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Date: 7/24/2013

Title: Crop Progress and Growing Degree Days

 With July winding down and as we head into the “Dog Days of Summer” we will be keeping a close watch on crop progress across the Corn Belt and Midwest. The cooler than normal temperatures that developed this spring have continued in many areas of the Northern Plains and Midwest.

Yes, there have been some periods of hot weather, but each time a heat wave gets going it has ended quickly. As we head into August, all indications suggest that most of the hot areas of the United States will be found in the northeastern states and the far west while the middle part of the country will continue to have either normal or slightly below normal temperatures for the month of August.
The temperature for the year to date across the lower 48 states shows up quite well in the graphic below of Divisional Temperature Anomalies.

 The core of the cooler temperatures have been centered across the eastern Dakotas, Minnesota and portions of Nebraska, Iowa, Kansas and Missouri.
At the moment, crop progress has been slow, but steady and frequent rains and improved drought conditions have resulted in excellent crop conditions in many areas. It could be a bountiful harvest this year if all goes well and commodity prices may be impacted come harvest time if we have a big corn crop.
However, there is a little concern about growing degree accumulation and crop development due to the cooler temperatures this season (in stark contrast to last year). The Achilles heel of this growing season is the growing degree day deficit in many areas and the possibility of an early season freeze that could impact yields if crops don’t have time to fully develop before harvest.
 The graphic below shows modified growing degree day accumulation in Midwest since May 1st.

The graphic below shows modified growing degree day accumulation departure from normal in Midwest since May 1st.

 The purple and blue areas show the locations that would be most susceptible to an early freeze. It is interesting to note how far south the growing degree day departure extends into the southern and western Corn Belt areas.
Keep an eye on the blue and purple areas of the map as we head into September. Since we are expecting no prolonged heat in the Midwest in August, we may still be looking at a growing degree day deficit at the end of the growing season. An early season frost or freeze could have a big impact.