The effect of wounding, temperature, and inoculum on the development of pink rot of potatoes caused by Phytophthora erythroseptica

The effect of wounding, temperature, and inoculum on the development of pin k rot caused by Phytophthora erythroseptica, was studied for its potential impact on postharvest infection. Tissue plugs cut from pink rot infected tu bers and plugs of similar size from laboratory cultures of the pathogen wer e highly effective inoculum sources on wounded tubers. Severe wounding, tem peratures of 15 to 25 degreesC, and high inoculum density affected the infe ction risk. Regardless of source or amount of inoculum, any degree of wound ing greatly increased incidence of infection of tubers by P, erythroseptica . Infections in unwounded tubers started at 15 degreesC, whereas in wounded tubers infection started at 10 degreesC. Incidence of pink rot was high wh en two or three of the factors (severe wounding, high temperature, high ino culum level) were favorable. Incidence of pink rot was intermediate when on ly one factor was favorable. Incidence of pink rot was low or absent withou t a favorable factor (no wounding, low temperature, and low inoculum), Sinc e infected tuber tissue may serve as potential inoculum source for postharv est infection of tubers by P. erythroseptica, the removal of pink rot infec ted tubers at harvest is desirable. Avoidance of wounding and rapid cooling of storage bins to 10 degreesC may also help control pink rot.