Table 1: Percent reduction in soybean fresh weight and dry weight at harvest (40 days after emergence) caused by early season interference by Palmer amaranth in greenhouse experiment.a,b

Palmer amaranth biotype Fresh weight reduction Dry weight reduction   % Individual Palmer amaranth biotypesc      Emanuel (GR) 24ab 23ab  Macon (GR) 31a 28a  Wayne (GR) 13b 11b  Crisp (GS) 31a 26a  Emanuel (GS) 37a 31a  Johnston (GS) 26ab 24ab Palmer amaranth biotypes grouped by response to glyphosated      GR group 23z 21z  GS group 31y 27y

Data are pooled over runs of the experiment. Abbreviations: GR, glyphosate resistant; GS, glyphosate susceptible. Means within a parameter and analysis followed by the same letter are not significantly different according to Fisher’s Protected LSD test at P ≤ 0.05 for fresh weight reduction and P ≤ 0.10 for dry weight reduction. Consists of six Palmer amaranth biotypes. Consists of a group of three glyphosate-resistant (GR) and a group of three glyphosate-susceptible (GS) Palmer amaranth biotypes.