As you would expect…

We had a beautiful Saturday here in Winchester. Temperature high was above 90F and as you would expect, vines are pushing their buds. As of noon, Chardonnay was about 10-15% bud break and Cabernet sauvignon was still in bud swell, but buds became larger than previous few days. We’ll see what happens tomorrow.

We are expecting slight chance of rain on Wednesday and Thursday. It seems these are isolated thundershowers, thus, I’m not sure it will be enough duration and amount of rain to be concerned about Phomopsis infection. But as I mentioned in the notes, it takes only 4 hours under the optimal condidtions (temperature between 60-70F) for Phomopsis fungus to cause light level of infection. And this fungus starts to be active around this time of the year. If you had Phomopsis in previous years, this fungus can survive for several years and produce spores from infected older canes and trunks. Thus, even if you didn’t see Phomopsis problem last year, you may still need to be careful.

Observe growth of vines and weather forecast closely. If your vines are yet to be bud break, you do not need to be concerned. However, if your vines are growing to 1-3 inches, and in coming rain event(s) is expected to last for a while, you may need to consider a fungicide application prior the rain. Protective fungicide application of Mancozeb (Penncozeb, Dithane, etc), Captan, or Ziram have a good efficacy against Phomopsis.

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