Corn Response to Harvest Date as Affected by Plant Population and Hybrid

Many corn (Zea mays L.) growers in Ohio delay harvest as a management strategy for reducing grain drying costs. However, this practice increases the risk of yield loss due to extended crop weathering. Field studies were conducted at three Ohio locations in 2002 to 2004 to determine effects of three harvest date periods, early to mid-October (HD1), early to mid-November (HD2), and early to mid-December (HD3), and four plant densities (59,000; 74,000; 89,000; and 104,000 plants ha(-1)) on the agronomic performance of four corn hybrids differing in maturity and stalk strength. Interactions between harvest date, plant population, and hybrid indicated that decreases in grain yield and increases in stalk rot and lodging associated with harvest delays were influenced by plant population and hybrid characteristics. Significant yield losses due to delayed harvest were evident only aft er HD2. When harvest was delayed until HD3, yields decreased at the higher plant populations, especially at 104,000 plants ha(-1). Stalk rot and lodging increased at the higher plant populations, and this effect was magnified by late harvesting. Hybrids with lower stalk strength scores exhibited greater stalk lodging and yield loss when harvest was delayed beyond HD2. Stalk rot showed a greater increase between HD1 and HD2, whereas stalk lodging generally showed a greater increase aft er HD2. Harvest delays aft er HD2 achieved little or no additional grain drying. Results of this study indicate that harvest delays should be avoided when using plant populations above 74,000 plants ha(-1), especially if planting hybrids that are not highly rated for stalk strength.