The effect of plant population on yield is very small over the normal range of seeding rates and for any particular set of conditions. For a crop planted before May 20 in narrow rows, final populations of 100,000 to 120,000 plants per acre are generally adequate for maximum yield. Final populations for mid-June plantings should be in the range of 130,000 to150,000 plants per acre. Final populations for early July plantings (double crop) should be greater than 180,000 plants per acre. Final population is a function of seeding rate, quality of the planting operation, and seed germination percentage and depends on such things as soil moisture conditions, seed-soil contact, disease pressure, fungicide seed treatments, etc. Final harvest stands are typically 60 to 80 percent of the seeding rate when high quality seed is used and there are few impediments to stand establishment. Some seed is dead when planted, other seeds may not have the vigor needed to emerge and grow rapidly, some will be lost to disease and insects prior to emergence, some emerged plants will be killed by disease and some will not grow fast enough to compete adequately for sunlight and thus perish during the growing season.