Agriculture: Fig Pest Management Guidelines

Aspergillus Rot

  • Aspergillus Rot: Aspergillus flavus, Aspergillus parasiticus, Aspergillus spp.
  • Symptoms and Signs

    Infection by these Aspergillus fungi causes the internal tissues of the cavity of fresh figs to turn bright yellow (A. ochraceus and A. melleus), bright green (A. flavus), brown green (A. tamarii), or dark green to olive color (A. parasiticus). Eventually the tissues become powdery from the production of masses of spores. Parts of the cavity (usually close to the ostiole – eye of fig) or the entire interior of the figs can be infected and turn into a mass of powder (conidia of Aspergillus fungi).

    Comments on the Disease

    Similar to smut, which is caused by other Aspergillus spp., Aspergillus rot refers to symptoms seen on fresh figs, whereas smut occurs on dried figs. Most cultivars of figs are affected by Aspergillus fungi, but the Calimyrna and Conadria figs are affected the most. In general, cultivars with small ostioles 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 powdery spore masses. The incidence of this type of rot is very small, for instance 1 in 2,500 figs can be infected by A. flavus or 1 in 10,000 figs can be infected by A. parasiticus. However, figs infected by A. flavus or A. parasiticus usually are contaminated with aflatoxins. Figs that are infected by A. flavus usually show a yellowish green fluorescence under UV light, which can be used to separate contaminated figs from uncontaminated ones.

    Management

    Avoid creating excess dust or letting the trees become water stressed. Choose cultivars with a small ostiole. No chemical treatments are recommended for this disease. For dried figs, remove figs at the processing plant that show characteristic yellowish green fluorescence.

    Text Updated: 01/09