPORT MARKET TOLERANCE TOWARDS PHOSPHOROUS ACID RESIDUES
Australia has a maximum residue limit (MRL) for phosphorous acid (phosphonate) in grapes of 200 mg/kg.
The export markets listed below accept residue levels equal to or greater than the Australian MRL. If grapes are being grown for the domestic market or for export to these three markets only, the only requirement regarding the use of phosphorous acid is that label directions are followed.
- European Union member states
- New Zealand*
- United States of America*
*In these countries, phosphorous acid is exempt from the requirement of an MRL
The export markets listed below accept residue levels greater than 50 mg/kg but less than 200 mg/kg. If exporting to these markets it is recommended that no more than three phosphorous acid sprays are applied and the last spray is applied no later than E-L 33, berries still hard and green.
Important note: Phosphorous acid labels are in the process of changing and the withholding period of DO NOT apply after E-L 33 is in the process of being implemented. Growers using a phosphorous acid product with an ‘old’ label can still follow the previous recommendation (no more than three phosphorous acid sprays and the last spray applied no later than 30 days before harvest).
- Great Britain
The export markets listed below have residue tolerances lower than 50 mg/kg. Trials indicate that residues of phosphorous acid are highly variable and a reliable recommended use for phosphorous acid cannot be made for these markets.
- Canada (21 mg/kg)
- China (7.5 mg/kg)
- Hong Kong (10 mg/kg)
- India (10 mg/kg)
- Korea (25 mg/kg)
- Liquor Control Board Ontario (temporary 21 mg/kg) **
- South Africa (25 mg/kg)
- Taiwan (20 mg/kg)
** The LCBO has temporarily matched the MRL for phosphorus acid to the Canadian MRL, subject to its further review.
As such, the LCBO will accept Australian wines produced from vintages leading up to and including the 2023 vintage, provided that:
- any phosphorous acid residues found in the finished, commercial wines imported by the LCBO are within the maximum residue level of 21 ppm expressed as phosphorous acid (or 30 ppm expressed as fosetyl-Al)
- prior to export, prospective Australian exporters test their wines (that have been produced from grapes that have had phosphorous acid applied) to ensure compliance with the relevant MRL
- exporters provide the LCBO with a copy of the relevant Certificate of Analysis, upon the LCBO’s request.
Exporters should note that the changes to the LCBO’s MRL for phosphorous acid is temporary only and is subject to its further review.
The export markets listed below have no or very low tolerance for any phosphorous acid residues and phosphorous acid should not be used for wine destined for these markets.
This information is correct as of January 2023.