Utilization of the fermentation residues of validamycin as a potential platform for seed treatment†
Seed coating is a versatile means to control crop pests and diseases, which can effectively reduce pesticide quantity and improve pesticide efficacy. Herein, 6% tebuconazole flowable concentrate for seed treatment (FS) was prepared by using the validamycin fermentation residue (VFR) as a pesticide carrier. Then, the effects of the VFR and dispersants on the physicochemical properties of the FS were systematically evaluated. Moreover, the germination rate and antibacterial performance of wheat seeds coated with FS were investigated through a bioactivity experiment. The experimental results show that the FS prepared by VFR, dispersant SD-816 and NNO exhibits superior suspension stability. The suspension rates at 1 h and 24 h are 99.78% and 95.11% respectively. Furthermore, the viscosity of the system only slightly changes after 30 days. In addition, the obtained FS system exhibits shear thinning behavior under high speed shearing showing typical features of pseudo-plastic non-Newtonian fluids, which conforms to the Herschel–Buckley model. A bioactivity experiment showed the germination rate of coated wheat seeds reached 90%, and increased by 7.0% and 3.0% compared to the control group and positive control Raxil respectively. Futhermore, the antibacterial rate reached 80.5%, and was higher than the control group and Raxil. In addition, the obtained FS was very efficacious in controlling wheat powdery mildew compared to the commercial formulation Raxil.