Soybean Rhizoctonia aerial blight / Web blight

Soybean Rhizoctonia aerial blight / Web blightRhizoctonia solani

Symptom:
  • Infected seeds have irregularly shaped tan or light brown sunken lesions.
  • Infected leaves appear as water soaked at first instance. They soon take on a greenish brown to reddish brown appearance.
  • The infected portion later turns tan brown or black in colour.
  • Under high rainfall or high humid conditions, the web like the mycelial growth of fungus forms on the leaves.
  • Dark brown sclerotia are formed on leaves and petioles.
  • The pathogen survives as sclerotia in soil.
  • Humid and cool (24-32o C) are favourable weather condition.
Management:
  • Avoid dense planting.
  • Completely cover plant residue by clean ploughing the field soon
    after harvest.
  • Destroy infected stubble.
  • Seed treatment with Thiram + Carbendazium (2:1) @ 3g/kg seed.
  •  Use Mancozeb or copper fungicide at 2.5gm/l or carbendazim 1 g/lit.

 

Source-

  • TamilNadu Agritech Portal