Transcript Weed Control Update for Wheat

Weed Control Update for Wheat
Managing Ryegrass
Managing Ryegrass in Wheat
• Currently available: Finesse
Hoelon
Sencor
Axiom
• In development:
Mesosulfuron
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
Timing Hoelon POST
Wheat:
Before first node (jointing)
of wheat
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.
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
Tank mixing Hoelon
with other herbicides:
Don’t do it; will lead to antagonism.
Sequential applications of
Hoelon and broadleaf herbicides:
Do not apply 2,4-D
within 5 days of Hoelon application
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
Hoelon-resistant Ryegrass
Estimated percentage in GA:
??????????????
Alternatives to Hoelon
• Currently available: Finesse
Hoelon
Sencor
Axiom
• In development:
Mesosulfuron
Using Sencor in Wheat

Metribuzin-tolerant cultivar
AgriPro Mason
Hunter
Clark
Coker 9134
Pioneer 2684
Cultivar Wheat
Screening Trial;
Plains 2001.
Sencor Rates Limited by Soil Types

Label: wheat 2 leaf - 2 tiller
soil
texture
coarse
medium
fine

organic matter
0.75
0.094 lb ai
0.125 lb ai
0.125 lb ai
2.0
0.125 lb ai
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
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
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)
93
94
69
26*
*Ryegrass
94
3 leaf or less
**Ryegrass 1 tiller or larger
*Hoelon resistant ryegrass present.
Alternatives to Hoelon
• Currently available: Finesse
Hoelon
Sencor
Axiom
• In development:
Mesosulfuron
Axiom 68 DF
• Section 18 granted for 29 GA counties
Georgia counties infested with diclofop-resistant Italian ryegrass.
1.
2.
3.
4.
5.
6.
7.
8.
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12.
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14.
15.
16.
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18.
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21.
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28.
29.
Bleckly
Bullock
Burke
Chattooga
Crawford
Dooly
Early
Elbert
Franklin
Glascock
Hart
Jefferson
Johnson
Laurens
Lee
Macon
Peach
Pulaski
Randolf
Schley
Screven
Sumter
Taylor
Terrell
Twiggs
Walker
Washington
Webster
Wilkinson
26
4
9
11
8
10
27
3
12
5
23
20
29
17
25
1
18
16
6
22
28
19
24
7
15
13
14
21
2
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
Axiom at 8 oz PRE
Non-treated
Experiment at Griffin, GA during 2000/2001 season
Wheat Response to Axiom. Plains, GA, 2001.*
Axiom 10 oz PRE
*Axiom applied to emerged wheat caused no significant injury.
Non-treated
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)
Ryegrass Response to Axiom. Averaged over
Plains and Tifton, GA 2001/2002.
26 DAP
100
% injury
80
95
98
73
60
80
8 oz
10 oz
40
20
0
PRE
Spike
Late-season Italian ryegrass control by Axiom applied
at spike wheat. Plains and Tifton GA. 2001 and 2002.
100
80
84
60
40
20
0
52
Spike
ryegrass
2-leaf
ryegrass
Experiment designations, left to right: Tifton, 2001; Plains, 2002.
Axiom applied at 9 oz/A.
Hoelon is still more effective than
Axiom on non-Hoelon resistant
ryegrass if a timely application is
made
Alternatives to Hoelon
• Currently available: Finesse
Hoelon
Sencor
Axiom
• In development:
Mesosulfuron
Ryegrass Response to Mesosulfuron.
North Carolina, 2001.
Non-treated
Mesosulfuron POST
Late-season Italian ryegrass control by mesosulfuon plus
iodosulfuron applied postemergence. Plains and Tifton GA.
2001 and 2002.
100
99
80
93
94
60
40
20
0
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
Broadleaf Weed Control Options
Sencor
Peak
MCPA
Express
Buctril
Harmony Extra
Bronate
2,4-D
Finesse
Clarity
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
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
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
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
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
Susceptibility of Small Grains to Phenoxy Herbicides
Increasing tolerance
As Affected by Growth Stage
Wheat Response to 2,4-D.
Macon County, 2000.
2,4-D (1 pt/A)
80
60
40
73
53
20
0
3-leaf
full tiller
Wheat Stage at Time of Application
Wild garlic
• Not a yield problem
• Major quality problem
Wild Garlic Control in Wheat
Harmony Extra: 0.5 to 0.6 oz
garlic < 12”, 2-4” new growth
Peak:
0.25 to 0.5 oz
garlic < 6-8”
rotational concerns
2,4-D ester:
2 pt; after tillering, before jointing
injurious to wheat
Wild radish size response to grain herbicides.
Herbicide
0-8 inch
8-14 inch
bolting
2,4-D
90+
70-80%
<50%
MCPA
90+
50-70%
<30%
MCPA + Express
90+
80-85%
<65%
Peak
90+
75-85%
<50%
Express
90+
50%
<50%
Harmony Extra
90+
50%
<50%*
*At some stage after bolting becomes more susceptible.
Preharvest Herbicide Options for Small Grains
Crop
Wheat &
Herbicides
Rate
2,4-D amine*
1-2 pt
Barley, Rye 2,4-D ester*
Remarks
Hard dough stage or later.
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