|
Appearance |
Symptoms |
Possible Cause(s) |
| Scattered dead or poorly growing plants |
Uneven growth (see Uneven Corn) |
- Soil compaction
- Variation in planting depth, soil moisture, etc.
- Drainage problems
- Poor growing conditions
- Cloddy seedbed
- Anhydrous or aqua ammonia injury
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Slow growth |
- Low fertility
- Cold (mainly below 55 degrees F)
- Dry
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Plants stunted, wilted and/or discolored |
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Plants cut off above or below ground level or rapid wilting |
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Sudden death of plants |
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- Frost in low areas of field
- Lightning
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| Wilting |
Upper leaves roll and appear dull or sometimes purple; stunting of plants; plants may die |
- Drought conditions
- Insect damages
- Mechanical damage due to root pruning by cultivator
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Whorl dead |
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Crown roots not developing |
- Dry surface soil
- Shallow planting depth
- Wind
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| Discolored Plants |
Pale green color |
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Yellow or dying leaf edges |
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Yellowing of upper leaves |
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Yellowing of lower leaves |
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Purpling or reddening of leaves from tip backward |
- Phosphorus deficiency
- Soil compaction
- Cold weather
- Hybrid characteristics
- Injured, broken leaves
- Insects
- Herbicide injury (Dinitroaniline)
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Whitish or yellow striping between leaf veins |
- Nutrient deficiency
- Magnesium
- Iron
- Manganese
- Boron
- Low pH or acid soil condition
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Whitish striping along leaf veins |
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White areas in the center and towards base of leaves |
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Lower leaves dead, tips dying on upper leaves |
- Fertilizer injury or burn (nitrogen and potash too close)
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Leaves appear sandblasted; pale green or whitish in color |
- Wind damage
- Thrips
- Spider mites
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Yellowing or browing beginning from leaf tips |
- Excessive herbicide rates
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Leaves turn white to tan and die |
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Light and dark mottling or mosaic on leaves |
- Maize dwarf mosaic virus (MDMV) or maize chlorotic dwarf virus (MCDV)
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Yellow to white strips with smooth margins running length of leaves |
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Bleached bands across leaf blades; leaf tips may die back; leaf collapse and fold downward |
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| Discolored and stunted plants |
Yellow leaves; spindly, stunted plants |
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Purple or red discoloration of leaves, especially leaf margins; stunting; stubby, malformed roots; drouthy appearance |
- Herbicide injury
- Phosphorus deficiency
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| Discolored, stunted and/or malformed |
Tillering, stunting |
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Yellow-green tint; severely stunted; inability of leaves to emerge or unfold |
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Leaves yellow and not expanded; roots sheared off or dried up |
- Shallow application of ahydrous ammonia
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Yellow strips in leaves, stunting |
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Leaves fail to unfurl properly, often underground; plants may be lodged, lying flat on ground |
- Herbicide injury - Amide (Lasso or Dual)
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Leaves stunted and twisted and may appear knotted |
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Shoots and roots malformed; onion-leafing (leaves remain wrapped) |
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Plants bent or twisted; stunted; irregular row of holes in unfolded leaves |
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| Lesions on leaves |
Spots of dead tissue on leaves |
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Oval, circular or rectangular lesions on leaves |
- Helminthosporium leaf spot
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Long, irregular yellow to brown streaks in leaves |
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Tan, spindle-shape lesions with parallel sides and buff to brown borders |
- Southern corn leaf blight
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Oblong, oval, tan colored spots with yellowing of leaves |
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Brown, oval lesions; yellow to reddish-brown |
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Small transluscent, circular to oval lesions |
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Circular to oval cinnamon-brown pustules |
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| Plant tissue missing or removed |
Plant cut off at ground level |
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Leaves eaten off or large areas of leaf tissue removed |
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Ragged leaves shredded or torn |
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Rows of circular to elliptical holes across leaves (shothole affect) |
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Ragged holes in leaves |
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Longitudinal slits chewed out from between leaf veins |
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Irregular brown lines or tracks scratched from the top layer of leaf tissue |
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"Window effect" of leaves - interior leaves eaten out |
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Yellow, weakened area on leaf mid-rib from tunneling feeding damage |
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