Download Common Corn Diseases in Tennessee

Common Corn Diseases
in Tennessee
Heather M. Kelly
Extension/Research Plant Pathologist
University of Tennessee
Gray Leaf Spot (GLS)
Cercospora zeae-maydis
~ Disease favored by warm,
wet/humid conditions
~ Overwinters in corn residue
~ Can be problematic in
continuous corn
~ Small lesion develop initially
on lower leaves and elongate
parallel to leaf veins
(rectangular spots)
Northern Corn Leaf
Blight (NCLB)
Exserohilum turcicum
Most damaging if:
~Prolonged periods of
dew and moderate temp.
(64 - 80°F)
~Infection before silking
Foliar Corn
Diseases
Northern Corn Leaf Blight
Helminthosporium turcicum
Common Rust
Puccinia sorghi
~ Disease favored by cool (6570°F), humid conditions
~ Spores blown in from the
South. Does not commonly
effect yield in TN
Common Rust
(Puccinia sorghi)
• Disease favored by cooler temp
(65-70°F)
• Brown, elongated ½ - inch pustules
on both sides of leaf
• Rarely causes yield loss
Upper side of
leaf
Lower side of
leaf
Southern Rust
(Puccinia polysora)
• Disease favored by
warm temp (77-82°F)
• Orange, round 1/16 inch pustules primarily
on upper leaf surface
• Can cause yield loss
Know the difference
between rusts!
Common Rust
–
–
–
–
Cooler temperatures (61-77 F)
½ in. brown, elongated pustules
On both sides of leaf
No yield loss
Upper side of
leaf
Southern Rust
–
–
–
–
warmer temperatures (77-82 F)
1/ in. orange, round pustules
16
On upper leaf surface
Fungicide application/resistant hybrid
recommended to prevent yield loss
Lower side of
leaf
Holcus Spot OR
Paraquat/Gramoxone Drift
• Both disease and drift have
same lesion symptoms
• Both occur early in season
• Holcus spot caused by
bacteria and prolonged wet
weather with warm temp
(76-86 °F)
With either no action needed,
no yield loss usually occurs