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2005 Annual Report: Demonstrate the Effect of Planting Date on Tassel Emergence


Demonstrate the impact of planting date on tassel emergence of corn.

Materials and Methods

Three corn hybrids were planted April 5 and April 18. The hybrids were Pioneer 34B24, Pioneer 33P62 and Pioneer 31G68. The date of tassel emergence (VT) was recorded when 10% plants reached this stage.

Crop Management Info
Planting Date: April 5; April 18
Herbicides: Dual + Atrazine
Hybrid: Pioneer 34B24; Pioneer 33P62; Pioneer 31G68
Insecticides: Lorsban
Population: 28,500 seeds/acre
Row Width: 30-inchh

Demonstration Design
Replications: 3
Design: Randomized Block
Size: 10 X 30
Statistics: Analysis of Variance


Repeated frosts and slow growing degree day (GDD) accumulations during the last of April and first part of May resulted in slow growth of corn.

VT was difficult to determine with the amount of variability of the first planting date resulting from multiple frosts. The decision was made to make observations of the nonfrosted plants for VT dates to give an appropriate comparison. The GGDs needed to reach VT were greater than expected compared to company data.

Avg. GDD
Days to VT
April 5
Avg. GDD
Days to VT
April 18
110 day15541467
115 day16271458
118 day15741458

The later planted corn reached VT with less GDDs compared to the early planted corn. However, according to calendar date, the later planted corn reached VT, in general, 2-3 days later. The yield data will not be reported because of stand loss and weed competition from loss of plants for the April 5 planting date.

To reduce risk from drought stress, plant the earliest hybrid first followed by medium and longest maturity last. Longer season corn hybrids will speed their growth at late planting dates.