Powdery Mildew Late Season - UPDATE 29/12/2009

Look out for these signs deep in the canopy. Powdery Mildew in bunches (above).

Some Powdery Mildew is beginning to show in vineyards not sprayed effectively earlier this season.

Powdery Mildew is called a dry weather disease because it does not need rain to spread. In fact, large rainfalls can wash the disease from leaves and berries. Organic growers use this principle by using mild anti-fungal agents applied with high water rates.

Powdery does however like warm (21-28OC), humid (RH<70 br="br" comes="comes" conditions="conditions" from="from" like="like" north.="north." that="that" the="the" those="those" tropical="tropical" weather="weather">
Monitor now for the disease. Pay close attention to areas like low-hanging shoots or freshly growing laterals. Take time to check inside your canopy to assess your program.

Any sprays now may help reduce the amount of disease on outer leaves but at this late stage, they will not help in reducing levels of powdery on the bunches.

Avoid spraying sulphur at high temperatures (>350C) when the humidity is >70% within 24 hours of spraying.

Before spraying crops designated for sparkling wine, check your winery’s withholding periods. White varieties for table wine are likely to begin harvest in mid February.


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