Table 3. Genotypes(s) and frequency of surviving Palmer amaranth (Amaranthus palmeri S. Watson) plants treated to chlorimuron-ethyl, fomesafen, and glyphosate separately and in all possible combinations^a.

Herbicide treatmentb	Resistance mechanism(s) tested	Genotype(s)c	Survival frequency
			#
Chlorimuron-ethyl	Trp574Leu	Heterozygous	30
		Homozygous	4
		Wild type	37
Fomesafen	ΔG210	Heterozygous	6
		Homozygous	3
Glyphosate	Amplified EPSPS copy number	≥10 EPSPS copies	33
Chlorimuron-ethyl plus fomesafen	Trp574Leu and ΔG210	Heterozygous and heterozygous	7
		Homozygous and homozygous	1
		Wild type and heterozygous	1
Chlorimuron-ethyl plus glyphosate	Trp574Leu and amplified EPSPS copy number	Heterozygous and ≥10 EPSPS copies	7
		Homozygous and ≥10 EPSPS copies	7
		Wild type and ≥10 EPSPS copies	14
Fomesafen plus glyphosate	ΔG210 and amplified EPSPS copy number	Heterozygous and ≥10 EPSPS copies	7
		Homozygous and ≥10 EPSPS copies	4
Chlorimuron-ethyl plus fomesafen plus glyphosate	Trp574Leu, ΔG210, and amplified EPSPS copy number	Heterozygous, heterozygous, and ≥10 EPSPS copies	3
		Heterozygous, homozygous, and ≥10 EPSPS copies	4
		Heterozygous, wild type, and ≥10 EPSPS copies	1
		Heterozygous, homozygous, and wild type	1
		Homozygous, homozygous, and ≥10 EPSPS copies	1
		Wild type, heterozygous, and ≥10 EPSPS copies	4
		Wild type, wild type, and ≥10 EPSPS copies	1

^a Abbreviations: EPSPS, 5-enolpyruvylshikimate-3-phosphase synthase.

^b A total of 100 A. palmeri plants were exposed to each herbicide treatment. The frequency of surviving herbicide treated plants and their respective genotype for each resistance mechanism are presented.

^c Alleles for Trp₅₇₄Leu and ΔG210 resistance mechanisms were heterozygous, homozygous-resistant, or wild type for a total of three possible genotypes. Two genotypes were possible for EPSPS copy number. Plants with ten or more EPSPS copies possessed the EPSPS amplified genotype and plants with EPSPS copy number from 1 to 9 were denoted as the wild type.