Diplodia Leaf Streak

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Symptoms of Diplodia Leaf Streak

  • Disease occurs primarily on leaves, but may also affect ears or stalks.
Diplodia Leaf Streak lesions on corn leaf. Diplodia leaf lesions are mostly oval to elongated and contain black pycnidia.

Leaf lesions are brown, often with yellow margins. Lesions are mostly
oval to elongated and contain black pycnidia (fungal fruiting structures)
imbedded in leaf tissue.

Look-Alike Disease

  • Northern corn leaf blight (NLB) caused by Exserohilum turcicum can look similar to Diplodia leaf streak.
  • NLB is a common fungal leaf disease with elongated, mostly oval lesions.
  • Main difference — lesions of NLB do not contain pycnidia.
Diplodia Leaf Streak lesions (left) and northern corn leaf blight lesions (right)

Diplodia leaf streak (left) and northern corn leaf blight (right)

Facts on Diplodia Leaf Streak

  • Fungal disease caused by Stenocarpella macrospora (Diplodia macrospora).
  • Generally of minor importance in the U.S., but localized infections have been observed in Indiana, Illinois and Kentucky.
  • Disease is more common in regions of Latin America.
  • The more familiar Diplodia disease of corn is caused by Stenocarpella maydis (Diplodia maydis) and affects ears and stalks.

Disease Cycle

  • Fungi overwinter in diseased corn debris.
  • Spores are rain-splashed or wind-blown to leaves where infections may occur.
  • When the fungus infects the leaf tissue, a characteristic lesion develops, followed by formation of pycnidia containing spores.
  • Secondary infection occurs as the disease spreads from plant to plant and field to field by dissemination of spores.


  • Crop rotation, as the fungus survives in infected crop residue.
  • Tillage encourages breakdown of crop residue.
  • Specific management for this disease is not typically required, as occurrence is sporadic and the effect on yield is usually minimal.
  • Pioneer does not currently rate hybrids for resistance to this disease.