We had fairly dry month so far and grasses are start to getting brown, but a thunderstorm dropped about 0.5 inch of rain last Friday around Winchester area. It stared little after 5:30 pm then continued for two hours or so. The relative humidity was high until next morning (10:30 am) with an average temperature of around 70F. This accounted for infection event for Phomopsis and Botrytis on berries and Downy mildew on leaf.
I listed Phomopsis here simply because it can infect berries at any time; however, often time infection around this time is not common. It is probably due to less inoculum (this fungus mainly creates the fruiting body in the spring), and it favors cooler climate. Thus, your risk depends on how chronically you have Phomopsis in your vineyards. If Phomopsis appears year after year, then your risk is higher. If you just see them only when we have a wet spring as we did this year, you probably have less risk.
As for downy mildew, I started to see foliar symptoms on my sprayed vines here and there. Probablty they have spread using dew periods. Since last week, there were many nights with high relative humidity which promote sporulation of downy mildew, and with a combinaiton of wind and a dew, they can infect some leaves. If day time weather is dry, it is not an issue, but as I mentioned in the last post, you need to protect your foliage to some extent to keep general health of vines. Thus, it is probably a good idea to scout around your vines, and apply curative application if necessary. (i.e., if you have many leaves with downy already, and received as much rain as we did, you probably need some action.) PHI for Ridomil Gold copper and Ridomil Gold MZ is 42 days and 66 days, respectively, and that for Prophyt is 0 day.
I listed Phomopsis here simply because it can infect berries at any time; however, often time infection around this time is not common. It is probably due to less inoculum (this fungus mainly creates the fruiting body in the spring), and it favors cooler climate. Thus, your risk depends on how chronically you have Phomopsis in your vineyards. If Phomopsis appears year after year, then your risk is higher. If you just see them only when we have a wet spring as we did this year, you probably have less risk.
As for downy mildew, I started to see foliar symptoms on my sprayed vines here and there. Probablty they have spread using dew periods. Since last week, there were many nights with high relative humidity which promote sporulation of downy mildew, and with a combinaiton of wind and a dew, they can infect some leaves. If day time weather is dry, it is not an issue, but as I mentioned in the last post, you need to protect your foliage to some extent to keep general health of vines. Thus, it is probably a good idea to scout around your vines, and apply curative application if necessary. (i.e., if you have many leaves with downy already, and received as much rain as we did, you probably need some action.) PHI for Ridomil Gold copper and Ridomil Gold MZ is 42 days and 66 days, respectively, and that for Prophyt is 0 day.
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