Controlling Controlling Palmer Palmer

Amaranth in Amaranth in SoybeanSoybean

Eric P. Prostko

Associate Professor and Extension Weed Specialist

Department of Crop & Soil Sciences

The University of Georgia

Prostko’s Picks for PigweedProstko’s Picks for Pigweed

• Know your enemy!

• Drill a well!

• Start Clean!

• Use a residual!

• POST treatments when 3” tall or less

• Remove escapes before seed production

• Think About the Future– Overuse of PPO’s

Palmer Amaranth FactsPalmer Amaranth Facts (Amaranthus palmeri)

• grows faster than other pigweeds (1-2” per day!!)

• more competitive than other pigweeds

– 1 plant/row meter = 33% soybean yield loss

• prolific seed producer

– 400,000+/plant

• Most emerges from 1” or less!

• Pollen can move at least 900’!

• Seed do not last very long in soil!

May Rainfall – CPES TiftonMay Rainfall – CPES Tifton1996-20091996-2009

0

1

2

3

4

5

6

7

Year

Inch

es .

8/14 years (57%) less than average rainfall!!8/14 years (57%) less than average rainfall!!

Soybean Irrigation in GeorgiaSoybean Irrigation in Georgia

0

5

10

15

20

25

1970 1975 1977 1980 1986 1992 1995 2000 2004 2008

Year

Acr

es (%

) .

Source: Kerry Harrison, UGA Extension Engineer

23.2%23.2%

Start Clean!!!!!!Start Clean!!!!!!Tillage/Cover Crops/ HerbicidesTillage/Cover Crops/ Herbicides

Burndown Options for Reduced Burndown Options for Reduced Tillage Soybean Production Tillage Soybean Production SystemsSystems• Primary

– Glyphosate– Gramoxone Inteon/

Firestorm/Parazone– Ignite

• Tank-mixes– 2,4-D (7-15 DBP)– Aim (0 DBP)– ET (0 DBP)– Valor (0 DBP)– Harmony Extra (14 DBP)– Express (14 DBP)– Clarity/Vision (14 DBP + 1” rainfall) – FirstShot (7-14 DBP)– Sharpen (30 DBP) DBP = days before planting

Palmer Amaranth Control with Gramoxone Inteon 2SL @ 2.5 pt/A + 80/20 @ 0.25% v/v

6 hours 4 days

7 days 19 daysAMAPA HeightLow = 8”High = 23”Average = 17”

Residual HerbicidesResidual Herbicides

• Treflan, Prowl

• Dual, Intrro (Lasso)

• Pursuit, Scepter

• Metribuzin Products**– Authority MTZ, Boundary,

Canopy, Sencor/Metri

• Valor, Valor XLT, Reflex, Envive, Prefix

Why metribuzin on soybean?Why metribuzin on soybean?

• Not a PPO

• Good on pigweed

• Can be applied PPI

• Issues

– soil texture, OM, pH

– Varieties

– Rotations

– Company support

– Lack of incentive at dealer level

– Cost/A

TriCor 75DF

Metribuzin 75DF

GR-Pigweed Control in Soybeans - 2008GR-Pigweed Control in Soybeans - 2008

SB-06-08Macon County48 DAP

NTC Canopy 75DG @ 6 oz/A + Prowl H2O 3.8ASC @ 2.1 pt/A (PRE)

GR-Palmer Amaranth ControlGR-Palmer Amaranth ControlMacon County - 2009Macon County - 2009

NTC Boundary 6.5EC @ 1.75 pt/A (PRE)Roundup W-Max 5.5SL @ 28 oz/A (36 DAP)SB-06-09

65 DAP

NTC Authority MTZ 45DG @ 12 oz/APRE

(49 DAT)SB-12-09SB-12-09AttapulgusAttapulgus

Metribuzin HeadachesMetribuzin Headaches

• Soil texture, OM– Metribuzin should not be used

on sands, loamy sands, and sandy loams with less than 1% OM!

• pH

• Varieties

• Rotations

Metribuzin Crop Rotations

Crop Authority MTZ Boundary Canopy

Metribuzin

TriCor

Field corn 4 months 8 months 10 months 4 months

wheat 4 months 4.5 months 4 months 4 months

cotton 12 months 8 months 10 months 18 months

peanut 12 months 12 months 18 months 18 months

sorghum 12 months 12 months 12 months 18 months

onions 18 months 18 months 18 months 18 months

*not for use on sands, loamy sands, or sandy loams with less than 1% OM.*not for use on sands, loamy sands, or sandy loams with less than 1% OM.

Metribuzin Soybean Metribuzin Soybean ToleranceTolerance

• Group IV: Asgrow 4903 RR/STS, Southern States RT4808

• Group V: Asgrow 5905RR, AGS 568RR, Delta Pineland DP5634, Pioneer 95Y20, Pioneer 95Y40, Pioneer 95Y70, Southern States RT5951NRR

• Group VI: Asgrow 6301RR, Delta Pineland DP6568, Pioneer 96M60, Southern States RT 6451NRR, Vigoro V61N9

• Group VII: AGS 758RR, Asgrow H7242, Benning, Dekalb H7242, Northrup King NKS 76L9, Northrup King NKS 78G6, Pioneer 97M50, USG 7732nRR, Vigoro V74N9, Woodruff

• Group VIII: Northrup King NKS 80P2, Prichard RR

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co.Soybeans with PRE’s (2008) - Macon Co.

NTC Dual Magnum 7.64EC @ 1 pt/ASB-05-0848 DAT

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co.Soybeans with PRE’s (2008) - Macon Co.

NTC Prefix 5.29EC @ 2 pt/ASB-05-0848 DAT

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co.Soybeans with PRE’s (2008) - Macon Co.

NTC Envive 41.3WG @ 3 oz/ASB-05-0848 DAT

GR-Palmer Amaranth Control in Soybeans – GR-Palmer Amaranth Control in Soybeans – 2009 (Macon Co.)2009 (Macon Co.)

NTC Valor @ 3 oz/A (PRE)Roundup W-Max @ 22 oz/A (POST)SB-09-09

46 DAP

PostemergencePostemergence

• PPO’s– Ultra Blazer, Cobra, Storm, ET, Aim, Reflex, Prefix,

Flexstar GT (RR), Cadet

• ALS– Harmony SG, Pursuit

• Other– Ignite (LL)

• Must be applied before 3”!!!!!

This is what a 2” pigweed looks This is what a 2” pigweed looks like!!!!like!!!!

Palmer Amaranth Control with Ultra Blazer and Cobra - 2008

NTC Ultra Blazer @ 1.5 pt/ALI-700 @ 0.25% v/v

Treatments applied to 2-10” tall pigweed , 6.23” average heightPhoto 16 DAT

Cobra @ 12.5 oz/APeptoil @ 1% v/v

PPO InjuryPPO Injury

Liberty-Link SoybeansLiberty-Link Soybeans

• Not necessarily a direct replacement for Roundup!

• Use a residual herbicide in this system!!!!!!!

• Not usually good on pigweed bigger than 3”

• Tank-mixes with POST grass herbicides may reduce grass control

– Assure (10-21%); Fusilade (8-12%); Poast (25-41%); Select 4-22%)

• Variety performance?

Liberty-Link Soybeans - 2009

NTC Boundary 6.5EC @ 1.5 pt/A (PRE)Ignite 2.34SL @ 22 oz/A (19 DAP)54 DAP

Ponder Farm

Liberty-Link Soybean Variety Liberty-Link Soybean Variety Performance – 2009Performance – 2009(Bu/A +/- test average) Test Rank(Bu/A +/- test average) Test Rank

Variety Athens(May 15)

Calhoun(May 21)

Griffin(May 15)

Midville(June 10)

Tifton(June 1) Average

SS LL511N

-1.9 (24)

+4.6

(7)

+2.6 (11)

+10.1

(4)

+3.3 (9)

+3.74

SS LL595N

+3.5 (12)

-6.5

(25)

+11.6 (2)

+6.1

(7)

+3.3

(9)

+3.60

Halo 4:65

-2.8 (25)

-16.4

(30)

-17.9 (31)

-17.3 (32)

-13.5 (31)

-13.58

Halo 4:94

+10.6 (1)

+8.1

(3)

-0.8 (19)

-3.3

(26)

+0.4 (17)

+3.0

Halo 5:25

-0.8 (23)

+6.4

(5)

-0.2 (17)

-0.3

(21)

+1.9 (16)

+1.4

Halo 5:65

+2.6

(15)

+0.6

(14)

+7.3 (6)

-1.0

(22)

+6.1 (3)

+3.12

Harmony GT XP or Harmony Harmony GT XP or Harmony SGSG

• Harmony GT XP (75%)– GT = grass-tank mix– XP = extruded pellet– 1/12 oz/A

• Harmony SG (50%)– SG = soluble granules– 1/8 oz/A

• 1st trifoliate until 60 days before harvest

• tank-mix with glyphosate• ALS inhibitor• up to 12” tall pigweed?????• variable amounts of soybean

injury

Harmony - YESHarmony - YES

Harmony Extra – NO!!!Harmony Extra – NO!!!

GR-Palmer Amaranth Control with Flexstar GT – 65 DAP

NTC Flexstar GT 3.31SL @ 3 pt/AAMS @ 2.5% v/vAppled 18 DAP

On the HorizonOn the Horizon

• KIH-485

• DHT Soybean – DowAgroScience Herbicide Tolerance– Enhanced tolerance to 2,4-D– Stacked with glyphosate– 2013?

• GAT Soybean – Glyphosate ALS Tolerance– DuPont– 2011?

• Dicamba Resistant Soybeans– Monsanto/BASF– Stacked with glyphosate– 2013?

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Soybeans with PRE’s (2008) - Macon CoCo..

NTC KIH-485 85WG @ 4.2 oz/ASB-05-0848 DAT

DHT SoybeansDHT Soybeans

We are overusing the PPO We are overusing the PPO inhibiting herbicides!!!!!!!!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)

Could this happen in SE?Could this happen in SE?

Crop PPLNT PRE POST/PDIR Harvest Aid

Soybean Valor Reflex Cobra Aim

Cotton Valor Reflex Valor Aim/ET

Corn Valor Sharpen Aim Aim

Peanut Aim/ET Valor Ultra Blazer Aim

In this 4 year rotation, we could use 16 PPO’s!!!!In this 4 year rotation, we could use 16 PPO’s!!!!

PPO-Resistant Waterhemp(Dr. Bryan Young, Southern Illinois Univ.)

Prostko’s Picks for PigweedProstko’s Picks for Pigweed

• Know your enemy!

• Drill a well!

• Start Clean!

• Use a residual!

• POST treatments when 3” tall or less

• Remove escapes before seed production

• Think About the Future– Overuse of PPO’s

For More Weed Science InfoFor More Weed Science Info

www.gaweed.com