Bacterial Soft rot potato: Erwinia carotovora subsp caratovora
Symptom:
- Infection at two phases is blackleg and soft rot.
- The black lesion appears 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.
- The soft, reddish or black ring appears 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%
Management:
- 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 control the disease. Soaking of tubers in Mercuric chloride 0.1% formalin.
