Vermont Grape IPM: Immediate Prebloom disease management

Passing this on from Bethany again. -TB

Hi there again folks,

I’m writing in to you on the eve of the most important disease prevention period of our grape systems! Over the past two weeks we have had several Phomopsis and black rot infection events according to our NEWA models. As we enter pre-bloom it is essential that we are using our most powerful disease prevention and suppression tools against black rot, Phomopsis, and maybe even powdery mildew in vineyards where this is a particular concern.

Part of why there have been so many infection events is because we are experiencing so much rain. Both Phomopsis and black rot infections are spread by rain splash and are encouraged by humid and warm temperatures over 60 degrees. While we can’t do much about the weather, other management strategies will include:

Cultural methods (EXTREEMELY important for organic growers)

  • Making sure you’ve thinned shoots! By removing excess plant material you not only better balance the vine, but also allow for better spray penetration and airflow both now and into the summer months.
  • Remove any woody material that has not flushed out by now. This material will act as a disease reservoir if not removed promptly. It is worth taking a walk through the vineyard to find what you may have missed

Chemical Methods

  • Check available NEWA models to track possible infection periods. The model uses climatic data such as rainfall, temperature, and hours of leaf wetness to predict infection events. Be sure to enter the shoot stage and use the closest station to you for the most accurate predictions. Contact Terry if you are interested in hosting a station!
  • Because pre- and post- bloom is THE MOST IMPORTANT infection window for diseases such as black rot and powdery mildew we should all be applying our best and most reliable materials. Recs from Terry: “Every vineyard should be covered with the full suite of disease management products this week. That means mancozeb or captan plus a DMI, SDHI, or strobilurin (group 3, 7, or 11, respectively) material for non-organic vineyards; and sulfur plus copper (watch for incompatibilities on certain varieties, page 9 here) on organic vineyards. This would also be a good time to add biologicals, since we’re at ‘all hands on deck’ right now. Some materials, like Lifegard and Howler, are systemic acquired resistance promoters and need to go on a few days prior to infection. Others, like Serenade and Double Nickel, are biological extracts but can be mixed with other materials. Either way, these applications should be made a before infection, so spraying in the next day or two is a good idea.”

That’s all for now- I myself have to prep for a spray tomorrow. I will be in touch soon to introduce our good friend Downy Mildew and talk about weed and canopy management!

Signing off,

Bethany Pelletier & UVM Fruit Lab

__

Terence Bradshaw (he/him)
Associate Professor, Specialty Crops

Chair, Dept of Agriculture, Landscape, and Environment
(formerly Plant and Soil Science)
College of Agriculture and Life Sciences

University of Vermont
117/210 – Jeffords Hall | 63 Carrigan Dr
Burlington, VT 05405

(802) 922-2591 | tbradsha
https://go.uvm.edu/pssbradshaw

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