Bud Break in Grapes

May 16, 2014

At the UVM Vineyard in South Burlington, VT, we are just coming into bud break. This gives us a good chance to make an initial assessment of bud damage from this past winter’s cold events. It’s still a but early to start a thorough shoot thinning, since a lot can happen and many shoots that break from secondary or tertiary buds may not be fruitful. But this is a good time to clean up your vines if you rough-pruned and left a generous bud count like we did. Extra canes that were kept for insurance in the event of cordon death can be removed if the cordon looks good, or laid down to form develop a new cordon if it doesn’t. Vines with trunk injury may still leaf out at this time, the damage is more apparent in a few weeks when the developing growth requires water and nutrients beyond those that were stored in vine tissues over the winter.

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This is a good time to remove what I call ‘nubs’, those little spur lengths beyond the last retained node that breaks bud. These dead wood pieces can harbor disease inoculum, especially Phomopsis, and do you no good in the vineyard.

Speaking of disease, it’s time to start thinking about your disease management program if you haven’t already. Growers should have fungicide coverage to protect against Phomopsis, Black Rot, and Downy Mildew by the 5-8″ shoot growth stage, which will be too far off. Get your sprayers calibrated, start ordering materials, and start to plan your season. My predecessor Dr. Lorraine Berkett’s  Initial IPM Strategy for Cold Climate Grapes is still a great first step, and the archived  Northern Grapes Project 2012 Webinar ” by Drs. Patty McManus and Wayne Wilcox is another great resource for helping you get up to speed.

Terence Bradshaw, UVM Tree Fruit and Viticulture Specialist

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The UVM Tree Fruit and Viticulture Program is supported by the University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM Grant, and USDA Risk Management Agency Funds.