Bioactivity of mefentrifluconazole against different Fusarium spp.

Emergence and development of resistance to 14 alpha-demethylase inhibitors (DMIs) have become a critical issue in both agriculture and medical fields. Mefentrifluconazole, the first isopropanol triazole fungicide belonging to a new subclass of DMIs, has been proposed to show high activity, minimal adverse side effects, and inconsistent cross resistance with other DMIs due to its high structural flexibility. In this study, mefentrifluconazole showed disparate inhibitory activity against the mycelium growth of seven tested Fusarium species. The most sensitive species included F. oxysporum, F. proliferatum, F. commuae, and F. fujikuroi, followed by F. equiseti and F. graminearum, while F. solani was most insensitive. Consistently, mefentrifluconazole presented the strongest inhibiting effects on conidium germination, cell membrane integrity, and ergosterol biosynthesis in F. fujikuroi, followed by F. graminearum, while F. solani ranked last. Further results indicated that all F. fujikuroi isolates causing rice bakanae disease (RBD) were sensitive to mefentrifluconazole regardless of their resistance to pro-chloraz, tebuconazole, carbendazim, and phenamacril. Additionally, the inoculation tests found that mefentri-fluconazole presented a better protective efficacy on rice seedlings when applied 12 h before the F. fujikuroi inoculation, compared to applied 12 h post the inoculation. Overall, this study demonstrated the various bioactivity of mefentrifluconazole combating Fusarium spp. and put new insights into RBD management as well as the applications of DMIs.

Automated summary

This study demonstrated the varying inhibitory activity of mefentrifluconazole against different Fusarium species, with the strongest effect observed on F. fujikuroi and the weakest effect on F. solani. All F. fujikuroi isolates causing rice bakanae disease (RBD) were sensitive to mefentrifluconazole regardless of their resistance to other DMIs. Furthermore, pre-treatment with mefentrifluconazole 12 hours before inoculation showed better protective efficacy on rice seedlings compared to post-inoculation treatment.