September 30, 2009

Pre-dawn temperatures fell into the low- and mid-30s Fahrenheit across corn and soy-producing areas of North Dakota, South Dakota, Nebraska and western Minnesota early Tuesday (September 29), raising the potential for some damage to the region's late-maturing fall crop.

 

"Frost is likely in progress in these areas," said T-Storm Weather. "Coldest readings included 30 degrees in central Nebraska and eastern North Dakota, though most were a few degrees warmer. 28 degrees and colder is required for a hard freeze/end of the growing season."

 

The cold snap is generally thought to be the greatest threat to crops in North Dakota, which last month was forecast to harvest 204 million bushels of corn and 120 million bushels of soy by the USDA.

 

"We had a very unusual spring, where people couldn't get into the fields and they planted later than normal...and the cool summer has delayed [crop development] a lot," North Dakota State University extension agronomist Hans Kabel told Dow Jones Newswires.

 

Kabel added that corn appears to be at the greatest risk of suffering yield/quality losses.

 

"I'm not too greatly worried about the soy. Most of the soy should have made it by this point," he said. "The corn is in a different league. It needs to dry-down a lot. There might be a few fields that are even still in the milk" stage of development.

 

The USDA on Monday estimated that although 75 percent of all North Dakota corn had dented, only 5 percent was fully mature, and therefore completely safe from frost damage. By contrast, nearly three-quarters (73 percent) of the state's soy had begun to drop leaves; a stage of development viewed as a measure of full maturity for beans.

 

"A lighter frost of 30-32 degrees, lasting an hour or two, could kill [corn] leaves but not the stalk or ear shank," said a study conducted by the University of Minnesota. "When only a portion of the leaves are killed, those not killed can continue to function and contribute to grain yield, if good growing conditions follow frost."

 

The study estimated yield losses on corn in dent stage, or earlier, at between 15 to 32 percent.

 

Corn development "has really moved along nicely the last three weeks, with above-average temperatures," said Kabel. "The critical period is the next ten days...if we can get through the next 10 days with no frost I think many of the plots will make it."

 

The average date of the normal first frost is already past in many sections of North Dakota, falling between Sept. 19-23.