Biologie des organismes et des populations appliquée à la Protection des plantes

The increase in agricultural production over the past fifty years is due to the improvement of yield potential of major crop cultivars, as well as on the massive use of plant health products. However, the current model of crop protection generates complex problems, largely detailed in the Collective Scientific Expertise report 'Pesticides, agriculture and environment' (INRA/CEMAGREF, autumn 2005) and in the discussions of the French seminars of the 'Grenelle de l'Environnement' (autumn 2007). Setting up and implementing alternatives to the 'pesticide only' approach implies research to improve currently existing methods (Decision Support Systems, longer rotations, more robust cultivars), to assess their applicability in practice, but also to develop new knowledge that can be put to use in integrated and innovative crop protection and crop production systems. ARCHIDEMIO is positioned in the latter objective, and associates a generic modelling approach with targeted, specific field experiments.

The ARCHIDEMIO project envisions the plant as the heart of the crop protection system. It aims at acquiring, structuring and exploiting new informations about the plant : disease interactions within a crop canopy, in order  i) to analyse how plant architectural traits modify the expression and development of epidemics, ii) to define which of these traits (alone or combined, at the plant or at tyhe canopy scale) can reduce epidemic progress and iii) to model the plant development and the epidemic development. This project reinforces and expands the research dynamics started within the multidisciplinary INRA network EpiArch about plant -pathogen interactions within host canopies. The model systems chosen within ARCHIDEMIO are all economically important pathosystems: pea ascochyta blight (caused by Mycosphaerella pinodes), potato late blight (caused by Phytophthora infestans), grape powdery mildew (caused by Erysiphe necator), and yam anthracnose (caused by Colletotrichum gloeosporioides).

All the plant species selected display indeterminate growth (simultaneous presence of vegetative and reproductive organs, indefinite growth), but have either erect (pea, potato) or flexuous (grape, yam) growth habits. In all cases, the indeterminate growth of these plants generates a large vegetative mass, which can be acted upon through planting/sowing densities in the first case, crop husbandry practices in the second (pruning, staking, etc...). For the three weedy species, the modulation of architecture can also be achieved through genotypic determinants. The pathogens chosen illustrate the different dispersal processes acting in external microbial plant infectors: wind-dispersed spores, splashed spores, or water run-off.

ARCHIDEMIO involves seven partners, including specialists in plant pathology, plant genetics, agronomy, applied mathematics and modelling. The project also involves research and development organisations, with whom the research teams have a history of collaboration: UNIP and FNAMS (pea), IFV (grapevine), FNPPPT and ACVNPT (potato) and UPROFIG (yam). This project focuses on an emerging scientific theme - plant and canopy architecture as a driver of epidemic processes. It aims, through its scientific and methodological coherence, at overcoming disciplinary boundaries to gain new knowledge directly applicable to the elaboration of environmentally -friendlier crop production systems.