Airborne Alternaria spores in SE Spain (1993-98) - Occurrence patterns, relationship with weather variables and prediction models

The annual, seasonal and hourly distribution of Alternaria spores in the ai r of Murcia, SE Espana, was studied on a six-year period. The relationships between Alternaria spore concentrations and meteorological factors were in vestigated. Alternaria is a late afternoon taxon in the Murcia city, with maximum spore concentrations occurring between 13.00 h and 21.00 h. Alternaria spores ar e present in the atmosphere throughout the year, with a main spore season e xtending from March to October, and showing two peaks as a consequence of t he summer drop in concentration. Alternaria spore concentrations correlate well with Poaccae and Chenopodiac eae pollen counts, suggesting these plants Could be important hosts, but no t the only ones, because many crops are growing just Mien peaks Occur. Low wind velocities favoured high spore counts. Correlation with temperature wa s positive in the of the six years. Mean temperature is the Factor which be st explain spore levels. The best prediction model obtained explains 74% of the observed variance in Alternaria levels (in a five steps scale) by usin g mean temperature alone.