The effect of store conditions on the rotting of apples, cv. Bramley's Seedling, by Nectria galligena.

The log of the time interval between inoculation with Nectria galligena in October and the onset of rotting in apples held in air was proportional to the deficit between the temperature of incubation and 25 degrees C, but temperature did not affect the rate of subsequent rot expansion. Rots expanded equally fast whether apples were held in dry or moist air. The quantity of rotted tissue obtained after incubating inoculated apples in atmospheres containing up to 12.5% CO2 increased with increasing concentrations of CO2 greater than 2.5%. The quantity of rotted tissue obtained in apples incubated in 10% CO2 was three times as great as that obtained after incubation in air. The incidence of natural rots was lower in apples stored at 4% CO2 than in those stored in air and rotting increased with increasing concentrations of CO2 higher than 4%. Colonies of N. galligena grew faster on malt agar plates incubated in 5% CO2 than in air, but growth was slower in 10% CO2 than in air. The quantity of benzoic acid per mg hyphae accumulated in developing lesions was similarly related to the CO2 concentrations up to 2.5% but decreased at higher concentrations, and the quantities found in apples stored in CO2 concentrations > 5.0% CO2 were less than in those stored in air.