High-efficiency control of poplar Cytospora canker by six-arm star polymer nanocarrier pesticides

Fungicides currently used to control poplar Cytospora canker (PCC), mainly caused by Cytospora chrysosperma, exhibit variable field efficacy, require high application frequency, pose resistance risks, and impose considerable environmental burdens. In this study, we developed a six-arm star polymer (SSP)-based nanocarrier system to deliver benomyl and carbendazim, aiming to enhance the control efficacy against C. chrysosperma. The SSP formed stable complexes with benomyl and carbendazim through hydrogen bonding and Van der Waals interactions, reducing their particle sizes from 864.36 nm to 14.76 nm and 2725.44 nm to 33.16 nm, respectively. Nanoagents demonstrated markedly enhanced antifungal efficacy over standalone fungicides. Specifically, SSP-benomyl at 3.8 mg/L (IC50 of benomyl) reduced the colony diameter of C. chrysosperma from 80 mm to 23 mm, while SSP-carbendazim at 2.6 mg/L (IC50 of carbendazim) reduced it from 80 mm to 29 mm. Besides high inhibition of fungal growth and control efficiency of PCC, these SSP-based nanoagents exhibited potential disease prevention. Our results provide a nanopesticide delivery system of SSP to manage PCC.