A freeze could stop the growing season in the upper Midwest as far south as Nebraska and Iowa, leaving farmers in a difficult situation because much of the region's corn and soybean fields are not quite ready for harvest.
The area of most concern includes Minnesota, North Dakota, South Dakota and Wisconsin, where the corn crop is just 40 percent to 50 percent mature. A freeze could stop growth, leaving the crop underdeveloped and lower in quality.
This year's corn crop was planted two to three weeks later than normal, and rainy, cool weather in May and June got the plants off to a slow start. Some farmers near the Nebraska and Iowa state line saw hail damage from spring storms and others had puddles of water standing in fields from heavy rain, forcing them to replant much later than desirable.
About 60 percent of the corn crop in the U.S. is mature, well behind the five-year average of 70 percent, according to the U.S. Department of Agriculture's weekly crop update. Soybean development is 2 percentage points behind the 71 percent average. Just 12 percent of corn is out of the fields, half the average at this point in the growing season, and 10 percent of soybeans are harvested, seven points behind the average.
USDA Meteorologist Brad Rippey said in a Thursday agricultural weather update for this weekend that "a growing season-ending freeze...can be expected in the Dakotas and environs, with temperatures near 32 degrees Fahrenheit as far south as Nebraska and Iowa."
Curt Sindergard, who farms 700 acres of corn and soybeans on his farm near Rolfe, Iowa, about 130 miles northwest of Des Moines, said corn is probably most vulnerable to extreme cold.
"A hard, killing freeze could definitely cause some problems with the very high moisture corn," said Sindergard, who also harvests another 1,800 acres with a business partner. "We're not out of the woods if we get a killing frost, which is temperatures down to 28 for several hours."
Growing conditions in the summer months were very good for filling ears with corn kernels and soybean pods with soybeans. Those conditions have led the USDA to expect record crops. Now, farmers need some warm, dry days to dry the grain.
"Normally, September is when you get the grain dried down," said Mark Licht an agronomist at Iowa State University. "By the time we got to October, the grain dry-down was about half of what it would normally be."
Harvested too wet, corn and soybeans develop quality issues including mold.
"With the later crop we've got and the cold snap that's coming through, I personally always have a concern about snow before you can get things out of the field," said Roger Elmore, an agronomist at the University of Nebraska-Lincoln. "You don't want that wet, sticky snow on top of our crops before you get them out, but you want to leave them out as long as you can to get the dry-down to save on propane costs."
Farmers use propane dryers to extract excess moisture from grain if it's too wet before storing or selling it.