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Diagnostic Guide for Corn Problems (Emergence to knee-high (V7) (Yellow…
Diagnostic Guide for Corn Problems
No Plant Emerged
No seed planted
Planter Problems: Clogged seed delivery system, Planter unit drive problems
Seed not sprouted
Ammonia Injury, seed not viable, Fertilizer in contact with seed, insect or disese, Lack of oxygen (flooding)
Seed is normal, not swelled
Soil to dry
Seed swelled, not sprouted
Soil dried out, Soil to wet, Seed not viable
Rotted seed or seedings
Seed Rots: Pythium, Diplodia, Gibberella, Fusarium, Colletotrichem, ect
Sprout twisted or leaves expanded underground
Mechanical injury, seed too deep, cloddy soil, chloroacetamide herbicide injury, insecticide injury, fertilizer injury, biuret damage
Seed eaten, dug up, or sprout cut off
Seeds hollowed out
Planter problems---- Clogged seed delivery system and planter unit drive problems
Plants pulled up, eaten
Bird damage: Crows, pheasants, blackbirds Rodent damage: Mice, voles, ground squirrels
Before Emergence
Emergence to knee-high (V7)
Small area of dead plants
Plant missing
Problem at or near planting
Dead plants present
Lightning
Cultivator injury
Scattered spots of dead or poorly growing plants
Uneven growth
Poor growing conditions
uneven drainage
Ammonia injury
Dead or stunted, discolored plants grading into normal plants at margin of affected area
Ammonia injury
Cultivator injury
Stewart's leaf blight
Nematodes
Wireworm
Glyphosate drift injury
Insect damage : Garden symphylan and white grub
Plants irregularly shaped, broken, or wilted
Leaves rolled, plants wilted
Root feeding insects
White grub
Garden symphylan
Grape colaspis
Corn rootworm
Corn root aphid
Mechanical injury to root
Drought stress
Nematodes
Leaves tightly rolled, no wilted
Herbicide injury
2, 4-D, dicamba
Chloroacetamide herbicide
Plants suddenly wilt and die, or cut off at ground level
Insect damage
Wireworm
Black cutworm
Cultivator injury
Leaves appear water-soaked, to grayish becoming necrotic
ammonia injury
Forst
Paraquat injury
Plants twisted or broken off
High acetamide herbicide rates
Cultivator damage
Thiocarbamate herbicide injury
Insecticide injury
Plants discolored and stunned
Leaves yellow; plants weak and stunted
Nitrogen, sulfur deficiency
Purple or red discoloration of leaves, especially margins; stunting of roots
Dinitroaniline herbicide injury
Dicamba herbicide injury
Imidazolinone or sulfonylurea herbicide injury
Phosphorus deficiency
Dull grey areas on upper leaves, often where leaf bends
Frost or intense sunlight (scalding)
Yellow-white area in leaf
Whitish or yellowish striping between leaf veins
Nutrient deficiency: Iron, Manganese, Magnesium, Boron
Low pH
Only on occasional plants
Physiological injury
Plant mostly white
Genetic mutation
Isoxaflutole, mesotrione, clomazone drift or carryover
Necrotic stripes between plants
Stewart's leaf blight
Whitish striping along veins
Sulfur deficiency
Broad white areas, in center toward base of leaves, stunting, failure of internodes to elongate
Zinc deficiency
Narrow whitish scratches in leaf surface only
Corn leaf beetle
Leaves appear sandblasted or speckled, tips shreaded
Thrips
Wind damage
Plants discolored
Pale green color
Gylphoste drift injury
Nitrogen deficiency
Waterlogged soils
Potassium Deficiency
Leaf purplish or reddish, especially at tips
Cold soils
Root insects: Grape colaspis, white grub, garden symphylan, wireworm
Wind damage
Nematodes
Glyphosate drift injury
Phosphorus deficiency
Dinitroaniline herbicide injury
Lower leaves dead, tips dying on upper leaves
Fertilizer injury
Chinch bug
Leaf edges yellow or dead
Plant tissue removed
Windowpane effect, leaf skeletonizing
Insect damage
Southern corn footwork adult
Cereal leaf beetle
Grape colaspis
Redheaded flea beetle
Palestriped flea beetle
Rows of holes across leaves
Wireworm
Cutworm
Armyworm
Billbug
Shredding or tearing of leaves
Wind, hail damage
Large holes in leaves
Sod webworm
Common stalk borer
Variegated cutworm
Slugs
Leaf margins damaged
Fall armyworm
Armyworm
Yellow-striped army worm
