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Postharvest Pathology and Mycotoxins

Suppression of Postharvest Plant Pathogenic Fungi by Carbon Monoxide. M. A. El-Goorani, Department of Pomology, University of California, Davis, 95616, Present address: Department of Plant Pathology, Faculty of Agriculture, Alexandria University, Egypt; N. F. Sommer, Department of Pomology, University of California, Davis, 95616. Phytopathology 69:834-838. Accepted for publication 26 February 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-834.

The effect on postharvest plant pathogens of controlled atmospheres (CA) enriched with carbon monoxide (CO) (9%) were studied in vitro and in vivo at 5.5 and 12.5 C. Test fungi differed greatly in response to CO. The mean percent growth in air + CO ranged from 20 to 100% of that in air alone. Generally the effect of CO was much greater if the atmosphere was low in O₂. An atmosphere of CO + 2.3% O₂ resulted in a mean percent growth 4.8 to 89.5% of that in air. Suppression sometimes was increased by CO₂ (5 or 18%) added to the low O₂ + CO atmosphere. The test fungi most sensitive to CO were Monilinia fructicola, Penicillium expansum, P. italicum, P. digitatum, and Whetzelinia sclerotiorum and the diseases they cause were similarly suppressed. Compared to similar fruit incubated in air, those exposed to CO in a CA (2.3% O₂ + 5% CO₂) showed 80–90% reduction in the rate of rot development caused in strawberries by Botrytis cinerea, in apples by P. expansum, in lemons by W. sclerotiorum, and in oranges by P. italicum and P. digitatum after inoculation and incubation for 11–23 days at 5.5 or 12.5 C. No phytotoxicity of CO was observed. Occasional off-flavors were associated more closely with O₂ and CO₂ modification than with CO addition.