Networks are sets of nodes connected by links in various ways (Box 1). Although the properties of random networks have already been systematically investigated in the 1960s, a growing body of literature is now using networks in a range of ecological applications, including the study and management of human, animal, and plant diseases (29,49,58,80,131) (Fig. 1). Given the generality and flexibility of the approach, network representations can be used at a variety of levels in plant pathology, from gene expression during host-pathogen interactions, to the development of plant epidemics among fields, farms, and landscapes and to trade movement of plants infected by pathogens or infested by insects among regions and countries.Network structure has profound effects on the dynamics of an epidemic within a population (51,61,127). In today's globally connected world, social and transportation networks play a crucial role in the spread of human infectious diseases (21,53,83). A network approach provides insights into the transmission of infectious diseases also in animals more generally (40,45,78,137). Although there is an increasing interdisciplinary application of networks in epidemiology, relatively little attention has been paid to these analytical approaches in plant sciences. Hence the need for this review, which aims to summarize recent progress in this rapidly developing field and to highlight research challenges specific to plant pathology.In today's plant pathology, as in other fields, there is a need for integrating investigations at the molecular, mycelium, plant, regional and international scale (9,48,102,111,118,120,132). Networks can provide such a unifying framework. They can be (i) perceived at an abstract level (e.g., fungal species occurring on the same plant species host), (ii) materialized by a physical structure (e.g., the root system of plant individuals connected by mycorrhiza, or vice versa), and (iii) underlying flows of energy, matter or information (e.g., the exchanges of knowledge, equipment and money among farmers, plant health consultants, researchers and phytopharmaceutical companies). There is increasing use of networks in ecology and epidemiology, but still relatively little application in phytopathology. Networks are sets of elements (nodes) connected in various ways by links (edges). Network analysis aims to understand system dynamics and outcomes in relation to network characteristics. Many existing natural, social, and technological networks have been shown to have small-world (local connectivity with short-cuts) and scale-free (presence of superconnected nodes) properties. In this review, we discuss how network concepts can be applied in plant pathology from the molecular to the landscape and global level. Wherever disease spread occurs not just because of passive/natural dispersion but also due to artificial movements, it makes sense to superimpose realistic models of the trade in plants on spatially explicit models of epidemic development. We provide an example of an emerging pat...