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Controlling Primrose With Low Rates of 2,4-D Alone and in Tank Mixtures. A. S. Culpepper and A. C. York. University of Georgia N. C. State University. Conservation Tillage Acreage. 1998 2003 GA 12% 40% NC 30% 55%.
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Controlling Primrose With Low Rates of 2,4-D Alone and in Tank Mixtures A. S. Culpepper and A. C. York University of Georgia N. C. State University
Conservation Tillage Acreage 1998 2003 GA 12% 40% NC 30% 55%
Cutleaf Eveningprimrose and Wild Radish are the Most Common Weeds For Cotton Burndown
0.75 lb ae NTC 0.5 lb ai glyphosate paraquat 30 DAT- primrose
Literature Review – Primrose Control • Reynolds, Crawford, Jordan. JCS, 2000. 2,4-D (0.75 lb/A) was the most effective tank mix partner with glyphosate or paraquat • Poston, Blaine, Griffin. SWSS, 2003. Control averaged 95% when 2,4-D (0.75 lb/A) was added to glyphosate • Culpepper and York. SWSS, 2002. Most effective tank mix partner with glyphosate or paraquat was 2,4-D (0.5 lb/A)
2,4-D Plant Back Intervals Barrage HF and Salvo – 30 day prior to plant Many other 2,4-D’s – 3 months or until disappeared
Objectives • How much 2,4-D alone is needed to control primrose? • How much 2,4-D do we need to add with a non-selective herbicide option to control primrose?
2003 Locations * Rocky Mount * Tifton
Methods Plot size: 6 by 25 feet, GA 12 by 20 feet, NC Design: RCB Reps: 4 GA, 3 NC MPH: 3 GPA: 15 Tips: flat fan
Treatments 2,4-D amine (4 lb ae/gal) 4 oz/A 8 oz/A 12 oz/A 16 oz/A
Treatments Roundup WeatherMax at 16 oz NC, 21 oz GA WeatherMax + Valor at 1 oz/A Gramoxone at 1 qt/A + Caparol at 1 qt/A Alone or with 4 oz/A of 2,4-D
a a Percent Control b c Primrose Response to 2,4-D. Pooled over Tifton, GA and Rocky Mount, NC. 2003.* 2,4-D (oz/A) *Primrose 6 to 9 inches at time of application.
a a a b a a Percent Control b c 2,4-D (oz/A) Primrose Response to 2,4-D. Pooled over Tifton, GA and Rocky Mount, NC. 2003.* *Primrose 6 to 9 inches at time of application. Statistical comparison is within rating date.
a a a a a a a b a a Percent Control b c 2,4-D (oz/A) Primrose Response to 2,4-D. Pooled over Tifton, GA and Rocky Mount, NC. 2003.* *Primrose 6 to 9 inches at time of application. Statistical comparison is within rating date.
a a Percent Control b c 2,4-D (oz/A) Large Primrose Response to 2,4-D. Tifton, GA. 2003.* *Primrose 16 to 20 inches at time of application.
a a ab b a a Percent Control b c 2,4-D (oz/A) Large Primrose Response to 2,4-D. Tifton, GA. 2003.* *Primrose 16 to 20 inches at time of application. Statistical comparison is within rating date.
Primrose Response to 2,4-D. 6 WAT. Rocky Mount, NC. 2003. Non-treated Control 8 oz 2,4-D
Primrose Response to 2,4-D. 6 WAT. Rocky Mount, NC. 2003. Non-treated Control 4 oz 2,4-D
15 DAT Percent Control a b + 4 oz 2,4-D + 4 oz 2,4-D + 4 oz 2,4-D Gramoxone + Caparol Roundup Roundup + Valor Primrose Response to 2,4-D Mixtures. Pooled over Tifton, GA and Rocky Mount, NC. 2003.* *Primrose 6 to 9 inches at time of application. Statistical comparison is with and without 2,4-D. Roundup WeatherMax 16 to 21 oz/A, Valor 1 oz/A, Gramoxone 1 qt/A, and Caparol 1 qt/A.
43-47 DAT a a a b b b Percent Control + 4 oz 2,4-D + 4 oz 2,4-D + 4 oz 2,4-D Gramoxone + Caparol Roundup Roundup + Valor Primrose Response to 2,4-D Mixtures. Pooled over Tifton, GA and Rocky Mount, NC. 2003.* *Primrose 6 to 9 inches at time of application. Statistical comparison is with and without 2,4-D. Roundup WeatherMax 16 to 21 oz/A, Valor 1 oz/A, Gramoxone 1 qt/A, and Caparol 1 qt/A.
Primrose Response to WeatherMax. 6 WAT. Rocky Mount, NC. 2003. Non-treated Control 16 oz WeatherMax
Primrose Response to 2,4-D. 6 WAT. Rocky Mount, NC. 2003. 16 oz WeatherMax + 4 oz 2,4-D
Primrose Response to 2,4-D Mixtures. 6 WAT. Rocky Mount, NC. 2003. 16 oz WeatherMax + 8 oz 2,4-D
Primrose Response to 2,4-D Mixtures. 6 WAT. Rocky Mount, NC. 2003. WeatherMax + Valor + 4 oz 2,4-D
Conclusions – 2,4-D Alone • At 30 DAT, only 12 and 16 oz/A of 2,4-D provided greater than 90% primrose control. • By 45 DAT, all rates of 2,4-D provided greater than 90% primrose control. • By 56 DAT, primrose control was nearly complete regardless of rate. • Primrose size did not appear to matter • What rate?? How long can you wait!!!
Conclusions – 2,4-D Mixtures • At 15 DAT: Roundup (32%), Roundup + Valor (87%), Gramoxone + Caparol (90%) • At 15 DAT: mixing 4 oz/A 2,4-D with Roundup improved control 25%. • At 45 DAT: Roundup (71%), Roundup + Valor (81%), Gramoxone + Caparol (81%). • At 45 DAT: mixing 4 oz/A of 2,4-D improved control of non-selective treatments by 18 to 28%.
Future Research • Results must be confirmed!! • Plant back interval to cotton??