Net blotch of Peanut

Phoma arachidicola:

Appearance: Phoma arachidicola causes a disease known as leaf spot or early leaf spot in peanuts (Arachis hypogaea). The symptoms typically include small, dark brown to black lesions with yellow halos on the leaves. These lesions often have a concentric ring pattern and can coalesce, leading to extensive defoliation under severe infections. Early leaf spot can negatively impact peanut yields and overall plant health.

Identification:

1. Leaf Lesions: Look for small, circular to irregularly shaped lesions on the leaves of peanut plants.
2. Dark Brown to Black Color: The lesions are usually dark brown to black in color, and they may have a yellow halo around them.
3. Concentric Rings: Lesions often display a concentric ring pattern, particularly as they mature.
4. Defoliation: Severe infections can lead to the premature defoliation of the peanut plant.

Management:

1. Cultural Practices:

   • Crop Rotation: Implement a proper crop rotation strategy to reduce the buildup of the pathogen in the soil.
   • Adequate Spacing: Plant peanuts with adequate spacing to promote air circulation and reduce humidity around the plants.

2. Fungicide Application:

   • Fungicidal Sprays: Application of fungicides, especially those effective against Phoma arachidicola, can be part of an integrated disease management strategy. Consult with local agricultural experts for recommended fungicides and application schedules.

3. Resistant Varieties:

   • Plant Resistant Peanut Varieties: Where available, consider planting peanut varieties that are known to be resistant or tolerant to early leaf spot caused by Phoma arachidicola.

4. Regular Monitoring:

   • Scouting Fields: Regularly monitor peanut fields for early symptoms of leaf spot, and initiate control measures promptly if symptoms are detected.