Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
Palmer amaranth is a dioecious species, meaning a plant will produce either male or female flowers. The female flowers are fertilized with wind-dispersed pollen from the male plants. And Palmer amaranth is very effective in spreading pollen over distances. Research at University of Georgia demonstrated that pollen can move at least 900 feet. Why is this important? Pollen carries the gene for glyphosate resistance and so you can see how resistance can spread very rapidly if plants are allowed to flower. A few male plants that survive a glyphosate treatment (resistant) will produce pollen to fertilize female plants. This results in the next generation of plants from these female plants being resistant to glyphosate.