THE NUMBER OF CLADOSPORIUM-CONIDIA IN THE AIR IN DIFFERENT WEATHER CONDITIONS

The effect of varying weather conditions on the hourly number of airbo rne Cladosporium conidia was studied in forest environments during thr ee summers. All factors having diurnal periodicity correlated signific antly with the number of spores. Because of the great variation in wea ther and the interaction of weather factors, the most important factor s were not the same for each summer. Temperature was important in each year. Relative humidify was most important in the first rainy summer, and precipitation was more important during the two drier summers tha n in the first summer. The maximum spore counts were obtained at the o nset of rain, indicating the effectiveness of the first rain drops in detaching conidia. The amount of water precipitated also promoted the production of conidia, since it correlated positively with the number of spores in the air several hours later. Spore detachment also seemed to be closely related to decreases in relative humidity and increases in wind velocity which occurred in the morning. An increase in wind v elocity from 0.5-1.0 m(-s) increased the number of spores most effecti vely.