06 Jun 2016 Recognizing PPO-Resistant Palmer Amaranth 06 Jun 2016 Author: Ginger Rowsey, Marketing and Communications Comments Off on Recognizing PPO-Resistant Palmer Amaranth Dr. Steckel recently shared a post about PPO-resistant Palmer amaranth. In this short video he covers the visual symptoms of PPO-resistance and how you can spot it in the field.