Title: Corn Stalk Rots An overview of stalk rots
1Corn Stalk Rots An overview of stalk rots
other corn diseases
- Your name here
- County Extension Educator - Agronomy
- Martin A. Draper
- Extension Plant Pathologist
2Corn Disease Concerns
- Seedling blights
- Leaf diseases
- Stalk rots
- Ear rots
- Post harvest diseases (grain molds)
3Corn disease concerns
- Seed and seedling blights
- Leaf diseases
- Root and stalk rots
- Ear rots
- Post harvest diseases
4Corn Disease Problems in No-Till
- Seedling blights
- Stalk and ear rots
- Emerging no-till diseases
- Anthracnose
- Gray leaf spot
- and others...
5Seedling Blights
6Seed and seedling blights
- Pythium blight
- Rhizoctonia blight
- Penicillium blight
- Fusarium blight
- Diplodia blight
- Aspergillus blight
7Seed and seedling blights
Symptoms of Diplodia blight look much like
other seedling blights.
8Managing seed seedling blights
- Plant in a good environment
- Rotation
- Seed treatments
- Captan
- Maxim
- Vitavax
- Apron
Mancozeb Maneb Thiram PCNB
9Leaf Diseases
10Leaf diseases
- Eyespot
- Rusts
- Northern corn leaf blight (NCLB)
- Gray leaf spot
- Anthracnose
11Leaf diseases
- Eyespot
- Residue-borne
- Produces small translucent spots
- Resistant hybrids available
12Leaf diseases
- Anthracnose
- Residue-borne
- Spots start small and coalesce, becoming large
and irregular in shape
13Leaf diseases
- Northern corn leaf blight (NCLB)
- Residue-borne
- Common in SD
- Causes large lesions
- Favored by moderate temperatures and high
humidity
14Leaf diseases
- Rusts
- Spores blown northward
- Resistant hybrids available
- Usually not severe
15Leaf diseases
- Gray leaf spot
- Residue-borne
- Emerging disease problem in SD
- Resistant hybrids available
16Managing leaf diseases
- Plant resistant hybrids
- Residue management
- Rotation
- Tillage
- Fungicides
- Tilt, Bravo, and Mancozeb are labeled
17Corn disease concerns
- Seed seedling blights
- Stalk and ear rots
- Diplodia stalk rot
- Fusarium stalk rot
- Gibberella stalk rot
- Gibberella zeae / Fusarium graminiarum
- Also causes Fusarium head blight (scab) in wheat
18Corn diseases to watch
- Anthracnose Gray leaf spot
- others also...
- Diseases of minimum tillage
- Compounded by
- Tight rotation or continuous corn
- High rainfall or irrigation
19Corn diseases to watch
- Anthracnose
- Leaf spot and stalk rot
20Corn diseases to watch
- Gray leaf spot
- Leaf spot
- Often severe in eastern corn belt
21Fungicide suppression of Gray leaf spot
GLS severity on ear leaf ()
No significant differences across treatments,
1998, West Lafayette, IN Shaner Buechley, FN
Tests 53142
22Stalk and Ear Rots
23Stalk rots
- Traditionally the most economically
- important diseases of corn
- Not immediately obvious disease symptoms
- Usually develop on lower 1-2 internodes
- May not be an issue unless there is wind before
harvest
24Corn Disease Concerns
- Stalk and ear rots
- Diplodia stalk rot
- Fusarium stalk rot
- Gibberella stalk rot
- Gibberella zeae / Fusarium graminiarum
- Also causes Fusarium head blight (scab)
- in wheat
25Stalk rots
- Anthracnose
- Fusarium stalk rot
- Gibberella stalk rot
- Pythium stalk rot
- Diplodia stalk rot
26Stalk rots
- Anthracnose stalk rot often begins as a leaf
blight that spreads into the stalk - Favored by
- Wet weather or irrigation
- Heavy residue
- Continuous corn
27Stalk rots
- Pythium stalk rot begins as a leaf blight that
spreads into the stalk - Appears soon after tasseling
28Stalk rots
- Pythium stalk rot
- Causes a soft, wet rot
- Less common in SD
- Favored by
- Cool, wet soils
- Heavy residue
29Stalk rots
- Fusarium stalk rot
- Caused by F. moniliforme
- Infects from residue, through roots
30Stalk rots
- Fusarium stalk rot
- Light pink color in pith
- Favored by
- Heavy residue
- Continuous corn
- Wet weather or irrigation
31Stalk rots
- Charcoal rot
- Early maturity
- Black specks (microsclerotia) in pith
- Favored by
- Continuous corn
- Wet weather early season
- Drought stress late in year
32Stalk rots
- Gibberella stalk rot infects through roots from
infected residue in soil - Also causes head blight in wheat (scab)
33Stalk rots
- Gibberella stalk rot favored by
- Heavy residue
- Continuous corn
34Managing stalk rots
- Reduce plant populations
- Manage fertility (avoid high N low K)
- Rotation
- Residue management
- Choose hybrids with good stalk strength and
lodging resistance ( resistant hybrids)
35Ear rots
- Fusarium moniliforme
- Gibberella zeae
36Ear rots
- Need to be aware of mycotoxin risk
- Store below 14 moisture, to minimize hazard
Penicillium ear rot
Aspergillus ear rot
37Ear rots
- Diplodia (A), G. zeae (B), and F. moniliforme (C)
ear rots - Need to be aware of mycotoxin risk
- Store below 14 moisture
38Post harvest diseases
- Penicillium, and Aspergillus seed rots (L-R)
- Need to be aware of mycotoxin risk
- Store below 14 moisture
39Rotation Disease Management
- Critical factor in No-Till
- Important in managing most diseases
- NOT a new concept!!