In an average year, according to a Lincoln personnel recruiting firm that specializes in the practice, around 100,000 high-school and college kids spend about a month every June and July participating in a Midwestern rite of passage: "detasseling corn."
The annual practice is as old as the invention of hybrid seed corn, the most common form of corn seed used by commercial farmers today. Seed-corn companies produce that hybrid seed by forcing two strains or breeds of corn plant to mate with one another, producing an offspring seed that then carries the best traits of both parents. Detasseling, the practice you're witnessing when you watch teams of teens walk the rows of cornfields or ride above the plants on elevated platforms, is the final step in ensuring the quality of that seed.
To produce that improved hybrid corn on a commercial scale, corn plants, which normally pollinate themselves, are instead cross-pollinated. Seed-corn companies accomplish this cross-polination by first planting a field with alternating blocks of plants from the two different parent strains. In one set of rows, workers then remove the "tassel" or top part of the maturing stalk that bears the pollen. That detasseling leaves only rows containing the second strain's plants capable of pollinating the now detasseled plants, which will then go on to bear the hybrid seed.
Some recent attempts at mechanization notwithstanding, says Varsity Detasseling, the helping hand of the detasseler is still needed to produce a pure and superior seed. When the time is right and the weather cooperates, they must work quickly, typically beginning in late June to late July, beating the summer heat by starting at sunrise and working until mid-afternoon. Detasselers, usually working in two or three passes through each field, must remove 99.5 percent of all female-plant tassels in order to completely "clean" a field.
Watch this explanation of how and why detasseling works to produce pure seed corn.