We have been seeing leaf spots across many vineyards. Pictured above is an inactive spot. Most of this is still at a very low level but some discoveries have caused growers to increase the frequency of their protective sprays to limit any spread. More significant signs of spread are shown below.
Check for Powdery before Christmas. Look for mildew on at least 50 bunches per block. Select the bunches from inside the canopy and look closely for grey-white mildew growth on the berries. If there is any sign of powdery, apply sprays of a suitable registered fungicide at 10-day intervals in attempt to stop the disease increasing.
The good news is if you get to Christmas clean : your bunches will be clean at harvest. Only bunch stems and leaves can get infected after that point.