I apologize for this overdue communication. Some grapes at the UVM Vineyard in South Burlington were starting bloom yesterday, and we are in peak disease management season. I’ll keep this brief:
- Pretty much every major disease is likely active now, including black rot, Phomopsis, powdery and downy mildew, and anthracnose. Vines should be protected with the best materials in your toolbox. For non-organic growers, that means mancozeb or captan plus a DMI (FRAC code 3, e.g., Rally, Vintage, Inspire super) or strobilurin (FRAC code 11, e.g., Flint, Sovran, etc) material. Rotate those FRAC codes and do not use materials with the same code more than twice in a row.
- For organic growers, this is the window to be using whatever copper material you choose.
- Keep fungicide coverage on at 7-14 day intervals, shorter as there is more rain.
- Keep an eye out for grape tumid gallmaker to be popping up. If these have been a problem in your vineyard, Movento or Assail are your best materials. I don’t know any organic option, so you’ll need to remove them by hand.
- Shoot thinning is still critical now, the sooner it’s done, the more resources you will leave for the remaining shoots. Shoots have not lignified enough to do any combing.
- If you suspect any nutrient deficiencies, this is a good time to collect petiole samples for analysis. I prefer the veraison timing, but bloom sampling allows for correction this season if somethings comes up particularly low. Details on petiole sampling can be found here.
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