Thursday, January 9, 2014

Ohio Winegrowers Worry As Frigid Weather Threatens Vines

We just received this news release from the Ohio Wine Producers Association about the impact of the “arctic blast” on Ohio grape growers.

While the entire state is reeling from this Arctic blast, winegrowers across Ohio are literally praying for their 2014 crop and that their very vines survive these next couple of days.
Grapes are generally considered 'tender' crops and are especially sensitive to low winter temperatures.  Based on a release from Dave Scurlock of the Ohio Agricultural Research and Development Center the key factor in all of this is the actual low temperatures recorded. Although strong winds can desiccate the buds as well as vine structures and cause some damage, the real fear comes from the sub-zero thermometer recordings.
Fierce winds in relation to cold temps do damage by drying out cell structures to exasperate damage.  Dave notes that wind chill, as we traditionally think of it, is much more critical to warm blooded animals than plants. We have not seen these lows for many years and they will especially test the “classic” vinifera grapes varieties.
Hopefully, it will not be bad as 1994 when the Wooster station recorded a -28 degrees actual temperature in their demonstration vineyards.   If temperatures drop much below -10 or 15 degrees, we'll see significant 2014 damage among the Cabernets, Chardonnays, Pinot Noirs and Pinot Gris. Up to 90% of the buds can be destroyed below those readings. Rieslings and French hybrids are less sensitive, but they too will likely see damage in the 50% range.
A greater fear is that if the frigid temperatures remain -- or return again in the winter for an extended time.  Then actual vine damage [or even death] will occur.  In January of 1994, when temperatures remained significantly below zero for fourteen days, many vineyards faced major replanting schedules....along the the loss of three or more years of production until the new vines were ready to harvest. In the 20 years since that long stretch of bitter cold, Ohio growers have learned a lot.
They have become more selective about the sites where their most tender varieties were planted, have added every-row tiling to drain excessive water which was identified as a culprit during those two frozen weeks, and added wind machines which, on a still night can mix the layers of air and raise vineyard floor temperatures several degrees. But that’s not much help with 30 mile-per-hour winds during the night, however.
Dave's alert to the growers included suggestions to delay any additional pruning for a while, to leave as many buds as possible, to wait until the coldest snap passes and do random bud cuts to check for dead tissue and then assess their pruning plans.
In the meantime, growers will be biting fingernails and quietly petitioning the weather 'gods' for a quick return to more normal conditions.

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