Crop conditions across the Midwest vary in early August depending on planting date, impacts from the heavy rains in June, timeliness and amount of July rainfall, and recent storm damage. Overall across southern Minnesota, most corn and soybeans have improved dramatically from conditions that existed 4-6 weeks ago. Much of the region received some very timely and significant rainfall right at the time of corn tasseling and pollination, after being fairly dry up until that point. The combination of adequate moisture and slightly above-normal growing degree units (GDUs) in the past few weeks has really improved the prospects for much of the 2008 corn and soybean crop.

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However, not all areas are facing the much improved prospects for the 2008 corn and soybean crop. A large area of west-central and northern south-central Minnesota was impacted by strong winds on July 31 that caused thousands of acres of corn to bend, and in the worst cases flatten. Even though most of the corn is not destroyed, the corn becomes much more susceptible to disease problems late in the growing season, and harvest losses usually increase. Yield reductions of 10-20% are not uncommon with this type of corn damage. There was also considerable wind damage to many sweet corn fields in the region, many of which were within 1-2 weeks of harvest.

The warmer temperatures in July have helped the corn and soybean crop catch up a bit on GDUs compared to a month ago. A total of 1,456 GDUs were reported since May 1 at the University of Minnesota Southern Research and Outreach Center at Waseca, which is about 5% behind normal for Aug. 1. Most corn and soybeans in the region are still about 5-10 days behind normal development. Crops are further behind in some areas of Iowa and southeast Minnesota that were impacted by the heavy rains in early June.

It takes about 60 days from the time of tasseling until the corn kernels reach physiological maturity (black-layer), with normal accumulation of GDUs. Once the kernel is black-layered, it is usually free of significant damage from a killing frost. Some of the later-planted corn and corn that was impacted by the June rains that did not tassel until very late July or early August could have some challenges being fully black-layered by the first frost. Corn is usually 28-32% moisture at the time it reaches black-layer, so some additional frost-free time will be required to dry the corn down naturally in the field to the desired 15-16% moisture for harvest and storage in order to avoid expensive corn drying this fall.