Southern Rust of Corn: Outline
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Transcript of Southern Rust of Corn: Outline
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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
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Uredia of southern rust (upper leaf surface view)
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Southern rust (right side) vs. common rust (left)
Upper leaf surface
Lower leaf surface
Images by Alison Robertson, Iowa State University
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Courtesy Greg Henson, McLean Co. Extension
Leaf desiccated by southern rust
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“Green islands” of southern rust
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Courtesy Greg Henson, McLean Co. Extension
Telia of southern rust
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“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
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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)
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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
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Watch for loss of stalk strength