Degree Days - More Heat and Humidity with Bigger Weeds

June 30, 2009

By Rich Pope, Department of Plant Pathology

Summer burst through the doors with a blast of heat and humidity. Although oppressive to people, it allowed for rapid growth of both crops and weeds.  Weeds are a considerable concern in most areas, most notably where pre-plant burn downs were skipped, and where spraying has been prevented by wet fields. Most areas of Iowa gained 20 to 25 degree days more than the average mid-June week.  

Mapped degree day accumulations by crop reporting district

Soybean aphid populations have now been reported in northeast, north central, northwest and central Iowa.  A cooler, potentially more aphid-favorable weather forecast for the coming week, increases the need to monitor soybeans for aphid populations.


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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