Crop Comments: Glyphosate Residue Persists Longer Than Expected

My first contact with herbicide residue injuring field crops came in the 1970s, as an agronomy Extension agent. A farmer had me examine his alfalfa seeding that had a weird mortality pattern. He had planted corn two years earlier, fallowed the piece in question the next year, planting a legume seeding the third year. He showed me a strip at the edge of the field where the alfalfa had sprouted, then promptly died.