Effect of soilborne inoculum on incidence of onion black mould ( Aspergillus niger)

Abstract

Aspergillus niger is the cause of black mould of onions which is primarily a postharvest disease Systematic sampling of soil from onion fields in the Pukekohe/Waikato regions of New Zealand in 2002 and 2003 showed that the highest levels of soilborne A niger occurred in fields that had not been recently rotated out of onions Levels of soilborne A niger were correlated with black mould incidence in bulbs stored at high temperature and high humidity but not in bulbs stored at ambient temperature and humidity It is likely that soilborne spores are a principal source of inoculum for black mould of onions in Pukekohe New Zealand