downy mildew orgreen ear disease of bajra

1. Green Ear of Bajara
By –
Dr. Gunmala Gugalia
Associate Professor
Dept. Of Botany
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2. Introduction- Overview
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DISEASE: Downy mildew or Green ear disease
•
PATHOGEN: Sclerospora graminicola
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HOSTS: Bajra / Pearl Millet or Sorghum
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3. Introduction
•
Green ear disease is the most destructive disease of
bajra and widely distributed throughout tropical and
temperate countries of the world.
•
The green ear disease of Bajra is a common disease
and has been reported from several countries
including-
•
India,
•
Iran,
•
Israel,
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China, Fiji,
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Japan and the countries wherever Bajra crop is grown.
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4. Cont…Introduction
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In India, the disease was first reported and studied by E. J.
Butler (1907) who considered the disease to be sporadic in
nature not causing much damage to the crop.
•
Mitter and Tandon (1930) reported the disease from
Allahabad, Uttar Pradesh and confirmed the observations
of Butler (1907).
•
Up to 27-30% losses has been estimated in India.
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5. •
The disease appeared in an epidemic form in Karnataka
and Maharashtra during 1975 causing almost total loss of
the crop.
Cont…Introduction 5

6. Etiology
•
One of the most important diseases of pearl millet
is downy mildew, also known as green ear, caused by the
fungus Sclerospora graminicola (Sacc.)
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•
Kingdom- Straminopila/ Chromista
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Classification
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Phylum- Oomycota
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Class- Oomycetes
Order- Peronosporales
Family - Peronosporaceae

7. Disease Cycle
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The oospores remain viable in
soil for five years or longer
giving rise to the primary
infection on the host seedling.
•
Oospores attached to the seed
also cause primary and
systemic infection of
seedlings.
•
Oospores are formed late in the
season in the necrotic tissues
on the leaves.
•
Secondary spread is through
sporangia, which are active
during rainy season,
disseminated by air and water.
•
Secondary infection may not
develop into systemic infection
but leads to local infection.
•
Seeds formed are internally
infected
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8. Cont…
Etiology
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9. Symptoms
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Two type of symptoms,
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Downy mildew and
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Green ear.
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10. Cont…Symptoms
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Downy mildew-
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Leaves
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Chlorosis starts at the base
of the leaf and soon covers
the entire lamina.
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11. Cont…Symptoms
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Green ear-
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Affecting the ears
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Panicle are drastic
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Bristles , glumes
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Stamens and Pistils
become green and
leafy
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12. Survival and spread
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The oospores remain viable for eight months to ten years
or more in the soil, which makes primary infection in host
plants.
•
The secondary spread of disease starts from sporangia,
which are most active in moist environment.
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13. Favorable conditions
•
The atmospheric temperatures between 15-25 °C and
relative humidity above 85%.
Light drizzling accompanied by cool weather is highly
favorable.
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14. Management
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15. Cont…
Management
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Selection of seed from healthy crop
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Rotation of crop
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Removal and burning of diseased plants.
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Spraying with dithane M- 45 helps in controlling
the disease.
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16. •
Seed treatment with 0.1%Agrosan GN and 0.4%
thiram has been reported to control the disease to
50%.
•
Use of disease resistant variety like ICMH88088
developed by the ICRISAT, Hyderabad has show
better results.
•
Other resistant varities include IP 18292 and 18298.
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Cont…
Management

17. Thank you
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