Thank you very much for attending the vineyard meeting at Doukenie last night. If you could not make it, you can download my note from here. As I mentioned several times in here and in this note, time period between bloom to 4-5 weeks after is the critical time to protect berries from downy mildew, powdery mildew, and black rot for most of wine grapes (V. vinifera varieties). Please scout your vineyards and make an adjustment to your spray schedule, if needed. There are some chance of rain tomorrow and on Sunday.

The average relative humidity was low (~50%) and average temperature was around 71F last night. Now we have five nights without favorable conditions for downy mildew spore production; however, we had so many nights with favorable conditions for spore production during early June, so, keep that in your mind.

Also, in our untreated vines, I start to see more and more powdery mildew. Rain events in last month or so probably provided enough opportunities for powdery mildew fungus to spread spores (ascospores) from its overwintering structure (cleistothecia). Thus, as temperature goes up, we probably see more powdery mildew development. As you know, we have several choices of fungicides for powdery mildew, so, you do not need to panic, but I just want to remind you that it’s coming.

Here are some pictures from our vineyard.

Up close and personal…
(You can almost see spores!)Powdery mildew prefers a location with diffused sunlight.
Such as the shaded leaf on the center of the picture.
Do you see powdery mildew?
I do. 😉