FULL RESEARCH PAPER Evaluation of models to predict take-all incidence in winter wheat as a function of cropping practices, soil, and climate S. Ennaı¨far Æ D. Makowski Æ J. -M. Meynard Æ P. Lucas Received: 22 June 2006 / Accepted: 8 March 2007 / Published online: 31 March 2007 Ó KNPV 2007 Abstract The incidence and severity of take-all, caused by Gaeumannomyces graminis var. tritici (Ggt), in susceptible crops depend on climate, soil characteristics and cropping practices. Take- all can be controlled by modifying crop rotation, crop management and fungicide treatment. When available, fungicides are used as a seed treatment and are partially effective. There is currently no reliable method for helping farmers to optimise their choice of cropping system to improve take-all control. In this study, we defined 16 models, based on various mathemat- ical functions and input variables, for predicting disease incidence in a wheat crop as a function of soil characteristics, climate, crop rotation and crop management. The parameters of these models were estimated from field experiments carried out at six sites in the north of France over a ten-year period. The root mean squared error of prediction (RMSEP) values of the models were estimated by cross validation and compared. RMSEP was in the range 16.34– 65.93% and was higher for the models based on multiplicative functions. The lowest RMSEP value was obtained for a dynamic model simu- lating disease incidence during the crop cycle and which included among input variables the percentage of diseased plants determined at GS30. Keywords Epidemiology  Decision support  Integrated crop protection  Model selection Introduction The incidence and severity of take-all, caused by the soilborne fungus Gaeumannomyces graminis var. tritici (Ggt), in susceptible crops depend on climate, soil environment (soil texture, structural stability, depth, water availability, pH and nutri- tional status), crop rotation and crop manage- ment (Cook 2003). These factors may affect the survival of primary inoculum in the soil, its growth and propagation and the risk of infection (Hornby et al. 1998). The sequence of crops in the rotation determines the build-up of primary S. Ennaı¨far (&) INRA, UMR d’Agronomie INRA/INA P-G, BP01, 78850 Thiverval-Grignon, France e-mail: ennaifar@grignon.inra.fr D. Makowski INRA, unite ´ Mathe ´ matiques et Informatique Applique ´es, 78352 Jouy en Josas Cedex, France J. -M.Meynard INRA, De ´ partement SAD, INRA, BP01, 78850 Thiverval-Grignon, France P. Lucas INRA, UMR BIO3P INRA-Agrocampus, Domaine de la Motte, BP 35327, 35653 Le Rheu Cedex, France 123 Eur J Plant Pathol (2007) 118:127–143 DOI 10.1007/s10658-007-9119-7