Pollen falls on or is blown by wind to the silk and corn kernels begin to develop. When corn is planted in a single row, inadequate amounts of pollen may reach the silk and poor kernel development results. It's best to plant sweet corn in three or more short rows rather than a single long row. Many gardeners worry about planting certain crops near one another for fear that insects or wind might deposit foreign pollen on a given vegetable and produce off-flavors or shapes. However, if we saved and planted seeds from these cross-pollinated pumpkins we might get fruits of many different shapes, sizes, and colors.
Corn is the one major exception to the rule.
When a yellow and white cultivar that flower at the same time are planted near each other the resulting kernels will be mixed yellow and white. When a supersweet type corn is planted near a traditional corn cultivar, it will not develop its sweet flavor. Popcorn will not pop if it has been pollinated by sweet corn or field corn.