When varieties are grown north of where they are adapted, maturity is delayed, resulting in seed fill during the cool, short days of fall. Frost before the crop reaches maturity is a possibility. Theories of risk, combined with known crop performance, suggest the latest variety used should be one that reaches physiological maturity just prior to the date when there is a 20 percent chance of a killing frost in the fall. Yield performance will often tell us when a variety is too late or too early, since yields of these varieties-will be lower than those of adapted varieties. Because of the potential for frost and late harvest, circumstances will seldom dictate choosing a variety that will mature too late.
Warm temperatures hasten the maturity of varieties.
For this reason, a farmer in southeast Missouri may be able to use an earlier-maturing variety than someone at the same latitude in southwest Missouri, where temperatures are cooler due to higher elevation. Both the genetic makeup of a variety and the environment in which it is grown can be responsible for standibility problems. Moist, fertile soils normally stimulate vegetative growth in soybeans and lead to tall lodging-prone plants. Certain varieties are inherently more susceptible to lodging than others. Consult University of Missouri yield trial results or other publications for information on the relative standibility of varieties.