Yesterday I sprayed the vines with sulfur again following the heavy rains we had a few days earlier, hoping to get a layer of dust on again, to prevent mildew. I brought up the drop wires to hold the canes in place. Everything looks good, so far. The weather remains cool, so I don't expect mold to be much of a problem, but better safe than sorry.
[Update: Because of more rain, I had to spray the grapes for a fourth time this season on May 28.]