The virulence of Mucor mucedo (L.) Fr. (the cause of mucor rot) and Botrytis cinerea Pers. (gray mold) on vegetables stored at 13C for 7 days or 1C for 70 days varied with the host and controlled atmosphere (CA). M. mucedo was severely pathogenic at 13C to cucumber (Cucumis sativus L.), eggplant (Solarium melongena L. var. esculentum Nees), pepper (Capsicum annum L.), and tomato (Lycopersicon esculentum Mill.), but not to bean (Phaseolus vulgaris L.). The fungus did not infect carrot (Daucus carota L. var. sativa DC.), celery (Apium graveolens L. var. dulce DC.), onion (Allium cepa L.), or parsnip (Pastinaca sativa L.) at 1C. B. cinerea was virulent on all of these crops at 13 or 1C. The severity of mucor rot and gray mold on eggplant stored at 13C for 14 days was suppressed most in a CA of 7.5% CO + 1.5% O2 and least in 1.5% 02, in comparison with the air control. Similarly, the growth and sporulation of each pathogen on eggplant-extract agar maintained at 13C for 4 or 14 days were suppressed most in 7.5% CO + 1.5% O2; suppression was least in 1.5% O2. The suppression of diseases on eggplant was highly correlated with the suppression of mycelial growth and sporulation of pathogens on agar.