The study investigates the relative importance of cotyledons vs. lower true leaves for blackleg infection. It is also be of interest to understand how quantitative resistance (QR) affects the success of stem infection via cotyledons or lower true leaves. The information may help fine tune the timing of fungicide, including use of seed treatment as a new option.
Early results showed that on a susceptible cultivar, infection via cotyledon resulted in >80 per cent blackleg, whereas true-leaf (tested at one- to six-leaf stages) infection caused only five to 15 per cent disease. On resistant cultivars based on the QR trait only, the disease incidence was much lower, especially via the true-leaf infection. The results are being validated in field trials, in combination also with fungicide seed treatment.