Early blight disease of potato is an important disease of potato
Which is the causal organism of early blight of Potato?
Fungus named Alternaria solani is the causal organism of early blight of potato
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What are the symptoms of early blight of potato?
It is present in both hills & plains.
Brown-black necrotic spot-angular, oval shape characterized by concentric rings.
Several spot coalesce & spread all over the leaf.
Shot holes develop on fruits.
What are the characteristic features of the fungus causing Early blight?
Hyphae are light brown or olivaceous which become dark coloured with age.
The hyphae are branched, septate and inter and intra cellular.
The coniophores emerge through the stomata or between the epidermal cells.
The conidia are club shaped with a long beak which is often half the long of the whole conidium.
The lower part of the conidium is brown while the neck is colorless.
The body of the conidium is divided by 5 – 10 transverse septa and there may or may not be a few longitudinal septa.
What are the Favourable conditions for the development of early blight disease?
Dry warm weather with intermittent rain.
Poor vigor of plants.
Temperature of 25-30°C.
Poorly manured crop.
What is the Mode of spread and survival?
The conidia and the mycelium in the soil or in the debris of the affected plants can remain viable for more than 17 months.
These conidia or the new conidia found on the overwintered mycelium bring about the primary infection of the succeeding potato crop.
Secondary infection is more important in the spread of the disease.
The conidia formed on the spots developed due to primary infection are disseminated by wind to long distances.
The conidia from the affected plant may also be disseminated to the adjoining plants by rain and insects.
What are the management practices for control of Early blight disease?
Disease free seed tubers should be used for planting.
Removal and destruction of infected plant debris should be done because the spores lying in the soil are the primary source of infection.
Very early spraying with Zineb or captan 0.2% and repeating it for every 15 – 20 days gives effective control.
The variety Kufri Sindhuri possesses a fair degree of resistance.
Further readings and references
Plant diseases by GN Agrios