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Angie Peltier


Angie Peltier
Former Extension Educator, Commercial Agriculture



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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. Soybean plant development in a planting date trial (June 26, 2014).
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Corn and Soybean Development: Planting Date


University of Illinois Planting Date Trials. Along with numerous other biotic and abiotic factors, environmental conditions such as soil water availability and air temperature drive the growth and development of field crops. Each year, under the direction of Dr. Emerson Nafziger, University of Illinois Research Center staff establish and maintain corn and soybean planting date trials throughout the state. These trials help to fine-tune regional planting date recommendations.

How heat drives plant growth. Corn plants require heat (between 50 and 86 °F) in order to grow, develop and reach vegetative and reproductive milestones on their way to physiological maturity. Growing degree days are a measure of the accumulated heat and associated corn growth and development during the growing season. Chapter 2 in the Illinois Agronomy Handbook has a good description of daily GDD calculations and the number of GDD that typically must accumulate in order for corn to reach specific growth stages.

Corn planting date. The earliest planted corn (April 9) has developed 11 leaves and is shoulder high, while corn planted on May 30 has developed just five leaves and has reached knee high (Table and Figure). When compared to 2011 and 2013 when rainfall seemed to completely stop after planting, a dry spring has turned into a wetter summer.

Table. Corn planting date, accumulated days, growing degree days (50 to 86 degrees) and rainfall and corn plant growth stage (June 26).

Planting Date

Days

Growing degree units

Accumulated rainfall

Plant Growth Stage

April 9

78

1131

12.14

V11

May 5

52

940

8.88

V7

May 19

38

783

8.83

V6

May 30

27

568

6.67

V5

Soybean planting date. Soybeans planted in the middle of April or the beginning of May are nearing the critical growth stage for disease scouting and fungicide decisions (Figure and Table). Although I have not yet seen frog eye leaf spot or Septoria brown spot (the two diseases that are targeted with foliar fungicides in Illinois), keep an eye on your beans before they get away from you!

Table. Soybean planting date, accumulated rainfall since planting and plant growth stage (June 26).

Planting Date

Days

Accumulated Rainfall

Plant growth stage

April 17

70

11.50

R2

May 7

50

8.88

R2

May 22

35

6.75

R1

June 9

17

3.88

V1

 

Additional Information about growth staging corn and soybean:

Soybean Growth and Development Quick Guide (D.A. McWilliams, D.R. Berglund, and G.J. Endres)

Corn Growth & Development: What Goes on from Planting to Harvest? (R.L. Nielsen)



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