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

Table 4

The percent of above-ground dry weight (with percent mortality in parenthesis) of ALS-resistant (AR1, AR2, and MS1) and -susceptible E. crus-galli populations at 21 d after treatment with different ALS herbicides applied alone or in combination with malathion^a,b,c,d,e.

		Above-ground dry weight
Treatment	Rate	SUS		AR1		AR2		MS1
	g ai ha^−1	% of control
Malathion	1000	105	A	92 (0)	A	137 (0)	A	126 (0)	A
Bispyribac-sodium	30	0.0	A	3.6 (70)	E	0.0 (100)	D	4.8 (85)	C
Bispyribac-sodium + malathion	30 + 1000	0.0	A	0.0 (100)^†	E	0.0 (100)	D	0.0 (100)	C
Imazethapyr	105	0.0	A	23 (0)	D	92 (0)	B	1.4 (80)	C
Imazethapyr + malathion	105 + 1000	0.0	A	33 (0)	C	87 (0)	B	0.0 (100)^†	C
Penoxsulam	35	0.0	A	71 (0)	B	51 (0)	C	33 (10)	B
Penoxsulam + malathion	35 + 1000	0.0	A	43* (15)	C	3.2* (75)^†	D	1.1* (95)^†	C

^aMeans for each population within a column followed by the same letters are not significantly different according to Fisher’s protected LSD test (𝛼=0.05).
^b*Represents reduced dry weight with addition of malathion to a particular herbicide treatment based on 𝑡-test (𝛼=0.05).
^c†Represents increased mortality with addition of malathion to a particular herbicide treatment based on chi-square test (𝛼=0.05).
^dImazethapyr and penoxsulam treatments contained a nonionic surfactant at 0.25% v/v.
^eBispyribac-sodium treatments contained a nonionic spray adjuvant and deposition aid at 2.5% v/v.