Early blight of potato

1. Early blight of Potato
(Alternaria solani)
Submitted by :- Dadhaniya Niv (12005379)
Submitted to :- Dr. Seweta Srivastava
Lovely Professional University
Phagwara, Punjab

2. Contents
 Taxonomic classification
 History of Alternaria solani
 Symptoms
 Disease Cycle
 Etiology
 Epidemiology
 Management

3. Taxonomic classification
• Kingdom :- Fungi
• Division :- Ascomycota
• Class :- Dothideomycetes
• Order :- Pleosporales
• Family :- Pleosporaceae
• Genus :- Alternaria
• Species :- A. solani

4. History of Alternaria solani
• Though the causal pathogen is distributed worldwide and can cause
crop yield reductions.
• early blight has never caused widespread famine or other sudden and
major detrimental effects on humanity.
• The causal organism of early blight was first described by Ellis &
Martin (1882) as Macrosporium solani.
• The first reference to the fungus as a parasite and its association with
potato leaf blight was by Galloway (1891) in Australia.
• Jones (1893) was the first to suggest the name ‘early’ blight to
distinguish the disease from ‘late’ blight.

5. • The first recorded observation of early blight in South
Africa was in KwaZulu-Natal.
• Between 1980 and 1984, a study was conducted to
determine the epidemiology and control of potato early
blight in the mist belt of the high-rainfall sourveld areas in
KwaZulu-Natal (Nevill 1985).
• Since then, however, very few similar studies have been
done in South Africa.
• The most important hosts of A. solani are tomato, potato
and eggplant.

6. Symptoms
• This is a common disease of potato occurring on the foliage at any
stage of the growth.
• The first symptoms of early blight appear as small, circular or
irregular, dark-brown to black spots on the older (lower) leaves.
• These spots enlarge up to 3/8 inch in diameter and gradually may
become angular-shaped.
• Initial lesions on young, fully expanded leaves may be confused
with brown spot lesions.
• These first lesions appear about two to three days after infection.
• Early blight lesions can be diagnosed in the field easily due to the
dark concentric rings alternating with bands of light-tan tissue,
giving them a distinctive target spot appearance.

7. • Early blight symptoms on infected tubers appear as dark-
colored, sunken lesions on the tuber surface.

8. Disease Cycle
• The primary infection of potato foliage by A. solani is caused by inoculum provided
from other infected hosts or inoculum that overseasoned on infected plant debris.
• Alternating wet and dry periods are most favorable for sporulation and dispersal.
The spores produced by primary inoculum are responsible for secondary spread of
the fungus to healthy tissue, which leads to an exponential increase of foliar
infection.

9. Etiology
• The conidia and the mycelium in the soil or in the debris of
the affected plants can remain viable for more than 17
months.
• The conidia formed on the spots developed due to primary
infection are disseminated by wind to long distances.

10. Epidemiology
• Favorable Temperature 25-30°
• Dry warm weather with intermittent rain
• Poorly manured crop

11. Management
• Select a late-season variety with a lower susceptibility to
early blight.
• Removal and destruction of crop debris.
• Time irrigation to minimize leaf wetness duration during
cloudy weather.
• Use of resistant variety : kufri sindhuri
• Avoid nitrogen and phosphorus deficiency.
• Rotate fields to non-host crops for at least three years.
• Spray fungicides like chlorothalonil, difenoconazole,
flusilazole + mancozeb.