Sour rot symptom on a ripe fruit is a scar that extends down to the side of the fruit. White fungal growth resembling appearance of cottage cheese can be seen where the crack is formed.

In green tomatoes, water soaking of fruits can be seen as an early symptom and collapse of the epidermis (skin) of the fruit can also be noticed.

Internal growth of the fungus can be noticed in green fruits also when cut open. Mechanical injuries during handling of plants is a major cause for the spread of the disease.

At advanced stage of the disease, a sour odor develops which is very distinctive. The disease progresses rapidly on ripe fruits if favorable conditions persist.

Individual arthroconidia of the fungus Geotrichum candidum. The fungus can survive in soil on plant debris, and on fruit handling equipment, and is an opportunistic pathogen.