By Brad Haire
University of Georgia

An ice storm brought nasty, freezing temperatures to Georgia last week. It closed airports, iced roads and knocked out electricity for many. But it did little damage to any crops planted now.

The freezing temperatures have been reported to have made some of Georgia's 8,000 acres of leafy greens a little "blue."

Cool pigments

When they get stressed, as during winter cold snaps, leafy greens like mustards, collards, kale and turnips produce less of the pigments that make them look green, said Terry Kelley, a vegetable horticulturist with the University of Georgia Extension Service.

When this happens, a pigment in the plant called anthocyanin appears more dominate in relation to the green pigments. It causes plants to look blue instead of the normal green.

Soil fertility problems can also cause leafy greens to turn blue. Once the stress has passed, most plants return to their greener hues, he said.

To cause severe damage to leafy greens, temperatures would have to stay in the low 20s (Fahrenheit) for 8 to 10 hours straight, he said. This rarely happens in Georgia.

"But some of the more tender plants like mustard greens have taken a hit from the cold weeks we've had since the first of the year," Kelley said.

Sweet weather

Georgia farmers plant about 1,500 acres of carrots annually. Carrots are a tough winter crop and don't mind a little freezing weather. A prolonged freeze can burn the leafy tops. But carrots with a good root system will grow those back. Younger carrots may have more trouble with cold weather, he said.

Carrots are planted from late August until January in Georgia. Farmers stagger planting dates to harvest for different market times, Kelley said. Harvest runs from late December through June.

Much like carrots, Georgia's sweet Vidalia onions don't mind cold weather as long as the ground doesn't freeze and rupture young bulbs. Temperatures haven't gotten that cold this year around Toombs and Tattnall counties, where most of the state's onions are grown, said George Boyhan, a horticulturist with the UGA Extension Service.

The icy weather may have hurt some outer quills (onion leaves) on young onions, he said. "But so far, this year's weather has been good for onions."

It's uncertain right now how many acres farmers planted, Boyhan said. But estimates range from 13,500 to 16,000 acres.

Onion diseases low

Georgia's winter has been mostly cool and dry. This has kept disease problems low in the onion crop this year, said David Langston, a plant pathologist with the UGA Extension Service.

Growers were concerned last year when two new viruses, iris yellow spot and tomato spotted wilt, were reported in Georgia's onion crop.

IYSV has caused major problems for onion growers in Washington, Colorado and South America. TSWV has caused major problems for other Georgia crops like peanuts, peppers, tomatoes and tobacco.

The Plant Pathology Virology Laboratory in Tifton, Ga., tested onion samples last year. About 7 percent of the samples tested positive for IYSV, and 9 percent tested positive for TSWV.

"But there was no evidence of yield losses in onions due to these diseases last year," he said.

So far, samples show the same amount of infection for each virus in the crop this year, he said.