Finally, almost a week long meeting is done and I’m back in Winchester. Here’s a summary of what happened during last week.

6/15: night time temperature ~64F, RH 7-80% (DM)
6/16: night time temperature ~68F, RH 9-100% (DM)
6/17: night time temperature ~65F, RH 7-80% (DM), plus, rain events from 3:40 am followed by high RH until 3:40 pm (~12 hr), average temperature was about 67F, a total precipitation was 0.64 in: (Phomopsis, Powdery mildew, Downy mildew, Black rot events)
6/18: Rain events from 12:20 am followed by high RH until 6:40 am (~ 6 hr), average temperature was about 60F, a total precipitation was 0.22 in: (Phomopsis, Powdery mildew, Downy mildew, Black rot events)
6/19: night time temperature ~65F, RH 90% (DM)
6/17: night time temperature ~70F, RH 90% (DM), plus, rain events from 8:40 am followed by high RH until 11:40 pm (~3 hr), average temperature was about 73F, a total precipitation was 0.53 in: (Downy mildew infection event). There were several right rains during the night, but RH was too low to account for a major disease event.

Thus, we had a series of weather events which is suitable for downy mildew infection and spore development. If you are planning to apply fungicides next week, it is probably a good idea to include a material that has a good curative (kick-back) activity against downy mildew (Ridomil products, Phosphorus acid products). If you have seen black rots, it may be a good idea to include myclobutanyl (Rally) in your spray mix. Rally has a good curative activity against black rot.

Other thing I noticed in our vineyard is powdery mildew. It is not to the point of concern, but I start to see symptoms here and there. Do not forget to add a material for powdery mildew. Sulfur is a cheap broad spectrum material for powdery mildew.

As you are aware, 4 to 5 weeks after bloom is the critical time for black rot, downy mildew, and powdery mildew infection on berries. Please make sure to protect your bunches.

FYI: our Chardonnay is 100% BB size and Cabernet sauvignon is 50% BB size.