Tolerance of Glyphosate-Resistant Maize to Glyphosate Plus MCPA Amine Is Influenced by Dose and Timing
Table 1
Parameter estimates and predicted MCPA rates from regression models of visible percent field maize injury 1, 2, 4, and 8 WAT, brace root injury 8 WAT, and percent lodging prior to harvesta.
Crop injury
Application timing
Parameter estimatesb (±SE)
Predicted MCPA ratec
%
g a.e./ha
1 WAT
4-leaf corn
45 (6)
0.015 (0.002)
380
867
2415
8-leaf corn
90 (5)
0.052 (0.005)
101
215
492
2 WAT
4-leaf corn
56 (9)
0.016 (0.002)
339
751
1914
8-leaf corn
78 (4)
0.056 (0.005)
95
204
479
4 WAT
4-leaf corn
63 (22)
0.009 (0.002)
630
1380
3403
8-leaf corn
65 (4)
0.081 (0.012)
67
146
357
8 WAT
4-leaf corn
21 (6)
0.008 (0.003)
820
2414
>5040
8-leaf corn
63 (5)
0.085 (0.014)
64
140
344
Brace root
4-leaf corn
3 (1)
0.002 (0.001)
267
671
2740
8-leaf corn
9 (0)
0.068 (0.009)
8
17
38
Lodging
4-leaf corn
0 (0)
0 (0)
—
—
—
8-leaf corn
37 (7)
0.034 (0.013)
168
400
1283
WAT, weeks after treatment. bRegression parameters ((1), rectangular hyperbola): , upper asymptote; , initial slope. c, , and are the MCPA rates predicted to result in 5, 10, or 20% crop injury.
