FUNGAL MICROBIOLOGY Seasonal and Diurnal Patterns of Spore Release Can Significantly Affect the Proportion of Spores Expected to Undergo Long-Distance Dispersal David Savage & Martin J. Barbetti & William J. MacLeod & Moin U. Salam & Michael Renton Received: 15 August 2011 /Accepted: 20 September 2011 /Published online: 4 October 2011 # Springer Science+Business Media, LLC 2011 Abstract Many of the fungal pathogens that threaten agricultural and natural systems undergo wind-assisted dispersal. During turbulent wind conditions, long-distance dispersal can occur, and airborne spores are carried over distances greater than the mean. The occurrence of long- distance dispersal is an important ecological process, as it can drastically increase the extent to which pathogen epidemics spread across a landscape, result in rapid transmission of disease to previously uninfected areas, and influence the spatial structure of pathogen populations in fragmented landscapes. Since the timing of spore release determines the wind conditions that prevail over a dispersal event, this timing is likely to affect the probability of long- distance dispersal occurring. Using a Lagrangian stochastic model, we test the effect of seasonal and diurnal variation in the release of spores on wind-assisted dispersal. Spores released during the hottest part of the day are shown to be more likely to undergo long-distance dispersal than those released at other times. Furthermore, interactions are shown to occur between seasonal and diurnal patterns of release. These results have important consequences for further modelling of wind-assisted dispersal and the use of models to predict the spread of fungal pathogens and resulting population and epidemic dynamics. Introduction Long-distance dispersal is an important ecological process that influences the long-term survival and genetic structure of populations, particularly within fragmented environ- ments [6–8, 20, 27]. For wind-dispersed fungal pathogens, long-distance dispersal can play a highly significant role in the transmission of disease to previously uninfected areas by allowing migration across uninhabitable regions [6, 8, 35]. Long-distance dispersal also facilitates genetic interac- tion between spatially separated populations, and can therefore result in the introduction of new virulent alleles into existing populations [35]. Understanding the drivers of long-distance dispersal can therefore provide insights into the management of diseases caused by fungal pathogens, and is therefore of significant importance to agriculture, human and animal health, biosecurity, conservation of natural ecosystems and pest management. Microb Ecol (2012) 63:578–585 DOI 10.1007/s00248-011-9949-x D. Savage : M. J. Barbetti : W. J. MacLeod : M. Renton School of Plant Biology and the UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia D. Savage : M. J. Barbetti : W. J. MacLeod : M. Renton Cooperative Research Centre for National Plant Biosecurity, University of Canberra, Level 2, Building 22, Innovation Centre, University Drive, Bruce ACT 2617, Australia W. J. MacLeod : M. U. Salam Department of Agriculture and Food Western Australia, Locked Bag 4, Bentley Delivery Centre, Perth, WA 6983, Australia M. Renton CSIRO Ecosystem Sciences, Floreat, WA 6014, Australia M. Renton Centre of Excellence for Climate Change and Woodland and Forest Health, Murdoch University, Perth, WA, Australia D. Savage (*) 23 Ingrams Rd, Research, Melbourne, VIC, Australia 3095 e-mail: david.savage@mac.com