Growth of Monilinia fructicola significantly declined with increased CO2 concentration, both in vitro and in vivo. CO2 concentrations at 15-25%, provided a significant reduction in lesion size and, at 30%, completely prevented lesion formation at 25 degreesC. Low temperature also inhibited growth and pathogenicity of M. fructicola. The fungus was more sensitive to high CO2 concentrations at 0 degreesC. Fungal growth on PDA was completely suppressed and brown rot was not found in inoculation sites on fruits in 10-30% CO2 after 30 days at 0 degreesC. Low temperature reduced ethylene production more than elevated CO2. Fruit ethanol content increased with increasing CO2 concentration and reached 92.8 mul l(-1) in 30% CO2 after 18 days at 0 degreesC. CO2 concentration of 25-30% did not affect SSC and pH, but increased firmness, vitamin C content and titratable acidity. No high CO2 injury or off-flavors were noted after 18 days at 0 degreesC for sweet cherries at any CO2 level tested. (C) 2001 Elsevier Science B.V. All rights reserved.