Agronomie 14 (1994) 305-318
DOI: 10.1051/agro:19940504

Perte de rendement due aux maladies cryptogamiques sur blé tendre d'hiver. Construction et validation d'un modèle de l'effet du système de culture

C. Chevalier-Gérard^a, JB Denis^b and JM Meynard<sup>c

a</sup>  INA-PG, laboratoire d'agronomie, 16, rue Claude-Bernard, F75231 Paris cedex 05
^b  INRA, laboratoire de biométrie, route de Saint-Cyr, F78026 Versailles
^c  INRA, station d'agronomie, F78850 Thiverval-Grignon, France

Résumé - Avec l'objectif de concevoir, pour le blé tendre d'hiver, des itinéraires techniques à bas niveau d'intrants, nous avons élaboré un modèle linéaire simple d'estimation de la perte de rendement due aux maladies d'origine cryptogamique, en l'absence de traitement fongicide. Les effets d'éléments du système de culture et de l'année climatique sur les dégâts dus aux maladies sont quantifiés. Nous présentons ici le modèle élaboré à partir de 454 essais fongicide des régions Haute-Normandie et Picardie, de 1978 à 1991, sa validation et son intérêt pour la conception d'itinéraires techniques à bas niveau d'intrants fongicide.

Abstract - Estimation of yield loss caused by fungal diseases on winter wheat: construction and validation of a model taking into account the effects of the cropping system. The risk of yield loss caused by fungal diseases on winter wheat has always been believed to be a limiting factor that farmers could only eliminate by using fungicides. These chemicals now represent about 25% of the supply costs in France. In order to grow winter wheat with low fungicidal inputs we must take into account possibilities other than fungicides to reduce the damage caused by disease. A statistical linear model of prediction that estimates the yield loss caused by fungal diseases has been built. The important variable is the percentage of the yield obtained without disease. The effects of the climate and various elements of the cropping system on yield loss were quantified: previous crop type; variety; and planting date. In this paper, we develop a model obtained from 454 fungicide trials in Haute-Normandie and Picardie (in northern France) from 1978 to 1991. The various steps of the conception of the model of prediction are discussed. Its validation is discussed together with its importance for the construction of new methods of growing wheat with low fungicide inputs.

Key words: winter wheat / fungal diseases / yield-loss prediction / crop management / linear model

Mots clés : blé d'hiver / maladies cryptogamiques / prédiction de perte de rendement / système de culture / modèle linéaire