Living and Learning with Herbicide Resistant Weeds

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Living and Learning withHerbicide Resistant Weeds

• Eric P. Prostko and A. Stanley Culpepper
• Extension Weed Specialists
• Department of Crop Soil Sciences

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UGA Weed Science TeamSupporting Cast Crew

• UGA Faculty
• Tim Grey (Tifton)
• Bill Vencill (Athens)
• Mark Czarnota (Griffin)
• Tim Murphy (Griffin)
• USDA-ARS
• Carroll Johnson
• Ted Webster
• Post-Docs
• Lynn Sosnoskie
• Valdosta State Univ.
• Richard Carter

• Technical Support
• Charlie Hilton
• Amy Davis
• Jesse Parker
• Kevin Baldree
• Administrative
• Dena Watson
• Graduate Students
• Rebekah Wallace
• Trey Cutts
• Student Workers
• Too many to mention but
• Very valuable to program

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Palmer Amaranth in Georgia
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Do what must be done?
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Why Palmer Amaranth (Amaranthus palmeri)?

• 38 species of Amaranthus in U.S.
• 27 species found in SE
• dioacious
• grows faster than other pigweeds (1-2 per day!!)
• more competitive than other pigweeds
• prolific seed producer
• seed to seed 9-12 WAE
• 2 generations/year
• herbicide tolerance

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Herbicide Resistance Concerns in Georgia

• glyphosate
• ALS herbicides
• Atrazine
• Multiple resistance
• Glyphosate ALS

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Georgia counties confirmed to be infested with
glyphosate-resistant Palmer amaranth.
2004 1 county
2005 2 counties
2006 7 counties
2007 10 counties
2008 6 so far
1-28-09
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GA Confirmed ALS-Resistant Palmer Sites
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2008 Triazine Resistance SurveyMacon County
4/20 sites resistant to 10X rate (4,5,15,20) 6/20
sites took 5 qts/A to kill (3,6,8,14,17,19)
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Site 5 Atrazine Resistance Survey
0
0.1
1
5
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Atrazine (qts/A)
Not resistant to Evik (ametryn) or Direx (diuron)
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How did this happen to us?????

• Economics drive farmer decisions
• No real long-term weed mgt. planning
• Farm logistics
• Overuse of glyphosate
• Overuse of Staple and Cadre
• Reduced herbicides rates
• Reduced tillage
• Reduction in use of residuals
• Dryland production systems

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Palmer Amaranth Biology

• How many seed?
• How long can the seed survive in the soil?
• Where does most of the germination occur?
• Pollen Drift

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Palmer amaranth seed production in Georgia from a
single female plant when competing with cotton
for the season
450,000 Macon Co. 2006
of seeds
1,000,000 seed/plant (Keeley et al. 1987. Weed
Science 35199-204) California
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R-Palmer amaranth seed longevity
Source Dr. Lynn Sosnoskie - UGA
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Influence of burial depth on Palmer amaranth
emergence in Georgia
Source Dr. Lynn Sosnoskie - UGA
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Herbicide Resistant WeedsPollen Drift

• Off-site movement (wind, gravity, insects, man,
  animal) of resistance trait through pollen
• Pollen from resistant male fertilizes susceptible
  female to produce resistant progeny (seed)
• UGA researchers have documented GR-trait movement
  of at least 960 (Palmer amaranth).

Palmer Amaranth Pollen Source Dr. Lynn Sosnoskie
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In-field Palmer amaranth pollen movement
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Cultural Practices

• Deep tillage
• Extreme cover crops

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No Deep Tillage
Deep Turn
No Herbicide Treatment
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Palmer amaranth seedling density as influenced by
tillage.
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(No Transcript)
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Dryland Systems
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Irrigation in Georgia
Source Kerry Harrison, UGA Extension Engineer
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May-June 2008 Rainfall Distribution in Midville
Crops planted from May 21-June 21 did not receive
enough rainfall to activate herbicides (0.26
total). June Rainfall 0.62 which occurred as
follows12 (0.08) 22 (0.36) 26 (0.08) 29
(0.10)
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If residual herbicides are not activated on a
timely basis with a reliable water source,
pigweed control will be very difficult, maybe
even impossible!
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Dryland Systems

• Growers need to think about mechanical herbicide
  incorporation
• Will help but not a guarantee
• Success will depend upon
• operator
• Implement
• Soil conditions

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Chemical Control Options

• Valor (flumioxazin)
• Reflex (fomesafen)
• Dual Magnum (S-metolachlor)
• Atrazine
• Liberty-Link (glufosinate)
• Sencor products (metribuzin)
• KIH-485

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Palmer Amaranth Control in PeanutsMacon County,
GA 2007 (38 DAT)
NTC
Valor SX 51WG _at_ 3 oz/A
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Palmer Amaranth Control in PeanutsMacon County,
GA 2007 (38 DAT)
Dual Magnum 7.62EC _at_ 1 pt/A
NTC
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Macon County GR Palmer Amaranth June 24, 2008
60 DAP CN-01-08
Atrazine 4L _at_ 1 qt/A PRE Atrazine 4L _at_ 1.5 qt/A
30 DAP Peptoil _at_ 1 v/v 30 DAP
NTC
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RR vs LL Corn - 2008
Roundup W-Max _at_ 22 oz/A Atrazine _at_ 1.5 qt/A Prowl
H2O _at_ 2.1 pt/A (POST)
Ignite 2.34 SL _at_ 23 oz/A Atrazine _at_ 1.5
qt/A Prowl H2O _at_ 2.1 pt/A AMS _at_ 3 lb/A (POST)
Untreated
CN-11-08 6/17/2008 81 DAP
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Metribuzin Products on Soybeans

• Sencor
• Boundary
• Dual Magnum Sencor
• Canopy
• Sencor Classic
• Read label
• Know soil texture and OM
• Varieties
• rotations

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GR-Pigweed Control in Soybeans - 2008
NTC
Canopy 75DG _at_ 6 oz/A Prowl H2O 3.8ASC _at_ 2.1
pt/A (PRE)
SB-06-08 Macon County 48 DAP
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GR-Palmer Amaranth Control in Soybeans - 2007
Gramoxone Inteon _at_ 3 pt/A Boundary _at_ 1.8 pt/A
NIS _at_ 0.25 v/v (7 DBP) Touchdown Total _at_ 1.5
pt/A (26 DAP)
NTC
SB-01-07 Macon Co. 76 DAP
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Soybean varieties screened in 2008 that had
adequate tolerance to Boundary 6.5EC (2 pt/A),
Canopy 75DG (5 oz/A), and Sencor 75DG (6 oz/A).

• Ag South AGS 568 Asgrow H7242
• Asgrow 4903 RR/STS Delta Pineland DP 5634
• Delta Pineland DP 6568 Northrup King NKS 80P2
• Northrup King NKS 76L9 Northrup King NKS 78G6
• Pioneer 95Y40 Pioneer 95Y70
• Pioneer 96M60 Pioneer 97M50
• Southern States RT5951 Southern States RT4808
• Vigoro V61N9 Vigoro V74N9

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GR-Pigweed Control in Soybeans 2008 Macon County
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Valor _at_ 3 oz/A Envive _at_ 3 oz/A Reflex _at_ 1
pt/A Prefix _at_ 2 pt/A Canopy _at_ 6 oz/A Sencor _at_
8 oz/A KIH-485 _at_ 4.2 oz/A Dual Magnum _at_ 1 pt/A
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KIH-485

• Pyroxasulfone
• Kumiai
• Developed for corn and soybeans
• PRE
• Herbicide Family
• Sulfonylioxazoline (?)
• Herbicide Mode of Action (?)
• plant growth inhibitor that affects apical
  meristem and coleoptile development of plants
  after seed germination
• Low use rates

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GR-Palmer Amaranth Control in Soybeans with PREs
(2008) - Macon Co.
KIH-485 85WG _at_ 4.2 oz/A
NTC
SB-05-08 48 DAT
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Under Utilized Modes of Action

• HPPD-inhibitors
• Mesiotrione (Callisto)
• Tembotrione (Laudis)
• Topramezone (Impact)

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Halex GT in Field Corn - 2008
Halex GT 4.39L 4 pt/A NIS (POST)
Untreated
CN-05-08 6/19/2008 83 DAP
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Dont forget!!! There are no steel resistant
weeds!!!
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We are overusing the PPO inhibiting
herbicides!!!!!!!!

• Resistance has already been reported in other
  areas!!!
• Common waterhemp
• 2001 (Kansas)
• 2002 (Illinois)
• 2003 (Missouri)
• Common ragweed
• 2005 (Delaware)
• Wild poinsettia
• 2004 (Brazil)

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For More Weed Science Infowww.gaweed.com
eprostko_at_uga.edu 229-386-3328 (office) 229-392-1
034 (cell)