Nitrogen–pathogen stress interactions modulate Fusarium head blight impacts in cereals: a quantitative synthesis

Nitrogen (N) fertilisation is a key determinant of crop productivity, yet its effects on Fusarium head blight (FHB) remain inconsistent due to strong context dependence. We conducted a PRISMA-based systematic review on N fertilisation and Fusarium–cereal interactions. A total of 41 studies (1771 observations) were analysed across disease parameters, agronomic factors, and mycotoxin contamination using random-effects models, moderator analyses, and dose–response assessments. N fertilisation significantly increased the percentage of Fusarium isolates (F%) (+61.6%, p = 0.0001), while disease severity and mycotoxin levels showed no consistent overall trends. Key sources of variability included climate, crop species, crop rotation, tillage, fertiliser form, and Fusarium community composition. Warmer environments and maize-based rotations were associated with stronger disease responses in specific contexts. Dose–response effects were generally weak, except for a positive association between N and F% in bread wheat (slope 0.0155, p < 0.0001) and a negative association between N and deoxynivalenol in barley (slope −0.0235, p = 0.0008). Overall, N effects on FHB are modulated by environmental, agronomic, and pathogen-related factors. This synthesis supports context-specific FHB risk assessment and improved nutrient management.