Time spray strategies for Septoria leaf blotch disease progress on winter wheat: The use of forecasting model

A mechanistic model, PROCULTURE, for assessing in real time the risk of progression of Septoria tritici (teleomorph Mycosphaerella graminicola) on winter wheat (Triticum aestivum L.) was used in Grand-Duchy of Luxemburg over 2003 to 2009 to simulate disease progression in the canopy at four-replicated field experiments located in three villages (Diekirch district: Reuler; Grevenmacher district: Burmerange and Christnach), representative of the different agroclimatological zones of Luxembourg. This model has been developed in order to guide field observations on the different leaf layers and to find the optimum time of fungicide spray in fields. The model provides information which explains disease progression on the upper leaves. The relationship between disease control by fungicides and yield loss varies from site-to-site and from season-to-season. A weekly PROCULTURE recalibration is routinely done using actual disease levels observed on site. On average, no spray of fungicides or only one application is required to control efficiently the septoria leaf blotch disease. The PROCULTURE forecasts have been validated to be correct in about 85% of all cases. The treatment defined with the simulation model over 2003 to 2009 gave an earning grain yield (80%) more than the other treatments tested and as important as the double treatment for Everlange, Christnach and Burmerange. At Reuler, over 2003 to 2009, treatments based on the Septoria risk simulation model were recommended only in 2007. The climatic conditions of this site tend to favour organic farming in this region where the evolution of the foliar disease is very weak.