Later Corn Planting Means Faster Development

Chad Lee, Extension Agronomist, University of Kentucky

Corn planted later will germinate and emerge more quickly, and go through crop stages faster than corn planted early.  Typically, corn requires about 100 growing degree days (GDDs) to emerge and about 200 GDDs to reach the V2 growth stage. An accumulation of about 475 GDDs is required to reach V6, the stage when the growing point moves above ground.



Typically, March accumulates about 170 GDDs, while April accumulates about 320 GDDs and May accumulates about 510 GDDs (Table 1). So far, the GDD accumulation for 2011 seems on track with the historical numbers (Table 2). Based on these long-term averages, corn planted the first of April will reach V6 early to mid May, corn planted the first week of May would reach V6 at the end of May or first of June and corn planted mid-May will likely reach V6 by mid-June.

The faster development from the later planting becomes very important for sidedress applications and timing of postemergence herbicides. Work that normally could be done four two five weeks after planting might need to be done three weeks after planting this year.

The faster development from later planting dates occurs through pollination and seed fill as well. Many corn hybrids require around 1200 to 1400 GDDs to reach pollination. Corn planted April 1 will reach pollination around mid-June while corn planted May 1 will reach pollination around the end of June or first week of July. So, a month delay in planting may only result in a two-week delay for pollination.

Table 1. Historical Corn Growing Degree Day Accumulations for Kentucky ¹

Location	Mar	Apr	May	Jun	Jul
	Accumulated Corn GDDs per Month 2
Mayfield	193	354	530	704	779
Paducah	162	324	529	721	828
Henderson	163	323	524	707	807
Hopkinsville	169	321	507	684	789
Bowling Green	168	313	515	692	805
Leitchfield	160	310	490	663	770
Somerset	172	306	474	639	743
Average	170	322	510	687	789

¹ Data from Tom Priddy, UK Ag Weather Center.
² Derived from 1961 to 1990 data.

Table 2. Corn Growing Degree Days accumulated in 2011.

Location	GDDs accumulated for March, 2011	GDDs accumulated from April 1 to April 25, 2011
Cape Girardeau, MO	155	310
Mayfield, KY	178	352
Paducah, KY	168	350
Henderson, KY	152	320
Bowling Green, KY	192	352
Glasgow, KY	182	324
Somerset, KY	169	312
Bardstown, KY	165	303
Covington, KY	105	248

References:
NCH-40 Growing Season Characteristics and Requirements in the Corn Belt. National Corn Handbook.
University of Kentucky Ag Weather Center: http://wwwagwx.ca.uky.edu/