Can available scientific information be mobilised to ensure the efficacy of microbial biocontrol agents against plant diseases in the field?

Microbial biocontrol agents are a promising option for reducing the use of chemicals in agriculture. Due to their characteristics as living organisms, their deployment is more complex than the application of chemicals and could result in the variability of their efficacy in the field, thus hindering their adoption. Taking this complexity into account would make their use more reliable. But is information about efficacy factors sufficiently well documented in peer-reviewed scientific articles to foster their optimal use by farmers against plant diseases? To answer such question, a literature review was carried out to gather in a dedicated database the information published on the biotic and abiotic factors that can modulate the protective efficacy of microbial biocontrol agents, including their biological properties, those of plant pathogens, and the characteristics of cropping systems. This review was focused on scientific publications relating to biocontrol agent strains authorized in Europe. An analysis of the database revealed that published information is rather limited for almost all biocontrol agents. The shortage of data was particularly striking for the use of biocontrol agents under field conditions. A focus on strains of Bacillus sp. and Trichoderma sp. revealed that even for those two most studied genera of biocontrol agents, information is highly patchy. Efficacy factors have been studied only on a few crops against a few of their target pathogens. Furthermore, only a small part of the available information was relevant for the use of those strains in a commercial situation. This highlights the need for further research into efficacy factors in order to produce data that can be used to improve the efficacy of biocontrol agents in the field.