Tolerance of Glyphosate-Resistant Maize to Glyphosate Plus MCPA Amine Is Influenced by Dose and Timing

Table 2

Parameter estimates and predicted MCPA rates from regression models of percent maize dry weight (4 WAT), height (8 WAT), and yield^a.

Corn measurement	Application timing	Parameter estimates^b (±SE)			Predicted MCPA rate^c
		% of check	%		g a.e./ha
Dry weight		4-leaf corn	0.024 (0.015)	48 (17)	105 (4)	488	844	1971
	8-leaf corn	0.054 (0.030)	33 (5)	96 (3)	14	136	616
		%
Height	4-leaf corn	0 (0)	100 (0)	0.00001 (0.000002)	>5040	>5040	>5040
	8-leaf corn	84 (1)	15 (1)	0.0008 (0.0002)	396	1116	—
Yield	4-leaf corn	0 (0)	103 (1)	0.00003 (0.000006)	2557	4247	>5040
	8-leaf corn	70 (3)	29 (4)	0.0009 (0.0003)	184	441	1245

WAT, weeks after treatment.
^bRegression parameters ((2), descending rectangular hyperbola): , initial slope; , lower asymptote; , -intercept.
((3), inverse exponential): , lower asymptote; , magnitude of response; , slope of response.
^c, , and are the MCPA rates predicted to result in a 5, 10, or 20% reduction in percent corn dry weight, height, and yield.