Soft rot of Potato
Causal organism
Bacteria named Erwinia carotovora
Symptoms
Black lesion appear on the base of the plant
Browning of infected tubers.
Yellow appearance of the plant.
Finally the plants wilt and die
Soft, reddish or black ring appear on the infected tuber
Pathogen characteristics
It is a gram negative rod shaped bacterium with 1 to 6 peritrichous flagella.
Mode of spread and survival
Infected tubers attract the flies (Hymelia and Phorlin sp)
Spread through contaminated soil and tuber
Optimum temperature 21 to 29 ºC and RH 94%
Control
Using Disease free seed tubers
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.
