Yesterday’s storm brought more than 2-inches of rain, and resulted in approximately 12.5 hours of wetness with an average temperature of 69F. It was an infection event for downy mildew and Botrytis (and Phomopsis and black rot, but they are less important at this time of the season, unless you have on-going Phomopsis issue).
The other thing yesterday’s storm brought was hails. We saw a minor, but obvious damages from the hail. Often time you will see random holes on leaves, clacks on berries, and sometimes, necrotic scars on canes. Please see the pictures below.
The question is what will be the consequence of these wounds on berries. It depends on a few factors. If we have a nice hot day like today, these damaged berries more likely to be dried out; however, if we have another prolonged rain event, it can introduce Botrytis and other late season rots. It may also depends on how much sugar is available on these berries. The more sugar they contain, the higher the risk of rot pathogens to come in since some of them like high sugar environment. If you have a risk of rots, you can consider applying captan and/or one of Botrytis materials.
I have downy mildew affecting some of my vines. I have 100 vines first year(cabernetSav). I have not treated them at all. What should I do at this point.
I have a new vineyard(first year) 100 vines cabsav signs of Downey Mildew on some vines. What is the best action to take
Sorry, Ron for taking a while to respond. I am at a meeting this week. At this point, the best material for you will be a Phosphonate (aka Phosphorous acid) product.
You can purchase a small amount of a Phosphonate product, such as Monterey Agri-Fos, from home garden center