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Corn development and yield forecast: Stress now reduces kernel number

by Jeff Coulter, Extension Corn Specialist

Much of the corn in Minnesota has finished pollinating and kernels are in the blister to milk stage. Kernels enter the blister stage at about 12 days after tassel emergence and the milk stage at about 20 days after tassel emergence. Stress to corn during the blister and milk stages from dry and/or hot conditions can diminish grain yield, primarily by reducing the number of kernels per plant.

Once kernels enter the dough stage, about four weeks after tassel emergence, kernel number is established and yield reductions caused by stress are due to a decrease in kernel size.

To evaluate the impact of this season’s weather on corn yield potential and its spatial variability across the Corn Belt, including three locations in Minnesota, yield forecasts were made on July 27 by University of Nebraska researchers as part of a multi-state project:

Updated yield forecasts will be available in mid-August.

For more educational resources on corn production, visit Extension's corn production website at
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