Grape bud break

By Terence Bradshaw

Buds have been breaking in Vermont vineyards in the past week, which signifies the real start of the growing season. This brings up a few pest management considerations for your vineyards. Most cold-climate cultivars will not need disease protection until 5-8” of shoot growth, but any vineyards with heavy disease pressure last year may wish to begin as soon as shoots are 3” in length, especially if inoculum reduction through thorough removal of diseased wood and mummy berries and/or dormant application of lime sulfur was not performed. Since we all likely have a couple of weeks before we need to get out there, now is a good time to make sure that your equipment is ready to go. I still recommend Dr. Lorraine Berkett’s Initial IPM Strategy for Cold Climate Grapes as the best resource to boil the decisions down to a simple ‘prescription’, with the caveat that since it was written some new pest management materials have been released and inoculum may have increased in your vineyards which could lead to increased disease pressure. Growers should have an up-to-date copy of the New York and Pennsylvania Pest Management Guidelines for Grapes as a reference for specific materials, their efficacy, and use considerations. Remember however that the guidelines are written largely for vinifera and less disease-resistant hybrids, so the specific spray programs recommended may be overkill in Vermont vineyards.

The warm weather in the next few days may increase emergence of grape flea beetle or cutworms. Grapes are susceptible through about the one inch shoot growth stage, so this could be a short window and the vines may well outgrow any threat pretty quickly. A scouting of your vineyard for feeding on swelling buds or developing shoots may be warranted. If damage is evident on more than 2% of buds, an insecticide treatment may be warranted. But if shoots expand rapidly over the weekend, don’t worry about this pest.

Since buds at ground level have begun to emerge, applications of systemic herbicides should either be halted or very carefully controlled to prohibit contact with green tissue. Now is an appropriate time for cultivation in vineyards to manage weeds. It’s also a good time to keep water on newly planted or young vines. With soil warming and growth beginning, nitrogen fertilizer applications, if needed based on foliar analyses or observed low vigor last year, may also be made now.

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