Early blight of potato: Alternaria solani
Symptom:
- It is present in both hills & plains.
- Brown-black necrotic spot-angular, an oval shape characterized by concentric rings.
- Several spot coalesce & spread all over the leaf.
- Shot holes on fruits.
Identification of pathogen:
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 too long distances.
- The conidia from the affected plant may also be disseminated to the adjoining plants by rain and insects.
Epidemiology:
- Dry warm weather with intermittent rain.
- Poor vigor. Temperature: 25-30°C.
- Poorly manured crop.
Management:
- 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.
Source-
- TamilNadu Agritech Portal
