Foliar diseases in sugarbeet – Influence of control strategy, variety and fungicide on yield and quality

In 2001 at 28 sites 33 field trials were carried out by the Institut für Zuckerrübenforschung (IfZ) Göttingen in co-operation with Landesanstalt für Pflanzenbau und Pflanzenschutz (LPP) Mainz and including numerous regional partners. Different control strategies, varieties and fungicides were tested for their influence on forcasting models for foliar diseases to be developed further.

Whenever, the infection was controlled sufficiently by the strategies “diseases oriented” and “complex attack”. In high risk areas the increased threshold value (35–45% DI (disease incidence) was not sufficiently to save the incidence by Cercospora beticola under the economic damage threshold. In the past year at most sites one fungicide application had controlled foliar diseases. In regions with an increased infection pressure control strategies taking into account damage thresholds led to higher white sugar yield (BZE) up to 1.4 t/ha.

At site Börßum with stronger infestation Cercospora-resistant varieties obtained the highest white sugar yield irrespective of control strategy. The varieties did not utilize the cropping capacity of site, when the incidence was lower (site Eich). Epoxiconazole and kresoxim-methyl in combination resulted in the highest white sugar yield, when strong incidence by Cercospora beticola appeared. The data base will be enlarge by data from further trials in 2002 and 2003 to validate and adapt the control strategies and the forecasting models for epidemic progress.