Since this year’s harvest has been hindered by wet field conditions and late maturing crops, winter wheat planting may also be delayed. It is difficult to determine the yield effect of late planting date, because planting and harvest occur in two different seasons with a winter dormant period in between.

Variability in autumn temperatures affects the amount of fall growth. Late planted wheat may not

develop enough to survive the winter when fall temperatures are cool. The Hessian fly-free date,

October 3 along the Highway 36 corridor, is considered the optimum soft red winter wheat planting date. The further planting date is delayed beyond this date, the more yield will be limited by the amount of growth that can occur before temperatures become too cold. Little growth occurs below 40 degrees Fahrenheit.

In order for wheat to survive the winter, three things must occur in the fall. First, it must have developed a strong enough root system to resist heaving. When roots are too shallow, water freezes under the crown and plants are forced out of the ground and die. Second, wheat must store adequate sugars in the crown for green-up in the spring. These sugars also help protect the growing point during the winter.

Without adequate sugars stored in the fall, the plants are susceptible to winter kill. Finally, wheat

produces tillers in the fall which produce grain heads the following spring. The plants will produce tillers in the spring, but the spring tiller development is usually not adequate to compensate for reduced yield due to poor tillering in the fall.

For more information contact Valerie Tate by email at tatev@missouri.edu or call 660-895-5123. University of Missouri Extension programs are open to all.

Valerie Tate is a University of Missouri Extension field specialist in agronomy in Linn County.