Distribution of Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri) in Georgia and North Carolina during 2005 and 2006

Glyphosate-resistant Palmer amaranth biotypes have been confirmed in Georgia and North Carolina. A survey was conducted in both states to determine distribution of the resistant biotype(s). Knowledge of the distribution of glyphosate resistance will alert producers to the severity of the problem and hopefully encourage them to adopt resistance management programs. Palmer amaranth seed were collected from 136 fields in 10 Georgia counties and from 290 fields in 29 North Carolina counties. Glyphosate-resistant Palmer amaranth was detected in 10 Georgia counties and in 71 of 136 surveyed fields. In North Carolina, glyphosate-resistant Palmer amaranth was detected in 11 counties and in 49 of the 290 fields sampled. Hectares infested with the resistant biotype more than doubled between 2005 and 2008.