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
Dec 14, 2015
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
“Puccinia pathways” for P. polysora
http://lib.utexas.edu/maps/americas/north_america_ref_2007.pdf
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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