A concern for corn fields damaged by this year's Derecho is how best to manage volunteer corn in 2021. Our recommendation is to rotate to soybean or some other crop if at all possible since additional control options are available in soybean (Sept 3, 2020 article). There have been questions regarding how much viable corn seed is left in these fields after abundant corn germination in September (Figure 1).
To estimate how much corn seed remains in these fields, we visited a field that was determined mechanically unharvestable and had received multiple tillage passes in late August/early September. Several one ft2 samples of soil were removed to a depth of six inches, and the number of intact corn seed determined. There were more than 1 million seeds per acre in the sampled areas (averaged 31 seed/ft2). Based on emerged plants and rotted seeds found in the samples we estimate the intact seed represent about one third of the seed that was present immediately following tillage.
It is likely that a significant percentage of these corn seed will be lost prior to spring. However, there were large numbers of partial corn ears (~15,000/acre) on the soil surface (Figure 3). It is likely these seeds will overwinter more successfully than the corn seeds within the soil profile, and these ears will be a major contributor to volunteer corn populations next spring. In spite of the large amount of corn germination in damaged fields, volunteer corn will still be a signficant problem in these fields.