It is May 25 and you have unplanted corn acres. Now what?
Compared to a May 1 planting, average yields decline about 15 percent for the last week of May. The yield and the yield reduction for late planting will vary greatly depending on the rest of the growing season.
One of the tough calls that comes with delayed planting is that of hybrid maturity choice. Information on this issue is complicated by the lack of a universal definition of maturity. Variations in growing seasons relative to available growing degrees, first frost date, and fall drying conditions complicate the issue.
It is suggested that if planting is delayed past May 25, hybrids earlier than the "adapted full season" maturity for the area may be a better choice. Obviously, an "adapted full season" hybrid in northern, central, and southern Iowa will be three different maturities. Producers will need to contact their seed dealers about hybrid maturity, availability, and other suggestions. Many producers will want to switch to a hybrid five to seven days earlier in maturity for corn planted the last week of May and first few days of June.
The main reason for switching hybrid maturity is not so much for yield, but to reduce the risk of immature and wet grain in the fall. Don't forget that most of the advantage of full-season hybrids is associated with on-time planting. The issue of hybrid maturity choice also is complicated by seasonal differences.
This article originally appeared on page 80 of the IC-476(11) -- May 27, 1996 issue.