ABSTRACT
Bernard Tivoli, Christophe Le May, Alexandra Schoeny, Marie-Hélène Jeuffroy,
Bertrand Ney
Yield losses caused by diseases are generally difficult to predict with accuracy. In order to characterize the quantitative and qualitative impacts of Ascochyta blight on pea crop, studies involving collaborations between pathologists, ecophysiologists and agronomists aim to determine the incidence of ascochyta blight (i) on the synthesis and transfer into the seeds of carbon and nitrogen compounds at the individual pea plant level and (ii) on yield components at the plant population level. The two main questions are: first, how is plant function disturbed by the disease? Second, what level of disease is associated with yield loss? These studies help to improve our understanding of the cause of the damage, and should reveal the effects of essential factors such as:
• The period of infection, by determining the incidence of the disease for various stages of canopy development;
• The site of infection, by determining the incidence of the disease when it develops on leaves, stems and/or fruiting organs, and according to the growth stage of the affected plants;
• The intensity of the infection, by quantifying relationships between the various levels of disease and yield loss.
