The impact of weathering associated with harvest delays on corn performance in the Eastern Corn Belt has received little attention. Field studies were conducted in 2002 to 2004 to determine effects of three harvest dates (early-mid Oct., Nov., and Dec.) and four plant densities (59,000, 74,000, 89,000, and 104,000 plants ha ^-1) on the agronomic performance and grain quality of four corn hybrids differing in maturity and stalk quality. Although the hybrids exhibited similar yield potential when harvested early (early-mid Oct.), differences in yield became evident with harvest delays, which could be attributed to differences in stalk quality. Yield differences among plant population were generally small on the first harvest date, but with harvest delays, major yield losses occurred at the higher plant populations, especially 104,000 plants ha ^-1, due to increased stalk lodging. Grain moisture, averaged about 23 to 25% on the first harvest date, 17 to 19% on the second harvest, and 16% or less on the third harvest date. Stalk rot increased from 44% on the first harvest date to 91% on the third harvest date. After the first harvest in early to mid October, stalk lodging increased as much as 80% for certain hybrids - resulting in yield losses of nearly 50%. Kernel breakage was not affected by plant population, or interactions involving population and hybrid. However, hybrid effects were significant with one hybrid consistently showing greater kernel breakage compared to the other three hybrids. Results of the study indicate little benefit from using high plant populations above 74,000 plants ha ^-1 when harvest is delayed beyond early November.