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 air of Murcia, SE Espana, was studied on a six-year period. The relationships between Alternaria spore concentrations and meteorological factors were investigated. 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 are present in the atmosphere throughout the year, with a main spore season extending from March to October, and showing two peaks as a consequence of the summer drop in concentration. Alternaria spore concentrations correlate well with Poaccae and Chenopodiaceae pollen counts, suggesting these plants Could be important hosts, but not the only ones, because many crops are growing just Mien peaks Occur. Low wind velocities favoured high spore counts. Correlation with temperature was positive in the of the six years. Mean temperature is the Factor which best explain spore levels. The best prediction model obtained explains 74% of the observed variance in Alternaria levels (in a five steps scale) by using mean temperature alone.