Many farmers remember the difficult planting conditions of 1996. The planting season was characterized as cool and wet, and planting progress through May was 20 to 30% behind the five-year average. During 1996, it didn't seem to matter when we planted during May. The April 26 planting date did not emerge until May 20. There was no difference in grain yield between planting dates on April 26 versus planting on May 20. Grower return tended to be similar among planting dates between April 26 and May 20.

Planting dates after May 20 performed significantly poorer. Grain yield on planting dates after May 20 were significantly affected by delayed planting.

What's important to remember from 1996 is that early planting did not affect performance even though conditions were not conducive for germination and early seedling growth. After April 20 and if field conditions are adequate, plant corn regardless of soil temperature. In most years, the optimum planting date is between May 1 (south) and May 7 (north), after which grain yield declines significantly with delayed planting. By the end of May corn yield decreases at the rate of 2 to 3 percent per day. Also, grain moisture increases thereby increasing drying costs and lowering grower return even more.

Table 1. Planting date effect on corn grown during 1996 at Arlington, WI.