The purpose of this study was to document the airborne pollen and mold spores present in central Minnesota (USA) and to provide a baseline for future studies. A total of 81 samples were collected with a Rotorod sampler from mid-May until late October (2004). Sample rods were analyzed after staining with Calberla's reagent. Raw data are reported in a web site (http://www.csbsju.edu/pollen). To confirm our counting accuracy, rods were counted by two individuals on twelve sample dates. There was no statistically significant difference in counts from the two observers. Dichotomous and polyclave keys to the pollen species observed were prepared.
Tree pollen was the predominant pollen-type observed in the early spring. The mean daily tree pollen concentration was 87.4 grains/m³. There was an early peak of oak/maple pollen followed by a peak of pine in early June. Grass pollens (including cattail and sedges) were detected the entire season (mean = 11.0 grains/m³). Cattails peaked in mid-July while sedges were most abundant in late May/early June. Grasses could be detected throughout most of the sampling season. Forb pollens appeared in high frequency in mid-July and were the dominant grains until the end of the counting period. The mean daily concentration was 27.1 grains/m³.
Mold spore abundance was highly variable (1311 - 13220 per m³). On average we observed 5541/m³. Rusts were observed in nearly all samples (96.3%) though in low abundance. Algae were relatively rare (mean concentration was 0.4 per m³).
Patterns of distribution of individual species will be reported and corroborates data previously reported for the Minneapolis/St. Paul area (Rosendahl, et al., 1940).