Yesterday’s heavy rains that marched across large part of central and north central Iowa coupled with recent storm systems across other parts of the state have resulted in significant areas of ponding as well as hail injury.
Flooded fields will take several days for the water to recede to fully evaluate how much crop areas was destroyed. A may be able to survive under water for 1 to 4 days depending on the crop stage and air temperature. And even if the crop does survive, saturated soil conditions will undoubtedly stall root growth and hinder nutrient uptake and growth.
At this stage of the growing season, it is unlikely that replanting drowned out areas will be a viable option. However, when the water recedes and field conditions are fit, it would be worthwhile to plant a cover crop to protect the soil and compete against weed growth.
ICM News Corn Survival in Flooded or Saturated Fields has some additional information on survival of corn that has been under water.
Hail injury to the corn and soybean crop will be relatively minor in the earlier growth stages. Yield loss from hail to corn increases through vegetative growth and peaks at pollination before decreasing through grain fill. Whereas, soybean hail injury increases as the growing season progresses and peaks during the seed filling stages. At this time of the year, hail injury may only result in a 5-20% corn yield loss or 5-30% soybean yield loss.