Rainy days

Thank you again for those of you who showed up at the vineyard meeting. As I mentioned in the previous post, information I presented can be downloaded from here too.

In Winchester, it rained again after the previous post. It started from 2:15pm and lasted until 19:55pm; however, relative humidity was near 100% until now (9:15 am, 4/30/2009), and there were almost no wind until 6:20am, thus, chances are that leaves did not have a chance to dry out. Average temperature was about 47F, and a total precipitation was about 0.24 inches. Temperature was little lower than the requirement for Phomopsis infection and powdery mildew ascospore discharge event. However, with combination of rain in the morning of 29th, it might be enough for powdery mildew ascospore discharge. Hopefully, this rain event was not good enough for Phomopsis and we do not need to worry about it (at least for now… local weather forecast does not look promising).

At the same time, I’m aware that Madison county area had more rain than we did. When I checked one of weather stations in that area, they had rain from 9:47am to 21:31pm (on and off, but almost continuously), a total precipitation from the rain event was 0.84 inches. Starting temperature was 56F and ended with 48F. Thus, in that area, it was probably a light infection event for Phomopsis, and it was enough for powdery mildew ascospore to be discharged.

The southern VA is 1-2 weeks ahead of us and they are probably thinking about pre-bloom application at this moment. I wish I can do this type of assessment for all the regions, and I’ll do my best to incorporate as much regions as possible in the near future. At the time being, please check your local weather forecast carefully and make your fungicide application decisions wisely.

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