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Integrating cover crop residue and moldboard plowing into glyphosate-resistant Palmer amaranth management programs Culpepper, Kichler, Sosnoskie, York, Sammons, Nichols

Dryland production with severe GR Palmer Infestation. Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby

Palmer Amaranth Plants During Early Season. Macon Co., Georgia 2008.* No Deep Tillage Deep Turn No Herbicide Treatment

No Deep Tillage Deep Turned Prowl H20 + Reflex PRE; WeatherMax + Dual Magnum POST; Direx + MSMA Layby

Conservation Tillage is Very Important To the Southeast

Percent reduction in Palmer emergence by cover crops without herbicides. GA and NC. 2007. 42 DAP.* 100 80 60 57 a 53 ab 40 40 b 38 b 20 0 59,895 lb/A 66,429 lb/A 68,607 lb/A 96,921 lb/A wheat biomass rye biomass *Compared to the no cover conventionally tilled system.

Prowl + Cotoran PRE fb Roundup + Dual fb Direx + MSMA PD Conv Strip-Till

Objective � Determine the impacts of integrating both deep turning and intense cover crop residues in Roundup- and Ignite-based programs.

Experimental Location: Macon County, 2009

Experimental Design Factorial: 2 deep tillage options 2 cover crop options 4 herbicide systems

Two Deep Tillage Options deep turn or no deep turn All land was disked prior to planting

Two Cover Crop Options rye (75 lb/A) or no rye 2009 rye emerging through 2008 rye residue

Four Herbicide Options 1. no herbicide 2. WMax: 1, 5, 15 lf cotton 3. Staple + Direx + Reflex PRE; Wmax + Parrlay POST 5 lf; Direx + MSMA LPD 13 lf 4. Staple + Direx + Reflex PRE; Ignite (29 oz) + Parrlay POST 5 lf Direx + MSMA LPD 13 lf

Herbicides and Rates PRE POST Direx 2.0 pt/A WeatherMax 22 oz/A Staple 1.7 oz/A Parrlay 21 oz/A Ignite Reflex 1.0 pt/A 29 oz/A Layby Direx 2 pt + MSMA 2 lb Roundup-based program: DP 0949 B2RF Ignite –based program: PHY 485 WRF

Methods Plot size: 4 rows by 50 feet Herbicide applications: 15 GPA Palmer emergence: row and row middle Cotton Injury: 7-10 d after applications Weed control: late-season reported Harvest: two center rows

Rainfall Rainfall on PRE’s: 0.25” at 4 d; 0.75” at 5 d Rainfall on Parrlay: 0.77” at 3 d Rainfall on Layby: 1.1” at 5 d

Herbicide Injury Reflex PRE 12 to 15% at 10 DAT Minor injury noted thorough 27 DAT

Herbicide Injury RU + Parrlay Ignite + Parrlay 9 to 12% at 7 DAT 19 to 21% at 7 DAT No visual injury detected 9 d later.

Reduction in Palmer emergence as affected by deep turning/cover crop residue at 16 DAP. Macon Co., GA 2009. 100 96 a 94 a 80 percent 60 65 b 40 50 c 47 c 46 c 20 0 Drill Drill Drill Middle Middle Middle Deep turn Rye cover Deep turn + Rye cover Non-treated: 620 plant/m2. No herbicides applied.

GR Palmer amaranth control at harvest with Roundup-based systems. Macon Co., GA 2009. 100 98 a 80 80 b 81 b 60 percent 63 c 40 20 0 No deep turn Deep turn No deep turn Deep turn No Cover No cover Rye Cover Rye Cover Rye 7 foot when killed, rolled, planted. Deep turn 12 inch in previous fall. Herbicide program: Direx + Reflex + Staple PRE; RU + Parrlay POST, Direx + MSMA at layby.

GR Palmer amaranth response to glyphosate. Macon County, GA. 2009. No-herbicide control Glyphosate 3 X

Palmer amaranth response to deep tillage. Macon County, GA. 2009. No deep tillage Deep tillage No cover crop No cover crop Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby

Palmer amaranth response to cover crops. Macon County, GA. 2009. No deep tillage No deep tillage No cover crop Rye cover crop Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby

Palmer amaranth response to deep tillage and cover crops. Macon County, GA. 2009. No deep tillage Deep tillage No cover crop Rye cover crop Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Direx + MSMA Layby

Seed cotton yield (lb/A) with Roundup-based systems. Macon Co., GA 2009. 2100 2078 a 1627 b 1400 1524 bc 1298 d 700 0 No deep turn Deep turn No deep turn Deep turn No Cover No cover Rye Cover Rye Cover Rye 7 foot when killed, rolled, planted. Deep turn 12 inch in previous fall. Herbicide program: Direx + Reflex + Staple PRE; RU + Parrlay POST, Direx + MSMA at layby.

Palmer amaranth response to deep tillage and cover crops. Macon County, GA. 2009. No deep tillage No deep tillage No cover crop No cover crop Staple + Reflex + Direx PRE Staple + Reflex + Direx PRE Roundup WMax + Parrlay POST Ignite + Parrlay POST Direx + MSMA Layby Direx + MSMA Layby

GR Palmer amaranth control at harvest with Ignite- based systems. Macon Co., GA 2009. 100 98 a 99 a 97 a 97 a 80 percent 60 40 20 0 No deep turn Deep turn No deep turn Deep turn No Cover No cover Rye Cover Rye Cover Rye 7 foot when killed, rolled, planted. Deep turn 12 inch in previous fall. Herbicide program: Direx + Reflex + Staple PRE; Ignite + Parrlay POST, Direx + MSMA at layby.

Seed cotton yield (lb/A) with Ignite-based systems. Macon Co., GA 2009. 2100 2090 a 1810 bc 1715 cd 1400 1552 d 700 0 No deep turn Deep turn No deep turn Deep turn No Cover No cover Rye Cover Rye Cover Rye 7 foot when killed, rolled, planted. Deep turn 12 inch in previous fall. Herbicide program: Direx + Reflex + Staple PRE; RU + Parrlay POST, Direx + MSMA at layby.

Conclusions – Tillage/Cover 1. Heavy residue reduced pigweed emergence 50 (row) to 94% (middle). 2. Deep turning reduced pigweed emergence 46 to 47%. 3. Deep turning and cover crop residue reduced Palmer emergence 65 (row) to 96% (middle).

Conclusions – RR System 1. Deep turning or cover crops improved late- season control 17 to 18%. 2. Deep turning plus cover crops improved late- season control 35%. 3. Yields followed trends with Palmer control but was influenced by tillage/cover crop residue.

Conclusions – Ignite System 1. Palmer control at least 97%; more effective than RR systems except when using deep turning and cover crop residue. 2. Yields were increased 10% (numerical) by deep turning, 15% with cover crop, and 26% with deep turning plus cover crops.

QUESTIONS OR COMMENTS? Culpepper, Kichler, Sosnoskie, York, Sammons, Nichols