Fungal spora of softwood timber drying kilns in Scotland

Fungal spoilage of kiln dried timber is considered with respect to the airspora of softwood timber drying kilns and timber storage yards at two Scottish sawmills. The spore load of operating kilns became enriched in comparison with external airspora at certain stages of the drying schedule with an abundance of Aspergillus spp. Although viable propagules of several mould and stain fungi were isolated from sawdust on the concrete floor of the kiln, none were isolated from the aluminium walls. Heavy colonisation of Sitka spruce (Picea sitchensis) limber by surface discolouring Ophiostoma spp. was practically sterilised, but not physically removed, by kiln drying. Colonisation of timber surfaces with Aspergillus spp. was increased by kiln drying, occasionally leading to moulding during drying. Unidentified species of Aspergillus, Paecilomyces, Penicillium and an imperfect fungus isolated from kiln air and dried wood demonstrated radial growth in vitro at temperatures expected at timber surfaces during kiln drying.