Stacking of Residual Herbicides.

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Stacking of Residual Herbicides.
Eric Johnson1, J. R. Moyer, F.A. Holm, K. L.,
Sapsford, L.M. Hall, J.J. Schoneau, A. M.
Smigielska, M.E. Kuchuran, and R.G.
Hornford 1Scott Research Farm
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Whats the issue?

• A number of soil residual herbicides with same
  mode of action (ALS inhibitors) introduced in the
  past 10-15 years.
• Droughts on prairies
• Concerns raised by industry agronomists about
  Everest (flucarbazone-sodium) on wheat followed
  by Odyssey (imazamoximazethapyr 11) on field
  pea.
• Injury more frequently observed on field pea when
  2 used in succession.

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Everest Odyssey
Everest
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Residual Group 2 Herbicide Usage Weed Survey
Data 1996 - 2003
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of respondents that applied a residual ALS
herbicidea, Weed Survey Questionnaire, Prairie
Provinces, 2001-2003.
aimazamethabenz, imazethapyr, imazethapyrimazamox
, flucarbazone-sodium, sulfosulfuron, and
florasulam
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Percentage of ALS soil residual herbicidesa that
were applied in successive years, Weed Survery
Questionnaire, Prairie Provinces, 2001-2003
aimazamethabenz, imazethapyr, imazethapyrimazamox
, flucarbazone-sodium, sulfosulfuron, and
florasulam
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a Other group includes sulfosulfuron
(sulfonylurea)
flucarbazone-sodium (sulfonylamino
carbonyltriazolinone) and florasulam
(triazolopyrimidine sulfonanlide)
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Group 2 Repeat Application Study

• Is a crop predisposed to Group 2 injury if a
  residual Group 2 herbicide was applied the
  previous year?
• Does the repeated application of different Group
  2 herbicides in two successive years result in
  additive or synergistic plant-back injury to
  susceptible crops grown in years three or four?

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Herbicide Residue Stacking

• The repeated application of different residual
  herbicides which results in additive or
  synergistic injury to rotational crops.

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Experiment 1

• Crop Sequence
• Year 1 Field pea
• Year 2 Wheat
• Year 3 RR canola/ Clearfield canola
• Herbicide treatments
• Year 1 Non-Group 2 Check, Odyssey
• Year 2 Non-Group 2 Check, Assert, Sundance,
  Everest, Frontline

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Site Characteristics
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Field pea wheat canola sequence

• Year 2 wheat results (predisposition to
  injury phase)

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Graph explanation
Year 1 herbicide
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Scott 1st injury rating in spring wheat (7
DAT). 2003.
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Colbys Equation
Expected Response (E)
X1 growth as a percent of control with
herbicide A
Y1 growth as a percent of control with
herbicide B
If Observed response antagonistic If Observed Response Expected
Response additive If Observed Response
Expected Response - synergistic
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Predicted vs. Observed Growth Reduction (Based on
Visual Injury Ratings 7 DAT) in Spring Wheat,
Scott, SK. 2003
Growth Reduction
Odyssey- Assert
Odyssey- Everest
Odyssey- Sundance
Odyssey- Frontline
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Scott 3rd injury rating in spring wheat (28
DAT). 2003.
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2003 - Photos taken about 14 DAT
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Scott Yield of spring wheat (bu/acre). 2003.
2002 Odyssey vs. No Odyssey p0.02


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Predicted vs. Observed Yield Reduction in Spring
Wheat, Scott, SK. 2003
Yield Reduction
Odyssey- Assert
Odyssey- Everest
Odyssey- Sundance
Odyssey- Frontline
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2004- Photos taken about 21 DAT
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Scott 3rd injury rating to spring wheat (28
DAT). 2004.
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Scott Yield of spring wheat (bu/acre). 2004.
2002 Odyssey vs. No Odyssey p NS
ab
b
b
a
b
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Ellerslie 2nd injury rating to spring wheat
(7DAT). 2004.
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Ellerslie Yield of spring wheat. (bu/acre).
2003.
2002 Odyssey pNS 2003 Group 2 NS Interaction
p0.06
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Saskatoon Yield of spring wheat. (bu/acre).
2003.
2002 Odyssey p0.03 Odyssey yield No Odyssey
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Melfort Yield of spring wheat. (bu/acre). 2003.
2002 Odyssey p0.02 2003 Group 2 NS No
interaction
Yields on Odyssey Sign. Higher Than No Odyssey
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Fairview Yield of spring wheat. (bu/acre).
2003.
2002 Odyssey p No Odyssey 2003
Group 2 NS No interaction
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Pea-Wheat-Canola Sequence Wheat phase

• Odyssey application in the pea phase predisposed
  the wheat crop to post-emergence Group 2 injury
  at Scott.
• Only 1 site-year (out of 11) where injury
  resulted in an additive or synergistic yield
  reduction.

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Field pea wheat canola sequence

• Year 2 canola results (stacking phase)
• Most responsive sites were dry in 2002 and 2003.

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Scott 1st injury rating to Roundup ready canola.
(7 DAE). 2004.
Year 1 herbicide
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Scott 3rd injury rating to Roundup ready canola.
(28 DAE). 2004.
Year 1 herbicide
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Scott Days to Flower - Roundup ready canola.
2004.
Year 1 herbicide




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Scott Yield of Roundup ready canola
(bushel/acre). 2004.
Year 1 herbicide


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Vanscoy 2nd injury rating to Roundup ready
canola. (14 DAE). 2004.
Year 1 herbicide
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Vanscoy Days to Flower - Roundup ready canola.
2004.
Year 1 herbicide


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Vanscoy Yield of Roundup ready canola
(bushel/acre). 2004.
Year 1 herbicide


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Fairview 1st injury rating to Roundup ready
canola. (7 DAE). 2004.
Year 1 herbicide
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Fairview 3rd injury rating to Roundup ready
canola. (28 DAE). 2004.
Year 1 herbicide
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Fairview Days to Flower - Roundup ready canola.
2004.
Year 1 herbicide

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Fairview Yield of Roundup ready canola
(bushel/acre). 2004.
2002 Odyssey pNS 2003 Group 2 NS No
interaction
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Ellerslie Yield of Roundup ready canola
(bushel/acre). 2004.
2002 Odyssey pNS 2003 Group 2 NS No
interaction
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Melfort Yield of Roundup ready canola
(bushel/acre). 2004.
2002 Odyssey pNS 2003 Group 2 NS No
interaction
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Lethbridge Yield of Roundup ready canola
(bushel/acre). 2004.
2002 Odyssey p0.08 2003 Group 2 NS No
interaction
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Saskatoon Yield of Roundup ready canola
(bushel/acre). 2004.
2002 Odyssey pNS 2003 Group 2 NS No
interaction
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Odyssey / Check
Check / Check
Scott 2005
Odyssey / Assert
Odyssey / Sundance
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Pea-Wheat-Canola sequenceCanola phaseSummary

• Fairview (6-7 OM) very dry in 2003, similar
  early injury ratings as Scott and Vanscoy. High
  rainfall in July and August 2004 crop
  recovered, no clear yield reduction trends.
• Yield reduction from repeated applications most
  evident at Scott and Vanscoy (dry 2002-03).

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Experiment 1

• Crop Sequence
• Year 1 Wheat
• Year 2 Field Pea
• Year 3 Wheat/ barley
• Year 4 RR Canola
• Herbicide treatments
• 2002 Non-Group 2 Check, Assert, Refine Extra,
  Sundance, Spectrum, Frontline, Everest
• 2003 Non-Group 2 Checks, Odyssey

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Results on Field Peas Year 2 (2003)

• No significant difference in field pea plant
  number over all sites
• Minimal injury observed (all locations (Combined data)
• No significant yield reduction in field peas in
  2003 with the exception of Assert carryover at
  Scott evident (no additive effect with Odyssey)
  Not registered.

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Year 3(2004)Wheat and BarleyDoes Stacking
Exist?
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Scott 2nd injury rating to barley. 2004.
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Scott 3rd injury rating to barley. 2004.
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Scott Yield of barley (bus/acre) 2004.
Year 1 Group 2 p0.23 Year 2 Group 2 p0.04 No
interaction Odyssey No Odyssey
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Vanscoy 1st injury rating to barley. 2004.
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Vanscoy 2nd injury rating to barley. 2004.
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Vanscoy barley 2004 REP 3
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Vanscoy Yield of barley (bus/acre) 2004.


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Vanscoy Yield of wheat (bus/acre) 2004.
Year 1 herbicide p0.71 Year 2 herbicide p
0.004 Odyssey No Odyssey No interaction
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Conclusions Experiment 1

• Two out of 8 site-years revealed some indication
  of stacking (Assert-Odyssey Sundance-Odyssey)
  injury in barley. Yield loss in barley occurred
  at 1 site. Dry sites (Scott and Vanscoy) most
  responsive.

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Summarize

• In some situations
• A residual Group 2 herbicide can predispose the
  following crop to injury from a post-emergence
  Group 2 herbicide
• Back to back Group 2 residual herbicides can
  result in additive or synergistic phytotoxicity
  to rotational crops Risk is higher in drought
  conditions.
• Additive or synergistic crop injury does not
  always cause crop yield loss.

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Bottom Line

• While stacking can occur, the issue is
  preventable
• Good product stewardship
• Follow herbicide rotation recommendations
  suggested for managing herbicide resistance
• Avoid sequences of Odyssey-Assert and
  Odyssey-Sundance in back-to-back applications.

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Acknowledgements Technical help of Glen
Forster, Herb Schell, Lyle Boswall, Gerry Stuber,
Lisa Ratz, Bill Sullivan and Three Links
AgResearch is much appreciated. Matching Funds
provided by Agriculture and Agri-Food Canada
Matching Investment Initiative.