Signalling a significant step forward in the phosphorous acid (PA) story, the Winemakers Federation of Australia (WFA) received confirmation that the Liquor Control Board of Ontario will continue to allow Australia the permission for phosphorous acid treated wine for another 12 months.
Until all of Australia’s major export markets have an MRL in place for PA, this chemical remains ‘not recommended for use on grapes destined for export wines’ as stated in the AWRI’s ‘Dog book’. Growers should consult their winery or grape purchaser for permission prior to use.
For winemakers, this current news means that Canada will accept the Australian MRL of 50 mg/kg for PA for the 2012 vintage. To ensure that this MRL is not exceeded, growers are advised to apply no more than three PA sprays during the season and where three sprays are applied, to cease spraying 30 days before harvest. This recommendation is based on findings from a recent GWRDC-funded study conducted by the AWRI. In this study, the AWRI sourced fruit from the 2011 vintage where PA was known to have been used.
For more information about the grape growing or winemaking implications of using PA, please contact Marcel Essling or Con Simos on 08 8313 6600.
Hot and sunny days have been missing this season and in regions that continue to experience mild, cloudy weather conditions, growers should be on the lookout for powdery mildew.
Symptoms are being observed in the Hunter Valley in blocks where every spray has included powdery mildew chemistry and adequate control would normally have been achieved. Liz Riley speculates that this could be due to the lack of hot weather and the reduced vapour activity of sulfur in the cooler temperatures.
Peter Magarey recommends careful monitoring inside canopies with both leaves and bunches closely inspected. Corrective action taken now is better than two weeks away because the disease will spread steadily if left uncontrolled. Coverage is critical in these conditions and growers should be using high water volumes and the appropriate chemical rate.
It’s well known that awful botrytis years largely come down to the weather, but there are things you can do during the year to influence how badly you are affected should conditions turn warm and wet in the lead up to harvest.
- Manage a canopy that’s open and promote air flow. This will help foliage to dry more quickly when the rain stops and it will be easier to get spray coverage where it’s needed.
- Minimise damage to bunches. This means managing light brown apple moth and diseases that affect berries earlier in the season.
- Manage your yield. It’s in crowded bunches and bunch zones that disease is often found. Bigger yields also take longer to ripen and when it comes to botrytis – a week can be a long time.
- Use the resources available. There is a lot of information out there from industry experts.
- Managing powdery mildew
- Powdery mildew questions and answers
- Botrytis fact sheet
- Botrytis questions and answers
- Botrytis technical notes
- Botrytis presentation
Industry Support over Christmas break
The AWRI will be closed over the Christmas / New year period from 23rd Dec until 3rd January, if you should require assistance over the holiday period please contact
For winemaking technical problem solving issues
Con Simos 0448889432 or firstname.lastname@example.org
For Viticulture and agrochemical related issues
Marcel Essling 0418816311 or email@example.com