Few states in the Midwest have had true summer-like conditions the past few weeks.

In fact, states such as the Dakotas, Minnesota and Wisconsin, have had temperatures between 6 and 12 degrees below normal, says Gail Martell, Storm Exchange senior agriculture analyst. Martell says if history repeats itself, these cool temperatures could be good for corn yields.

A History Lesson

The entire growing period was unseasonably cool in 2004, Martell says. Since 2009 is off to a similar start, she decided to compare the two seasons to determine if comparable outcomes might occur.

In 2004, Martell says, farmers across the Corn Belt completed a record-early planting season and had more-than-sufficient precipitation.

In the northern Corn Belt, planted their regular corn varieties for a normal growing season. The crops came up and looked good during the cool growing season, equaling good crop ratings from USDA. It was good-looking corn, but was a struggle to the finish.

“During a cool season the northern states struggle to get enough heat units to mature,” she says.

Yet, in the southern Corn Belt the cool growing season still provided plenty of heat units, equaling in record corn yields, Martell says.

“What I learned is that the normal climate in Missouri, southern Illinois, southern Iowa and Nebraska, the normal climate is too hot for the optimum yields,” she says. “You had such high yields in the southern growing areas, the national yields 11% above trend.”

Martell says the reason coolness is so great for corn in the southern areas is because evaporation is so much lower and the corn can optimize the soil moisture that is there.

Current Outlook

Martell says June was dramatically cooler than the norm for several of the Midwestern corn-producing states.

But, she says, the outlook continues the cooler-than-normal weather pattern in the same area, but not as intense.

“It looks pretty much warmer, even into Canada,” she says. “We need that to kind of reverse the cooling trend we’ve had.”

Martell notes that planting this season has been significantly slower than 2004, which will probably have an impact on yields this fall.

“Even if we have identical weather, with the coolness continuing and sufficient rain, maybe we wouldn’t get the same amount of yields because of the lagging in planting this year,” she says.

For now, Martell will continue to keep her eyes on the radar maps.

SOURCE: Sara Muri, AgWeb Crops Online Editor