This study examines the microbial ecology of the surface of developing banana fruits, at Carnarvon (Latitude 25 degrees S) in Western Australia.The fruit surface microflora was determined in April (autumn), August (winter) and December (summer) for three stages of fruit development. The number of bacteria, yeasts, and filamentous fungi were determined and the fungal isolates identified. The peel of the mature preharvest stage fruits harboured more microorganisms than the two earlier stages of fruit development. More microorganisms were isolated from fruits sampled in August than in April or December. In December, a high number of yeasts were isolated from the fruits at the mature preharvest stage of fruit development. When considered separately as yeasts, bacteria or filamentous fungi, there was no significant difference in the number between development stages, but there was a difference between seasons. We conclude that season influences microbial populations on banana fruit surfaces in the arid environment of Carnarvon, more than the stage of fruit development. (C) 1997 Elsevier Science B.V.