Development and application of laboratory method for rapid screening of fungicides against corn smut

A laboratory method for the screening of fungicides against corn smut was developed using microplate reader, which has provided references for the correspounding field trials. In this method the pesticide-added protato dextrose broth(PDB) was used for screening. The initial spore culture concentration of the medium was 10⁶ sporidia/mL, and cultures were incubated on a shaker at 28 ℃ and 200 r/min. The optical density (OD) value can be mearsured 16 h after incubating. And the optimum wavelength was 590 nm. Tebuconazole, pyraclostrobin, azoxystrobin, propiconazole and sedaxane were screened by this method. The results showed that tebuconazole and sedaxane had obvious inhibitory effect on Ustilago maydis, and their EC₅₀ values were both 0.03 mg/L. In this study, a rapid screening method for fungicides against corn smut was established using the microplate reader. The method is rapid, accurate and repeatable, which should be a recommended detection method.