• Infection at two phases is black leg and soft rot.
• Black lesion appear on the base of the plant .
• Systemic and browning of infected tubers.
• Yellow appearance of the plant.
• Finally the plants wilt and die.
• Rot and collapse of tubers.
• Soft, reddish or black ring appear on the infected tuber.

Identification of pathogen:

Mode of spread and survival:

• Infected tubers attract the flies (Hymelia and Phorlin sp).
• Spread through immature contaminated soil and tuber.
• Optimum temperature 21 to 29 ºC and RH 94%

• The pathogen is difficult to control because of long survival both on seed tubers and in soils.
• However using disease free seed tubers could minimize the disease incidence.
• Before planting the seed tubers are treated with Boric Acid (3% for 30 minutes) and dried in shade.
• The same treatment is repeated before the storage of the tubers.
• The disease can be reduced by soil application of PCNB (30 kg/ha) at the time of planting.
• Following crop rotations with wheat, pea, oats, barley, lupin, soybean, sorghum and bajra checks the disease development.
• In plains, treatment of the seed tubers with TBZ + acetic acid + 0.05% Zinc Sulphate solution or Carbendazim 1% for 15 minutes effectively controls the disease. Soaking of tubers in Mercuric chloride 0.1% formalin.