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Diagnostics Guide for Corn Problems (Emergence to knee high (v7) (Yellow…
Diagnostics Guide for Corn Problems
Knee high to tasseling text
Plants have abnormal shape or position
plants lean or fall over
Rootworm
Strong winds before brace roots have formed
Nematodes
2,4-D herbicide injury
Mechicanal injury
Stalks collapse for rot
European corn borer
2,4-D herbicide injury
Cutworm
Stalks collapse from stem rot
Pythium stalk rot
Bacterial stalk rot
Brace roots malformed or missing
Herbicide injury
2,4-D, dicamba
Slugs
Plants malformed and discolored
Stunting, tillering, twisting
Crazy top disease
Galls; silvery white then black
Smut
Stunting, red leaves, excessive silvering
Maize chlorotic mottle
Narrow leaves, striping
Sorghum downy mildew
Plants discolored, white, yellow, or purple on leaves
Leaves completely white, or top leaves or scattered leaves white
Extreme heat
White stripes and some white leaves on scattered plants only
Genetic stripe
Yellowing of plants, beginning with lower leaves at leaf tip along midrib
Nitrogen deficiency
Standing water
Yellowing of leaf margins, beginning at tips; affected tissue later turns brown and dies
Potassium deficiency
Yellowing and necrosis of lower leaves beginning at leaf tip
Herbicide injury
Photosynthetic inhibiting herbicide (applied post-emergence
Interveinal Chlorosis or purpling
Amino acid synthesis inhibitor herbicide
Purpling or reddening of leaves, from tip backward; affects lower leaves initially; leaf tips may later turn dark brown and die
Phosphorus deficiency
Yellow to white intervenaial striping on leaves or reddening of leaves
Magnesium deficiency
Pale green to white striping on leaves
Iron deficiency
Upper leaves show pale green to yellow interveinal discoloration
Magnesium deficiency
Lesions or necrotic spots on leaves
Paraquat, atrazine + oil, or other photosynthetic inhibitor herbicides
Foliar diseases:
Yellow leaf blight
Anthracnose
Stewart's leaf blight
Helminthosporium leaf blights
Leaves have a window effect but neither surface is broken
Corn blotch leaf miner
Leafhopper eggs
Upper leaves brown and sticky
Corn leaf aphid
Yellow or dead leaves, or plants
Ammonia burn
Glyphosate herbicide injury
Holes in leaves
Leaves eaten
Armyworms
Variegated cutworm
Stalk borer
European corn borer
Grasshopper
Cutworm
Livestock or wildlfie
Leaves skeletonize or window like
Western corn rootworm adult
Leaves shredded
Hail damage
Wind damage
Before Emergence , No plant Emerged
No seed planted
Planter problems,
Clogged seed delivery system
Planter unit drive problems
Seed normal, not swelled
Soil too dry
Seed not Sprouted
Ammonia Injury
Seed not Viable
Fertilizer in Contact with Seed
Insect or Disease
Lack of Oxygen (Flooding)
Seed swelled, not sprouted
Soil dried out
soil too wet
seed not viable
Rotted Seed or Seedlings
Types of Seed Rots
Pythium
Diplodia
Gibberella
Fusarium
Colletotrichum
Sprout twisted or leaves expanded underground
Mechanical injury
seed too deep
cloddy soil
Chloroacetamide herbicide injury
insecticide injury
fertilizer burn
biuret damage
Before Emergence, Seed Eaten, Dug Up, or Sprout Cut Off
Seeds hollowed out
Insect damage
Seed corn maggot
wireworm
seed corn beetle
thief ant
flea larva
Plants Pulled Up or Eaten
Bird Damage
Crows
Pheasants
Black Birds
Rodent damage
Mice
voles
Ground squirrels
Emergence to knee high (v7)
Scattered spots of dead or poorly growing plants
Uneven Growth
Ammonia Injury
Poor Growing Conditions
Uneven Drainage
Dead or stunted
Insect damage
Garden symphylan
White Grub
wireworm
stewards leaf blight
Ammonia injury
cultivator injury
Nematodes
Glyphosate drift injury
Plants Discolored
Lower Leaves Dead Tips Dying on Upper Leaves
Fertilizer Injury
Cinch Bug
Pale Green Color
Water Logged Soils
Glyphosate drift injury
Nitrogen Deficiency
Leaf edges yellow or dead
Potassium deficiency
Plants irregularly shaped, broken, or wilted
Leaves rolled, plants wilted
corn root aphid
Grape colaspis
Drought stress
White grub
Garden symphylan
Corn rootworm
Leaves tightly rolled, not wilted
2,4-D, Dicamba
Chloroacetamide herbicide
Leaves appear water-soaked, to grayish becoming necrotic
Frost
Paraquat injury
Ammonia injury
Plants suddenly wilt and die, or cut off at ground level
Black cutworm
Cultivator injury
Wireworm
Plants twisted or broken off
High acetamide herbicide rates
Cultivator damage
Thiocarbamate herbicide injury
Insecticide injury
Small area of dead plants
Plants missing
Problem at or near planting
Dead plants present
Lightning
Cultivator injury
Plant tissue removed
Windowpane effect, leaf skeletonizing
Grape colaspis
Redheaded flea beetle
Cereal leaf beetle
Palestriped flea beetle
Southern corn rootworm adult
Yellow-white areas in leaf
Whitish striping along veins
Sulfur deficiency
Broad white areas,in center toward base of leaves, stunting, failure of internodes to elongate
Zinc deficiency
Necrotic stripes between veins
Stewart's leaf blight
Narrow whitish scratches in leaf surface only
Corn flea beetles
Only on occasional plants
Physiological injury
Leaves appear sandblasted or speckled, tips shredded
Thrips
Wind damage
Whitish or yellowish striping between leaf veins
Magnesium
Manganese
Boron
Iron
Low pH
Plant mostly white
Isoxaflutole, mesotrione, clomazone
Drift or carryover
Genetic mutation
Plants discolored and stunded
Leaves yellow, plants weak and stunted
Nitrogen, sulfure deficiency
Purple or red discoloration of leaves, especially margins, stunting of roots
Imidazolinone or sulfonylurea herbicide injury
Dinitraoniline herbicide injury
Dicamba herbicide injury
Phosphorus deficiency
Dull grey areas on upper leaves, often where leaf bends
Frost or intense sunlight (scalding)
Plant tissue removed
Leaf margins damaged
Armyworm
Yellow-striped armyworm
Fall armyworm
Rows of holes across leaves
Cutworm
Armyworm
Wireworm
Large holes in leaves
Slugs
Common stalk borer
Sod webworm
Variegated cutworm
Shredding or tearing of leaves
Wind, hail damage
