Late season rains are hard on crop root systems. Standing water can cause suffocation-like conditions where oxygen deprived soil cause death to plant roots and subsequent deterioration of above ground foliage. Heat can intensify the situation as warm, wet scenarios provide favorable conditions for fungal diseases to develop.
Corn with a damaged or impaired root system is predisposed to root and stalk rots. Photosynthetic stress imposed by the limited root system during the important grain filling period following pollination reduces yield potential. Compromised roots due to flooding and/or disease may later cause the plant to remobilize stored carbohydrates from the loser stalk tissue to the developing grain. While it helps make grain, it weakens the lower stalk tissue. Cannibalized tissues are then again susceptible to the development of fungal and bacterial diseases resulting in stalk rots.
Corn and Soybean crop survival in mid-season flooding
Photo courtesy of University of Nebraska-Lincoln CropWatch.