Questions swac 2016

Peter H. Sikkema Eastern Ontario

Crop Conference Kemptville, ON

February 18, 2016

Weed Management in Corn, Soybean & Wheat Questions from Ontario Farmers

Atriplex in corn

Giant ragweed in corn Ragweed in soybean

Wild Carrot in corn

Canada fleabane in wheat

Sikkema, UG

Sikkema, UG Sikkema, UG


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?

Question # 1

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

Yiel

d (b

u/ac

)

Nurse, AAFC Sikkema, UG

Corn yield decreases as weed size increases at time application

203 195

0

50

100

150

200

250




Yiel

d (b

u/ac

)



8 bu/ac Yield loss

2 bu/ac loss

for every 2.5 cm

203 195 181

0

50

100

150

200

250




Yiel

d (b

u/ac

)



8 bu/ac Yield loss

22 bu/ac Yield loss

3.5 bu/ac loss

for every 2.5 cm in

weed height

2 bu/ac loss

for every 2.5 cm in

weed height

203 195 181

159

0

50

100

150

200

250




Yiel

d (b

u/ac

)



8 bu/ac Yield loss

22 bu/ac Yield loss

44 bu/ac Yield loss

5.5 bu/ac loss

for every 2.5 cm in

weed height

3.5 bu/ac loss

for every 2.5 cm in

weed height

2 bu/ac loss

for every 2.5 cm in

weed height

1. Corn yield decreases as weed size at the time of application increases

a. 10 cm weeds – reduction in corn yield of 8 bu/ac b. 20 cm weeds – reduction in corn yield of 22 bu/ac c. 30 cm weeds – reduction in corn yield of 44 bu/ac

Summary

Question # 1

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?

Question # 1

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.

Peter, I have always applied Roundup at 0.67 L/ac. Am I doing the right thing?

Question # 2

Weed Height = 30 cm tall

You have to adjust the rate of Roundup depending on weed species for 90% control


0.5 0.7

0.6

0

0.5

1

1.5

2

2.5

Green foxtail Barnyard grass Redroot pigweed Lamb's-quarters Commonragweed

Rou

ndup

Rat

e (L

/ac)

Roundup Weathermax Rate (L/ac)

Weed Height = 30 cm tall

You have to adjust the rate of Roundup depending on weed species for 90% control


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 Commonragweed

Rou

ndup

Rat

e (L

/ac)

Roundup Weathermax Rate (L/ac)

0.07

0.22

0.50

0.00

0.50

1.00

1.50

10 20 30

Rou

ndup

Rat

e (L

/ac)

Green foxtailNurse, AAFC Sikkema, UG

Weed Height (cm)

You have to adjust the rate of Roundup depending on weed height for 90% control

0.46

0.67

1.28

0.00

0.50

1.00

1.50

10 20 30

Rou

ndup

Rat

e (L

/ac)

Lamb's-quartersNurse, AAFC Sikkema, UG

Weed Height (cm)

You have to adjust the rate of Roundup depending on weed height for 90% control

1. The rate of Roundup needs to be adjusted depending on weed species. In general, the weeds to control from easiest to most difficult with Roundup 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 # 2

2. Weed control decreases as size at the time of application increases

a. Generally, the increase in size can be overcome by increasing the rate of Roundup

Summary

Question # 2

Peter, I have always applied Roundup at 0.67 L/ac. Am I doing the right thing?

Question # 2

Answer

Probably not

Question # 3

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?

Corn Injury Symptoms

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

Sensitive Hybrid – 25 bu/acre yield loss

189 bu/ac 164 bu/ac Sikkema, UG

2,4-D Injury in Corn

Lodging or goose-necking

Brace-root malformation Onion leafing Sikkema, UG

Sikkema, UG

Brittle snap Sikkema, UG

Sikkema, UG

0 4

0

11

0

10

20

30

40

50

Roundup 2,4-D Roundup + 2,4-D

1X 2X

Sikkema, UG

Cor

n In

jury

(%) –

1 W

AA

V5 application - Mean of 2 hybrids at 2 sites = 4 data points

Can I add 2,4-D to Roundup for the control of GR Canada fleabane?

Corn Injury (1 WAA)

0 4

9

0

11

28

0

10

20

30

40

50


1X 2X

Cor

n In

jury

(%) –

1 W

AA

Sikkema, UG


5-17% Synergistic

Increase in Injury

V5 application - Mean of 2 hybrids at 2 sites = 4 data points

Corn Injury (1 WAA)

269 253

269 241

0

50

100

150

200

250

300


1X 2X

Cor

n Yi

eld

(bu/

ac)

Sikkema, UG


16-28 bu/ac Yield loss

V1, V3, V5 application - Mean of 2 hybrids at 1 site = 6 data points

269 253 241

269 241

223

0

50

100

150

200

250

300


1X 2X

Cor

n Yi

eld

(bu/

ac)

Sikkema, UG




V1, V3, V5 application - Mean of 2 hybrids at 1 site = 2 data points

Question # 3

Answer

No. There is potential for corn injury and yield loss.

It would be OK if you have Enlist corn

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?


Question # 4

Peter, ever since I started growing RR corn and soybean, field horsetail is an increasing problem on

my farm. How can I control it?

Field Horsetail Control in Corn

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 experiments

Postemergence

Sikkema, UG

Field Horsetail Control in Corn

37

50

66

57

73

83

85

0 20 40 60 80 100

Ultim

Broadstrike

MCPA

Ultim + Broadstrike

Ultim + MCPA

Broadstrike + MCPA


Weed Control (%) Summary of 6 experiments

Postemergence

Sikkema, UG

Weedy Check

Field Horsetail - Corn - POST

MCPA (66%) Broadstrike + MCPA (83%)

Broadstrike (50%)

Sikkema, UG


Sikkema, UG

Field Horsetail


June 11 Litwin

June 24 Litwin

Litwin

What about MCPA injury in corn?

Lodging or goose-necking Brace-root malformation

Onion leafing


Brittle snap Sikkema, UG Sikkema, UG

MCPA Tolerance in Corn

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)

44 bu/ac yield loss when applied late!

Sikkema, UG

MCPA Tolerance in Corn

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)

It is pretty safe applied at V2 (4 leaf stage)

Sikkema, UG

Field Horsetail in Soybean

Roundup + Broadstrike + Dual

Applied: June 8

July 11 Litwin

Field Horsetail Control in Soybean

89

95

46

91

84

97

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 6


Sikkema, UG

Field Horsetail in Soybean


Applied: June 8

July 11 October 15

Litwin

Litwin Litwin

Field Horsetail


One month after application After harvest

Litwin Litwin

Field Horsetail in Wheat

MCPA is the product of choice


Question # 4

Peter, ever since I started growing RR corn and soybean, field horsetail is an increasing problem on

my farm. How can I control it?

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

Question # 5

Should I add AMS to Roundup in my RR corn and soybean?

1. The purpose of adding AMS is to tie up cations prior to adding glyphosate to the tank

a. Calcium b. Magnesium

To take note of …

Should I add AMS to Roundup?


How did we answer this question?

These are the rates and prices used:

Roundup Rate 0.67 L/ac Roundup Cost $8.00/L

Price/acre $5.36/ac

AMS Rate 1 L/ac AMS Cost $3.00/L Price/acre $3.00/ac


There are two options …

Roundup (0.67 L/ac) $5.36/ac

AMS (1.0 L/ac) $3.00/ac

Total cost/acre $8.36/ac




Farmer A

Add AMS

Farmer B

Increase the rate of Roundup

72 81

74 84

0

20

40

60

80

100

1/2X 1X

Roundup Roundup + AMS

Wee

d C

ontro

l (%

)

Sikkema, UG

Weed Control (1 WAA)

Glyphosate Rate


72 81

74 84 81

86

0

20

40

60

80

100

1/2X 1X

Roundup Roundup + AMS Roundup + Roundup

Wee

d C

ontro

l (%

)


Glyphosate Rate

Sikkema, UG


83 90

84 92 88 92

0

20

40

60

80

100

1/2X 1X

Roundup Roundup + AMS Roundup + Roundup

Wee

d C

ontro

l (%

)

Sikkema, UG


Glyphosate Rate


Question # 5

Answer

1. There is a greater increase in weed control by simply increasing the rate of Roundup.

2. Corn and soybean yields were equivalent

Should I add AMS to glyphosate in my RR corn and soybean?

1. Results may vary depending on a. Water source b. Weed species c. Environmental conditions d. Glyphosate formulation

Summary Thoughts


Peter, I really would like to underseeded my wheat to red clover. What are my herbicide

options?

Question # 6


61

26

52

71

69

30

0 20 40 60 80 100

2,4-D

Target

Estaprop

Buctril M

Refine

Trophy

Infinity

Red Clover Biomass (% of control) - 19 site yearsRobinson, UG

Winter Wheat – Red Clover

61

26

52

100

71

69

30

0 20 40 60 80 100

2,4-D

Target

Estaprop

Buctril M

Refine

Trophy

Infinity

2,4-D Target Estaprop Buctril M Refine Trophy InfinityRobinson, UG


Red Clover biomass (% of control)

Check

Buctril M

Sikkema, UG

Sikkema, UG

Target

Infinity

Sikkema, UG

Sikkema, UG


Peter, I really would like to underseeded my wheat to red clover. What are my herbicide

options?

Question # 6

Answer

I think Buctril M is your best option

Buctril M

Winter Wheat & Red Clover

1. Apply when the red clover is in the 1st to 3rd trifoliate and when the wheat provides a protective canopy over the clover a. May burn clover when hot &

dry i. May not come back

b. Most of the time at harvest there is no difference

Bourassa, Dupont

Bourassa, Dupont

Buctril M

Question # 7

I have heard about glyphosate resistant weeds so I want to add a

tankmix partner to my preplant burndown. Is it safe to add 2,4-D

prior to seeding soybean?

Less than 1% injury with 2,4-D 600 ester at 0.5 L/acre applied 7 or 14 DPP

0.6

0.5

0.0 2.0 4.0 6.0 8.0 10.0

14 DPP

7 DPP

1 DPP

7 DAP

Injury (%) 7 DAE - Mean of 6 Studies

0.5 L/acHamill, AAFC Swanton, UG Sikkema, UG

Less than 1% injury with 2,4-D 600 ester at 0.5 L/acre applied 7 or 14 DPP

0.6

0.5

3.4

3.2

0.0 2.0 4.0 6.0 8.0 10.0

14 DPP

7 DPP

1 DPP

7 DAP

Injury (%) 7 DAE - Mean of 6 Studies


Control

2,4-D PP Injury in Soybean

Leaf Strapping

Leaf Strapping Leaf Strapping

Sikkema, UG

Sikkema, UG

Sikkema, UG

Sikkema, UG

0 20 40 60 80 100

14 DPP

7 DPP

1 DPP

7 DAP

Yield (% of check) - Mean of 6 Studies


No yield loss with 2,4-D 600 ester at 0.5 L/acre applied 7 or 14 DPP

Question # 7

I have heard about glyphosate resistant weeds so I want to add a tankmix partner to my preplant

burndown. Is it safe to add 2,4-D 600 ester prior to seeding soybean?

Answer

Yes, when applied at 0.5 L/acre, 7 or 14 days prior to seeding, there was …

Less than 1% injury No yield loss

OK Peter, you convinced me that I should use a PRE residual in

my RR corn.

Does it matter which one I use?

Question # 8

Converge Engarde Integrity Lumax

Primextra

Which soil applied herbicide should I use?

Lots to choose from…

Which one is the best?

0

20

40

60

80

100

Pigweed, Green Lamb's-quarters Lady's Thumb Barnyard Grass Foxtail, Green

Integrity Converge Primextra Lumax

Wee

d C

ontro

l (%

) 4 W

AE

Depending on the weed spectrum, sometimes it does not matter*


Nurse, AAFC Gillard, UG

Sikkema, UG *Set up rates were used. Weed control ratings prior to Roundup applied POST

64

74

65

77

44

64

76 83

0

20

40

60

80

100

Velvetleaf Ragweed, Common

Integrity Converge Primextra Lumax

Wee

d C

ontro

l (%

) 4 W

AE

Which soil applied herbicide should

I use? Depending on the weed spectrum, sometimes it does matter *


Sikkema, UG *Set up rates were used. Weed control ratings prior to Roundup applied POST

107 d

205 abc 204 abc 202 abc 210 ab 207 ab

0

50

100

150

200

250

Weedy Integrity Converge Primextra Lumax Weed-free

Corn Yield (bu/ac)

Cor

n Yi

eld

(bu/

ac)


No difference in corn yield*


Sikkema, UG *Two-pass weed control – PRE residual fb Roundup POST

OK Peter, you convinced me that I should use a PRE residual in my RR corn.

Does it matter which one I use?

Question # 8

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

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?

Question # 9

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 10Weed free up to the above leaf stage

Average of 13 weed species in 11 experiments

Wee

d C

ontro

l (%

) – 4

2 D

AA

End of season weed control improves

the longer corn is kept weed free


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

Weed free up to the above leaf stage


Yiel

d (b

u/ac

)


Everman, MSU Sprague, MSU

WF to 4-leaf (-6 bu/ac) WF to 2-leaf (-19 bu/ac)

Weed free to 6-leaf

Weed free to 8-leaf

Weedy (- 99 bu/ac)

Weed free to 10-leaf

Keep corn weed-free until at least the 6-leaf stage

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?

Question # 9

Answer

Probably not

I applied a PRE herbicide in soybean and it was perfectly clean up to the V2 stage (2nd

trifoliate leaf), however, the last time I scouted the field, I noticed some weeds. Will

they reduce soybean yield? Is it worth it to apply a POST herbicide?

Question # 10

Weed free to VC Weedy check

Experimental Design

Weed free to V2 Weed free to V1



45

80

93 98 100 100

0

20

40

60

80

100

VC V1 V2 V3 V4 V5

Average of 13 weed species in 6 experiments

Wee

d C

ontro

l (%

) – 4

2 D

AA

End of season weed control improves the longer soybean is kept weed free

Sikkema, UG

Weed free until the above leaf stage

Keep soybean weed-free until the V2 stage

86 89 99 99 100 100 99 100

0

20

40

60

80

100

Weedycheck

VC V1 V2 V3 V4 V5 Weed freecheck


Yiel

d (%

of w

eed-

free

cont

rol)

Sikkema, UG

5 bu/ac yield increase

Weed free until the above leaf stage

Weed free to VC (- 5 bu/ac) Weedy check

Weed free to V2 Weed free to V1

Keep soybean weed-free until V2 stage



Question # 10

Answer

Probably not

I applied a PRE herbicide in soybean and it was perfectly clean up to the V2 stage (2nd

trifoliate leaf), however, the last time I scouted the field, I noticed some weeds. Will

they reduce soybean yield? Is it worth it to apply a POST herbicide?

1. To be conservative, and to avoid any yield loss … a. Corn should be kept weed-free until the 6-leaf stage (V4) b. Soybean should be kept weed-free until the 2nd trifoliate

leaf stage (V2) 2. There are other benefits to controlling late emerging weeds

a. Improved harvest efficiency b. Less staining of beans (ie) nightshade c. Reduced weed seed return to the soil

i. Reduced weed density in the following years

Further Thoughts

Late Emerging Weeds

What is the impact of weed competition on the yield of field crops?

Question # 11

Weed competition in corn Weed competition in soybean

56

49

34

12

3

0

10

20

30

40

50

60

Dry Bean Corn Soybean Spring Cereals Winter Wheat

Ridgetown & Exeter, ON (2007-2015) - 224 Field Studies

Yiel

d Lo

ss (%

)

Sikkema, UG

Yield Loss due to Weeds

$ lost in Ontario if no weed control

Crop

Farm Gate Value*

($ ‘000, 000)

Yield Loss (%)

Farm Gate Value

($ ‘000, 000) Corn 1397 49 680 Soybean 1939 34 663 Dry bean 118 56 66 Cereals, spring 380 12 11 Wheat, winter 92 3 11 Total 4653 1431

* 2014 - http://www.omafra.gov.on.ca/english/stats/crops/estimate_new.htm

Average 31% financial loss

Question # 11

Answer 1. If Ontario farmers did not employ any weed

management tactics the yield loss would be … a. 56% in dry beans b. 49% in corn c. 34% in soybean d. 12% in spring cereals e. 3% in winter wheat

2. $1.43 billion dollars annually

What is the impact of weed competition on the yield of field crops?

Acknowledgements

• Funding agencies • Research technicians

• Graduate students • Summer research assistants

Weed Management in Corn, Soybean & Wheat Questions from Ontario Farmers

Food

Questions swac 2016