Maize diseases

1. Diseases of Maize
1) Downy mildew
2) Bacterial stalk rot
3) Black bundle disease or late wilt
4) Common rust
5) Brown stripe downy mildew

2. Downy Mildew
Symptoms: The most characteristic symptom is the
development of chlorotic streaks on the leaves.
Plants exhibit a stunted and bushy appearance due to
shortening of the internodes. White downy growth is
seen on the lower surface of leaf. Downy growth also
occurs on bracts of green unopened male flowers in
the tassel. Small to large leaves are noticed in the
tassel. Proliferation of axillary buds on the stalk of
tassel and the cobs is common (Crazy top).
Favourable Conditions Low temperature (21-33°C)
High relative humidity (90 per cent) and drizzling.
Young plants are highly susceptible Zinc deficiency
disposes plants to infection

3. Management
1) Deep ploughing
2)Crop rotation with pulses
3) Rogue out infected plants
4)Grow resistant varieties and hybrids viz. CO1,
COH1, COH2,DMR 1, DMR 5 and Ganga 11
5)Treat seeds with metalaxyl at 4-6g/kg Spray crop
with metalaxyl + mancozeb @ 2g/l on 20th day after
sowing

4. Bacterial Stalk rot : Erwinia dissolvens
Symptoms: The basal internodes develop soft rot and
give a water soaked appearance
. A mild sweet fermenting odour accompanies such
rotting. Leaves some time show signs of wilting
andaffected plants topple down in few days. Ears and
stem may also show rot. They fail to developfurther
and the ears hang down simply from the plant
Disease cycle: Borer insects play a significant role in
initiation of the disease. The organism is soil borne and
makes its entry through wounds and injuries on the
host surface.

5. Management
1)Use of disease resistance varieties;while no absolute
resistance has been identified so far, Hybrids Ganga Safed-
2, DHM 103, show significantly less disease incidence than
other hybrids
.
2) Avoid waterlogging and poor drainage.

6. Black Bundle Disease
• Symptoms
• Blackening of vascular bundles appears as
black dots on the cut ends of the stalk.
• In severe cases, leaves dry and plants wilt.
• Ears, may rot or may not form at all.

7. Management
• Use of resistant varieties like Ganga Safed 2.
• Crop sanitation, crop rotations.
• Avoiding water stress at flowering
• Seed treatment with Thiram or Captan 3g/kg
seed.

8. Common Rust
• Symptoms:
• Circular to elongate golden brown or
cinnamon brown, powdery pustules appear
on both leaf sufaces.
• In severe cases infection spreads to sheaths
and other plant parts.

9. Management
• Plant hybrids like Deccan, Ganga-5, Deccan
hybrid which are resistant to this disease to
minimise the disease intensity.
• Spray Mancozeb 2.5g/lit or Dithane M-45
spray can be taken as soon as first symptoms
are observed and it can be repeated at 10
days interval till flowering.

10. Brown Stripe Downy Mildew
• Symptoms:
• Disease symptoms have been observed only
on leaves, they are vein limited.
• Characteristic symptoms are chlorotic to straw
coloured stripes on the lower leaves and after
sometime on upper leaves also.
• Find cottony growth of the fungus can be seen
on the affected leaf surface during morning
hours.

11. Management
• It can be controlled by three to four foliar
sprays of 0.25% Zineb or Mancozeb.
• Give first spray as soon as disease appears in
the field.
• The sprays should be given between 10 to 15
days interval depending upon the severity of
disease