Wirkung von Vorkeimung, organischer Stickstoffdüngung und einer Kupferbehandlung auf Ertrag und Qualität von Kartoffeln im Ökologischen Landbau

Summary in the original language of the document

Limiting factors in organic potato production are predominantly nitrogen and infesta-tion with late blight disease (Phytophthora infestans). To maintain high yields, organic nitrogen fertilization, presprouting and control of potato late blight with copper-treatments are potential measures. A field trial was conducted in 2005 and 2006 to evaluate which single measure and combination of measures was most likely to achieve the best results. In both years, organic nitrogen fertilization led to an average yield increase of 16%. Tuber presprouting before planting accelerated plant emer-gence, increasing yields by up to 24%. It was the most effective single measure, provided that late blight disease appeared (2005). In absence of infection with late blight, presprouting had no influence on potato yield (2006). Only copper-treatments in combination with optimized plant nutrition and presprouting had a positive impact on potato yield. Varieties with early tuber development (e.g.: Princess) have almost com-pleted formation of yield when infection with late blight sets in. Up to this time, all measures to increase yield should be finished. It can be assumed, that application of copper can be reduced or left out subject to yield development at the beginning of infection with P. infestans and the specific potato variety.