southern rust of corn: outline
DESCRIPTION
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). - PowerPoint PPT PresentationTRANSCRIPT
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)
Southern rust (right side) vs. common rust (left)
Upper leaf surface
Lower leaf surface
Images by Alison Robertson, Iowa State University
Courtesy Greg Henson, McLean Co. Extension
Leaf desiccated by southern rust
“Green islands” of southern rust
Courtesy Greg Henson, McLean Co. Extension
Telia of southern rust
“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
Watch for loss of stalk strength