Corn Leaf Diseases and Disorders

Most of the common corn diseases found in Iowa in the mid to late August (and some uncommon ones) have been included, but this is not a comprehensive list.

Stalk diseases and ear rots were not included because they are rarely observed during the period from Aug 15 to Aug 31.

[Common diseases] [Occasional/infrequent diseases] [Rare diseases] [Disorders/non-diseases]


Diseases that are relatively common in Iowa fields

Common Rust Puccinia sorghi
Common Smut Ustilago maydis
Gray leaf spot Cercospora zeae-maydis
Northern leaf blight Exserohilum turcicum (Helminthosporium turcicum)
Eyespot Kabatiella zeae
Stewart's wilt Erwinia stewartii
Carbonum (Northern) leaf spot Cochliobolus carbonum (Helminthosporium carbonum)

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Diseases that are occasionally found in Iowa fields

Southern corn leaf blight Cochliobolus heterostrophus (Helminthosporium maydis)
Southern Rust Puccinia polysora
Crazy top Sclerophthora macrospora
Physoderma brown spot Physoderma maydis

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Rare (or never found) diseases

Maize dwarf mosaic virus
Head Smut Sphacelotheca reiliana- found 2 or 3 times in past 20 years
High Plains Virus - never found; would be big news
Leaf freckles or Goss' Wilt Clavibacter michiganensis ssp. nebraskensis

[Common diseases] [Occasional/infrequent diseases]

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Heat injury
Yellow spots, rings, circles - things that can be mistaken for eyespot
Purple spots on leaf sheath

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