Modeling diseased xylem networks

Vascular wilt pathogens induce xylem blockages that disrupt plant water transport, posing critical threats to agricultural productivity and food security. Key processes including xylem transport, vessel blockage, and pathogen spread within the xylem remain poorly understood, largely due to our limited ability to internally monitor infected tissues. This review explores how complementary mathematical modeling alongside laboratory studies can elucidate features governing these critical processes. I first provide a brief history of xylem imaging and quantification, highlighting technological advances, and persistent limitations. I then review modeling approaches to describe xylem water transport and pathogen dynamics, emphasizing that different pathogens require fundamentally different modeling frameworks. Existing xylem flow models may provide suitable hydraulic conductivity estimates for healthy stems under idealized conditions; however, they lack explicit representation of pit membranes and lumen-occluding structures, limiting their applicability to diseased stems where these features are actively modified during infection. Previously described biofilm models can replicate bacterial colony growth in controlled experimental settings but are often too complex for integration with flow simulations and rely on parameters that are difficult to quantify experimentally. Finally, I highlight directions and challenges for modeling occlusion and spread at the local scale and discuss how these models might be scaled to network-level architecture. While these types of models remain computationally challenging, advances in multiscale imaging technologies and scaling approaches promise significant progress in the coming decades. Insights from such models stand to advance both our understanding of disease progression and the development of resilient crops for an uncertain climate future.