Degree Days - Temperature Roller Coaster

July 7, 2009

By Rich Pope, Department of Plant Pathology

Iowa crops continue in good condition as we finish one of the coolest July 4 holidays on record.  Each of the last three weeks have alternated between above and below normal temperatures. As of July 5, we have accumulated 87 fewer degree days statewide since May 1 compared with the 30-year average. That is roughly equivalent to 3.5 average July 4 days, so we aren't in terrible shape. The cool-warm-cool pattern appears now to continue as the forecast is for above normal temperatures through the middle of July.

Degree day accumulation map May 1 through July 5, 2009

Soybean aphid has been reported in several fields in the northern half of Iowa, and scouting is now the watch word. Many cornfields, especially where corn is following corn, are still uneven but that may even out as we experience good growing conditions.   


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

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