Dr. Eric P. Prostko

Extension Weed Specialist

Dept. Crop & Soil Sciences

University of Georgia December 2004

2005 Weed Control Update(Peanut, Field Corn, Soybeans, Sunflowers)

PeanutsPeanuts

Spartan Cobra newer metolachlor formulations Valor Issues others issues

Spartan in PeanutSpartan in Peanut

Labeled in 2004 not in FL

4F formulation 4.8 to 8.0 ozs/A soil-applied broadleaf weed control nutsedge cotton rotation concerns crop injury on lighter

soils PPO inhibitor

Spartan Rotation RestrictionsSpartan Rotation Restrictions

Spartan InjurySpartan Injury

Cobra in PeanutCobra in Peanut

Labeled in Fall 2004 postemergence

6 leaf peanut90 day PHI

12.5 ozs/A broadleaf weed control a hotter Blazer tank-mixes with Basagran,

Cadre, Pursuit, Select, 2,4-DB PPO inhibitor

Metolachlor Mysteries?Metolachlor Mysteries?

9 formulations in marketplace

new metolachlors (88% s + 12% r)Dual Magnum, Dual II Magnum (Syngenta)Cinch (DuPont)

old metolachlors (50% s + 50% r)Stalwart, Stalwart C (Sipcam)Me-Too-Lachlor, Me-Too-Lachlor II (Drexel) Parallel PCS, Parallel (Makhteshim-Agan)

Metolachlor PricesMetolachlor Prices

Dual Magnum $95/gal $11.88/pt($8.16/11 ozs)

Stalwart C* $65/gal $8.13/pt

Me-Too-Lachlor $61/gal $7.63/pt

*only labeled for use in field corn and popcorn

Tropical SpiderwortTropical Spiderwort

Tropical Spiderwort Response to Dual Tropical Spiderwort Response to Dual Magnum and Stalwart, Grady Co., 2004 - IMagnum and Stalwart, Grady Co., 2004 - I

89 89

74

8682

61

0

20

40

60

80

100

9 DAT 29 DAT 43 DAT

Time

Co

ntr

ol

- %

Dual MagnumStalwart

Applied PRE at 1 pt/A.

*

Tropical Spiderwort Response to Dual Tropical Spiderwort Response to Dual Magnum and Stalwart, Grady Co., 2004 - IIMagnum and Stalwart, Grady Co., 2004 - II

89 88 89

78

64

87 89 86

72

51

0

20

40

60

80

100

9 DAT 21 DAT 29 DAT 41 DAT 92 DAT

Time

Co

ntr

ol

- %

Dual MagnumStalwart

Applied POST at 1 pt/A with glyphosate to 3” tall COMBE.

*

Valor Issues: Is that hose clean?Valor Issues: Is that hose clean?

Tank/Line RinsateLine in Glyphosate

Valor and Sprayer CleanupValor and Sprayer Cleanup

Which plot had AMS?Which plot had AMS?(Both had Cadre at 1.44 ozs/A + Agrioil @ 1% v/v applied 24 DAP)

PE-08-04July 1 ,200428 DAT

Which plot had AMS?Which plot had AMS?

PE-08-04August 3, 200454 DAT

403 404

Field CornField Corn

Option vs. Accent RR corn issues

glyphosate timings

Field CornField CornOption vs. AccentOption vs. Accent

POST grass control except crabgrass OP/SU interaction roughly same cost/A 2004 Option was less

effective than Accent

Texas Panicum Control - ITexas Panicum Control - IAccent vs Option - 2004Accent vs Option - 2004

70

90

71

48

70

84

49

30

0

20

40

60

80

100

9 DAT 28 DAT 54 DAT 104 DAT

Time

Con

trol

- %

Accent Option

CN-03-04 (Ponder Farm)Applied 22 DAPPANTE = 1”, 3-4 leaf

a a

abcbcd

b

c c

d

Texas Panicum Control - IITexas Panicum Control - IIAccent vs Option - 2004Accent vs Option - 2004

79

94 90 90

7566

6055

0

20

40

60

80

100

14 DAT 35 DAT 55 DAT 104 DAT

Time

Con

trol

- %

Accent Option

CN-04-04 (Attapulgus)Applied 21 DAPPANTE = 1-2”, 2-4 leaf

ab b

a

b

a

b

a

b

Texas Panicum Control - IIITexas Panicum Control - IIIAccent vs Option - 2004Accent vs Option - 2004

73 71 687676

6156 55

0

20

40

60

80

100

13 DAT 35 DAT 55 DAT 104 DAT

Time

Con

trol

- %

Accent Option

CN-06-04 (Attapulgus)Applied 21 DAPPANTE = 1-2”, 3-4 leaf

ab ab ababc

a

ab

a

bcd

Texas Panicum Control (104 DAT) - IITexas Panicum Control (104 DAT) - IIAccent vs Option - 2004Accent vs Option - 2004

CN-04-04 (Attapulgus)Applied 21 DAPPANTE = 1-2”, 2-4 leaf

Untreated Accent @ 0.67 ozs/AAgrioil @ 1% v/v

Option @ 1.5 ozs/AMSO @ 1.25% v/v

AMS @ 3 lbs/A

Conventional or RR Systems?Conventional or RR Systems?

Are the RR hybrids any good?Are the RR hybrids any good?

79

245226

76

234 239 237

0

50

100

150

200

250

300

Untreated Accent +Atrazine

Dual fb Accent Roundup WM(split 22 ozs/A)

Weed Management System

Bu/

A

Pioneer 31G98 DK 67-60RR

CN-07-04

b b

a a a a a

Use Rates for Glyphosate in RR CornUse Rates for Glyphosate in RR Corn

RR-Corn RR-Corn 2

Normal Rate/A 0.75 ae 0.75 ae

Maximum Rate/A 0.75 ae 1.12 ae

Maximum TotalIn-Crop

1.50 ae 2.25 ae

Timing Up to V8 or 30” Up to V8 or 30”30-48” (drops)

SoybeansSoybeans

Nutsedge control in RR beans

RR cotton in RR soybeans

Mn tank-mixes Sequence tropical spiderwort glyphosate timings

Nutsedge Management in RR SoybeansNutsedge Management in RR Soybeans split applications of

glyphosatebetter on purple than yellow

tank-mix with Classic controls yellow suppresses

purple

tank-mix with Pursuitbetter on purple than yellow rotations/cost

Controlling RR Cotton in RR SoybeansControlling RR Cotton in RR Soybeans

Canopy - PREmetribuzin + chlorimuron8 ozs/A

POST glyphosate tank-mixesResource (4 ozs/A)Reflex (12 ozs/A)Classic (0.33 ozs/A)

need PRE fb POST to be most effective

Glyphosate/Manganese Tank-MixesGlyphosate/Manganese Tank-Mixes

research from VA has shown that Mn will reduce weed control when tank-mixed with glyphosate 9 to 38% reductions

depending upon species Mn not a problem with

Blazer, Classic, Pursuit, or Basagran.

Sources: Bailey et al., 2002 (Weed Technology 16:792-799) and Heckman et al., 1999 (Journal of Production Agriculture 12:445-448)

Sequence for Weed Control in RR Sequence for Weed Control in RR SoybeansSoybeans

label in October 2004 mixture of glyphosate -K

+ Dual Magnum 2.5 -3.0 pts/A

$/15-18/A0.70 ae + 0.94 ai (2.5 pts)0.84 ae + 1.13 ai (3.0 pts)

prior to 3rd trifoliate tropical spiderwort?

Tropical Spiderwort Management in RR Tropical Spiderwort Management in RR SoybeansSoybeans

Use Dual Magnum or generic PRE in known fields

tank-mix Pursuit or Classic with glyphosate

Extreme 2.17SC @ 3 pts/A = glyphosate (0.75 lb ai/A) + Pursuit (0.063 lb ai/A)

To Prevent Yield Loss in RR SoybeansTo Prevent Yield Loss in RR Soybeans

control weeds by 4-5 weeks after planting

or control weeds before

they reach 6-9” in height

or control weeds before

the V3 stage

Source: Purdue University Extension Weed Science Group, 2004(4.7 million acres of RR soybeans planted)

SunflowersSunflowers

Spartan PPI or PRE 4F @ 3-3.75 ozs/A only soil applied

broadleaf herbicide registered

University ofGeorgia

Extension Weed Science

(gaweed.com)