Research
One Pound Power
by Greg Stewart, OMAF Corn Specialist
Research
continues to confirm the value of atrazine within modern weed control strategies.
Dr. Clarence Swanton and Kevin Chandler (Department of Plant Agriculture,
University of Guelph) with financial support from the OCPA are carefully assessing
the value of atrazine within modern weed control strategies. Most producers
will not be startled to know that atrazine continues to play a key role in
herbicide mixtures. However, these preliminary results (one year in a multi-year
study) may reinforce some of these concepts for growers and are a further
step in allowing OCPA to gather an accurate assessment of the economic value
of atrazine to the Ontario corn industry.
Table 1 summarizes the data from 2002 research sites at Elora and Woodstock.
The benefit of atrazine was greater with pre-emergence than with post-emergence
treatments. The addition of atrazine increased average yields by 16% with
pre-emergence treatments compared to 5% with post-emergence treatments. The
addition of atrazine improved overall weed control with pre-emergence treatments.
In particular, atrazine improved the control of wild buckwheat and lamb’s-quarters
with all pre-emergence treatments, and gave greater common ragweed control
with Fieldstar, Banvel, and Callisto. The addition of atrazine improved wild
buckwheat control with post-emergence treatments of Striker and Peak Plus
and improved common ragweed control with post-emergence treatments of Striker
and Callisto.
| Table 1. Weed control and corn yields with selected pre-emergence and post- emergence herbicide treatments alone and tank-mixed with atrazine at Elora and Woodstock, 2002. | |||||
| Treatment |
DOSE
(grams
ai/ha)
|
WEED
CONTROL
(%)
|
CORN
YIELD
(%
of weed free control)
|
||
| Pre-emergence |
|
no
atrazine
|
with
atrazine
|
no
atrazine
|
with
atrazine
|
| FIELDSTAR |
185
|
77
|
99
|
85
|
103
|
| BANVEL |
600
|
69
|
96
|
97
|
110
|
| CALLISTO |
175
|
71
|
98
|
92
|
109
|
| CONVERGE |
79
|
80
|
99
|
94
|
111
|
| Average of all pre-emergence treatments |
74
|
98
|
92
|
108
|
|
| Post-emergence | |||||
| STRIKER |
236
|
85
|
99
|
97
|
103
|
| BANVEL |
288
|
95
|
100
|
103
|
107
|
| CALLISTO |
100
|
91
|
99
|
97
|
105
|
| PEAK PLUS |
10/140
|
92
|
99
|
99
|
102
|
| Average of all post-emergence treatments |
91
|
99
|
99
|
104
|
|
| (C.
Swanton and K. Chandler, U. of Guelph) Notes: All treatments received a pre-emerge application of Dual II Magnum. Weed spectrum consisted of Wild Mustard, Lamb’s Quarters, Wild Buckwheat, Green Foxtail, Pigweed, and Common Ragweed. Converge was tank-mixed with 800 gai/ha of atrazine; all other treatments tank-mixed with 1000 gai/ha atrazine. |
|||||
In a separate trial to evaluate control options for wild buckwheat, atrazine provided greater wild buckwheat control when applied post-emegence than pre-emergence. Wild buckwheat was controlled with 500 g ai/ha of atrazine when applied pre-emergence and with 250 g ai/ha when applied post-emergence.