Evaluation of a sand-bran inoculation technique for assessment of resistance of apple seedlings against Phytophthora cactorum (Lebert & Cohn) Schroeter.

摘要

A sand-bran inoculation technique was evaluated to assess apple (Malus x domestica [M. pumila]) seedlings resistance to collar, crown and root rot caused by Phytophthora cactorum. Root dry weight and shoot height were used as a measure of resistance. Five P. cactorum isolates were tested. Inoculum was mixed with sterile planting medium to make up mass (inoculum): mass (planting medium) concentrations of 0.0, 0.5, 1.0, 2.0, 5.0, and 10.0% inoculum levels. Thirteen week-old cv. Jonathan seedlings were transplanted into the inoculated soil and kept in a greenhouse for 13 weeks at 25℃ with daily watering. All tested isolates were pathogenic to seedlings but differed significantly in their levels of aggressiveness. The degree of disease at varying inoculum concentrations did not differ significantly.