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Culpepper, York, MacRae, Whitaker
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TABLE OF CONTENTS
SLIDE CONTENTS
- Managing glyphosate-resistant Palmer amaranth in conventional and strip-till cotton Culpepper, York, MacRae, Whitaker
- Conservation Tillage is Very Important To the Southeast
- Objective Determine the impacts of conservation tillage on the management of glyphosate-resistant Palmer amaranth.
- Experiment 1: 2006 and 2007 Locations Mount Olive * Macon Co. * * * *
- Materials and Methods Split Plot/Factorial Design 7 herbicide systems 2 tillage practices Plot size GA = 4 rows by 35-45 feet NC = 4 rows by 25-30 feet
- Herbicide Systems* *Direx + MSMA applied at layby for each herbicide program.
- Herbicides and Rates
- Direx + MSMA directed over entire trial area. Percent glyphosate-resistant Palmer amaranth control at harvest. Five locations, GA & NC.* 77 ab +Cotoran +Reflex +Cotoran +Reflex +Staple 74 ab WeatherMax + Dual 40 d 56 c 70 b 64bc 82 a WeatherMax + Staple Prowl Prowl
- Direx + MSMA directed over entire trial area. Seed Cotton Yield. Five locations, GA & NC.* 1413 a +Cotoran +Reflex +Cotoran +Reflex +Staple 1416 a WeatherMax + Dual 724 c 972 bc 1335 a 1040 b 1563 a WeatherMax + Staple Prowl Prowl
- Tillage Systems Conventional: no weeds or residue Strip Tillage: cover controlled several weeks ahead of planting followed by Gramoxone PRE
- Wheat height (inches) at time of burndown.* 4 32 24 8
- Residue= 9760 lb/A
- Percent glyphosate-resistant Palmer amaranth control at harvest. Tillage main effects.* * * * *An asterisk denotes control greater in strip-till production.
- Number of Palmer amaranth (sq yd) infesting the non-treated control 21 to 28 DAP. * * *An asterisk denotes less pigweed in strip-till production. *
- Prowl + Cotoran PRE fb Roundup + Staple
- Prowl + Cotoran PRE fb Roundup + Dual 4 inch fb Direx + MSMA PD Conv Strip-Till
- Prowl + Reflex PRE fb Roundup + Dual 4 inch fb Direx + MSMA PD Conv Strip-Till
- Seed Cotton Yield as Impacted by Tillage. Georgia and North Carolina. 2006-2007. * * *An asterisk denotes significantly higher yields in strip-till production. *
- Conclusions Experiment 1 Heavy residue improved control. A. Reduced pigweed emergence B. Slowed pigweed emergence and growth Heavy residue would likely benefit areas not infested with resistance by reducing selection pressure.
- Conclusions Experiment 1 3. Heavy residue would likely put more selection pressure on ALS chemistry (Staple) controlling those plants escaping residual herbicides.
- Experiment 2: Materials and Methods Cover crop options rye controlled 2 or 4 wk before planting wheat controlled 2 or 4 wk before planting no cover Herbicide systems (1st rainfall 17 DAP) None or Prowl + Reflex, RU + Staple, Direx + MSMA
- Materials and Methods Liter Produced (at planting) wheat 4 WBP (knee high): 59,895 lb/A of liter wheat 2 WBP (waist high): 66,429 lb/A of liter rye 4 WBP (waist high): 68,607 lb/A of liter rye 2 WBP (head high): 96,921 lb/A of liter
- Percent reduction in Palmer emergence by cover crops without herbicides. 42 DAP.* *Compared to the no cover conventionally tilled system. 38 b 53 ab 40 b 57 a
- Percent Palmer amaranth control at harvest with herbicide programs. Macon County, GA. 2007. 68 bc 79 ab 81 a 59 c 87 a
- Conventional tillage Prowl + Reflex PRE RU + Staple POST Direx + MSMA layby
- Knee high wheat Prowl + Reflex PRE RU + Staple POST Direx + MSMA layby
- Waist high wheat Prowl + Reflex PRE RU + Staple POST Direx + MSMA layby
- Cotton yield as impacted by cover crop residue. Macon County, GA . 2007.* 700 b 780 ab 835 a 500 c 820 ab
- Conclusions Experiment 2 Heavy residue improved control. A. Reduced pigweed emergence B. Slowed pigweed emergence and growth Heavy residue would likely put more selection pressure on ALS chemistry (Staple) controlling those plants escaping residual herbicides.
- Palmer amaranth infests strip till cotton.
- Comments
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