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.