The control of plant diseases using microorganisms has been the subject of intensive research study over recent decades, leading to the identification of numerous beneficial microorganisms and the marketing of a growing number of microorganism-based biocontrol products. These micro-organisms can act according to different modes of action, which are increasingly well described. However, their protective efficacy under field conditions is often considered variable and sometimes unsatisfactory by the farmers and farm advisors. Knowledge of the factors modulating the protective efficacy of microbe-based biocontrol products is essential to better guide their use in the field and their integration into integrated pest management strategies, and consequently their commercial success. During this presentation, the various biotic and abiotic factors that can affect the protective efficacy of biocontrol microbes will be presented. The construction of a database gathering these factors, based on data collected in the scientific literature, will be explained. Finally, the perspective of developing decision-support tools to promote the use of biocontrol agents in the field based on this database will be discussed.