Fire Blight of Apple and Pear: A Global Challenge for Global Fruit Production

Fire blight, caused by Erwinia amylovora, remains one of the most destructive bacterial diseases affecting apple (Malus domestica) and pear (Pyrus communis) production worldwide. Despite extensive research on pathogen biology and disease management, the magnitude of yield losses associated with fire blight has not been comprehensively synthesized. This study presents a semi-quantitative meta-analysis of recent literature (2023-2025) to assess the global impact of fire blight on apple and pear yield performance. Peer-reviewed field studies reporting direct or indirect yield losses under natural infection conditions were systematically identified and synthesized. Due to substantial heterogeneity in study designs and the lack of standardized yield metrics, classical quantitative meta-analysis was not feasible; instead, yield effects were summarized using estimated proportional yield reductions and interpreted descriptively within a log response ratio (lnRR) framework. Across all included studies, fire blight caused severe and highly variable yield losses, with reported reductions ranging from 15 to 80%. The integrated meta-effect indicated a mean global yield reduction of approximately 40%. Pear was consistently more susceptible than apple, exhibiting higher average losses (40-60%) compared with apple orchards (25-40%), corresponding to more negative pooled lnRR values (≈ -0.60 for pear versus ≈ -0.45 for apple). Between-study heterogeneity was high (I² > 75%) for both hosts, reflecting differences in epidemic intensity, cultivar susceptibility, orchard systems, and management practices. The results demonstrate that fire blight exerts not only immediate yield losses but also long-term, structural, and regional impacts through tree mortality, orchard removal, and production collapse. The pronounced host-specific differences highlight the need for differentiated risk assessment, yield loss modeling, and phytosanitary strategies for apple and pear. Finally, this synthesis underscores a critical gap in standardized, quantitative yield reporting and emphasizes the necessity of well-designed field studies to enable robust future quantitative meta-analyses of fire blight impacts.