Wheat planting should be delayed after the "fly-free" date that ranges from _____ at the Iowa line to _____ at the Arkansas line.

The correct answer indicates that wheat planting should be delayed after the "fly-free" date, which ranges from September 28 at the Iowa line to October 17 at the Arkansas line. This is important because the "fly-free" date refers to the time after which the risk of infestation by certain pests, such as the Hessian fly, is significantly reduced. Planting after this date helps to minimize potential damage to the wheat crop.

Understanding the timing of these dates is crucial for successful wheat production. By planting wheat too early, producers might expose their crops to pests that are more prevalent before the "fly-free" date. As a result, growers often monitor planting schedules closely based on local climate and pest cycles to optimize crop health and yield.

In this context, knowing that the date varies from September 28 to October 17 helps agronomists and farmers make informed decisions about when to plant, ensuring they align their planting practices with the pest management strategy specific to their region.