This year I will be tracking corn growth and development of a planting date experiment established at Arlington to examine the current model used for healthy corn growth and development in Wisconsin. The purpose of a corn development model is to predict when management decisions need to be made and implemented.

So far, planting dates in the experiment have occurred on 15 April, 3 May and 13 May. The 15 April planting date emerged on 8 May and is approaching the V2 stage of development. The plants in the corn plots are light green to yellow, and good to excellent plant population is observed. The cool, wet weather has not helped "greening" of the crop even though starter fertilizer was used.

The current model used for tracking corn growth and development predicts emergence at 125 GDUs, V3 at 300 GDUs and V6 at 475 GDUs. As seen last week, emergence of the 15 April planting date was "right on" in relation to GDU accumulation and the corn growth and development model (Figure 1).

The model predicts that the 15 April planting date should be at V3 on 22 to 24 May and V6 on 6 to 8 June. The 3 May planting date normally should emerge on 15 to 17 May, and achieve V3 on 31 May to 1 June. Since 3 May, the GDU accumulation for 2003 has slowed compared to the 40-yr average, so these development stages will likely also be somewhat delayed. I'll try to keep you posted weekly.