@article{WANG2026, 
author = {SiQi WANG and XiaoMing ZHU and HongXia MA and Hua SUN and Shuo ZHANG and Ning GUO and Jie SHI},
title = {Toxicity Determination and Field Control Efficacy of Different Fungicides Against Southern Corn Rust},
year = {2026},
journal = {Scientia Agricultura Sinica},
volume = {59},
number = {17},
pages = {3795-3806},
keywords = {southern corn rust (SCR), Puccinia polysora, toxicity determination, control efficacy, yield loss recovery rate},
url = {https://www.sciopen.com/article/10.3864/j.issn.0578-1752.2026.17.007},
doi = {10.3864/j.issn.0578-1752.2026.17.007},
abstract = {ObjectiveSouthern corn rust, caused by Puccinia polysora, is an important maize disease that seriously threatens crop yield. This paper aimed to screen high-efficiency fungicides for the control of southern corn rust and clarify their indoor toxicity, seedling-stage persistent efficacy, protective and curative effects, as well as field control efficacy and yield loss recovery rate (yield retention rate), so as to provide a scientific basis for rational pesticide application.MethodThe spore germination inhibition assay and germ tube elongation inhibition assay were used to determine the indoor toxicities of six fungicides, including 95% difenoconazole, 98% pyraclostrobin, 95% fluopyram, 94.4% phenamacril, 96% thifluzamide, and 97% pydiflumetofen, against P. polysora. Fungicides with superior toxic activity were selected for subsequent seedling-stage and field experiments. In the seedling experiment, two treatment procedures were adopted: pesticide application prior to pathogen inoculation and pathogen inoculation prior to pesticide application. 35% pyraclostrobin·epoxiconazole SC was set as the conventional reference fungicide, and clean water served as the blank control to evaluate the persistent duration, protective effect, and curative effect of tested fungicides. In the field, three application modes (protective, curative, and comprehensive) were established at the maize big trumpet stage, and field trials were conducted in Jingxiu District and Dingxing County of Baoding City. Disease incidence of individual plants was investigated at 14, 21, and 45 days after inoculation (maturity stage). The disease index and control efficacy were calculated, and ear traits were measured at harvest to determine the yield retention rate.ResultThe indoor toxicity results showed that 98% pyraclostrobin, 96% thifluzamide, 95% difenoconazole, and 97% pydiflumetofen exhibited stronger inhibitory effects on germ tube elongation than on spore germination of P. polysora urediniospores. The EC50 values for spore germination inhibition were 0.019, 5.468, 6.362, and 8.440 mg·L-1, respectively; the EC50 values for germ tube elongation inhibition were 0.007, 0.072, 3.738, and 4.136 mg·L-1, respectively. Seedling tests indicated that 25% pyraclostrobin EC possessed a persistent efficacy of no less than 10 d, with favorable protective and curative effects of 88.89% and 73.97%, respectively. The persistent period of 10% difenoconazole WDG was approximately 7-10 d, and it showed a good protective effect with a control efficacy of 80.00%. Field trials further verified that 25% pyraclostrobin EC presented the best and relatively stable control efficacy. Under comprehensive application, its control efficacies were 67.72%-70.00% at 14 d and 58.89%-60.80% at 45 d after inoculation, with a yield retention rate of 37.06%-40.29%. As a suitable protective fungicide, 10% difenoconazole WDG showed control efficacies of 67.78%-70.43% (14 d) and 22.22%-58.39% (45 d), with a yield retention rate of 24.75%-35.01%, but its persistent efficacy was short. Both pydiflumetofen and thifluzamide showed poor control efficacy and low yield retention rate.Conclusion25% pyraclostrobin EC is recommended for application as both a protective and comprehensive fungicide against southern corn rust. 10% difenoconazole WDG is suitable for tank mixture with fungicides of different modes of action. Pydiflumetofen and thifluzamide are not recommended for the control of southern corn rust.}
}