Resistance of Echinochloa crus-galli Populations to Acetolactate Synthase-Inhibiting Herbicides

Table 3

Bispyribac-sodium, imazamox, and penoxsulam dose required to kill 50% (LD₅₀) and 90% (LD₉₀) of ALS-resistant (AR1, AR2, and MS1) and -susceptible E. crus-galli populations (with 95% CI in parenthesis)^a,b,c,d.

Herbicide	Population	LD50 (95% CI)		R/S ratio (LD50)	LD90 (95% CI)		R/S ratio (LD90)
		g ai ha^−1			g ai ha^−1
Bispyribac-sodium	AR1	49	(43–56)	15	94	(78–122)	8.3
	AR2	3.0	(1.8–4.8)	0.9	8.6	(5.3–26)	0.8
	MS1	24	(14–43)	7.2	81	(44–312)	7.1
	Susceptible	3.3	(2.4–4.7)		11	(7.5–22)
Imazamox	AR1	>1120		>94	>1120		>52
	AR2	>1120		>94	>1120		>52
	MS1	39	(34–45)	3.3	73	(61–94)	3.4
	Susceptible	12	(10–14)		21	(18–28)
Penoxsulam	AR1	>1120		>94	>1120		>42
	AR2	358	(297–437)	30	1110	(835–1669)	41
	MS1	112	(94–133)	9.4	308	(245–422)	12
	Susceptible	12	(10 to 14)		27	(22 to 35)

^aLD₅₀ and LD₉₀ were determined by conducting Probit analysis in SAS.
^bR/S ratio was calculated by dividing the LD₅₀ and LD₉₀ dose of resistant population by the LD₅₀ and LD₉₀ dose, respectively, of susceptible population.
^cAll imazamox and penoxsulam treatments contained a nonionic surfactant at 0.25% v/v.
^dBispyribac-sodium treatments contained a nonionic spray adjuvant and deposition aid at 2.5% v/v.