Assessing the contribution of fallen autumn leaves to airborne fungi in an urban environment

© 2015, Springer Science+Business Media New York. Many street trees in urban areas are deciduous and drop leaves during autumn. These leaves are a potential growing substrate for fungi, which when aerosolized and inhaled, can lead to allergy along with more serious diseases. This investigation assessed the potential contribution of fallen leaves to the diversity of airborne fungal propagules during autumn. The senescent leaves of five deciduous tree species prevalent in urban environments were subject to a manipulative experiment in which their phyllospheric fungi were aerosolized, cultured and identified. Aerosolized fungi were compared with fungi detected from direct observation of the phyllosphere. Thirty-nine fungal genera were identified across the plant species sampled, of which twenty-eight were present in corresponding air samples. Significant differences were observed amongst the fungal genera growing on the leaves of the different trees, however few differences were found in the composition of fungal spores that were aerosolized. The dominant genera that were aerosolized were: Penicillium, Cladosporium, Alternaria, Chaetomium, Botrytis and Trichothecium. Some of these fungi are known to produce allergy and other symptoms in humans. As these fungal genera have been commonly identified in autumn air samples in other studies, it is likely that the phyllospheric fungi present on deciduating leaves contribute to the aeromycota of urban areas