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Southern Rust of Corn: Outline. Distinguishing common rust vs. southern rust Southern rust is potentially much more destructive Guidelines to consider in fungicide decisions Monitor for stalk strength. Uredia of southern rust (upper leaf surface view).
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Southern Rust of Corn: Outline • Distinguishing common rust vs. southern rust • Southern rust is potentially much more destructive • Guidelines to consider in fungicide decisions • Monitor for stalk strength
Southern rust (right side) vs. common rust (left) Upper leaf surface Lower leaf surface Images by Alison Robertson, Iowa State University
Leaf desiccated by southern rust Courtesy Greg Henson, McLean Co. Extension
Teliaof southern rust Courtesy Greg Henson, McLean Co. Extension
“Puccinia pathways” for P. polysora ? http://lib.utexas.edu/maps/americas/north_america_ref_2007.pdf
U.S. corn: susceptible to low levels of resistance Image at left courtesy Bob Kemereit, Univ. Georgia
Pace of disease progress under worst-case conditions • 5-6 weeks: From undetected to substantial damage • 2-3 weeks: Can cause substantial damage, if disease is present… • …More or less throughout the field (even at very low levels) • …In all levels of the canopy (lower, middle, and upper)
Days after mid-silk • R2 (blister stage): 10-14 days • R3 (milk stage): 18-22 days • R4 (dough stage): 24-28 days • R5 (dent stage): 35-42 days • R6 (physiological maturity): 55-65 days http://www.agronext.iastate.edu/corn/production/management/growth/yield.html
