Tuber rot of Potato is an important Post harvest disease of Potato
Fungus called Sclerotium rolfsii is the causal organism of Potato Tuber rot
Also read –
Symptoms of Tuber Rot
Wilting is the initial symptom.
Yellowish brown coloured Sclerotia appeared on the infected tuber.
Rotting of the tuber.
Milky white and floccose appearance of the tuber.
Characterisitcs of fungus causing tuber rot
The mycelium is silky white and floccose.
It is comprised of septate and branched hyphae.
The branching take place just below the septum. The cells are large in size.
Sclerotia of the fungus are white to begin with and become clove brown at maturity.
They are globose and smooth surfaced.
Favorable condition for development of tuber rot in Potato
Optimum temperature 30-35ºC.
Alternate period of wet and dry soil condition.
Mode of spread and survival
The mycelium and sclerotia of the organisam subsist in the soil and are responsible for the infection of the crop.
The pathogen is disseminated with infected soil, in running water and on farm implements.
Mycelium and sclerotia may also be carried to soil with the seed tubers.
In dry soil scleritia can remain viable for more than two years.
What are the control measures for Potato tuber rot?
Treating seeds with mercury compounds after harvest reduces tuber rot.
Treating the furrows at planting with PCNB @ 15kg/ ha reduces the disease icidence.Cultural practices like heavy earthing and irrigation at regular intervals can also check the disease.
The disease is low in the variety Kufri Sindhuri.
Among the Indian commercial cultivars, Kufri Bahar, Kufri Chamatkar, Kufri Jyothi, Kufri muthu and Kufri swarna are resistant.
The disease can be controlled to a certain extent by growing non susceptible crops like corn and sorghum.
Further readings and references
PLant Patholgy by G N Agrios