|
Disease
|
Resistant or tolerant hybrids
|
Crop rotation
|
Clean plow-down
|
Balanced fertility
|
Fungicides
|
Other controls and comments
|
| Stewart's bacetrial wilt |
1
|
|
|
|
|
Early control of corn flea beetles may be helpful on
susceptible hybrids |
| Seed rots and seedling blight |
2
|
|
|
|
1
|
Sow injury-free, plump seed. Plant seed in soils 50
to 55 F or above. Prepare seedbed properly and place fertilizer, herbicides,
and insecticides correctly. |
| "Helminthosporium" leaf blights; Northern
leaf blight, Northern leaf spot, "Helminthosporium" leaf
spot, southern leaf blight |
1
|
2
|
2
|
|
2
|
Fungicide applications are generally only justified
in seed production fields and only if the lower three leaves up to
2 weeks after tasseling are infected. |
| Physoderma brown spot |
1
|
3
|
2
|
|
|
|
| Yellow leaf blight and Eyespot |
1
|
2
|
1
|
|
3
|
See comments for "Helminthosporium" leaf blights |
| Gray leaf spot |
2
|
2
|
2
|
|
3
|
See comments for "Helminthosporium" leaf blights |
| Anthracnose |
1
|
2
|
1
|
3
|
|
|
| Crazy top and sorghum downy mildew |
1
|
3
|
3
|
|
|
Avoid low wet areas and plant only downy mildew-resistant
sorghums in sorgum-corn rotations. Control of shattercane (an alternate
host) is very important. |
| Goss's bacterial wilt |
1
|
1
|
2
|
|
|
Rotations of 2 or more years will provide excellent
control. |
| Smut |
2
|
3
|
3
|
3
|
|
Avoid mechanical injuries to plants. Control insects. |
| Common and southern rusts |
1
|
3
|
|
|
3
|
Fungicides may be justified in seed-production fields. |
|
Stalk rots:
Diplodia
Charcoal
Gibberella
Fusarium
Anthracnose
Nigrospora
|
2
|
2
|
2
|
2
|
|
Plant adapted, full-season hybrids at recommended populations
and fertility. Control insects and leaf diseases. Survey at 30 to
40% moisture to determine potential losses. |
Ear and kernel rots:
Diplodia
Fusarium
Gibberella
Physalospora
Penicilliuma
Aspergillusa
Others |
2
|
2
|
3
|
3
|
|
Control stalk rots and leaf blights. Hybrids that mature
in a downward position with well-covered ears usually have the least
ear rot. Ear and kernel rots are increased by bird, insect, and severe
drought damage. |
Storage molds:
Penicillium
Asperigillus, etc. |
|
|
|
|
|
Store undamaged corn for short periods at 15 to 15.5
percent moisture. Dry damaged corn to 13 to 13.5 percent moisture
prior to storage. Low-temperature-dried corn has fewer stress cracks
and storage mold problem s if an appropriate storage fungicide is
sued. See your nearest Extension adviser for details. Corn stored
for 90 days or more should be dried to 13 to 13.5 percent moisture.
Inspect weekly for heating, crusting, or other signs of storage molds. |
| Maize dwarf mosaic |
1
|
|
|
|
|
Control Johnsongrass and other perennial grasses (alternative
hosts) in and around fields |
| Wheat streak mosaic |
1
|
|
|
|
|
Plant winter wheat (an alternative virus host) after
the fly-free date and control volunteer wheat. Separate corn and wheat
fields. |
Nematodes:
Lesion
Needle
Dagger
Sting
Stubby-root |
|
2
|
2
|
3
|
|
Clean plow-down helps reduce winter survival of nematodes.
Nematicides may be justified in some situations. See your Extension
adviser for information on chemical control. |
| |
|
|
|
|
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|
|
Note: Description of these diseases
can be found in the Corn Disease Compendium, published by the American
Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121.
|
| 1 = highly effective control measure |
|
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| 2 = moderately effective control |
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| 3 = slightly effective control |
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| A blank indicates no effect |
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