Khalil I. Al-Mughrabi
Abstract: Pink rot, caused by Phytophthora erythroseptica, is one of the most
important potato tuber diseases worldwide. A simple, cost-effective technique
was developed to test for the presence of P. erythroseptica in soil. Positive
(vermiculite and sterilized field soil mixed with P. erythroseptica inocula) and
negative (vermiculite and sterilized field soil free of P. erythroseptica) controls
were included. A hole, 5 mm wide and 20 mm deep, made at the stem end of
disease-free, surface sterilized potato tuber was filled with 1 g of soil and then
sealed with the part of the removed core. Tubers were incubated in moist
chambers at 10 °C and 95% relative humidity. Three weeks later, when tubers
were longitudinally cut and exposed to air for 30 minutes, positive controls
showed pink-black flesh discoloration. When tested, P. erythroseptica was
recovered from infected tissues. Negative controls did not yield any symptoms.
This simple technique can be used to identify P. erythroseptica infested fields in
three weeks' time.