DWA Logo Lo ResWinter may be coming to a close but the East Coast has been hit with some challenges of ice and late-winter snows.  Have you ever wondered if harsh winter weather on the East Coast harms grapevines?  We asked our members to provide some insight on winter weather, grapevines and details on any protective measures they take for their vineyard.

Adrian Mobilia of Fenwick Wine Cellars in Selbyville, Delaware gave us his opinion:  “Grape vines, like most other perennials, adapt to the environment, so when a particular environment has extreme weather, the vines are at risk.  Most vines are able to tolerate some extreme weather, as long as they are healthy, for short periods of time.  Winter injury can occur if lots of moisture were present directly before a quick and deep freeze.  Given the time of year, the vines are dormant, and we would not expect much winter injury, if any thus far.

If vines are grafted, “hilling up” is a practice used to protect the graft union from the elements.  This is a practice where the grower uses a machine to move the topsoil on, and around the vine, to protect it from the cold weather. ”

Jason Hopwood, Vineyard Manager at Harvest Ridge Winery in Marydel, Delaware, “There are several factors that may influence a grapevine’s capacity to tolerate weather extremes.  Most vinifera cultivars are able to withstand temperatures down to -5F for short periods, while hybrid varieties tend to be hardier, withstanding temperatures dipping to -10F, and some even tolerating -20F to -30F.

Besides cultivar selection; vine health status prior to winter dormancy, periderm formation on canes/cordons, and whether vines are own-rooted or grown on alternative rootstock, are all factors that may affect the capability of a vine to maintain productivity after experiencing weather extremes.

Additionally, growers have options through the use of cultural practices, both prior to the onset of winter, as well as prior to bud break in the spring to help prevent a potential  decline in output.  Hilling up is a practice often used in cool climate areas, such as the Northeast after harvest has been completed.  This practice entails mounding soil around the trunk just above the graft union, which acts as an insulator against harsh winter temperatures.  The task is typically performed with the help of a specialized disc or plow implement mounted onto a tractor.   This practice is less common in the Mid-Atlantic, as minimum winter temperatures are typically within grapevine tolerances, and the practice entails additional labor costs.

One cultural practice that may have more broad utilization in our region is the maintenance of grapevine bud wood or canes during dormant pruning.  Buds may also be damaged due to extreme cold, potentially effecting vine productivity and yield.  It may be sound to leave additional canes or buds on the vine above and beyond the normal number typically left as to ensure that any potential damage might be negated.  Canes with the highest bud fertility may then be maintained, while canes exhibiting less than optimal growth are removed.  As with any agricultural product, human intervention may often only have limited effect in balancing the impact of climatic conditions, but at least growers have some viable options in attempts to maximize grapevine health and productivity.”

So there you have it!  With proper selection and maintenance, grapevines can be maintained throughout winter months with little to no harm. Grape yields can be maintained and we can be assured of enough grapes to continue making (and drinking) Delaware wines!

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