Source: University of Mississippi

Planting too early unnecessarily exposes wheat to potential development, fertility, weed and numerous pest problems which ultimately reduce yield potential.

The purpose of wheat planting date is only to establish a stand and begin tillering activity before winter causes dormancy. Thus, growers accustomed to gaining developmental advantages from planting summer crops early, such as corn and soybeans, may run into severe problems by using the same strategy with winter wheat.

Developmental problems result when early planted wheat proceeds past the tillering stages before winter induces wheat dormancy. Winter wheat growth becomes dormant during the winter to help plants survive during cold temperatures. Early planting may promote excessive fall wheat growth relative to the extended growing period. This causes problems because winter wheat is most tolerant of cold temperatures during the tillering (prostrate) growth stages. Thus, early planting substantially increases the likelihood of subfreezing temperatures damaging plants during the winter and/or spring. Excessive fall growth may also cause wheat to grow taller in the spring and promote lodging.

The suggested wheat planting dates (within 10-14 days of the average first frost date in the fall) should provide warm enough temperatures and long enough days for seedling emergence and tillering to begin before dormancy occurs.

Early planting may also cause nitrogen timing problems which reduce yield potential. The warm, rainy winter climate in the Midsouth necessitates the majority of nitrogen application be delayed until the spring to avoid losing nitrogen during the winter. However, wheat nitrogen needs increase substantially beginning at stem elongation. Thus, if stem elongation begins in the fall, the wheat plants will suffer from nitrogen deficiency (nitrogen guidelines) until the spring. This will cause reduced head number and size, significantly reducing yield potential.

Early planting encourages infestation of insects and disease infection by increasing exposure. Lush vegetative development encourages fall infestation of aphids, Hessian fly and Fall armyworm. Aphids vector Barley yellow dwarf, a virus which stunts wheat development and may cause substantial yield reduction, particularly from fall infection. Fall infestations of both Hessian fly and Fall armyworms may destroy stands. Hessian fly also cause broken stems and lodging in the spring. The development of Leaf rust and Take-all, a fungus which prematurely kills plants by rotting the lower stem and root system, is also encouraging by early planting.

Early planting also promotes winter weed competition. Early planting allows the entire winter weed seed bank in the soil to potentially emerge and compete with the wheat crop. Delayed planting allows a flush or two of winter weeds to germinate before planting commences. Thus, producers may control these weed flushes with fall tillage or burndown herbicide application to reduce the potential weed population. This system is particularly important for hard to control winter annual grass species, such as ryegrass and cheat.