|
Appearance |
Symptoms |
Possible Cause(s) |
| Silking impaired |
Delayed silking or failure to silk |
- Moisture stress
- Stress on plants earlier in season
- Plant population too high
- Nutrient deficiency
- Corn leaf aphids
|
| |
Silks clipped off |
|
| Tassels malformed |
Tassels fail to emerge |
|
| |
Tassels and upper stalk and foliage bleached, premature drying |
|
| |
Tassels develop as a mass of leaves |
|
| |
Leafy condition in the tassels |
|
| Plants discolored |
Yellowing of leaf margins, beginning at tips; affected tissue later turns brown and dies |
|
| |
Irregular, purple-brown spots or blotches on sheaths |
|
| Stalks malformed and/or broken |
Lower stalk internodes easily compressed; stalks may lodge (break over) - (see Stalk Rot) |
|
| |
Lower internodes easily compressed; black linear streaks on stalk surface |
|
| |
Plants lodge, stalk may break |
|
| Premature death of all or some parts of plants |
Sudden death of entire plant |
|
| |
Extensive areas of leaf tissue die prematurely resulting in leaf drying |
|
| |
Top kill - premature death of all or portion of plants above ears. |
|
| Leaf tissue removed |
Ragged holes in the leaves |
|
| |
Shredding, tearing of leaves |
|
| |
Small, irregular holes in leaves |
|
| |
Large irregular holes in leaves |
|
| Plants discolored or stunted |
Slight to severe stunting; yellowing and sometimes reddening of foliage |
- Maize dwarf mosaic or Maize chlorotic dwarf
|
| Lesions on plants |
Irregularly- or wavy-margined, pale green to yellow or pale brown streaks |
|
| |
Tan leaf lesions with parallel sides or spindle shaped and with buff to brown borders |
- Southern corn leaf blight
|
| |
Long, elliptical, gray-green or tan lesions |
|
| |
Small (1/16 to 3/8 inch) circular to oval lesions |
|
| |
Elongated irregular brown water-soaked leaf stripes or spots on lower leaves |
- Bacterial leaf spots and stripe
|
| |
Oval, circular or rectangular lesions on leaves |
- Helminthosporium leaf spot
|
| |
Circular to oval lesions, brown centers with yellow to orange borders |
|
| |
Numerous brown to black pustules on any above ground part, especially the leaves; leaves dry out |
|
| Damage to ears |
Dark 'bruises' on husks |
- Hail damage - all plant material in an area affected; damage often more severe on one side of plant
|
| |
Large chunks removed from husks and ears; kernels eaten off |
- Grasshopper Damage
- Birds - ears often upright, husks shredded
- Rodents
- Raccoons, squirrels or other animals
|
| |
Tunneling or chewing feeding damage on kernels |
|
| |
Ears break over and/or drop to ground |
|
| Ears or kernels malformed |
Ears not filled, partially filled, or smaller than normal ('nubbins') |
- Maize dwarf mosaic or Maize chlorotic dwarf
- High temperatures during pollination causing sterility
- Drought conditions
- Timing of silking not synchronized with pollen shed
- Plant population too high
- Low fertility
- Silks clipped back by insects
- Corn leaf aphids - caused delay or failure of silking
- Sorghum downy mildew
- 2,4-D herbicide injury - applied during tasseling or pollen shed stage
|
| |
Excessive ear shoots which are leafy and barren |
|
| |
Soft, glistening galls on the ear, later black and powdery |
|
| |
Ears twisted with irregular kernel rows and imperfectly developed ear tips |
|
| |
Red streaking of seed coats; most common at ear tip |
|
| Ears rot or are moldy |
Individual kernels or scattered groups of kernels with pinkish mold |
|
| |
Pink to red mold growing through kernels from the silk end |
|
| |
Powdery, green or blue-green mold on and between kernels, usually at ear tips |
|
| |
Husks bleached; white mold between kernels |
|