Weed Control Update for Wheat

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Weed Control Update for Wheat
Managing Ryegrass
2

• Managing Ryegrass in Wheat
• Currently available Finesse
• Hoelon
• Sencor
• Axiom
• In development Mesosulfuron

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Rates of Hoelon POST on wheat and barley
Ryegrass size pt Hoelon 1- to 3-leaf 1.33
pt 3- to 4-leaf 1.33 to 2 pt 5-leaf to 2
tiller 2 to 2.67 pt
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Timing Hoelon POST
Wheat Before first node (jointing) of wheat
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Use of adjuvants with Hoelon POST
Wheat Can add 1 to 2 pt/acre COC. Suggested
only on large grass or dry conditions. Will
increase risk of injury. Do not add if cool and
wet. Do not use silicones or MSO.
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Precautions on Hoelon label
Do not apply if one or more conditions
exist Cold temperature Anytime during 72 hr
preceding application temperature drops below
35 degrees Delay application if freezing
temperature predicted within 3 days of
application Soil moisture Moisture at or
above field capacity
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Tank mixing Hoelon with other herbicides
Dont do it will lead to antagonism.
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Sequential applications of Hoelon and broadleaf
herbicides
Do not apply 2,4-D within 5 days of Hoelon
application
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• Hoelon Tank Mixes in Wheat
• Label may tank mix with liquid nitrogen
  fertilizer (28 to 32) if the timing for use
  is compatible
• UGA recommends no herbicide tank
• 1) often to late to control weeds
• 2) injury potential increased
• 3) reduced control of ryegrass

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Hoelon-resistant Ryegrass
Estimated percentage in GA ??????????????
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• Alternatives to Hoelon
• Currently available Finesse
• Hoelon
• Sencor
• Axiom
• In development Mesosulfuron

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• Using Sencor in Wheat
• Metribuzin-tolerant cultivar
• AgriPro Mason Hunter
• Clark Coker 9134
• Pioneer 2684

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Cultivar Wheat Screening Trial Plains 2001.
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• Sencor Rates Limited by Soil Types
• Label wheat 2 leaf - 2 tiller
• soil organic
  matter
• texture 0.75 2.0
• coarse 0.094 lb ai 0.125 lb ai
• medium 0.125 lb ai 0.125 lb ai
• fine 0.125 lb ai 0.1875 lb ai
• UGA research shows we need 0.25 to 0.31 lb ai
  per acre when wheat is 3 to 4 leaf

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• Sencor Rates Limited by Soil Types
• Need ideal weather conditions
• warm (not hot) periods with optimum wheat and
  ryegrass growth
• no significant rainfall for several days
• Do not add crop oil
• May add nonionic surfactant but may see 10
  additional injury

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• Sencor Efficacy on Ryegrass
• Locations
• 1 2 3 4 5
• Sencor (0.25 - 0.31 lb ai) 80 87 78
  53 97
• Hoelon (0.5 - 0.75 lb ai) 94 93 94
  69 26
• Ryegrass 3 leaf or less
• Ryegrass 1 tiller or larger
• Hoelon resistant ryegrass present.

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• Alternatives to Hoelon
• Currently available Finesse
• Hoelon
• Sencor
• Axiom
• In development Mesosulfuron

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• Axiom 68 DF
• Section 18 granted for 29 GA counties

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Georgia counties infested with diclofop-resistant
Italian ryegrass.

1. Bleckly
2. Bullock
3. Burke
4. Chattooga
5. Crawford
6. Dooly
7. Early
8. Elbert
9. Franklin
10. Glascock
11. Hart
12. Jefferson
13. Johnson
14. Laurens
15. Lee
16. Macon
17. Peach
18. Pulaski
19. Randolf

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Section 18 Granted for Axiom

• New wheat herbicide by Bayer
• 54.4 flufenacet 13.6 metribuzin
• 6 to 10 oz of product on medium or fine textured
  soils (8 to 10 oz for most soils)
• Do not apply preemergence

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Axiom at 8 oz PRE Non-treated Experiment at
Griffin, GA during 2000/2001 season
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Wheat Response to Axiom. Plains, GA, 2001.
Non-treated
Axiom 10 oz PRE
Axiom applied to emerged wheat caused no
significant injury.
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Section 18 Granted for Axiom

• New wheat herbicide by Bayer
• 54.4 flufenacet 13.6 metribuzin
• 6 to 10 oz of product on medium or fine textured
  soils (8 to 10 oz for most soils)
• Do not apply preemergence
• Apply to spike wheat hopefully before ryegrass
  emerges (must be activated by rainfall or
  irrigation)

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Ryegrass Response to Axiom. Averaged over Plains
and Tifton, GA 2001/2002.
26 DAP
98
95
80
73
injury
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Late-season Italian ryegrass control by Axiom
applied at spike wheat. Plains and Tifton GA.
2001 and 2002.
84

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Spike ryegrass
2-leaf ryegrass
Experiment designations, left to right Tifton,
2001 Plains, 2002. Axiom applied at 9 oz/A.
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Hoelon is still more effective than Axiom on
non-Hoelon resistant ryegrass if a timely
application is made
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• Alternatives to Hoelon
• Currently available Finesse
• Hoelon
• Sencor
• Axiom
• In development Mesosulfuron

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Ryegrass Response to Mesosulfuron. North
Carolina, 2001.
Non-treated Mesosulfuron POST
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Late-season Italian ryegrass control by
mesosulfuon plus iodosulfuron applied
postemergence. Plains and Tifton GA. 2001 and
2002.
99
93
94
95

Experiment designations, left to right
wheat3-01 wheat5-01 wheat6-01
Average. Mesosulfuron applied at 12.5 g ai/ha
mixed with iodosulfuron at 2.5 g ai/ha.
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Weed Control Update for Wheat
Managing Ryegrass
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• Broadleaf Weed Control Options
• Sencor Peak
• MCPA Express
• Buctril Harmony Extra
• Bronate 2,4-D
• Finesse Clarity

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Harmony Extra Rate 0.3 to
0.6 oz/A for wheat barley (0.5 oz in general)
0.3 to 0.4 oz for oats Timing 2-leaf until flag
leaf visible Adjuvant 0.25 NIS in water 0.125
NIS in nitrogen Weeds Controls garlic and most
broadleaf weeds Mixes 2,4-D to improve
cornflower, wild radish, and vetch Rotations No
restrictions of concern Grains Wheat, barley,
oats
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• Express
• 1. effective on wild radish, wild mustard, and
  other broadleaf weeds
• 2. 2-lf stage until just before flag leaf wheat
  and barley
• 3. less effective than Harmony Extra on garlic,
  henbit, shepherdsurse, and wild radish. No
  rotational restrictions of concern
• 4. tank mix with 0.125 to 0.375 lb ai of 2,4-D
  or MCPA

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Express Rate/timing 0.25 to .33 oz POST, after
2 lf to flag leaf Adjuvant 0.25 NIS
Carrier water or specific N Weeds Less
effective than Harmony Extra on garlic, henbit,
and shepherdsurse Mixes Mix with 0.25 to 0.5
pt/A of MCPA or 2,4-D Rotations No rotation
restriction Grains Wheat, barley
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• MCPA
• 1.) Similar to 2,4-D, 0.5 to 1 pt/A POST
• 2.) After wheat has 2 tillers (some labels allow
  application after 2 leaf) but before jointing
  (oats should be fully tillered)
• 3.) Wheat, barley, rye, oats

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• 2,4-D
• 1. Controls most broadleaf weeds except
  chickweed, henbit, knawel. For wild garlic
  and wild onion, increase rate according to
  label.
• 2. Apply after fully tillered but before
  jointing in wheat, oats, barley, and rye

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Susceptibility of Small Grains to Phenoxy
Herbicides As Affected by
Growth Stage
Soft dough
Fully tillered
Jointing
Increasing tolerance
Seedling
Heading
Flowering
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Wheat Response to 2,4-D. Macon County, 2000.
73
Bushels/A
53
Wheat Stage at Time of Application
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• Wild garlic
• Not a yield problem
• Major quality problem

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Wild Garlic Control in Wheat Harmony
Extra 0.5 to 0.6 oz garlic lt 12, 2-4 new
growth Peak 0.25 to 0.5 oz garlic lt
6-8 rotational concerns 2,4-D ester 2 pt
after tillering, before jointing injurious to
wheat
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Wild radish size response to grain herbicides.
Herbicide 0-8 inch 8-14 inch
bolting 2,4-D 90 70-80
lt50 MCPA 90 50-70 lt30 MCPA
Express 90 80-85 lt65 Peak
90 75-85 lt50 Express 90
50 lt50 Harmony Extra 90 50 lt50
At some stage after bolting becomes more
susceptible.
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Preharvest Herbicide Options for Small
Grains Crop Herbicides Rate
Remarks Wheat 2,4-D amine 1-2 pt Hard dough
stage or later. Barley, Rye 2,4-D ester 1-2
pt Oats 2,4-D acid/ester 1-2 pt Wheat
Glyphosate 0.5 to After hard dough stage 1.5
lb ai (30 or less moisture), at least 7 days
before harvest. Not for seed wheat. 3.8
L formulations