The spore discharge mechanism is a defining characteristic of the Basidiomycota and is used by the majority of the species within it. It is powered by fluid movement over the spore surface and propels basidiospores from Mushroom Buddies gills and spines, as well as the inner surfaces of tubes in polaroid species such as Aspergillus and yeast (Fig 2B).
The fungi produce a spray or puff of airborne spores when they reach maturity. This spray consists of a cloud of tiny dust particles that reaches a diameter of about one-hundredth of a centimeter at a distance of about 100 cm away from the spore source (Fig 3). Each particle is shaped like a bullet and travels in a stream parallel to the spore surface.
Mushroom Cultivation 101: Starting with Spores in the UK
Fungal spores contain allergens that can trigger respiratory symptoms in susceptible individuals. These symptoms include sneezing, runny nose, mucous production, coughing, congestion, sinusitis, and asthma. These allergens are released at different times of the year, depending on the species. The spores of some species are also released at very high rates, causing a sudden attack in those with asthma or other respiratory conditions.
Spore risk is higher in warm and humid weather. It begins to rise in mid-June in central England and is at its highest in late August, September and October. The spore season in western coastal regions and in mountainous areas tends to start a few days or weeks later than in central England.
In cold weather there is generally no significant spore risk from mushrooms. However, spores from the toxic saprobic grassland mushroom Panaeolus semiovatus, or Dung Roundhead, and from other hallucinogenic species such as Didymella and Sporobolomyces can be released during damp weather.