unwettable spores which are resistant to desiccation and light damage.
They become airborne in the same way as fine dry dust particles by
physical disturbance and wind. Spores ofPenicilliumandAspergillus
(Figure 2.4) seem to get everywhere in this passive manner and species of
these two genera are responsible for a great deal of food spoilage. The
individual spores ofPenicilliumare only 2–3mm in diameter, spherical to
sub-globose (i.e.oval), and so are small and light enough to be efficiently
dispersed in turbulent air.
Some fungi, such asFusarium(Figure 2.5), produce easily wettable
spores which are dispersed into the atmosphere in the tiny droplets of
water which splash away from the point of impact of a rain drop and so
may become very widely distributed in field crops during wet weather.
Figure 2.4 (a) Pencillium expansum and (b) Aspergillus flavus
Figure 2.3 Geosmin
Chapter 2 9