An Impending Disaster for Arizona Cotton?
Glyphosate Resistant Palmer Amaranth
William B. McCloskey, Ayman Mostafa & Peter C. Ellsworth

A probable case of glyphosate (Roundup) resistant Palmer Amaranth, Amaranthus Palmeri, (i.e., carelessweed or pigweed) has been discovered in an Arizona cotton field where glyphosate was the only herbicide used. Seed collection and testing is underway to confirm this conclusion.

Palmer Amaranth plants are either male or female and resistance genes can be spread by both pollen and seed. Studies show Palmer Amaranth pollen can move at least 164 feet in gentle breezes, longer distances with winds or "dust-devils". One female plant can produce over a million seeds.