Effects of Long Term Exposure to High‐CO2 During Storage at 0°C on Biology and Infectivity of Botrytis cinerea in Red Chicory

The effects on Botrytis cinerea of prolonged exposures to CO2‐enriched atmospheres were studied in vitro and in vivo at 0°C. Mycelial growth on potato dextrose agar decreased linearly with increasing CO2 concentrations from 5, 10, 15 and 20% CO2. The growth reduction was greater after 30–40 days of incubation. A reduced production of sclerotia in air by the colonies formerly exposed to various CO2 concentrations was also detected. Conidial germination was delayed and the amount of germinated conidia decreased with increased CO2 and at 20% CO2 it was inhibited. Germ tube elongation was affected in the same way. In artificially inoculated red chicory, lesion area caused by B. cinerea decreased with increasing concentrations of CO2 up to 60 days storage, later only 10 and 15% CO2 were really effective, while in the final inspection after 120 days all the concentration tested showed a low efficacy. Similar results were obtained in naturally infected chicory where the severity of the disease decreased by increasing CO2 from 5 to 10%, higher values did not improve the suppressive effect or determined, after 150 days of storage, an increased vulnerability of the tissues to disease due to the phytotoxic effects of the gas. An atmosphere enriched with 10% CO2 is advised to suppress Botrytis rot during storage at 0°C of red chicory.