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It’s Time for Glyphosate Stewardship Can PSEP Help?. Chris Boerboom Extension Weed Scientist University of Wisconsin-Madison. Glyphosate Technologies. Burndown treatments in no-till. Glyphosate Technologies. Glyphosate-resistant crops in-season glyphosate use. Benefits
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It’s Time for Glyphosate StewardshipCan PSEP Help? Chris Boerboom Extension Weed Scientist University of Wisconsin-Madison
Glyphosate Technologies Burndown treatments in no-till
Glyphosate Technologies • Glyphosate-resistant crops • in-season glyphosate use Benefits Broad spectrum weed control Crop safety Rotational crop flexibility Environmentally favorable
Confirmed Glyphosate Resistant Weeds in the US(2006) Horseweed (Marestail) Common Ragweed Italian Ryegrass Rigid Ryegrass Palmer Amaranth Common Waterhemp Giant Ragweed
Glyphosate Resistant Weeds in the US Giant ragweed Waterhemp Palmer amaranth Italian ryegrass Common ragweed Horseweed Rigid ryegrass
"Stupidity is doing the same thing over and over again expecting different results" ~ A. Einstein
Horseweed or “Marestail” Photo credit: Larry Steckel
2004 Common Horseweed Burndown Program Photo credit: Larry Steckel
Common Ragweed 96 oz/a WeatherMax York, NCSU
Palmer Amaranth WeatherMax 88 oz at 1 inch WeatherMax 88 oz at 4 inch WeatherMax 88 oz PDIR Culpepper, UG
Culpepper, UG Prowl H20 1.75 pt + Reflex 1 pt PRE WeatherMax 22 oz + Dual Mag 18 DAP before Pigweed emergence WeatherMax 22 oz + Direx 1.5 pt PDIR
Distribution of Glyphosate-Resistant Palmer Amaranth Culpepper, UG
Herbicide Cost Needed To Manage Palmer Amaranth in Georgia and North Carolina Sensitive Palmer $18 $8 $10 Resistant Palmer $42 $24 $14 Cotton Soybean Corn Culpepper, UG
“Giant” Ragweed Johnson, PU
Sensitive Henry co. Suspect Noble co. 2.25 lb ae/A at 21 DAT Untreated Untreated Johnson, PU
To which herbicide has waterhemp NOT developed resistance? • Blazer • Pursuit • Glyphosate • Reflex • Classic
Resistance trait will move through pollen Culpepper, UG
Critical factors affecting the development of herbicide resistance • Mutation rate for resistance traits • Initial frequency of resistant weeds • Herbicide selection intensity • Inheritance of resistance traits • Gene flow
Soybean Adoption of Roundup Ready Technology in the US (million acres) 94% 96 97 98 99 00 01 02 03 04 05 06 Cotton Corn 43% 67% 98 99 00 01 02 03 04 05 06 97 98 99 00 01 02 03 04 05 06
Adoption of Next Crops • Roundup Ready alfalfa? • Roundup Ready sugar beets?
Reduce Selection Pressure • Diversify herbicide use • Ideally, use more than one herbicide mode of action on all weeds every year • Rotate glyphosate with other herbicides • Use preemergence herbicides in sequential programs • Apply glyphosate in combination with other POST herbicides • Use cultivation
Resources Available Glyphosate, Weeds, and Crops (GWC) Series http://www.glyphosateweedscrops.org/