Highly sensitive methods for trace-level aflatoxin determination are indispensable for cereal food safety and public health protection. This study developed a ZrO₂-assisted QuEChERS-UHPLC-MS/MS method for the simultaneous determination of AFB₁, AFB₂, AFG₁, and AFG₂ in maize, wheat, rice, and soybean. Systematic optimization identified acetonitrile as the optimal extraction solvent and 10 mg ZrO₂ in combination with PSA, C₁₈, and GCB as the optimal cleanup formulation, providing recoveries of 107.33–111.60%. Chromatographic baseline separation was achieved within 8.0 min using a moderate gradient program. The method exhibited excellent linearity (R² > 0.999) with LODs of 0.15–0.25 µg/kg and LOQs of 0.50–0.75 µg/kg. Negligible matrix effects (0.85–1.02) validated the efficacy of ZrO₂-assisted cleanup in eliminating co-extractive interferences in maize. Satisfactory accuracy (recoveries of 86.66–111.04%) and precision (RSDs < 14%) were obtained across all matrices. The method demonstrated consistent performance across diverse cereal and soybean matrices, fulfilling international regulatory requirements for routine aflatoxin monitoring in agricultural commodities.

This study clarified the field control efficacy, yield regulation effect and action mechanism of 40% cyproconazole suspension concentrate (SC) against southern corn rust caused by Puccinia polysora, aiming to provide scientific support for its registration, extension and field application. Indoor toxicity was assayed using urediniospore germination and germ tube elongation inhibition combined with seedling pot tests and field efficacy trials. Wheat germ agglutinin staining was applied to observe the pathogen infection process. Cyproconazole showed strong inhibition on spore germination and germ tube elongation, with EC₅₀ values of 70.455 mg·L⁻¹ and 21.686 mg·L⁻¹. On corn seedlings, its protective and curative control efficacies reached 91.11% and 82.19%. At 45 days after application during ear maturity, the field protective and curative efficacies were 65.93–78.38% and 69.26–80.79%, respectively. Notably, the integrated control strategy with two applications achieved even higher efficacy, ranging from 73.33% to 86.80%, and a yield loss recovery rate of 54.09–54.51%, both of which were superior to those of the conventional fungicide pyraclostrobin·epoxiconazole SC. Using WGA fluorescence staining, fluorescence microscopy directly visualized that the fungicide suppressed infection by inhibiting spore germination, germ tube elongation and appressorium formation. In summary, 40% cyproconazole SC has prominent persistent control efficacy and a yield-improving effect with a definite action mechanism, which is worthy of accelerated registration and popularization for southern corn rust management.

Southern corn rust, caused by Puccinia polysora Underw, is a major foliar disease that threatens corn yield in China. Detection of P. polysora during the corn growing period is critical for timely intervention and disease management. In this study, specific primers and probes were designed based on the variable region of the rDNA-ITS sequence. After conventional PCR validation, specificity screening, and sensitivity evaluation, an optimal primer–probe combination was successfully established. The developed assay achieved a detection limit of 1 pg·μL⁻¹ genomic DNA and a DNA equivalent of 57.6 urediniospores of P. polysora. The reaction conditions were further optimized, and stable amplification could be completed under a constant temperature of 38 °C for 15 min. The developed MIRA-LFIA was evaluated using 70 field maize leaf samples, with the reported OTNPCR (One-Tube-Nested PCR) method used as the gold-standard reference. MIRA-LFIA produced 55 positive and 15 negative results, whereas OTNPCR yielded 57 positive and 13 negative samples. A diagnostic evaluation revealed that the MIRA-LFIA assay achieved a sensitivity of 96.49%, specificity of 100%, positive predictive value of 100%, negative predictive value of 86.67%, and Youden’s index of 0.965., with a Kappa value of 0.911. This MIRA-LFIA system enables rapid detection and visual interpretation of southern corn rust. It features simple operation and low technical requirements, making it suitable for rapid on-site monitoring at grassroots institutions and in fields.