weed management in corn questions from ontario farmers · pdf fileweed management in corn...
TRANSCRIPT
Peter H. Sikkema
Eastern Ontario Crop
Conference
Kemptville, ON
February 23, 2012
Weed Management in Corn
Questions from Ontario Farmers
Untreated check
Giant ragweed in corn Volunteer RR corn in corn
High rate Roundup
applied late
Primextra; Roundup
I seeded RR corn after RR
corn and noticed I have
some volunteer RR corn.
a. What can I do to control
it?
b. What is the effect on
corn yield?
Question # 1
Poor control of volunteer RR
corn in RR corn 15
6
16
0
0
0
0
0
0 20 40 60 80 100
Roundup
Liberty
Roundup + Liberty
Elim
Accent
Ultim
Option
Summit
Average of 3 studiesNurse, AAFC
Sikkema, UG
Volunteer RR corn control (%) – 56 DAA
Volunteer RR corn in RR
corn can reduce yield
252 249 245 241 234 232 228
0
50
100
150
200
250
300
Weed Free 3000 6000 12000 18000 24000 30000
Volunteer RR corn density (#/acre)
Average of 3 experiments
Yie
ld (
bu/a
c)
Nurse, AAFC
Sikkema, UG
1. There are no effective postemergence herbicides for the control of volunteer RR corn in RR corn
a. Interrow cultivation (UM)
2. Yield loss is correlated with density and environment
a. Up to 10% yield loss at 30000 plants/acre (UG)
b. Up to 13% yield loss at 16000 plants/acre (SDSU)
c. Up to 19% yield loss at 21000 plants/acre (UM)
Summary
Volunteer RR corn in RR
corn can reduce yield
I sprayed my corn at the 6? leaf stage and I noticed
some weeds that came up after application.
Will they reduce corn yield?
Is it worth it to spray again?
Question # 2
Weed free to 2-leaf Weed free to 10-leaf
Weed free to 4-leaf Weed free to 2-leaf
Weed free to 6-leaf
Weed free to 8-leaf
Weedy check
Experimental Design
Weed free to 10-leaf
61
82
91 97 99
0
20
40
60
80
100
2 4 6 8 10
Corn leaf stage at last Roundup application
Average of 13 weed species in 11 experiments
Weed C
ontr
ol (%
) – 4
2 D
AA
End of season weed control improves
the longer the corn is kept weed free
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
Keep corn weed-free until at
least the 6-leaf stage
105
185 198
206 207 206 204
0
50
100
150
200
250
Weedycheck
2 4 6 8 10 Weed freecheck
Corn leaf stage at last Roundup application
Average of 11 experiments
Yie
ld (
bu
/ac)
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
Weed free to 4-leaf Weed free to 2-leaf
Weed free to 6-leaf
Weed free to 8-leaf
Weedy check
Weed free to 10-leaf
Keep corn weed-free until at
least the 6-leaf stage
1. To be conservative, and to avoid any yield loss, corn should be kept weed free until the 6-leaf stage
2. In our studies, if corn was kept weed free until the …
a. 2-leaf state - there was no yield loss 45% of the time
b. 4-leaf stage - there was no yield loss 82% of the time
c. 6-leaf stage - there was no yield loss 100% of the time
3. There are other benefits to controlling late emerging weeds
a. Improved harvest efficiency
b. Reduced weed seed return to the soil and therefore reduced weed density the following years
Summary
Keep corn weed-free until at
least the 6-leaf stage
My weeds are pretty big, should I increase the
rate of Roundup?
Question # 3
0
20
40
60
80
100
Lady's thumb Lamb's-quarters Flower-of-an-hour
Mustard, wild Pigweed
10 cm weeds 20 cm weeds 30 cm weeds
Weed C
on
trol (%
)
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
Decrease in weed control with
Roundup as the weeds get bigger
0
20
40
60
80
100
Ragweed Smartweed, green Velvetleaf Foxtail, green
10 cm weeds 20 cm weeds 30 cm weeds
Weed C
on
trol (%
)
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
Decrease in weed control with
Roundup as the weeds get bigger
50
60
70
80
90
100
10 20 30
Weed size (cm)
112.5 225 450 675 900 1350
Weed C
ontr
ol (%
) -
42 D
AA
Sikkema, UG
Increase the rate of Roundup as
weeds get bigger
Ragweed control
203 195
181
159
0
50
100
150
200
250
Weed Free 10 cm 20 cm 30 cm
Weed size at the time of herbicide application
Average of 5 experiments
Yie
ld (
bu/a
c)
Nurse, AAFC
Sikkema, UG
Corn yield decreases as weed size at
time application increases
1. Weed control decreases as size at the time of application increases
2. Increasing the rate of glyphosate partially overcomes the problem
3. Corn yield consistently decreases as weed size at the time of application increases
a. 10 com weeds – reduction in corn yield of 8 bu/ac
b. 20 com weeds – reduction in corn yield of 22 bu/ac
c. 30 com weeds – reduction in corn yield of 44 bu/ac
Summary
Weed Size
Peter, I planned to spray much earlier but due to
frequent rain events I could not. My corn is now at
the 10-leaf stage and the weeds are more than 12
inches in height.
How high a rate of Roundup can I use and not hurt
my RR corn?
Question # 4
Untreated check High rate Roundup applied late
High rates and late application of
Roundup can injure RR corn
0 0
2
5
0 0
3
12
0
3
6
9
12
15
0.67 1.33 2.67 5.33
Roundup Weathermax Rate (Litres/acre)
8-leaf stage 10-leaf stage
Cro
p I
nju
ry (
%)
– 1
4 D
AA
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
1. Leaf tissue deterioration
a. Breakdown of tissue of the leaf that was in the whorl at the time of application
b. Usually only one leaf is affected (sometimes two)
2. Leaf wrapping
a. Looks similar to Banvel injury
3. Stem leans over 900 to 1200 cm above the ground
4. Cob deformity
What does it look like?
Roundup injury symptoms in RR corn
High rates and late
application of Roundup
can injure RR corn
9.9 9.8 9.7 9.2
9.9 9.7
8.7 8.1
0
2
4
6
8
10
0.67 1.33 2.67 5.33
Roundup Weathermax Rate (Litres/acre)
8-leaf stage 10-leaf stage
Co
b D
efo
rmity (
1-1
0)
High rates and late application of
Roundup can cause cob deformity
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
8-leaf; 5.33 L/ac 8-leaf; 2.67 L/ac
10-leaf; 1.33 L/ac
10-leaf; 2.67 L/ac
8-leaf; 1.33 L/ac
10-leaf; 5.33 L/ac
High rates and late
application of Roundup
can cause cob deformity
220 219 219 219 210
220 213 217
209 197
0
50
100
150
200
250
Weed FreeCheck
0.67 1.33 2.67 5.33
Roundup Weathermax Rate (Litres/acre)
8-leaf stage 10-leaf stage
Co
rn Y
ield
(b
u/a
c)
High rates and late application of
Roundup can reduce RR corn yield
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
1. No injury and yield loss with labeled rates and application timing
2. At 8-leaf stage there was minimal injury and no yield loss at rates up to 2.67 L/ac
a. 10 bu/ac yield loss at 5.33 L/ac
3. At 10-leaf stage there was minimal injury and no yield loss at rates up to 1.33 L/ac
a. 11 bu/ac yield loss at 2.67 L/ac
b. 23 bu/ac yield loss at 5.33 L/ac
4. To summarize
a. Increased injury with higher rates of Roundup
b. Increased injury as application was delayed
Summary
Injury and yield loss increase as the rate is
increased and application is delayed
Peter, I have no-till RR corn where I planned to put on
my preplant burndown. The corn was seeded and
it has rained ever since. I have huge dandelions
and other perennials, biennials and winter annuals.
The corn has emerged.
How high a rate of Roundup can I use and not injure
the corn?
Question # 5
Very little injury from high rates of
Roundup applied early in RR corn
0 0 0
1
0 0 0
2
0
2
4
6
8
10
0.67 1.33 2.67 5.33
Roundup Weathermax Rate (Litres/acre)
Spike - 1 leaf 1-2 leaf stage
Cro
p I
nju
ry (
%)
– 2
8 D
AA
Sikkema, UG
9.9 9.9 9.7 9.7 9.8 9.9 9.8 9.5
0
2
4
6
8
10
0.67 1.33 2.67 5.33
Roundup Weathermax Rate (Litres/acre)
Spike - 1 leaf 1-2 leaf stage
Co
b D
efo
rmity (
1-1
0)
Sikkema, UG
Very little cob deformity from high rates of
Roundup applied early in RR corn
229 226 227 228 225 229 227 223 222 221
0
50
100
150
200
250
Control 0.67 1.33 2.67 5.33
Roundup Weathermax Rate (Litres/acre)
Spike - 1 leaf 1-2 leaf stage
Co
rn Y
ield
(b
u/a
c)
Sikkema, UG
Very little yield loss from high rates of
Roundup applied early in RR corn
1. Very little impact of high rates of Roundup applied early in RR corn in respect to …
a. Visible crop injury
b. Cob deformity
c. Cob length
d. Maturity
e. Yield
Summary
Very little Injury and yield loss from high
rates of Roundup applied early in RR corn
I have used Roundup for weed control in corn for the
past few years. I am happy with the weed control
at the end of the season but it works so slow. I am
convinced that I am losing yield because Roundup
is such a slow acting herbicide.
What can I add to Roundup to increase the speed of
control and thereby increase my corn yield?
Question # 6
Speed of Roundup
0 20 40 60 80 100
Roundup alone
Ammonium Sulfate
Atrazine
Distinct
Marksman
Pardner + Atrazine
Callisto + Atrazine
Impact + Atrazine
Primextra
Elim
Weed Control (%) - 3 DAA
Average of 13 weed species in 7 experiments
Roundup Tankmixes
Sikkema, UG
Roundup plus …
Speed of Roundup
0 20 40 60 80 100
Roundup alone
Ammonium Sulfate
Atrazine
Distinct
Marksman
Pardner + Atrazine
Callisto + Atrazine
Impact + Atrazine
Primextra
Elim
Pigweed Control (%) - 3 DAA
Summary of 4 studies
Roundup Tankmixes
Sikkema, UG
Roundup plus …
Speed of Roundup
0 20 40 60 80 100
Roundup alone
Ammonium Sulfate
Atrazine
Distinct
Marksman
Pardner + Atrazine
Callisto + Atrazine
Impact + Atrazine
Primextra
Elim
Polygonum Species Control (%) - 3 DAA
Summary of 6 evaluations
Roundup Tankmixes
Sikkema, UG
Roundup plus …
Speed of Roundup
0 50 100 150 200 250
Weedy check
Roundup alone
Ammonium Sulfate
Atrazine
Distinct
Marksman
Pardner + Atrazine
Callisto + Atrazine
Impact + Atrazine
Primextra
Elim
Weed free check
Corn Yield (bu/ac)
Summary of 6 studies
Roundup Tankmixes
Sikkema, UG
Roundup plus …
1. The benefits of a tankmix partner was species specific
2. Improved control of …
a. Wild buckwheat and green smartweed with atrazine
b. Velvetleaf, ragweed, lamb’s-quarters, wild buckwheat, lady’s thumb, green smartweed and Eastern black nightshade with Distinct
3. Decreased control of …
a. Pigweed and barnyard grass with atrazine
4. The faster control did not translate into a yield increase
Summary
Speed of Roundup
Peter, there are so many formulations of glyphosate
on the market.
Is there any difference in respect to weed control, crop
tolerance and yield?
Question # 7
0
3
0 0
1
5
0
2
4
6
8
10
1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Cro
p I
nju
ry (
%)
– 1
4 D
AA
Sikkema, UG
Small difference in crop injury among
glyphosate formulations
20.1 20.2 19.9 20.1 20.0 19.5
0.0
5.0
10.0
15.0
20.0
25.0
1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Cob L
ength
(cm
)
Sikkema, UG
Small difference in cob length
among glyphosate formulations
9.7 9.1
9.7 9.2
9.7
9.0
0.0
2.0
4.0
6.0
8.0
10.0
1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Cob D
efo
rmity (
0-1
0)
Sikkema, UG
Very little difference in cob deformity
among glyphosate formulations
229 227 233 232 230 216
0
50
100
150
200
250
1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Corn
Yie
ld (
bu/a
c)
Sikkema, UG
Small difference in yield among
glyphosate formulations
45
67
88
46
70
87
51
74
87
0
20
40
60
80
100
0.5X 1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Weed C
ontr
ol (%
) -
56 D
AA
Sikkema, UG
Small difference in weed control
among glyphosate formulations
Mean of 12 weed species in 4 corn experiments
68
86
96
64
80
95
75
91 96
0
20
40
60
80
100
0.5X 1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Weed C
ontr
ol (%
) -
56 D
AA
Sikkema, UG
Small difference in weed control
among glyphosate formulations
Mean of 8 weed species in 4 soybean experiments
177 186
203
169
197 203
181 194 188
0
50
100
150
200
250
0.5X 1X 2X
Glyphosate Rate
Roundup Weathermax Clearout Wise-up + N-Tank
Corn
Yie
ld (
bu/a
c)
Sikkema, UG
Small difference in corn yield among
glyphosate formulations
Mean of 4 RR corn experiments
1. Generally little difference among glyphosate formulations in …
a. Weed control
b. Crop tolerance
2. However, it appears that Wiseup + N-Tank may …
a. Provide slightly better weed control
b. Cause slightly more crop injury and yield loss
3. The above will need to be confirmed in future studies
Summary
Glyphosate Formulations
I heard about glyphosate resistant weeds and
would like to add more diversity to my weed
management program in RR corn.
What is the best setup program in RR corn?
Question # 8
Roundup Ready Soybean
4
12 16 18
28
42
56
64 64 64 65 65 64 66
72
0
20
40
60
80
Year
Stratus
Market Share - Eastern Canada
Mark
et
Share
(%
)
Roundup Ready Corn
4 7
10 12
21
30
40
56
69
80
90
0
20
40
60
80
100
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Year
Market Share - Eastern Canada
Stratus
Mark
et
Share
(%
)
Giant Ragweed
2008
One Resistant Site
Giant Ragweed
2009
18 Resistant Sites
Essex county and Pelee Island
Giant Ragweed
2010
29 Resistant Sites
Essex, Kent and Lambton counties
Pelee Island
Giant ragweed in corn
Canada fleabane
8 sites
Essex county
Canada fleabane
2011
69 Resistant Sites
Essex, Kent, Lambton and Elgin
counties
Canada fleabane in Essex county
Two-Pass Programs
86
91
95
98
0 20 40 60 80 100
Roundup EP
Roundup LP
Roundup; Roundup
Residual; Roundup
Average of 11 species in 6 experiments
Weed Control
Sikkema, UG
Weed Control (%) – 56 DAC
Two-Pass Programs
98
98
98
97
98
99
99
99
97
97
99
50 60 70 80 90 100
Marksman
Prowl + Atrazine
Prowl + Marksman
Integrity
Converge + Atrazine
Primextra + Broadstrike
Dual + Broadstrike + Lontrel
Battalion
Atrazine
Primextra
Primextra + Callisto
Average control of 11 species in 6 experiments
Weed control
Sikkema, UG
Weed Control (%) – 56 DAC
PRE Herbicide fb
Roundup POST
Two-Pass Programs
99
96
98
98
99
98
99
99
96
96
99
50 60 70 80 90 100
Marksman
Prowl + Atrazine
Prowl + Marksman
Integrity
Converge + Atrazine
Primextra + Broadstrike
Dual + Broadstrike + Lontrel
Battalion
Atrazine
Primextra
Primextra + Callisto
Average of 6 experiments
Common ragweed control
Sikkema, UG
Ragweed Control (%) – 56 DAC
PRE Herbicide fb
Roundup POST
Two-Pass Programs
84
180
177
192
192
194
0 40 80 120 160 200
Weedy check
Roundup EP
Roundup LP
Roundup; Roundup
Residual; Roundup
Weed free check
Average of 5 experiments
Corn Yield
Sikkema, UG
Corn Yield (bu/ac)
1. Weed control was reduced with one pass Roundup programs
1. 86% control with Roundup EP
2. 91% control with Roundup LP
2. Corn yield was reduced with the one pass Roundup programs
a. 14 bu/ac less with Roundup EP
b. 17 bu/ac less with Roundup LP
Summary
Two-Pass Programs
3. The best weed control was with the two pass programs
a. 95% control with sequential application of Roundup
b. 98% control PRE residual followed by Roundup
4. Corn yield was maximized with two pass programs
a. Within 2 bu/ac of weed free control
Summary
Two-Pass Programs
5. The PRE residual followed by Roundup POST is recommended
a. Protect the full yield potential of the crop
b. Open the window for the POST Roundup
c. Reduce the selection intensity for glyphosate-resistant weeds
6. The ideal PRE residual herbicide is field specific and depends on
a. Weed species composition
b. Soil texture, pH, OM and CEC
c. Future crops in the rotation
Summary
Two-Pass Programs
Weed Management in Corn
Questions from Ontario Farmers
Untreated check
Giant ragweed in corn Volunteer RR corn in corn
High rate Roundup
applied late
Primextra; Roundup
Peter H. Sikkema
Eastern Ontario Crop
Conference
Kemptville, ON
February 23, 2012