Since the advent of Roundup Ready crops designed to withstand potent weedkillers, seeds and sprays have been entwined in the agriculture industry. Chuck Magro, CEO of Corteva, wants to undo that: Next month, his $55 billion company will split, creating separate businesses focusing on seeds and pesticides.

Corteva's stock fell 6% the trading day after The Wall Street Journal reported the breakup plan. But its shares have gained 23% this year, and Magro says the shift will help focus investment on R&D for cutting-edge seeds without taking away from the pesticide business.

Magro says the new seed company, Vylor, is working on nearly a dozen new corn and soybean seed technologies to help combat disease and insects. Farmers will continue to pay top dollar for seeds to grow bigger harvests, despite higher costs: "Farmers are very willing to invest," Magro says in an interview.

The spinoff will complete next month.