Symptoms and Signs
Symptoms of sour rot, or souring, are more distinct on fruit of cultivars that need no caprification (pollination), such as Adriatic figs. In cultivars needing caprification (e.g., Calimyrna), the symptoms of souring may be confused with the symptoms of endosepsis. The symptoms of souring become noticeable only when the fruit ripens and the eye opens.
Infected figs develop a pink color and later become water soaked. A pink syrupy liquid exudes through the eye, dropping on to the leaves or jellying at the eye; gas bubbles and the odor of fermentation are characteristic of this disease. In later stages the pulp disintegrates and usually is covered by a white scum. The affected figs turn soft and black, sag, shrivel, dry up, and either drop or hang on the twig until harvest. A dead spot or eye canker often develops in the bark around the attachment of the stem of the fruit.
Comments on the Disease
Nitidulid beetles and vinegar fruit flies are the primary carriers of yeasts and other microflora that cause souring.
No chemical controls are suggested. However, controlling driedfruit beetles, Carpophilus hemipterus, and vinegar (fruit) flies, Drosophila melanogaster and D. ampelophila, may have some benefit in reducing souring.