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Title: Effective use patterns for HPPD herbicides in non-transgenic conservation tillage sweet corn.

Author
item PEACHEY, R - Oregon State University
item Boydston, Rick

Submitted to: Western Society of Weed Science Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2010
Publication Date: 3/7/2011
Citation: Peachey, R.E., Boydston, R.A. 2011. Effective use patterns for HPPD herbicides in non-transgenic conservation tillage sweet corn.. Western Society of Weed Science Meeting Proceedings. (89). http://wssaabstracts.com/public/6/proceedings.html#pres89.

Interpretive Summary: Weed control is still a challenge in non-transgenic sweet corn due to the suite of weeds present (including wild proso millet and triazine resistant species) and conservation tillage systems that are evolving to meet challenges of environmental stewardship and increasing input costs, mainly the rising costs of fuel and fertilizer. The HPPD herbicides tembotrione and topramezone are labeled and widely used, and have greatly improved the potential for one-pass POST weed control. But challenges still remain when using these herbicides in conservation tillage systems, notwithstanding potential crop injury when these herbicides are tankmixed with soil-applied herbicides such as s-metolachlor. Experiments conducted from 2007 through 2010 evaluated weed control in strip tillage and conventional tillage corn with one-pass HPPD herbicide treatments, sweet corn tolerance to tank mixes of HPPD and chloroacetamide herbicides, and potential causes of injury. Experiments were located in the Columbia Basin near Prosser, WA and the Willamette Valley of OR. HPPD herbicides tank mixed with chloroacetamide herbicides and applied at V2-4 in 2007 damaged corn leaves, but the symptoms were transient and did not resemble symptoms commonly associated with chloroacetamide injury in sweet corn. In strip-tillage corn in OR in 2008, weed control was exceptional with topramezone plus s-metolachlor or dimethenamid-P but may have reduced corn yield by 20% or more at one of two experimental sites when applied at V5-6. In 2009 at trials near Prosser and at Corvallis, yield of both Coho and Basin varieties was reduced by 10 to 15% when topramezone and tembotrione were applied at V2. Yield of these two varieties was reduced by as much as 25% when water was poured over the corn plants before applying the tank mix of HPPD and chloroacetamide herbicide in 2010. And finally, HPPD herbicides had little to no effect on nutsedge in a strip-till field in 2010 unless tank mixed with bentazon or halosulfuron, but there was no significant injury to the corn and yield was not reduced. One-pass herbicide applications in sweet corn may require lower rates of chloroacetamide or HPPD herbicide when they are tank mixed, or possibly lower rates of the adjuvants typically used to enhance efficacy, but the precautions needed to limit injury may depend on corn variety, stage of growth, and soil and plant moisture when herbicides are applied.

Technical Abstract: Weed control is still a challenge in non-transgenic sweet corn due to the suite of weeds present (including wild proso millet and triazine resistant species) and conservation tillage systems that are evolving to meet challenges of environmental stewardship and increasing input costs, mainly the rising costs of fuel and fertilizer. The HPPD herbicides tembotrione and topramezone are labeled and widely used, and have greatly improved the potential for one-pass POST weed control. But challenges still remain when using these herbicides in conservation tillage systems, notwithstanding potential crop injury when these herbicides are tankmixed with soil-applied herbicides such as s-metolachlor. Experiments conducted from 2007 through 2010 evaluated weed control in strip tillage and conventional tillage corn with one-pass HPPD herbicide treatments, sweet corn tolerance to tank mixes of HPPD and chloroacetamide herbicides, and potential causes of injury. Experiments were located in the Columbia Basin near Prosser, WA and the Willamette Valley of OR. HPPD herbicides tank mixed with chloroacetamide herbicides and applied at V2-4 in 2007 damaged corn leaves, but the symptoms were transient and did not resemble symptoms commonly associated with chloroacetamide injury in sweet corn. In strip-tillage corn in OR in 2008, weed control was exceptional with topramezone plus s-metolachlor or dimethenamid-P but may have reduced corn yield by 20% or more at one of two experimental sites when applied at V5-6. In 2009 at trials near Prosser and at Corvallis, yield of both Coho and Basin varieties was reduced by 10 to 15% when topramezone and tembotrione were applied at V2. Yield of these two varieties was reduced by as much as 25% when water was poured over the corn plants before applying the tank mix of HPPD and chloroacetamide herbicide in 2010. And finally, HPPD herbicides had little to no effect on nutsedge in a strip-till field in 2010 unless tank mixed with bentazon or halosulfuron, but there was no significant injury to the corn and yield was not reduced. One-pass herbicide applications in sweet corn may require lower rates of chloroacetamide or HPPD herbicide when they are tank mixed, or possibly lower rates of the adjuvants typically used to enhance efficacy, but the precautions needed to limit injury may depend on corn variety, stage of growth, and soil and plant moisture when herbicides are applied.