Managing Palmer AmaranthManaging Palmer AmaranthPeanutsPeanuts

Field CornField Corn Soybeans Soybeans

Eric P. ProstkoEric P. Prostko

Extension Weed SpecialistExtension Weed Specialist

Dept. of Crop & Soil SciencesDept. of Crop & Soil Sciences

The University of GeorgiaThe University of Georgia

Managing Palmer AmaranthManaging Palmer Amaranth

Know your enemyKnow your enemy Resistant or not??Resistant or not??

– ALS or GR

Residual herbicideResidual herbicide– Activation (irrigation or

incorporation)

Timely POST’sTimely POST’s Avoid overusing Avoid overusing

PPO’sPPO’s

Why Palmer Amaranth?Why Palmer Amaranth? 38 species of 38 species of AmaranthusAmaranthus in in

U.S.U.S. 27 species found in SE27 species found in SE grows faster than other grows faster than other

pigweeds (1-2” per day!!)pigweeds (1-2” per day!!) more competitive than other more competitive than other

pigweedspigweeds prolific seed producerprolific seed producer

– Up to 1,000,000 seeds/plant– 9-12 WAE– 2 generations/year

herbicide toleranceherbicide toleranceSWSSWeed IDGuide

Palmer Amaranth is very competitive!!!Palmer Amaranth is very competitive!!!

Yield loss caused by Yield loss caused by 1 plant/meter of row1 plant/meter of row– Soybean (27%)Soybean (27%)– Peanut (28%)Peanut (28%)– Corn (32%)Corn (32%)– Cotton (48%)Cotton (48%)

GA Confirmed Glyphosate-Resistant Palmer SitesGA Confirmed Glyphosate-Resistant Palmer Sites

2005

2006

Current Testing2007

Commonly Used ALS HerbicidesCommonly Used ALS Herbicides AccentAccent Ally/CimarronAlly/Cimarron BeaconBeacon BeyondBeyond Cadre Cadre ClassicClassic EnvokeEnvoke ExceedExceed Express Express FinesseFinesse FirstRateFirstRate

GleanGlean Harmony ExtraHarmony Extra Maverick ProMaverick Pro Osprey Osprey PeakPeak PermitPermit PursuitPursuit PythonPython ScepterScepter StapleStaple Strongarm Strongarm

GA Confirmed ALS-Resistant Palmer SitesGA Confirmed ALS-Resistant Palmer Sites

Use a residual herbicide!!!!Use a residual herbicide!!!! CornCorn – atrazine, Dual Magnum/Generics, – atrazine, Dual Magnum/Generics,

Callisto, ProwlCallisto, Prowl– Atrazine resistance in Macon Co (2007)

PeanutPeanut – Valor, Dual Magnum/Generics, Prowl, – Valor, Dual Magnum/Generics, Prowl, SonalanSonalan

SoybeanSoybean – Valor, Valor XLT, Reflex, Canopy, – Valor, Valor XLT, Reflex, Canopy, Sencor, Dual Magnum/Generics, Boundary, Sencor, Dual Magnum/Generics, Boundary, Prefix, Treflan, Prowl Prefix, Treflan, Prowl

Residual Herbicides Must Be Activated!!!!!!Residual Herbicides Must Be Activated!!!!!!

RainfallRainfall IrrigationIrrigation Herbicide incorporationHerbicide incorporation

– Conventional tillage– Dryland fields– No chance of rain– will help but not a guarantee– 2X, angle– Some herbicides should not

be incorporated• Valor

Things You Do Not Often See in GeorgiaThings You Do Not Often See in Georgia

UFO’s

Bigfoot

Applications to 2” tall pigweed

PPO Resistance???PPO Resistance???

PPO or ProtoxPPO or Protox– Protoporphyrinogen oxidase– Enzyme found in chloroplast

and mitochondria

3 species worldwide3 species worldwide– Common waterhemp– Common ragweed– Wild poinsettia

Many common herbicides have Many common herbicides have this mode of action!!this mode of action!!– Ultra Blazer, Cobra, Goal,

Reflex, Ronstar, Resource, Aim, Valor, Storm, Spartan, ET

Herbicide Modes of Action InfoHerbicide Modes of Action Info New Table in 2008 Pest Control HandbookNew Table in 2008 Pest Control Handbook

MOA’s listed in crop sectionsMOA’s listed in crop sections

www.gaweed.comwww.gaweed.com

diclosulam (Strongarm) 84WG 0.45 oz

0.024 Provides general broadleaf weed control. Incorporate into top 1-3" of final seedbed. Goodto excellent control of many species includingbristly starbur, wild poinsettia, eclipta, andcopperleaf. Should be tank-mixed with a grassherbicide. Poor control of sicklepod. Controlof nutsedge has been variable and inconsistent. Can also be applied preemergence. Croprotation restrictions: cotton = 10 months;soybeans = 0 months; wheat, barley = 4months; oats, rye = 6 months; corn = 18months (10 months - IR hybrids); tobacco,sorghum = 18 months; other crops = 30months. MOA = 2.

Field Trial ResultsField Trial Results

PeanutsPeanuts

Palmer Amaranth Control in PeanutsPalmer Amaranth Control in PeanutsMacon County, GA – 2007 (38 DAT)Macon County, GA – 2007 (38 DAT)

NTC Valor SX 51WG @ 3 oz/A

Palmer Amaranth Control in PeanutsPalmer Amaranth Control in PeanutsMacon County, GA – 2007 (38 DAT)Macon County, GA – 2007 (38 DAT)

NTC Dual Magnum 7.62EC@ 1 pt/A

Palmer Amaranth Control in Palmer Amaranth Control in Peanut with PRE HerbicidesPeanut with PRE Herbicides

0

20

40

60

80

100

11 18 23 38 53 94

Time (DAT)

Con

trol

- %

.

Valor Dual Magnum Stalwart Outlook

Valor @ 3 oz/ADual Magnum @ 1 pt/AStalwart @ 1 pt/AOutlook @ 1 pt/A

2,4-DB fb Cobra or Ultra Blazer?????2,4-DB fb Cobra or Ultra Blazer?????

POST: June 5 (17” tall pigweed)POST2: June 9Photos taken 24 days after POST application

Untreated Cobra 2EC @ 12.5 oz/AAgrioil @ 1% v/v

POST

2,4-DB 1.75SL @ 1.1 pt/A +Agrioil @ 1% v/v (POST)

fbCobra 2EC @ 12.5 oz/A

Agrioil @ 1% v/vPOST2

Field CornField Corn

GR-Palmer Amaranth Control in Field CornGR-Palmer Amaranth Control in Field CornMay 31, 2007 (38 DAP)May 31, 2007 (38 DAP)

NTC Roundup Original Max (22 oz/A)Atrazine (2 qt/A)

Prowl H20 (2.1 pt/A)EPOST (18 DAP)CN-07-07

GR-Palmer Amaranth Control in Field Corn May GR-Palmer Amaranth Control in Field Corn May 31, 2007 (38 DAP)31, 2007 (38 DAP)

NTC Halex GT 4.38SC @ 4 pt/A80/20 @ 0.25% v/v

AMS @ 8.5 lbs/100 galsEPOST (18 DAP)CN-07-07

Palmer Amaranth Control in Sorghum-Palmer Amaranth Control in Sorghum-Sudangrass SilageSudangrass Silage

NTC 2,4-D amine @ 1 pt/A(27 DAT)

GS-01-07

SoybeansSoybeans

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybean – 2007 (83 DAT)Soybean – 2007 (83 DAT)

Untreated Boundary 6.5EC @ 1.8 pt/ASB-01-07

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybean – 2007 (83 DAT)Soybean – 2007 (83 DAT)

Untreated Prefix 5.2EC @ 2.03 pt/ASB-01-07

GR-Palmer Amaranth Control in GR-Palmer Amaranth Control in Soybean – 2007 (77 DAT)Soybean – 2007 (77 DAT)

Untreated Valor SX 51WG @ 3 oz/ASB-02-07

Harmony GT XP or Harmony SGHarmony GT XP or Harmony SG

Harmony GT XP (75%)Harmony GT XP (75%)– GT = grass-tank mix– XP = extruded pellet– 1/12 oz/A ($1.17)

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

11stst trifoliate until 60 days before trifoliate until 60 days before harvestharvest

tank-mix with glyphosatetank-mix with glyphosate ALS inhibitorALS inhibitor up to 12” tall pigweed?????up to 12” tall pigweed????? Soybean injurySoybean injury

Managing Palmer AmaranthManaging Palmer Amaranth

Know your enemyKnow your enemy Resistant or not??Resistant or not??

– ALS or GR

Residual herbicideResidual herbicide Timely POST’sTimely POST’s Avoid overusing Avoid overusing

PPO’sPPO’s

www.gaweed.com