Biocontrol of postharvest fungal apple decay at 20 °C with Muscodor albus volatiles.
Muscodor albus, a fungal bio-fumigant, was tested for control of postharvest fungal diseases on 5 apple cultivars ('Delicious', 'Golden Delicious', 'Gala', 'Granny Smith' and 'McIntosh'). Surface-clean fruit were inoculated with known fungal pathogens (Botrytis cinerea, Penicillium expansum and Sclerotinia sclerotiorum) by placing 20 µl drops of spore suspension on marked puncture locations on each fruit. Inoculated fruit were exposed to volatiles produced by rehydrated air-dried M. albus mycelium growing on rye seeds in sealed 4 L glass jars with air circulation for 24h at 20°C. The amount of dry M. albus - rye seed culture varied from 0 (control) to 1 g·L-1 of jar volume. Immediately after bio-fumigation, the fruit were removed, aerated and placed at 20°C until decay occurred. Fumigation of apples for only 24h with 0.5 g·L-1 culture of M. albus gave complete control of blue mould (P. expansum), grey mould (B. cinerea) and S. sclerotiorum in wound-inoculated fruit. There were no significant changes in fruit quality (i.e., fruit firmness, soluble solid content and titratable acidity) in treated fruit. However, there was some degree of lenticel darkening in 'Golden Delicious' using 1 g·L-1 of rehydrated M. albus - rye seed.