Living and Learning with Herbicide Resistant Weeds Eric P. Prostko - PowerPoint PPT Presentation

Living and Learning with Herbicide Resistant Weeds Eric P. Prostko and A. Stanley Culpepper Extension Weed Specialists Department of Crop & Soil Sciences

UGA Weed Science Team Supporting Cast & Crew • UGA Faculty • Technical Support – Tim Grey (Tifton) – Charlie Hilton – Bill Vencill (Athens) – Amy Davis – Mark Czarnota (Griffin) – Jesse Parker – Tim Murphy (Griffin) – Kevin Baldree • USDA-ARS • Administrative – Carroll Johnson – Dena Watson – Ted Webster • Graduate Students • Post-Doc’s – Rebekah Wallace – Lynn Sosnoskie – Trey Cutts • Valdosta State Univ . • Student Workers – Richard Carter – Too many to mention but – Very valuable to program

Palmer Amaranth in Georgia

Do what must be done?

Why Palmer Amaranth ( Amaranthus palmeri )? • 38 species of Amaranthus in U.S. • 27 species found in SE • dioacious • grows faster than other pigweeds (1-2” per day!!) • more competitive than other pigweeds • prolific seed producer • seed to seed 9-12 WAE • 2 generations/year • herbicide tolerance SWSS Weed ID Guide

Herbicide Resistance Concerns in Georgia • glyphosate • ALS herbicides • Atrazine • Multiple resistance – Glyphosate + ALS

Georgia counties confirmed to be infested with glyphosate-resistant Palmer amaranth. 2004 – 1 county 2005 – 2 counties 2006 – 7 counties 2007 – 10 counties 2008 – 6 so far 1-28-09

GA Confirmed ALS-Resistant Palmer Sites

2008 Triazine Resistance Survey Macon County 4/20 sites resistant to 10X rate (4,5,15,20) 6/20 sites took 5 qts/A to kill (3,6,8,14,17,19)

Site 5 – Atrazine Resistance Survey 0 0.1 1 5 10 Atrazine (qts/ A) *Not resistant to Evik (ametryn) or Direx (diuron)

How did this happen to us????? • Economics drive farmer decisions • No real long-term weed mgt. planning • Farm logistics • Overuse of glyphosate • Overuse of Staple and Cadre • Reduced herbicides rates • Reduced tillage • Reduction in use of residuals • Dryland production systems

Palmer Amaranth Biology • How many seed? • How long can the seed survive in the soil? • Where does most of the germination occur? • Pollen Drift

Palmer amaranth seed production in Georgia from a single female plant when competing with cotton for the season 500,000 400,000 300,000 # of seeds 450,000 200,000 Macon Co. 2006 100,000 0 *1,000,000 seed/plant (Keeley et al. 1987. Weed Science 35:199-204) California

R-Palmer amaranth seed longevity 100 Percent (%) viable 90 80 70 60 0.5" 1" 50 4" 16" 40 0 mon. 3 mon. 6 mon. 9 mon. Length of burial Source: Dr. Lynn Sosnoskie - UGA

Influence of burial depth on Palmer amaranth emergence in Georgia 50 S-Palmer amaranth Percent (%) emergence R-Palmer amaranth 40 30 20 10 0 0.5" 1" 4" 16" Depth of burial (inches) Source: Dr. Lynn Sosnoskie - UGA

Herbicide Resistant Weeds Pollen Drift • Off-site movement (wind, gravity, insects, man, animal) of resistance trait through pollen • Pollen from resistant male fertilizes susceptible female to produce resistant progeny (seed) • UGA researchers have documented GR-trait Palmer Amaranth Pollen movement of at least 960’ Source: Dr. Lynn Sosnoskie (Palmer amaranth).

In-field Palmer amaranth pollen movement 100 % Resistant offspring per parent plant 2006 2007 80 60 40 20 0 1 5 10 25 50 75 100 150 200 250 300 Distance (m) from source of resistance

Cultural Practices • Deep tillage • Extreme cover crops

No Deep Tillage Deep Turn No Herbicide Treatment

Palmer amaranth seedling density as influenced by tillage. to a depth of 5 cm 14000 12000 10000 8000 AMAPA density/m2 6000 4000 2000 0 No-Break Break Treatments

Dryland Systems

Irrigation in Georgia Peanut Soybean C otton C orn 70 60 50 cres (%) 40 30 A 20 10 0 1970 1975 1977 1980 1986 1992 1995 2000 2004 2008 Y ear Source: Kerry Harrison, UGA Extension Engineer

May-June 2008 Rainfall Distribution in Midville 1.6 1.6 1.4 1.4 1.2 1.2 1 1 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 June May Crops planted from May 21-June 21 did not receive enough rainfall to activate herbicides (0.26” total). June Rainfall = 0.62” which occurred as follows:12 (0.08”); 22 (0.36”); 26 (0.08”); 29 (0.10”)

If residual herbicides are not activated on a timely basis with a reliable water source, pigweed control will be very difficult, maybe even impossible!

Dryland Systems • Growers need to think about mechanical herbicide incorporation • Will help but not a guarantee • Success will depend upon…… – operator – Implement – Soil conditions

Chemical Control Options • Valor (flumioxazin) • Reflex (fomesafen) • Dual Magnum ( S -metolachlor) • Atrazine • Liberty-Link (glufosinate) • Sencor products (metribuzin) • KIH-485

Palmer Amaranth Control in Peanuts Macon County, GA – 2007 (38 DAT) NTC Valor SX 51WG @ 3 oz/A

Palmer Amaranth Control in Peanuts Macon County, GA – 2007 (38 DAT) Dual Magnum 7.62EC NTC @ 1 pt/A

Macon County – GR Palmer Amaranth June 24, 2008 – 60 DAP CN-01-08 Atrazine 4L @ 1 qt/A – PRE NTC Atrazine 4L @ 1.5 qt/A – 30 DAP Peptoil @ 1% v/v – 30 DAP

RR vs vs LL Corn LL Corn - - 2008 2008 RR Roundup W-Max @ 22 oz/A Ignite 2.34 SL @ 23 oz/A Untreated Atrazine @ 1.5 qt/A Atrazine @ 1.5 qt/A Prowl H 2 O @ 2.1 pt/A Prowl H 2 O @ 2.1 pt/A (POST) AMS @ 3 lb/A (POST) CN-11-08 6/17/2008 81 DAP

Metribuzin Products on Soybeans • Sencor • Boundary – Dual Magnum + Sencor • Canopy – Sencor + Classic • Read label • Know soil texture and OM • Varieties • rotations

GR-Pigweed Control in Soybeans - 2008 Canopy 75DG @ 6 oz/A + NTC Prowl H 2 O 3.8ASC @ 2.1 pt/A (PRE) SB-06-08 Macon County 48 DAP

GR-Palmer Amaranth Control in Soybeans - 2007 Gramoxone Inteon @ 3 pt/A + NTC Boundary @ 1.8 pt/A + NIS @ 0.25% v/v (7 DBP) SB-01-07 Macon Co. Touchdown Total @ 1.5 pt/A (26 DAP) 76 DAP

Soybean varieties screened in 2008 that had adequate tolerance to Boundary 6.5EC (2 pt/A), Canopy 75DG (5 oz/A), and Sencor 75DG (6 oz/A). • Ag South AGS 568 Asgrow H7242 • Asgrow 4903 RR/STS Delta Pineland DP 5634 • Delta Pineland DP 6568 Northrup King NKS 80P2 • Northrup King NKS 76L9 Northrup King NKS 78G6 • Pioneer 95Y40 Pioneer 95Y70 • Pioneer 96M60 Pioneer 97M50 • Southern States RT5951 Southern States RT4808 • Vigoro V61N9 Vigoro V74N9

GR-Pigweed Control in Soybeans – 2008 Macon County 13 DAT 29 D AT 47 D AT 91 D AT ) . 100 90% Control (% 80 60 40 20 0 V E R P C S K D a n r e e a I u e H l v n f n a o l f i e c - i o v l r x 4 x o p M e 8 r y 5 a g n u m . Herbicide Valor @ 3 oz/A; Envive @ 3 oz/A; Reflex @ 1 pt/A; Prefix @ 2 pt/A; Canopy @ 6 oz/A; Sencor @ 8 oz/A KIH-485 @ 4.2 oz/A; Dual Magnum @ 1 pt/A

KIH-485 • Pyroxasulfone • Kumiai • Developed for corn and soybeans • PRE • Herbicide Family – Sulfonylioxazoline (?) Sulfonylioxazoline (?) – • Herbicide Mode of Action (?) – plant growth inhibitor that affects apical meristem plant growth inhibitor that affects apical meristem – and coleoptile development of plants after seed and coleoptile development of plants after seed germination germination • Low use rates

GR-Palmer Amaranth Control in Soybeans with PRE’s (2008) - Macon Co . KIH-485 85WG @ 4.2 oz/A NTC SB-05-08 48 DAT

Under Utilized Modes of Action • HPPD-inhibitors – Mesiotrione (Callisto) – Tembotrione (Laudis) – Topramezone (Impact)

Halex GT in Field Corn - - 2008 2008 Halex GT in Field Corn Halex GT 4.39L Untreated 4 pt/A + NIS CN- -05 05- -08 08 CN 6/19/2008 6/19/2008 (POST) 83 DAP 83 DAP

Don’t forget!!! There are no steel resistant weeds!!!

We are overusing the PPO 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)

For More Weed Science Info: www.gaweed.com eprostko@uga.edu 229-386-3328 (office) 229-392-1034 (cell)