Barbara Scott, Research Associate; bascott@udel.edu & Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
Glyphosate-resistant Palmer amaranth has been confirmed on Delmarva. There has been suspicion of glyphosate-resistance in the region, but this is the first year of confirmed resistance. This discovery is not surprising since Palmer amaranth has a tendency to develop resistance. Fields with Palmer amaranth (or suspected Palmer amaranth) should not be treated with glyphosate alone. In soybeans glyphosate should be tank-mixed with an ALS inhibiting herbicide (group 2) or PPO herbicide (group 9).
Tags: 20:15, glyphosate, herbicide resistant weeds, palmer amaranth