Iowa's wet spring and cool temperatures not only slowed planting progress but also slowed Growing Degree Day accumulations. These factors contributed to yellow corn plants across the state as well as within-row variability in plant-to-plant growth and development. Seedling diseases reduced corn stands.
"We might expect all of those problems to surface in a spring like this, considering the conditions the crop has experienced," says Roger Elmore, Iowa State University Extension corn agronomist. "We expect stand losses in low areas of fields in wet years due to prolonged standing water on planted or emerged corn. However, one rarely seen problem has developed this year -- corn stand losses on sidehills." Elmore, along with a colleague, ISU Extension soil management specialist Mahidi Al-Kaisi, offer the following information and management recommendations regarding sidehill seeps.
Saturated soils result in reduced corn stands in Iowa this spring
Saturated soils on sloped areas (Figures 1 and 2) with corn planted in the second or third week in May resulted in poor germination and damping off and, in some cases, dramatically reduced stands. Soil temperatures at and soon after planting were conducive for rapid germination and emergence. "So, we can rule out temperature as a causal agent," says Elmore. In some cases, the seed swelled (imbibed water) but neither the radical nor mesocotyl emerged. In cases where the radical and/or mesocotyl did emerge, they died before much growth occurred (Figure 3). ISU colleagues at the Plant and Insect Diagnostic Clinic are examining seedlings for pathogens this year.