Black leg (Phoma lingum)

Symptoms

• Pale, irregular spots develop on leaves, which later become ashy gray with scattered black dots on the surface.
• Stem lesions are elongated with purple borders near the ground level and extend below the soil surface, causing a black rot of lower stem and roots.
• Stem of the affected plant when split vertically, shows severe black discoloration of sap stream.
• Whole root system decays from bottom upwards.
• Severely affected plants remain stunted and finally wilt.
• As plants mature, they fall due to lack of root anchorage.
• Seed crop symptoms include occasional cankers on stem bases and spots also appear on overwintered leaves.

Management

• Disease free seeds should be used for planting.
• As the main infection is through seeds, hot water treatment of seeds for 52oC for 15 minutes is recommended.
• For seed production plots, seed stock used should be free from fungal pathogen.
• Cultivation in the fields where crucifers have been continuously grown during last 2 years should be avoided.
• Seedbeds and seed plots should be regularly inspected for obvious foliar infections.
• Seedlings before transplanting should not be dipped in water.
• Seed treatment with Trichoderma viride 4g/kg.

Chemical Control

Extremely Toxic

Highly Toxic

Moderately Toxic

Slightly Toxic