Yesterday I sent Jerry out to spray for the first time this season.
We spray to prevent Powdery Mildew and to a lesser extent, Grey Rot or Botrytis. The plants have not yet started to grow so this was a dormant spray.
Normally I don't do dormant spraying. There's no scientific evidence that it does anything, and there's not even a really good hypothesis on how it could work. Because both Powdery Mildew and Grey Rot need green growth to attach spores to there's no reason it should help to dormant spray. Still this year I decided to do it. There's a lot of 'field' evidence that it helps. Which is a way of saying people think it helps.
I have read a lot over the past year though that Stylet oil is more effective if you first do a dormant sulfur spraying, and that does seem to make sense.
I haven't used sulfur for a few years now. It is an organic, but the amount we have to spray and the discomfort it causes when spraying make me an anti-sulfur guy. The bad part about using sulfur to is that it requires not just a high dose, but a lot of spraying through the year. I was glad to get away from it, and this might be the only time we use it this year.
JMS Stylet oil on the other hand, I really like. It works by coating the plant with a micro layer of inert mineral oil. The oil prevent the spores from Powdery Mildew from attaching to the plant and growing. It uses a low dose and I don't have to spray as often as with sulfur.
Both are 'contact' sprays though. If it rains, you have to spray again because the treatment is on the surface of the plant, not inside it. Stylet oil is also an organic.
This year we will treat all our vineyards except Vista Verde with 100% organic treatments. Vista Verde is a new vineyard and I had really bad luck a few years ago trying to take a non organic vineyard to all organic in a single year. Now I phase out the systemic chemicals slowly over a year or two and phase in the organics. Vista Verde may complete the transition this year, I'll just have to watch and see how it goes.
Jerry finished Vista Verde and Arastradero then helped stack some firewood at home. Monday he'll do Crimson Clover, and Sesson, then Tuesday Chaine d'Or. The weather looks good for the next week and we may see bud break at home next week.