Research of probenazole and sedaxane combined granule and the control efficacy on rice blast and sheath blight at seedling stage

The occurrence and control of rice seedling diseases has been well concerned. In order to clarify the safety and control efficacy of the combination of plant immune inducer probenazole and fungicide sedaxane on rice during the seedling stage, 16% probenazole + sedaxane granule formulation was prepared and the physical indexes of the formulation were measured. Two active ingredients contents in the formulation and the cumulative release rates were detected by HPLC. The safety of probenazole to rice seedlings and the control effect of the combined granules on rice blast and sheath blight were measured. The results showed that the quality of the prepared granules met the national standard requirements. The release dynamic curves of the active ingredient in a 30% (V/V) methanol solution showed that the cumulative release rate of sedaxane was 33% (m/m) after 4 h and then changed very slightly, while 7 d was needed for probenazole to achieve its highest peak cumulative release rate. It indicated that the combined granule might provide a combination of quick-acting and sustained-effect for disease control during the rice seedling stage. The results of safety tests showed that 16% probenazole granule was safe for the growth of rice seedling using the dose of 150 g/m². A stable resistance of rice seedlings to rice blast and sheath blight was induced by probenazole at the test dosage under the artificial inoculation conditions. The 16% probenazole + sedaxane granule, at the dose of 150 g/m², exhibited excellent activity for the control of rice blast and rice sheath blight, with the control efficacy of 64.79% and 68.32% respectively. This work has provided a good example for the development of premixtures with plant immune inducers and fungicides, which has also offered a reference for reasonably granules application in field.