Pathogen. The leak fungus is widely distributed in soils. It also attacks the underground parts of many other crops.
Disease development. The fungus cannot penetrate tubers directly, but enters through bruises and wounds, which usually occur at harvest. Harvesting the crop in hot weather or exposing the tubers to heat for several hours after harvest creates ideal conditions for leak.
Leak development is very rapid, and can cause serious losses in storage, in transit and on the market. When infected potatoes are stored, juice from rotten tubers drips down through the pile.
Pythium may be responsible for the decay of seed tubers if conditions are warm and wet immediately after planting.
Pythium leak rot has a sweet smell.