Grapevine Health Post-Polar Vortex

After the exceedingly cold temperatures much of the U.S. endured in 2014, there was concern about how grapevines in the Northeast and Midwest might fare this year, if they were able to recover at all. The good news is that many of them did recover, and experts are cautiously optimistic about 2015 and beyond.

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New York
“Overall, we saw less damage to trunks than we thought we would based on the temperatures that we reached,” Hans Walter Peterson, Cornell University viticulture extension specialist, says. “However, it is entirely possible that we will see more trunks failing over the next year or two. This is not uncommon to see after a very cold winter.”

Peterson adds that some locations in New York were hit harder than others, causing serious trunk injury that will require vines to be replanted. The more cold-sensitive varieties, such as Merlot, Gewurztraminer, Pinot Gris, and Sauvignon Blanc, suffered more than the hardier Riesling and Chardonnay, but there were still some pockets where even the hardier varieties were seriously injured.

For the most part, though, smart planning by growers allowed for close-to-normal crops in New York.

“Once growers knew the extent of bud damage, most ended up leaving more buds than usual to compensate for that injury,” Peterson says.

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To continue on the path to recovery, Peterson says growers are trying to train up new trunks to replace older ones that might have suffered damage.

“Carrying a full crop of grapes and supporting a fully functional canopy during the growing season puts a lot of demand on the vine’s roots and trunk to supply water and nutrients to them,” he says. “If the trunk is damaged during the winter, that stress can become too much for the trunk to handle, and the vascular system supporting the shoots and fruit above that trunk can collapse. Training up new trunks will allow growers to reduce that risk.”

Peterson anticipates that this year’s crop will be relatively normal, but of course, there’s no guarantee.

“There’s still a lot that can happen between now and harvest,” he says.

Michigan
Much like New York, Michigan’s vine damage varied depending on variety and location, with Gewurztraminer being especially hard hit.

“The vinifera vines, although they had such a horrible year in 2014, had really good growth following that,” says Duke Elsner, Michigan State University small fruit educator. “We let them have a lot of leaf area, we let them have all their shoots, so it’s an ugly thing, but we got lots of good canes out of it. It will be a challenge to prune, but I think we should be in good shape for 2015.”

Elsner says there were only a few sites where some varieties were actually killed down to below the graft unions. In some of those areas, there wasn’t enough snow cover to protect the lower parts of the vines. But for the most part, he expects the Northwest part of the Lower Peninsula to fare well.

“February is usually our bad month, so once we get through this one, we should be all right,” he says.

“I think we came though this remarkably well considering what last year’s temperatures were like,” he continues. “We should be able to hang a very good crop in 2015 — it’s just going to be a little bit harder during pruning times to straighten things out from last time around.”

Ohio
Vines in Ohio seemed to suffer the most damage. Imed Dami, associate professor and extension viticulturist at the Ohio Agricultural Research and Development Center in Wooster, OH, says the overall 2014 crop was half of normal years.

Vitis vinifera type varieties sustained nearly complete crop loss, and worse — vine death estimated at 20% to 30%,” he says.

Hardier varieties, including hybrids and juice grapes, fared only slightly better, with crop loss ranging between 30% and 70%.

To try and compensate for bud damage, growers adjusted their pruning on vines that could be salvaged. For the harder-hit varieties, growers had to remove dead trunks and renew them by training new shoots or, in some cases, remove whole vines and replace them with new ones.

“It was a very tough year — probably the worst ever in terms of economic losses,” says Dami. “Vinifera grapes are expensive to grow, and their products have a high value-added [potential], thus are profitable. However, for winery-vineyard owners, the loss is not for this year only but the next four, since replanted vines will take four years to produce a full crop again.”

A study conducted in New York a few years ago found that the estimated cost to replace just one vinifera vine was $155.

Dami anticipates, even barring any severe weather incidents in the next few weeks, this year’s crop will still be below average. But he’s optimistic.

“Despite a tough year, our growers rebounded well, either by ensuring adequate recovery of injured vines or replanting again,” he says. “Seasoned growers understand that the risk of freeze damage is part of farming grapes in Ohio, and a crop loss once in 10 years is an economically acceptable risk. Let’s hope 2014 is now a distant memory.”

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