Temperature and controlled atmosphere effects on efficacy of Muscodor albus as a biofumigant

Biofumigation with Muscodor albus was investigated to control four fungal decay pathogens (Phytophthora erythroseptica, Sclerotinia sclerotiorum, Botrytis cinerea and Penicillium expansum) and four bacterial pathogens (Erwinia carotovora pv. carotovora, Pseudomonas fluorescens, Escherichia coli, Listeria innocua) in controlled atmosphere conditions (regular air (20.8% O2 + 0.03% CO2), high CO2 (20.8% O2 + 15% CO2) or low O2 (1% O2 + 0.03% CO2)). In vitro experiments involved 48 h exposure to M. albus at 3 °C or 20 °C, in vivo experiments involved 72 h exposure to M. albus at 3 °C. In vitro biofumigation with M. albus in regular air at 20 °C killed all the pathogens. Bacterial growth was best controlled by M. albus at 20 °C regardless of atmospheric conditions whereas fungal growth was controlled regardless of both temperature and atmosphere. The growth of the pathogens was not affected by lowering the temperature to 3 °C whereas the growth of M. albus was minimized below 5 °C. The fungal decay pathogens were still controlled well at 3 °C, but the bacteria were not. The effectiveness of M. albus to control in vivo apple decay caused by S. sclerotiorum, B. cinerea or P. expansum was variable and poor, probably due to the short biofumigation period (72 h) employed. The positive results obtained for S. sclerotiorum in all conditions and for B. cinerea in regular air in vivo at 3 °C on apple fruit, indicate that M. albus could be a very useful tool for post harvest treatment in cool storage.