Degree Days - Will it be Septembrrrrrr??

September 8, 2009

By Rich Pope, Department of Plant Pathology

Cooler-than-normal weather continued as September dawned in Iowa. During the first week of September, Iowa lost about an additional 25 degree days to normal. This isn't great, but then not a crisis either. Open, sunny days and moderately warm temperatures are key to maturing and drying crops in the fields.

The Aug. 31, 2009 USDA crop condition report listed 76 percent of both corn and soybean acres in good to excellent condition. But the question now relates to dry down and potential harvest issues.  

Worries about a potential early killing frost are reasonable in most areas as well. There is no definitive predictor this far out that I know of for determining the likelihood of an early frost, and time will tell, of course.

Iowa map showing degree day departures for the season through Sept. 6.

As harvest approaches, keep in mind assessment of stalk strength to estimate standability of corn. That might help you schedule harvest to avoid losses.

Rich Pope is a program specialist with responsibilities with Integrated Pest Management. Pope can be contacted at or by calling (515) 294-5899.

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