"You start off with fields in a lot better shape than you'd have after a moderate winter when pests and disease problems are not killed off."
The subfreezing temperatures don't totally eradicate problems. Sometimes they only delay them, said Bill Troxell, executive secretary of the Pennsylvania Vegetable Growers Association, which has 950 members, including growers, farm supplies, and others in the agriculture industry.
"But from a crop perspective, it's definitely a plus," said Troxell, while attending the Mid-Atlantic Fruit and Vegetable Convention in Hershey last week. "We haven't had the severe cold weather the past few years, so this is good."
The extended frigid periods reduce insect populations and the likelihood of some diseases, Pennsylvania and New Jersey agriculture officials said.
The blanket of snow insulates plants such as overwintering spinach and strawberries from single-digit and below-zero temperatures. And it slowly releases nitrogen and moisture into the soil, they said.
The extreme cold even helps halt the spread of Dendroctonus frontalis, the southern pine beetle, which has been devouring parts of the Pinelands, officials said. The beetle had been moving north from Southern states.
Below-zero temperatures also kill the eggs of insects such as Asian tiger mosquitoes, which spread the West Nile virus and affect the region's equine industry.
In Southeast Pennsylvania, the temperature in January averaged 28 degrees, about 5 degrees below normal, said John Dlugoenski, meteorologist for Accuweather.com.
During the same time, 26 inches of snow fell across the area, six inches above normal.
In New Jersey, the winter has been the coldest since 2004 and the 25th coldest since 1895, said state climatologist David Robinson.
The normal average temperature across the state in January is 31.2 degrees. Last month, the mercury averaged 27.2 degrees. Hammonton and Berkeley Township in South Jersey got down to minus 9 degrees at least one morning last week.
"A brutal cold locked in on Jan. 21," Robinson said. "That cold stayed put and had several reinforcing shots."
At the same time, New Jersey has received about two feet of snow, about 13 inches above normal in the southern third of the state. "It's been a tough winter, a winter's winter thus far," Robinson said.
These conditions, though, "are beneficial to agriculture," Murray said.
They should help decimate Mexican bean beetles, which attack soybeans, as well as the southern pine beetles infesting the Pinelands, said Ed Wengryn, a research associate at the New Jersey Farm Bureau, a nonprofit advocacy group representing more than 11,000 farmers and other ancillary businesses in the state.
"This is good as long as it doesn't go on too long," said Wengryn. "If you have subzero temperatures in late February, you will see fruit-tree damage.
"The sun warms the bark, sap begins to flow, and then - if you get below 20 degrees - the sap freezes, expands and splits the bark, creating a path for diseases and insects to get into the tree," he said.
So far, though, the cold and snow have helped farmers while also likely delaying the onset of mosquitoes and leaving lawns greener since falling snow picks up nitrogen in the atmosphere, then slowly melts into the ground. "It's a poor man's fertilizer," said Murray.
For farmers growing wheat, the snow provides a protective cover against extreme temperatures, said farmer Erwin Sheppard, part owner of Sheppard Farms in Cedarville, Cumberland County. "The wheat could be windburned if there was no snow," he said. "It's like a coat."
If the winter is too warm, some crops such as blueberries, peaches, and apples can grow "too quickly and then a cold snap can hurt them," Sheppard said. "But this cold is a good thing; crops need a chilling time."
At Gala Orchard in Elmer, Salem County, the trees are "completely dormant," said Francisco Allende, part owner of the farm and a member of the New Jersey Peach Promotion Council. "If the temperature goes 8 below, we could start to see some damage."
Except for those extreme subzero temperatures and wide fluctuations closer to spring, the cold is a friend to farmers, he said. "If you don't have the pests, you don't have to apply pesticides," Allende said.