  This review focuses on microbiomes associated with residues within the
context of other microbial habitats in cereal-producing agroecosystems such as
phyllosphere or rhizosphere. We connect residue microbiome with the survival of
residue-borne fungal plant pathogens, thus combining knowledge in microbial
ecology and epidemiology, two disciplines still not sufficiently connected. We
provide an overview of the impact of residues on cereal disease epidemics and
how dynamic interactions between microbial communities of non-buried residues
during their degradation, along with soil and multitude of abiotic factors, can
contribute to innovative disease management strategies, including
next-generation microbiome-based biocontrol strategies. Starting from the
classical but still relevant view of crop residues as a source of pathogen
inoculum, we first consider possibilities for limiting the amount of residues
on the soil surface to reduce the pathogen pressure. We then describe residues
as a transient half-plant/half-soil compartment constituting a key fully
fledged microbial ecosystem: in other words, an ecotone which deserves special
attention. We focus on microbial communities, the changes in these communities
over time and the factors influencing them. Finally, we discuss how the
interactions between the microbial communities and the pathogens present on
residues could be used: identification of keystone taxa and beneficial
assemblages, then preservation of these taxa by adapted agronomic practices or
development of synthetic communities, rather than the introduction of a single
exogenous biocontrol species designed as a 'treatment product'.
