Maximum Residue Limits
By Dave Antrobus, Solutions Development Lead
As the Australian wine industry operates in both the domestic and global markets, it’s important to take into account Maximum Residue Limits (MRL’s), especially as grape harvest draws closer. countries we export wine to can have different food safety standards to us whereby they may have different, lower, or no MRL’s for the crop protection products we use in Australia. Unplanned or accidental use of the wrong product close to harvest can have costly consequences.
A list of MRL’s established for our domestic and export wine grape markets can be found at the Australian Wine Research Institute (AWRI) website at: http://www.awri.com.au/industry_support/viticulture/agrochemicals/mrls/
To assist with managing the risk of exceeding the MRL of one of our export countries, the AWRI publishes a list of agrochemicals registered for use in Australian viticulture (otherwise known as the Dog Book).
The Dog Book lists active constituents registered for use on wine grapes and includes tables of recommended products for each active ingredient. An AWRI Dog Book app for smart phone or tablets is also available.
As an example, the Australian SWITCH® Fungicide label, in the critical comments section, states application can be made at 5% capfall, 80% capfall and pre-bunch closure or veraison. These withholding periods are acceptable if the fruit is destined to remain in the domestic wine market
The withholding period for SWITCH in the Dog Book states a much longer period i.e. Use no later than E-L 29, berries peppercorn size (4 mm diameter). Do not use within 60 days of harvest. This is the recommendation growers should follow for any fruit destined for export wine.
The longer withholding period in the Dog Book is designed to minimise the risk of residue remaining on the fruit by allowing more time for the chemical to degrade through normal biological and environmental processes.
A late application to grapes destined for the export market is likely to be detected during testing where they can measure down to parts per billion – so it is best to adhere to the recommended application timings.
I recommend that you continuously consult the Dog Book recommendations as they are updated yearly and they contain the latest AVCARE resistance management strategies.