Growth of Penicillium sp. during shipment of onions between Tasmania and Europe has been identified by importers as a serious problem over the last two export seasons. This project determined when Penicillium grows and how environmental factors and transport methods influence growth. Spore release occurred 2-3 days after any period when the relative humidity was above 80%, surface moisture was present and the temperature was above 18 degrees celcius. These conditions occurred regularly between Tasmania and the Suez Canal. Efficient ventilation was identified as the most important factor in reducing the severity of infection.