Isolating Sweet Corn
Home Grown Corn
Genes for supersweet corn varieties are recessive, they're affected by any other corn that crosses with them.
The genes of yellow corn are dominant over white corn genes. If a yellow and a white variety cross, the white corn will more than likely have some yellow kernels. Yellow corn, in this scenario wouldn't be harmed by the cross pollination.
Popcorn and feed corn [field corn] have genes that are dominant over any sweet corn genes. If a cross takes place with either of these and sweet corn, the sweet corn will more than likely be tough ,starchy and inedible.
To avoid stray inadvertent cross breeding from stray pollen , sweet corn must be isolated from ornamental corn, feed corn and popcorn.
Isolating different varieties of corn requires a minimal separation of a 100 feet between plantings and may not be feasible in a small garden. The 100 ft. rule will minimize he potential for cross breeding, although it is still possible - the odds of it occurring are vastly diminished.
One strategy to prevent cross breeding, which is much more feasible in small gardens, is to stagger planting times, maturation 14 - 18 days apart is optimal. Select varieties with different maturation intervals to avoid them both from releasing pollen simultaneously. You may also want to start some indoors and transplant outdoors ,so they will be more mature than their cousins which are just beginning to sprout elsewhere in the garden.
Another tactic, if your yard is large enough, is to plant the dominant corn variety downwind from any variety that will suffer by their cross breeding. The wind swirls constantly, so if you're not certain what direction the prevailing wind blows in your area, check with your local weather service, or put a wind sock or weather vane in the yard and track the dominant direction.