Sensitivityof<italic>Sclerotiniasclerotiorum</italic>fromvegetablestotetramycininShandongProvince

The sensitivities of 151 Sclerotinia sclerotiorum isolates from various vegetables in Shandong Provice to tetramycin were determined by the mycelial growth rate method. Furthermore, the inhibitory activities of tetramycin against sclerotial production and sclerotial germination were also determined. The efficacy of tetramycin against S. sclerotiorum was assessed on detached cucumber leaves. The results showed that 151 S. sclerotiorum isolates were all sensitive to tetramycin, with the mean EC₅₀ values of (0.29 ± 0.01) μg/mL. And the frequency distribution of sensitivities was a unimodal curve, which indicated that the averaged EC₅₀ values can be regarded as the sensitivity baseline of tetramycin against S. sclerotiorum from vegetables. In addition, after treated with tetramycin, the number and dry weight of sclerotia was significantly decreased, and the shape of sclerotia also became smaller. Using tetramycin at 2 μg/mL can completely inhibit the myceliogenic germination of sclerotia. The results of in vitro leaf tests showed that tetramycin had protective activity and curative activity in the control of sclerotinia stem rot, and the protective activity was satisfactory. Applying tetramycin at 20 μg/mL, the efficacy against S. sclerotiorum was significantly higher than that of carbendazim and iprodione. In conclusion, good bioactivity of tetramycin against S. sclerotiorum demonstrates its potential application in the control of sclerotinia stem rot in the future.