210 likes | 365 Views
How Serious is the Herbicide Resistant Weed Issue?. Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences. Is the sky falling? Did it already fall?. Chicken Little. Consequences of Resistance? Macon County, Georgia (2008). Herbicide Resistant Weeds Selection Pressure.
E N D
How Serious is the Herbicide Resistant Weed Issue? Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences
Is the sky falling? Did it already fall? Chicken Little
Herbicide Resistant WeedsSelection Pressure Source: J.L. Gunsolus. Herbicide Resistant Weeds. 1998. North Central Region Extension Publication 468.
Herbicide Resistant WeedsPollen Drift • Off-site movement (wind, gravity, insects) of resistance trait through pollen • Pollen from resistant male fertilizes susceptible female to produce resistant progeny • UGA researchers have documented GR-trait movement of at least 900’ (Palmer amaranth). Palmer Amaranth Pollen Source: Dr. Lynn Sosnoskie
The US Wins the Gold Medal in Resistance!!!! Source: International Survey of Herbicide Resistant Weeds (6/4/09) #4 – France (32); #5 – Spain (31)
Worldwide Number of Glyphosate Resistant Weeds By Year (Cumulative)(Roundup was first introduced in 1974) Source: International Survey of Herbicide Resistant Weeds (6/4/09)
Confirmed Number of Herbicide Resistant Weeds in the Peanut Belt 9 10 11 3 15 1 5 5 12 3 5 7 5 Source: International Survey of Herbicide Resistant Weeds (6/4/09)
How did all this happen????? • Economics drive farmer decisions • No real long-term weed mgt. planning • Farm logistics • timeliness • Overuse (abuse) of glyphosate • Staple/Cadre in cotton/peanut • Reduced herbicides rates • Reduced tillage • Reduction in use of residuals • Reduction in cultivation • Dryland production systems Glyphosate-Resistant Palmer Amaranth Macon County, Georgia
What can we do about it now! • Must understand modes of action • Start clean! • Skimp up front, pay later • Conventional tillage if needed/practical • Dryland, reduced tillage systems are in jeopardy!!! • Use a RESIDUAL herbicide in ALL crops! • Prevent escaped weeds from going to seed!
2009Macon CountyGR-Palmer Tests PRE No PRE 18 DAP
2009 GR-Palmer Amaranth TestMacon County NTC Boundary 6.5EC 1.75 pt/A PRE SB-06-09 May 15, 2009 24 DAT
Herbicide Modes of Action • Do not worry about the technical stuff! • Check the label • Local Extension Service • Herbicide Resistance Action Committee (HRAC) • http://www.hracglobal.com/ • Know what you are spraying!! 2,4-D chemical structure
Under Utilized Herbicide Modes of ActionCan we use them????? • HPPD-inhibitors • Mesiotrione (Callisto) • Tembotrione (Laudis) • Topramezone (Impact) • Isoxaflutole (Balance Flexx)
Palmer Amaranth Control in Field Corn with HPPD Herbicides - 2009 Corvus 2.6SC @ 3.33 oz/A PRE (April 11) Photo June 4 (54 DAT) NTC
We are overusing the PPO inhibiting herbicides!!!!!!!! • Resistance has already been reported in other areas!!! • Common waterhemp • 2001 (Kansas) • 2002 (Illinois) • 2003 (Missouri) • Common ragweed • 2005 (Delaware) • Wild poinsettia • 2004 (Brazil)
For More Weed Science Info:www.gaweed.com eprostko@uga.edu 229-386-3328 (office) 229-392-1034 (cell)