Quantitative Studies of Fungus Spores in the Air

SUMMARY

Two hundred fifty-six silicone treated slides were exposed to the air in a Pady-Rittis sampler between June, 1953, and June, 1955, and the total number of fungus spores, as well as the commonest types were determined on a cubic foot basis. An exposure of 30 min. was made daily in summer and once or twice a week in winter. Fungus spores were present throughtout the year but were seasonal in their distribution with peaks in July and August and low concentrations in winter. Numbers in summer ranged from 50 to 700/cu ft with occasional peaks to over 1300/cu ft. In the winter numbers were usually 5 to 20/cu ft.

Cladosporium was present throughout the year, comprising the bulk of the spores in summer. Numbers, in the summer were usually 25 to 350/cu ft, but higher concentrations were common, with one spore load 1080/cu ft July 7, 1953. Ustilago chlamydospores were also present all year with a peak in June at harvest time, ranging from 3 to 50/cu ft in the summer with occasional spore loads up to 415/cu ft. In the winter numbers were from 1 to 10/cu ft. Puccinia urediniospores were found chiefly in June with high numbers on only a few days and in concentrations from 1.2 to 12/cu ft. Alternaria spores were seasonal in distribution with numbers ranging from 2 to 40/cu ft in the summer, with a maximum of 97.8/cu ft on July 7, 1953. Yeast, Fusarium, and basidiospores were definitely seasonal in their occurrence and appeared to be abundant following rains. Yeast cells were usually 1–40/cu ft with one high of 211/cu ft, whereas Fusarium spores were usually lower. Basidiospores were sporadic in appearance with numbers occasionally up to 75/cu ft.

Spores of the following were found occasionally on the slides: Helminthosporium, Cercospora, Penicillium (or Aspergillus), Septoria, Stemphylium, Sporormia, Pleospora, Venturia-like, Leptosphaeria-like, Curvularia, Erysiphe, Heterosporium, Nigrospora-like, Cephalothecium, Monilia-like chains and Sordaria-like. Unidentified spores, usually 1-celled, made up a large portion of the spore deposit. Hyphal fragments were present throughout the year without seasonal peaks, ranging from 2 to 15/cu ft and sometimes as high as 53/cu ft.