Thanks to a series of mergers and acquisitions over the last few years, four multinational agrochemical firms — Corteva, ChemChina, Bayer and BASF — now control over 60 percent of global seed sales. The same seed companies also sell more than 60 percent of the pesticides. Not a bad business. The end has probably already begun. Today’s food culture is experiencing a tectonic shift as the rebellious stakeholders of our modern food movement — farmers, independent retailers, nutritionists, educators, chefs and ever-more-informed eaters — upend the marketplace.