Take-off of Mould Spores in Relation to Wind Speed and Humidity

Using horizontal tube-cultures of various moulds belonging tothe genera Thamnidmmt, Phymatotrichum, Trichotheciwm, Ptptocephalis,Trichoderma, Mucor and Mycogone, the take-off of dispersal units(usually spores) under the influence of air currents of variousspeeds and of different humidities has been studied. It is foundthat in all the dry-spore forms the number of spores set freeincreases as the speed of the air stream rises. Further, atany given air-stream rate, the numbers of spores set free aregreatest in the first interval of time and rapidly fall offin subsequent intervals. In all species, spores are more readilyset free in air streams of relatively low as compared with thoseof relatively high humidity. Although Trichoderma viride hasbeen regarded as a slime-spore fungus, its conidia can readilybe blown from the conidiophores. No spores could be inducedto take off from Mucor ramarmianus even at the highest air speedsused.