ABSTRACT
The effect of wounding, temperature, and inoculum on the development of pink rot caused by Phytophthora erythroseptica, was studied for its potential impact on postharvest infection. Tissue plugs cut from pink rot infected tubers and plugs of similar size from laboratory cultures of the pathogen were highly effective inoculum sources on wounded tubers. Severe wounding, temperatures of 15 to 25°C, and high inoculum density affected the infection risk. Regardless of source or amount of inoculum, any degree of wounding greatly increased incidence of infection of tubers by P. erythroseptica. Infections in unwounded tubers started at 15°C, whereas in wounded tubers infection started at 10°C. Incidence of pink rot was high when two or three of the factors (severe wounding, high temperature, high inoculum level) were favorable. Incidence of pink rot was intermediate when only one factor was favorable. Incidence of pink rot was low or absent without a favorable factor (no wounding, low temperature, and low inoculum), Since infected tuber tissue may serve as potential inoculum source for postharvest infection of tubers by P. erythroseptica, the removal of pink rot infected tubers at harvest is desirable. Avoidance of wounding and rapid cooling of storage bins to 10°C may also help control pink rot.
