Symptoms and Signs
Smut causes the internal tissues of the fig cavity to turn black and powdery from the production of black spores produced by the three Aspergillus spp. Parts of the cavity (usually close to the ostiole) or the entire interior of the fig can be infected and converted to a mass of black powder, which is conidia of the Aspergillus fungi. When the dried fig is pressed, a clout of spores can erupt from the ostiole.
Comments on the Disease
Similar to Aspergillus rot, which is caused by other Aspergillus spp., smut refers to symptoms seen on dried figs whereas Aspergillus rot occurs on fresh figs.
Most cultivars of figs are affected by the smut fungus, but the Black Mission, Brown Turkey, and Kadota cultivars experience less damage than Adriatic and Calimyrna. In general, cultivars with small ostioles (pores) suffer less disease than those with larger ostioles. Decay usually begins at the eye-end of the figs when they are still green. In later stages, when the fruit is ripe, the fungus produces abundant black spore masses that are transferred to healthy fruit by nitidulid beetles, vinegar flies, and thrips. In some years up to 30% of the crop can be infected by the smut fungi, causing significant losses. Infected fruit is worthless and cannot be used except for feeding cattle.
Remove all old fruit culls and refuse from the orchard on which driedfruit beetles and vinegar flies might breed. Also, avoid creating excess dust, especially during August when fruit becomes susceptible to the smut fungi. No chemical treatments are recommended for this disease.