Management of Late Blight of Potato

Management of Late Blight of Potato

Symptoms:

1. On potato, early symptoms of late blight first appear on leaves as small, circular or irregularly shaped, dark necrotic lesions within 3 to 5 days of initial infection.

2. Symptoms may first appear on mature lower leaves where high humid/damp conditions and cooler temperature are most likely to prevail.

3. However, early infections can also occur on other parts of the foliage under favorable weather conditions. This includes air currents that can carry spores from nearby infected fields or volunteer potato plants. 

4. On petioles and stems, symptoms appear as dark, water-soaked lesions. Lesions expand with time as the pathogen colonizes the internal plant tissues. On mature lesions, the pathogen produces glistening white spore-bearing structures called sporangia on the underside of the leaves or surface of stems. 

5. As the disease progresses, the entire infected tissue will blight and decay. Tubers become infected at any stage of their development and they start to turn brown and rot slowly from the outside. Infected tubers become susceptible to secondary infections by other soft rot pathogens present in the soil or at storage.

Late Blight of Potato Symptom

Late Blight Management:

1. Avoid planting highly susceptible potato varieties.

2. Plant only clean, certified seed potatoes each year. Seed pieces should be treated with a protectant fungicide containing Haymancozeb (Mancozeb) or Provax to minimize the spread of late blight from infected tubers. 

3. Do not plant seed pieces showing signs of decay. Dispose of them off the farm where they will not be able to grow.

4. Do not over-fertilize or overwater. Dense lush foliage stays wet longer and is more likely to become infected. Avoid using overhead irrigation when possible.

5. Spray Haymencozeb (Mancozeb) or Acrobat MZ (Mancozeb + Dimethomorph) or Ridomil gold (Mancozeb + Metlexil)  @4gm/Li or  Headline Team (Pyraclostrobin + Dimethomorph) @2.50 gm/Li of water according to severity.

6. In severe stage include Defense 35SC (Carbendazim + Hexaconazole) or Cougar 28SC (Azoxystrobin + Cyproconazole) @ 01ml/Li of water with any one of the above.