Late blight, caused by Phytophthora infestans (Mont.) de Bary, is considered the most devastating disease in potato (Solanum tuberosum L.) production worldwide. Control methods involve mostly the use of fungicides, which are costly and are under political pressure for reduction in Europe.
Potatoes from the major potato cultivar in Sweden, King Edward, previously stacked with three resistance (R) genes (RB, Rpi-blb2 and Rpi-vnt1.1) were tested in a local Swedish field, with spontaneous P. infestans infection over three seasons to evaluate the effectiveness and stability of the resistance on leaves. In addition, testing of resistance was done in both in leaves and tubers.
Field results demonstrated that the 3R stacked into the cultivar King Edward, showed practically full resistance to infections of P. infestans, with no difference to fungicide use. Moreover, the resistance was effective in both leaves and tubers. The results reveal the 3R potatoes offer a functional field resistance, that could, alone, reduce the total use of fungicides in agriculture by several percent in Sweden, in an event of modifications in the EU legislation.
