A rapid method for evaluation of partial potato resistance to late blight and of aggressiveness of Phytophthora infestans isolates originating from different regions

The procedure of evaluation is based on mathematical simulation model of the late blight (LB) development in combination with laboratory testing of detached leaflets artificially inoculated with Phytophthora infestans. An incubation period, amount and sizes of lesions and sporulation capacity are estimated. Each couple “tested Phytophthora isolate and tested potato cultivar” is compared with a standard couple “Phytophthora isolate N161 and standard cultivar”. A simulator on the base of these data calculates area under the curve for LB development and yield loss due to LB for a situation when a yield loss of a standard cultivar infected with a standard isolate is equal 35%. Comparison of a new rapid laboratory method and field methods showed satisfactory correlation. Resistance to late blight was evaluated for 47 potato cultivars with the new method. It was also shown that some variations in foliar aggressiveness existed among P. infestans populations from different regions. Supported by ISTC grant #1640