Efficacy of succinate dehydrogenase inhibitor nematicides fluopyram and cyclobutrifluram against Hoplolaimus galeatus in Golf Turf

Following the cancellation of fernamiphos, lance nematodes (Hoplolaimus spp.) have become one of the most challenging plant-parasitic nematodes to manage in turfgrass systems. Succinate dehydrogenase inhibitor nematicides are among the most used nematode management tools on golf courses in the United States. Currently, there are two SDHI turfgrass nematicides registered in the United States: the fluopyram nematicide Indemnify, which was launched in 2016, and the cyclobutrifluram nematicide Trefinti, which was launched in 2025. The objective of this research was to compare the efficacy of these two nematicides against the lance nematode Hoplolaimus galeatus in microwell bioassays, greenhouse, and field experiments. Microwell bioassays compared the percent mortality of H. galeatus among the nematicides following exposure to different concentrations of the nematicides at different time intervals. Greenhouse experiments compared the efficacy of the nematicides when applied at field-relevant rates to H. galeatus-infested turfgrass in pots. Finally, the efficacy of the two nematicides for management of H. galeatus was compared in turfgrass field trials. In the bioassay experiment, exposure of H. galeatus to cyclobutrifluram resulted in higher nematode mortality than exposure to fluopyram. The greenhouse experiment demonstrated that cyclobutrifluram at 250 g a.i./ha and above significantly suppressed H. galeatus population density, whereas fluopyram did not. Finally, results from field trials indicate that cyclobutrifluram is an effective treatment for enhancing the health of golf turf infested by H. galeatus. These findings suggest that the cyclobutrifluram nematicide Trefinti exhibits strong efficacy against H. galeatus and could serve as an effective treatment for management of H. galeatus on golf turf.