Look out for late season powdery mildew. Recent milder conditions and dewy mornings have increased the likelihood of Powdery Mildew infections reinvigorating and light incidents on leaves are being discovered. If you think there is more than a month to go until leaf fall and you are discovering active powdery in your canopies, consider a post-harvest sulphur application to reduce Cleisothecia (spore) numbers for next season.
Powdery is not a particularly mobile disease, especially early in the season, and only blows around once it has sporulated (later in the year). If you see it on your leaves at this time of year there is no doubt that you are going to have additional pressure next season and control will be much more difficult.
Late season powdery is an indication that it was not completely controlled earlier in the year and growers who find it late in the season are encouraged to work harder at controlling it earlier. If powdery sporulation can be reduced or even halted with early/mid-season control, the chances of having the disease next season are diminished.
Powdery Mildew fact sheet
(provided by GWRDC)