Investigations on disease development and yield loss of early blight in potato cultivars of different maturity groups

Early blight is a major disease of potatoes which has established in most potato growing areas as a destructive disease. The integration of several factors like weather conditions, nutrition, the use of potent fungicides as well as the cultivation of tolerant varieties are essential parts of an integrated control strategy and can be effective in preventing early blight disease. Cultivar resistance to early blight disease has become more important due to losses in fungicide sensitivity. Nevertheless, little research has been directed towards this area. Several, perennial field trials were carried out in order to investigate disease susceptibility for varieties out of different maturity groups. Early maturing varieties have shown to be more susceptible. The disease intensity (AUDPC) was much more expressed in early varieties contrary to medium and late maturing varieties. However, a stronger impact on potato yield has been found in the medium to late maturing varieties. We discuss the relevance of time and amount of leaf damage for formation of tuber yield.