Corn Diagnostic Guide - 8-10 Leaves to Tasseling

Appearance

Symptoms

Possible Cause(s)

Severe wilting and/or death of plants Sudden death of plants
  • Lightning - plants in an approximately circular area suddenly killed
Plants discolored Yellowing of plants, beginning with lower leaves
  Yellowing or leaf margins, beginning at tips; affected tissue later turns brown and dies
  Purpling or reddening of leaves from tip backward; affects lower leaves initially; leaf tips may later turn dark brown and die.
  Yellow to white interveinal striping on leaves (see Striped Corn Leaves)
  • Genetic stripe
  • Magnesium deficiency
  • Boron deficiency
  Pale green to white stripes between leaf veins, usually on upper leaves
  • Iron deficiency
  Upper leaves show pale green to yellow interveinal discoloration; lower leaves appear olive green and somewhat streaked.
  • Manganese deficiency
Plants discolored and malformed Plants show stunting and/or a mottle or fine chlorotic stripes in leaves
  • Maize dwarf mosaic or Maize dwarf chlorotic
  Stunting, tillering; twisting and rolling of leaves. Yellow and striped leaves; narrow leaves; upright habit
  • Crazy top
  • Sorghum downy mildew
  Plants darker green; stalks twisted at mid to upper half.
  • Herbicide injury - Sutan+, Eradicane
Plants malformed and/or lodged Plants show 'buggy-whip' effect - upper plant portion tightly rolled, enclosing upper leaves and tassel; plant elbowing or lodging
  • 2,4-D herbicide injury - also may result in upcurling of brace roots and brittleness or lower nodes
  • mechanical injury
  Twisting and bending at corn stalks above the ear shoot; ear may be malformed
  • Herbicide injury - Sutan+, Eradicane - delayed symptom.
  • Mechanical injury
  • Hybrid characteristic
  Plants lodge or grow up in a 'goosneck' shape.
  Brown, soft rot of a lower internode; stalks twist and fall.
  • Pythium stalk rot or bacterial stalk rot
  • European Corn Borer - stalks weakened by borer feeding damage
  • Stalk Borer Damage
  • 2,4-D or dicamba (Banvel) herbicide injury - applied "over the top" on hot days - may cause stalk to be flat and brittle; often causes abnormal brace root formation
  Soft, glistening white galls soon become black and dusty; on stalks, leaves, ear or tassel
Plant tissue removed Ragged holes in the leaves and shredding of plants.
  Shredding, tearing of leaves
  • Wind damage
  Longitudinal slits chewed out from between leaf veins.
  • Cereal leaf beetles - adult feeding damage
  Green, upper layer of tissue stripped from leaves.
  Leaf tissue skeletonized or lacy in appearance.
  "Window effect" of leaves - interior of leaves eaten out.
  • Corn blotch leafminers
  Leaves entirely eaten off or large areas of leaf tissue removed
  Holes bored into stalks and area within stalk hollowed out by feeding damage
Lesions on plants Tan, oval to circular lesions
  • Holcus Spot
  • Fungal leaf spots
  • Paraquat herbicide injury
  Irregular to elliptical brown, water-soaked leaf spots
  • Bacterial leaf spot and stripe
  Small, circular tan spots with brown to purple margin.
  Brown, oval leasions with yellow to reddish brown borders
  Circular to oval, brown to black pustules on leaves

Planting to Emergence || Emergence to 8-10 Leaves || 8-10 Leaves to Tasseling || Tasseling to Maturity || Corn Diagnostic Guide

Adapted by James H. Hill, Iowa State University - Hancock County Extension Education Director, from information prepared by Dale M. Studt, retired ISU Extension Crop Production Specialist.
JHHill 10/16/2007