Most Grapes Unscathed by Heat Wave

Midwest, Eastern vineyards damaged more by spring frosts

by By Jane Firstenfeld
Situated in the rolling hills near Knoxville, Tenn., Richland Vineyards suffered more from frost damage than heat this year. Photo: Connie Perrin.
San Rafael, Calif.—National and local media reported widespread damage from the so-called “derecho” wind and thunder storms that plowed through the Midwest, Ohio Valley and mid-Atlantic states the last week of June. (“Derecho” means “straight ahead” in Spanish.) Temperatures soared into the triple digits; winds of 65 mph gusted to 91 mph in Fort Wayne, Ind.; millions sweltered without power for lengthy periods, and at least 12 deaths were reported. Virginia, West Virginia and Ohio declared states of emergency.

In the storm’s wake, Wines & Vines reached out to crop authorities and grapegrowers to learn how the extreme weather had affected this year’s winegrape crop. Surprisingly, of those who responded, most reported more damage from a spring freeze than thunder, wind, hail or heat.

“We have not had any derecho storms in the Midwest that I am aware of,” wrote Bruce Bordelon, Ph.D., professor and extension specialist, viticulture and small fruit at Purdue University in West Lafayette. “It is hot and dry, setting records for both heat and drought. That’s the big story in the Midwest.”

Coming on the heels of a March that was one of the warmest in history, Bordelon continued, spring frosts in April and May had already reduced crops. “Luckily for Indiana, grapes look pretty good—a bright spot in the fruit crop world. We have a near full crop on most varieties, with abundant secondary buds that broke after the freeze events.”

Most Indiana vineyards are planted in deep soils with abundant water capacity, he said. “So far, we are not seeing much signs of drought stress, but we are 8-10 inches below normal (precipitation). If we don’t get rains, vines are likely to begin showing stress.”

Grape crops, he said, are already at veraison for early varieties, making the season two to three weeks earlier than normal. Bordelon expects harvest will begin in late July for early varieties in the southern part of the state.

Frost losses in Michigan, Pennsylvania

Mature vines in southwestern Michigan are not yet affected by the extended drought, according to Diane Brown, commercial horticulture educator at Berrien County Michigan State University extension.  Vines planted within the last two years, though, are getting to a point requiring irrigation. 

“Yield has not yet been lost to heat,” she said, but “there was some loss of crop potential earlier due to freezes that killed primaries.”

When the heat began, she reported, winegrape varieties had buckshot-sized berries. “Right now, we are approaching or at bunch closure, depending on variety.” Disease and insect pressure have so far been light, and Brown said harvest will probably begin as normal at the end of August for early hybrid varieties in southwestern Michigan. Some rain was predicted for this week. “We could certainly use it,” Brown said.

Young Pennsylvania grapevines, still heading into veraison, “Could use some supplemental water, but older vines are holding up okay,” according to Mark Chien, extension educator at Pennsylvania State University (and Wines & Vines contributor). When the heat wave began, he continued, most berries were about pea-sized. “We have just passed lag phase. The entire region is about two to three weeks ahead, due to a very early bud break.”

Although native Concord and Niagara varieties along the Great Lakes were “severely affected” by the spring frost, winegrapes were much more variable: with early bud break, Chardonnay and Lemberger were most affected; later varieties like Cabernet Sauvignon least.

Chien predicted Pennsylvania’s grape harvest will begin in late August for early hybrid varieties, and early to mid-September for vinifera in the southeastern state. Because of frost damage, “I would guess 50 to 100%” of normal crop for most varieties, Chien said.

With “typical” eastern summer weather currently forecast—warm and muggy with afternoon thundershowers—“These conditions can cause problems with disease. The warm summer may also exacerbate insect problems,” he warned.

“It looks like a good season so far. It would be better if we had not had the frost. But here, the weather can turn on a dime, so no one knows what the vintage will be until it’s in the tank or barrel,” Chien concluded. “Call me in two months.”

Freeze causes short crop in Tennessee

Connie Perrin, who owns Richland Vineyards with her husband Troy in Blaine, Tenn., is expecting a later than normal harvest for their 17 acres of labrusca, vinifera, hybrids and Muscadine, 15 miles southeast of Knoxville. The derecho winds and storms passed them by “pretty much,” although the couple did fear wind damage.

With their vineyards under irrigation, the Perrins monitor vines, and a lack of rain prompted them to turn on the water. “Our vines are behind normal ripening, due to great loss of buds and growth from the late April freeze.” Coming back from secondary buds, “We have lost approximately 80% of our normal yield. Some of the other growers (nearby) experienced less loss, some more. A few vineyards even hired helicopters during the freezing temperatures to stir up warmer air. This had mixed results,” Perrin said.

Although normally crush in the region would begin in early to mid-August, “Ours will not begin until about two weeks later. Some of the Muscadine varieties may not be ready before the first early frost comes, which will render them useless, if it is a hard frost.”

This week, Perrin said, more rain is predicted, “Which will of course mean more danger from powdery and downy mildew, and the chance of split berries if there’s too much rain in vineyards where the fruit is near harvest.”

No disaster for Maryland wineries

Maryland was among the states hardest hit by the derecho, but two prominent wineries escaped major damage. “We have had years much worse than this,” said Carol Wilson at 5,000-case Elk Run Vineyards, Mt. Airy.

“The heat wave has not affected us yet. We have not had consistently hot days, and have had some rain. We anticipate more trouble in August should we get consecutive days of heat.” She said. “Normally, crush begins the second week in September. We expect crush a couple of weeks early, unless Mother Nature drops a lot of rain on us. Currently, I see no reduction in harvest amounts.”

In the East, Wilson noted, “Rain is the main problem, not heat. So spray schedules must be maintained even in a dry environment for powdery mildew.”

Elk Run saw no impact on visitors due to the derecho; 3,500-case Black Ankle Vineyards, also in Mt. Airy, did suffer about 20% loss of business, according to Melissa Schulte.

Aside from that, however, there was no damage at all, Schulte said. “It probably advanced ripening and harvest by a day or two, but that effect is very difficult to sort out.” At the time, grapes were through flowering and were about pea-size. “We had delayed leaf pulling by a week or so to reduce heat shock, and we had no problems with sunburn.”

Predicting crush in late August for whites, early September for Syrah and other early red varieties, “We are about a week to 10 days earlier than normal,” Schulte said, predicting a harvest 100% of normal. “But it’s early.”

Meanwhile, at least one major grape producing state was untouched by the storm. “Texas was not affected by the heat wave,” said Ed Hellman, professor of viticulture at Texas Tech University. “The 2012 crop will be about two weeks early because of an early spring. It looks to be a record-sized crop,” good news indeed for a state desiccated by drought in recent years, and perennially plagued by a shortage of local grapes.

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