Flooding and ponding injury to corn -- "Muddied Corn"

Heavy rains during the past week have resulted in flooding and ponding in Ohio corn fields. In some localized areas, this may have resulted in partial and complete immersion of corn plants, especially in low spots and in river bottoms and along streams. When water drains off these fields, plants may be covered to varying degrees with a layer of mud. Will corn plants covered by a layer of mud survive and can it perform normally? The layers of silty mud covering plants will limit or prevent leaf photosynthesis. Bacteria deposited in leaf whorls by flooding can result in disease and kill plants. On the positive side, most corn in Ohio was at a stage of growth less vulnerable to flood damage when it occurred. Corn planted through late May should be well beyond V6 (the six leaf collar stage) when the growing point is at or above the soil surface and less sensitive to flooding and associated anaerobic soil conditions. If the duration of flooding was brief, limited to several hours, and temperatures were moderate, damage should be minimal. Moreover, if corn was subjected to flooding at mid-vegetative stages of development, most leaves on affected plants should not be severely impacted by the mud coatings (assuming that mud in the whorl does not inhibit normal emergence of subsequent leaves). Corn plants produce up to 21 leaves, so at V10, about half the corn leaves have yet to emerge from the whorl. The leaves that have yet to emerge are the most important for the corn plant because the upper canopy produces most of the corn plant’s yield potential. According to the National Crop Insurance Service’s defoliation charts, complete leaf loss at about V10 results in 28% yield loss. However, it’s unlikely that the photosynthetic capacity of leaves has been completely destroyed in plants covered with mud. Rain this week will wash silt off leaves allowing for resumption of photosynthesis. It will also help wash mud out of leaf whorls allowing new leaves to emerge. 

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C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.