Weed Management - Peter Sikkema - 4

Weed Management in Corn, Soybean & Wheat
Questions from Ontario Farmers
1
Swanton, UG
Ragweed in soybean Giant ragweed in corn Canada fleabane in wheat
Atriplex in corn Wild Carrot in corn
Peter H. Sikkema
Eastern Ontario Crops
Conference
February 14, 2017
Sikkema, UG Sikkema, UG Sikkema, UG
Sikkema, UG Sikkema, UG

Question # 1
Peter, ever since I started growing RR corn and
soybean, field horsetail is an increasing problem on
my farm.
How can I control it?
2Sikkema, UG Sikkema, UG

Field Horsetail Control in Corn
3
Postemergence
37
50
66
57
73
0 20 40 60 80 100
Ultim
Broadstrike
MCPA
Ultim + Broadstrike
Ultim + MCPA
Broadstrike + MCPA
Ultim + Broadstrike +
MCPA
Weed Control (%)
Summary of 6 experimentsSikkema, UG

Field Horsetail Control in Corn
4
Postemergence
37
50
66
57
73
83
85
0 20 40 60 80 100
Ultim
Broadstrike
MCPA
Ultim + Broadstrike
Ultim + MCPA
Broadstrike + MCPA
Ultim + Broadstrike +
MCPA
Weed Control (%)

Field Horsetail – Corn – POST
Weedy Check Broadstrike (50%)
MCPA (66%) Broadstrike + MCPA (83%)

Field Horsetail
Ultim + Broadstrike + MCPA
June 11
Litwin, UG
Litwin, UGLitwin, UG
June 24

What about MCPA injury in corn?
Brace-root malformation Lodging or goose-necking
Brittle snap Onion leafing

MCPA Tolerance in Corn
8
It is pretty safe applied at V2 (4 leaf stage)
237
239
237
235
0 50 100 150 200 250
Control
1/4 X
1/2 X
1X
Yield (bu/ac)
V2 (4 leaf stage)Sikkema, UG

MCPA Tolerance in Corn
9
44 bu/ac yield loss when applied late!
237
220
207
193
0 50 100 150 200 250
Control
1/4 X
1/2 X
1X
Yield (bu/ac)
V6 (8 leaf stage)Sikkema, UG

Field Horsetail in Soybean
10
Roundup + Broadstrike + Dual applied PP
Applied: June 8
July 11
Litwin, UG

Field Horsetail Control in Soybean
11
Roundup + Broadstrike + Dual applied PP
97
95
91
89
84
0 20 40 60 80 100
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Weed Control (%)
Field horstail control in soybeanSikkema, UG

Field Horsetail Control in Soybean
12
Roundup + Broadstrike + Dual
97
95
91
89
84
46
0 20 40 60 80 100
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Weed Control (%)
Site 1 Site 2 Site 3 Site 4 Site 5 Site 6Sikkema, UG

Field Horsetail in
Soybean
13
Applied: June 8
October 15
Litwin, UG
Litwin, UGLitwin, UG
July 11

Field Horsetail
14
One month after application After harvest
Litwin, UG Litwin, UG

Field Horsetail in Wheat
MCPA is the product of choice
15

Question # 1
Peter, ever since I started growing RR corn and soybean, field
horsetail is an increasing problem on my farm.
Answer
1. Corn: Broadstrike + MCPA
a. Apply early POST
b. Only spray the patches (can cause crop injury)
2. Soybean: Roundup + Dual + Broadstrike applied PP
3. Wheat: MCPA applied POST
16

Question # 2
17
Peter, ever since I started
growing RR corn and soybean,
yellow nutsedge is an increasing
problem on my farm.
Sikkema, UG Tardif, UG

Yellow Nutsedge Control in Corn
18
Swanton, UG
Postemergence
55
0 20 40 60 80 100
Basagran
Permit (1/2X)
Permit (Low)
Permit (High)
Permit (2X)
Yellow Nutsedge Control (%) – 8 WAA

Yellow Nutsedge Control in Corn
19
Swanton, UG
Postemergence
55
82
90
93
95
0 20 40 60 80 100
Basagran
Permit (1/2X)
Permit (Low)
Permit (High)
Permit (2X)
Yellow Nutsedge Control (%) – 8 WAA

Permit provides excellent control of
yellow nutsedge POST in corn
Control
Permit (low Rate)

Classic is excellent for the control of
yellow nutsedge POST in soybean
21
Roundup + Classic Roundup
Tardif, UG

Question # 2
soybean, yellow nutsedge is an increasing problem
on my farm.
Answer
1. Corn: Permit (POST)
2. Soybean: Classic (POST)
22

Question # 3
soybean, wild carrot is an increasing problem on my
farm. How can I control it?
23
Wild carrot in wheat Wild carrot in soybean

Wild Carrot
24
Corn – Soil Applied Herbicides
40
39
68
62
64
62
0 20 40 60 80 100
Atrazine
Banvel
Marksman
Converge+Atrazine
Callisto+Atrazine
Integrity
Weed Control (%)

Wild Carrot
25
Corn – Postemergence Herbicides
50
37
69
47
56
59
46
74
0 20 40 60 80 100
Atrazine
Banvel
Distinct
Marksman
Pardner + Atrazine
PeakPlus
Callisto + Atrazine
Impact + Atrazine
Roundup
Weed Control (%)

Wild Carrot
26
Corn – Postemergence Herbicides
50
37
69
47
56
99
59
46
74
0 20 40 60 80 100
Atrazine
Banvel
Distinct
Marksman
Pardner + Atrazine
Peak + Banvel
Callisto + Atrazine
Impact + Atrazine
Roundup
Weed Control (%)

Wild Carrot
27
Sikkema, UG
Sikkema, UG
Sikkema, UG
Check
Banvel (69%)
Peak + Banvel (99%)

Wild Carrot
28
Soybean – Soil Applied Herbicides
45
37
61
58
47
71
78
51
0 20 40 60 80 100
Roundup
Lorox
Sencor
FirstRate
Boundary
Broadstrike
Pursuit
Conquest
Weed Control (%)

Wild carrot control in soybean
29
Roundup + Dual + Broadstrike
A couple of weeks after application A couple of months after application

Wild Carrot
30
Soybean – Postemergence Herbicides
6
8
27
13
79
52
56
48
33
0 20 40 60 80 100
Blazer
Reflex
Basagran
Pinnacle
Classic
FirstRate
Pursuit
Clean Sweep
Roundup
Weed Control (%)

Wild carrot control in soybean with Classic
31
Classic (79%) Classic (79%)

Wild Carrot
32
Soybean – Sequential Herbicides
98
99
0 20 40 60 80 100
Broadstrike
(PP); Classic
(POST)
Pursuit (PP);
Classic (POST)
Weed Control (%)

Wild Carrot
33
Winter Wheat – Postemergence Herbicides
23
40
35
46
73
26
76
46
51
88
0 20 40 60 80 100
2,4-D
MCPA
Target
Estaprop
Lontrel
Buctril M
Refine M
Trophy
Infinity
Peak + Pardner
Weed Control (%)

Wild Carrot
Sikkema, UG
Sikkema, UG
Sikkema, UG
Check
Refine M (76%)
Peak + Pardner (88%)

Question # 3
Ever since I started growing RR corn and soybean, wild carrot
is an increasing problem on my farm.
Answer
1. Corn: Peak applied POST
2. Soybean:
a. Broadstrike or Pursuit applied PP
b. Classic applied POST
c. Sequential of Broadstrike or Pursuit applied PP
followed by Classic POST
3. Wheat: Peak + Pardner or Refine M
35

Question # 4
Swanton, UG
Roundup Ready 2 Xtend soybean are going to be
grown for the first time in 2017.
What do you think?

What is RR2 Xtend soybean?
1. RR2 Xtend soybean
a. Same as RR2Y soybean plus…
i. Resistance to dicamba
b. Resistance to dicamba is provided by…
i. Dicamba monooxygenase (DMO)
ii. DMO rapidly metabolizes dicamba before
it can buildup to toxic levels
37

What is RR2 Xtend soybean?
2. The DNA that codes for the DMO enzyme was obtained
from a microorganism (Pseudomonas maltophilia) from a
storm water retention pond at the 25 year old dicamba
manufacturing plant near Beaumont, Texas
3. Decreases sensitivity of RR2 Xtend soybean to dicamba
by a factor of 5000
38

Benefits of RR2 Xtend Soybean
1. Improved control of …
a. Annual broadleaf weeds
i. Wild buckwheat
b. Perennial broadleaf weeds
i. Field bindweed
c. Glyphosate resistant weeds
i. Giant ragweed
ii. Canada fleabane
39

40
Glyphosate Resistant Giant Ragweed
Excellent control of GR giant ragweed with dicamba in RR2
Xtend Soybean
Vink, UG Vink, UG
Roundup Roundup + dicamba

41
32
0 20 40 60 80 100
Roundup (PP); Roundup
(POST)
Rdup (PP); Rdup + Banvel
300 (POST)
Rdup + Banvel 300 (PP);
Roundup (POST)
Rdup + Banvel 300 (POST)
Roundup (POST)
GR Canada fleabane control (%) – 8 WAA
Glyphosate Resistant Canada Fleabane
Byker, UG

42
32
83
87
0 20 40 60 80 100
(POST)
300 (POST)
Roundup (POST)
Roundup (POST)
Byker, UG

43
32
83
87
95
0 20 40 60 80 100
(POST)
300 (POST)
Roundup (POST)
Roundup (POST)
Byker, UG

44
32
83
87
95
97
0 20 40 60 80 100
(POST)
300 (POST)
Roundup (POST)
Roundup (POST)
Byker, UG

45
Roundup PP; Roundup POST Roundup + Dicamba 600 (PP); Roundup (POST)
Excellent control of GR Canada fleabane with dicamba in
RR2 Xtend Soybean

Question # 4
Swanton, UG
grown for the fist time in 2017.
What do you think?
Answer
I think this new technology will address some the
weed control challenges in soybean in Ontario, BUT
Applicators will have to be very careful to avoid off-
site injury

Question # 5
Swanton, UG
Roundup Ready 2 Xtend soybean are going to be grown
for the first time in 2017.
Are you concerned about off-site movement?
YES
Off-site movement could be due to …
Drift
Volatilization
Temperature Inversion

Dicamba – Off-site Movement
Swanton, UG
RR2 Xtend Soybean Field

Swanton, UG
1. Spray date – June 29 at 12:30 pm
2. Wind speed – medium from NW
3. Soybean growth stage at application – V2
4. Sprayer
a. Application speed – 8 mph
b. Water volume – 15 gal/acre
c. Spray pressure - 30-40 psi
d. Boom height – 18 inches
e. Boom length – 100 feet
f. Nozzles – Hypro ultra low drift nozzles 120o, Red, 20 inch spacing
5. Herbicides
a. Xtendimax – 0.7 L/ac (612 g/ha)
b. Roundup (1 l/ac)
c. Classic (14 g/ac)
Summary

Swanton, UG
RR2 Xtend Soybean Field
Sikkema, UG
RR2Y Soybean Field
Sikkema, UG
Sikkema, UG

Swanton, UG
Injury symptoms in RR Soybean 1 m from source of dicamba

Swanton, UG

Question # 5
Swanton, UG
Roundup Ready Xtend soybean are going to be
Are you concerned about off-site movement?
Answer
I am very concerned
Soybean yield losses of greater than 10 bu/ac have
been documented.

Question # 6
Swanton, UG
grown for the first time in 2017.
How important will tank clean out be prior to
spraying regular RR2Y soybean?

Severe injury in RR2Y soybean due to
dicamba tank contamination
59
0
20
40
60
80
0.125 0.25 0.5 1 2.5 5 10
2-3 trifoliate First flower
Dicamba Tank Contamination (%)
Sikkema, UG
SoybeanInjury-%7DAA
1/8 of 1% Tank Contamination
11% injury – 2-3 trifoliate
6% injury – first flower

Dicamba
Tank
Contamination
Control
Sikkema, UG

Dicamba
Tank
Contamination
Control 0.125%

Dicamba
Tank
Contamination
Control 0.125% 0.25%
0.5% 1.0%
2.5% 5% 10%

63
0
20
40
60
80
100
0.125 0.25 0.5 1 2.5 5 10
V2-3 (2-3 trifoliate) R1 (First flower)
Sikkema, UG
Soybeanyield-%ofcheck
Dicamba Tank Contamination (%)
Substantial yield loss in RR2Y soybean
due to dicamba tank contamination
1/8 of 1% Tank Contamination
7% yield loss – 2-3 trifoliate
10% yield loss – first flower

Question # 6
Swanton, UG
Roundup Ready Xtend soybean are going to be
How important will tank clean out be prior to
spraying regular RR soybean?
Answer
Extremely important!

Question # 7
Peter, I had planned to spray my corn before the
weeds were 10 cm (4 inches) in height but we
have had three rain events and the weeds are now
20 cm (8 inches) tall.
Will there be a yield loss?
65

Corn yield decreases as weed size
increases at time of application
66
203
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
Yield(bu/ac)
Nurse, AAFC
Sikkema, UG

67
203 195
0
50
100
150
200
250
300
Nurse, AAFC
Sikkema, UG
Yield(bu/ac)
8 bu/ac
Yield loss
2 bu/ac
loss
for every
2.5 cm in
weed
height

68
203 195
181
0
50
100
150
200
250
300
Yield(bu/ac)
Nurse, AAFC
Sikkema, UG
2 bu/ac
loss
for every
2.5 cm in
weed
height
3.5 bu/ac
loss
for every
2.5 cm in
weed
height
8 bu/ac
Yield loss
22 bu/ac
Yield loss

69
2 bu/ac
loss
for every
2.5 cm in
weed
height
3.5 bu/ac
loss
for every
2.5 cm in
weed
height
203 195
181
159
0
50
100
150
200
250
300
Yield(bu/ac)
Nurse, AAFC
Sikkema, UG
2 bu/ac
loss
for every
2.5 cm in
weed
height
3.5 bu/ac
loss
for every
2.5 cm in
weed
height
5.5 bu/ac
loss
for every
2.5 cm in
weed
height
8 bu/ac
Yield loss
22 bu/ac
Yield loss
44 bu/ac
Yield loss

Question # 7
Peter, I had planned to spray my corn before the weeds were
10 cm (4 inches) in height but we have had three rain events
and the weeds are now 20 cm (8 inches) tall.
Will there be a yield loss?
Answer
Most likely.
Corn is very sensitive to early weed competition. I think all
corn producers should consider a two-pass weed control
program of a PRE herbicide followed by a POST herbicide.
70

Question # 8
OK Peter, you convinced me that I should use a
PRE herbicide in my RR corn.
Does it matter which PRE herbicide I use?
71

Which soil applied herbicide should I
use?
Which one is the best?
72
Lots to choose from…
Primextra
Converge
Integrity
Lumax

Which soil applied herbicide should I use?
73
Depending on the weed spectrum, sometimes it does not matter*
0
20
40
60
80
100
Pigweed, Green Lamb's-quarters Lady's Thumb Barnyard Grass Foxtail, Green
Primextra Integrity Converge Lumax
WeedControl(%)4WAE
Nurse, AAFC
Gillard, UG
Sikkema, UG *Set up rates were used. Weed control ratings prior to Roundup applied POST

74
Depending on the weed spectrum, sometimes it does matter*
44
64
0
20
40
60
80
100
Velvetleaf Ragweed, Common
WeedControl(%)4WAE
Nurse, AAFC
Gillard, UG

75
44
6464
74
65
77
0
20
40
60
80
100
WeedControl(%)4WAE
Nurse, AAFC
Gillard, UG

76
44
6464
74
65
7776
83
0
20
40
60
80
100
WeedControl(%)4WAE
Nurse, AAFC
Gillard, UG

77
No difference in corn yield*
107 d
202 abc 204 abc 205 abc 210 ab 207 ab
0
50
100
150
200
250
Weedy Primextra Integrity Converge Lumax Weed-free
Corn Yield (bu/ac)
CornYield(bu/ac)
Nurse, AAFC
Gillard, UG
Sikkema, UG *Two-pass weed control – PRE residual fb Roundup POST

Question # 8
OK Peter, you convinced me that I should use a PRE residual
herbicide in my RR corn.
Does it matter which one I use?
Answer
1. Yes, it will depend on…
a. Weed control
i. Weed species composition and density
ii. Resistance management
b. Crop safety
i. Soil characteristics – texture, pH, OM, CEC
ii. Corn hybrid
c. Persistence – future crops in the rotation 78

Question # 9
I applied a PRE herbicide in corn and it was perfectly clean
up to the 6-leaf stage (V4), however, the last time I scouted
the field, I noticed some weeds.
Will they reduce corn yield?
Is it worth it to apply a POST herbicide?
79
Weed free to 2-leaf Weed free to 10-leaf

Experimental Design
80
Weedy check Weed free to 2-leaf Weed free to 4-leaf
Weed free to 6-leaf Weed free to 8-leaf Weed free to 10-leaf

End of season weed control improves
the longer the corn is kept weed free
81
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
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
WeedControl(%)–42DAA

82
Keep corn weed-free until at least the
6-leaf stage
105
185
198 206 207 206 204
0
50
100
150
200
250
Weedy
check
2 4 6 8 10 Weed free
check
Corn leaf stage at last Roundup application
Nurse, AAFC
Sikkema, UG
Everman, MSU
Sprague, MSU
Yield(bu/ac)
19 bu/ac yield
decrease
6 bu/ac yield
decrease
0 bu/ac yield
decrease

83
Weedy (-99 bu/ac) WF to 2-leaf (-19 bu/ac) WF to 4-leaf (-6 bu/ac)
Weed free to 6-leaf Weed free to 8-leaf Weed free to 10-leaf
Keep corn weed-free until at least the
6-leaf stage

Question # 9
I applied a PRE herbicide in corn and it was perfectly
clean up to the 6-leaf stage (V4), however, the last
time I scouted the field, I noticed some weeds.
Will they reduce corn yield?
Is it worth it to apply a POST herbicide?
Answer
Probably not
84

Question # 10
Swanton, UG
Peter, I have always applied Roundup at 0.67 L/ac.
Am I doing the right thing?

You have to adjust the rate of Roundup
depending on weed species for 90% control
86
0.5 0.7 0.6
0
0.5
1
1.5
2
2.5
Green foxtail Barnyard grass Redroot pigweed Lamb's-quarters Common
ragweed
RoundupRate(L/ac)
Roundup Weathermax Rate (L/ac)
Nurse, AAFC
Sikkema, UG
Weed Height = 30 cm tall

87
0.5 0.7 0.6
1.3
0
0.5
1
1.5
2
2.5
Green foxtail Barnyard grass Redroot pigweed Lamb's-quarters Common
ragweed
RoundupRate(L/ac)
Nurse, AAFC
Sikkema, UG

88
0.5 0.7 0.6
1.3
2.4
0
0.5
1
1.5
2
2.5
Green Foxtail Barnyard grass Redroot pigweed Lamb's-quarters Common
ragweed
RoundupRate(L/ac)
Nurse, AAFC
Sikkema, UG
5X the rate of Roundup

89
depending on weed height for 90% control
0.07
0.22
0.50
0.00
0.50
1.00
1.50
10 20 30
RoundupRate(L/ac)
Green foxtail
Weed Height (cm)
Nurse, AAFC
Sikkema, UG

90
depending on weed height for 90% control
0.46
0.67
1.28
0.00
0.50
1.00
1.50
10 20 30
RoundupRate(L/ac)
Lamb's-quarters
Weed Height (cm)
Nurse, AAFC
Sikkema, UG

Question # 10
1. The rate of Roundup needs to be adjusted
depending on weed species. In general, with
Roundup, the weeds that are easiest to most
difficult control are…
a. Easiest – Annual and perennial grasses
b. Intermediate – Annual broadleaf weeds
c. Most difficult – Perennial broadleaf weeds
i. There are species differences within each of
the above groups
Summary

Question # 10
2. Weed control decreases as weed size at the
time of application increases
a. Generally, the increase in weed size can be
overcome by increasing the rate of Roundup
Summary

Question # 10
Peter, I have always applied Roundup at 0.67 L/ac.
Am I doing the right thing?
Answer
Probably not

Question # 11
94
Swanton, UG
Peter, my corn is in the V5 stage and I noticed
some Canada fleabane escapes after my
POST application of Roundup. I have never
seen them on the farm before, so I assume
they are glyphosate resistant.
Is it OK to add some 2,4-D to my late in-crop
application of Roundup to control GR Canada
fleabane?

Phenoxies
1. Lodging or goose
necking caused by…
a. Heavy rain and high
winds
i. Saturated soils
b. Late application of
Roundup + 2,4-D
c. Sensitive hybrid
95
Corn Injury
Symptoms
Tolerant Hybrid
Sensitive Hybrid - 25 bu/acre yield loss
Sensitive Hybrid
Sikkema, UG

2,4-D injury in corn
Brace-root malformation Lodging or goose-necking
Brittle snap Onion leafing

Can I add 2,4-D to Roundup for the
control of GR Canada fleabane?
97
Corn Injury (1 WAA)
0
5
0
5
10
15
20
25
Roundup 2,4-D Roundup + 2,4-D
1X
Sikkema, UG
CornInjury(%)–1WAA
V1,3,5 application - Mean of 2 hybrids at 4 sites = 24 data points

98
Corn Injury (1 WAA)
0
5
19
0
5
10
15
20
25
1X
V1,3,5 application - Mean of 2 hybrids at 4 sites = 24 data points
CornInjury(%)–1WAA
Sikkema, UG
14% synergistic
increase in injury

99
5-17% Synergistic
Increase in Injury
248
233
0
50
100
150
200
250
300
1X
CornYield(bu/ac)
V1, V3, V5 application - Mean of 2 hybrids at 3 sites = 18 data points
Sikkema, UG
15 bu/ac
Yield loss

100
5-17% Synergistic
Increase in Injury
248
233 225
0
50
100
150
200
250
300
1X
CornYield(bu/ac)
V1, V3, V5 application - Mean of 2 hybrids at 3 sites = 18 data pointsSikkema, UG
23 bu/ac
Yield loss
Synergistic
15 bu/ac
Yield loss

Question # 11
Peter, I noticed some Canada fleabane escapes in
my Roundup Ready Corn.
Is it OK to add some 2,4-D to my late in-crop
application of Roundup to control the GR Canada
fleabane?
Answer
No. There is potential for corn injury and yield loss.
It would be OK if you have Enlist corn.
101

Weed Management in Corn, Soybean & Wheat
Questions from Ontario Farmers
• Funding agencies
• Research technicians
• Graduate students
• Summer research assistants
102
Acknowledgements

Weed Management - Peter Sikkema - 4

Weed Management - Peter Sikkema - 4

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