No abstract

Scytalidium ganodermophthorum (telomorph: Xylogone ganodermopthora) Kang, Sigler, Lee & Yun is a destructive fungal pathogen that produces a yellow pigment that is used in sustainable product development. Similar pigmenting ascomycetes cause soft rot in woody substrates, however, the decay capabilities of S. ganodermophthorum have not been assessed or related to pigment production. A wood block decay test showed highly variable production of the expected bright yellow pigment and a secondary darker pigment when tested against multiple wood species and nutrient conditions. Microscopic examination showed cell wall erosion typical of type-2 soft rot in wood, although enzymatic analysis did not show detectible levels of endocellulase. Chitinase was detected in plate cultures but not wood cultures, indicating adaption of the fungus to a variety of environmental growth conditions. The high variability of pigmentation in wood cultures suggests that growth of S. ganodermophthorum on liquid media and use of extracted pigment is a superior method for obtaining consistent yellow coloration.

Fungi cultured from air-seasoning blackgum and red oak timbers were assessed for their ability to cause wood decay using two hardwoods and one softwood species in an AWPA E10 soil block test. Weight losses were greatest for bigleaf maple and tended to be much lower on southern pine. Almost a quarter of the 35 taxa tested caused less than 5 % weight loss, suggesting they posed a relatively low decay risk, even under ideal laboratory conditions; despite all fungi tested having the ability to depolymerize wood. Three of the four fungi causing the largest weight losses were brown-rot fungi, although brown-rot fungi represented an only small proportion of the total isolates from the original hardwood timbers. These results illustrate the wide array of decay capabilities of fungi colonizing air-seasoning red oak and blackgum timbers, and the potential of many isolates to negatively affect wood properties through biodeterioration.

The effects of distance above ground on fungal colonization during air-seasoning were evaluated over time on blackgum (Nyssa spp.) and red oak (Quercus spp. Section Lobatae) ties 150, 200, and 300 mm from the ground by culturing increment cores removed from three locations on each of 200 ties over the seasoning period. Fungi were present in many ties at the start of seasoning. Fungal isolations steadily increased with time, but there were no significant differences in frequency for ties seasoned at different sill heights for either timber species. The results indicate that lowering the sill height had no noticeable effect on the rates of fungal colonization of the timber species tested.