Purpose of Review <p>Forest ecosystems are increasingly threatened by a dynamic array of fungal, oomycete, nematode, and viral pathogens. Accelerating climate change, globalized trade, and the expansion of intensively managed plantations are simultaneously broadening pathogen ranges and exposing naïve host populations, yet a comprehensive cross-kingdom synthesis of these threats has been lacking. This systematic review synthesizes the state of knowledge on forest pathogen biology, epidemiology, diagnostics, and management for the 2018–2026 period, identifying research and policy priorities to safeguard global forest health.</p> Recent Findings <p>A systematic review conforming to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, synthesizing 142 peer-reviewed articles and assessing for methodological quality using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool, reveals that while fungal pathogens (<i>n</i> = 80; ~56.3%) continue to dominate the research corpus, oomycetes (<i>n</i> = 27; ~19.0%) and nematodes (<i>n</i> = 31; ~21.8%) are also well-represented, reflecting their rising ecological and economic significance. Research is geographically biased toward Europe and East Asia, leaving tropical plantation pathosystems under-represented. Climate change is identified as a pervasive modifier of pathogen pressure, with drought-induced stress and temperature-driven range expansions documented across all four kingdoms. Concurrently, molecular diagnostics — specifically environmental DNA (eDNA) surveillance, Loop-Mediated Isothermal Amplification (LAMP) assays, and high-throughput sequencing (HTS) metagenomics — have transformed the field, enabling a transition from reactive symptom-based detection to prospective, landscape-scale early warning systems. We introduce the Pathogen Pressure Index (PPI) as a newly proposed conceptual framework to integrate driver-pathogen-outcome relationships for research prioritization.</p> Summary <p>This synthesis reveals that while diagnostic capabilities have undergone a step-change, an evidence-to-practice translation gap persists in integrated forest management. The ROBINS-I assessment confirmed broadly satisfactory methodological quality across the corpus, with molecular pathogen identification consistently rated low risk; the principal outstanding weakness — serious confounding in plantation and climate-change studies — reflects structural constraints of field-based research and flags where experimental designs require strengthening. Priority areas for the next decade include addressing the near-absence of viral pathology research, fostering cross-kingdom comparative epidemiology, and increasing investment in tropical forest surveillance. By leveraging the Pathogen Pressure Index (PPI) framework, future management can better integrate molecular diagnostics, biological control, and climate-smart silviculture to mitigate the compounding risks of global environmental change.</p>