Strategies to Improve Fungicidal Efficacy and Longevity Against Spring Dead Spot in Irrigated and Non-Irrigated Turfgrass

Spring dead spot (SDS) is a challenging disease to manage in places that experience sub-freezing wintertime temperatures. Spring dead spot is mainly a disease of bermudagrass ( Cynodon Rich spp.) and is primarily managed using chemical practices; however, this can be cost prohibitive. Additionally, fungicides are most effective against SDS when watered-in post-application, which may not be feasible for some turfgrass managers, particularly in non-irrigated turfgrass systems. Therefore, studies were conducted in Arkansas and Virginia to examine strategies to improve fungicidal efficacy against SDS in non-irrigated bermudagrass. In Arkansas, isofetamid and tebuconazole were applied in four carrier volumes (407, 814, 1,628 or 4,070 L ha ^-1 ) with or without pre-application solid tine aerification. Neither pre-application aerification nor carrier volumes had an effect on SDS incidence. A separate study in Virginia found little effect of nozzle types with varying droplet size on SDS suppression. Lastly, multiple studies were conducted in Arkansas to determine if various fungicides can suppress SDS for multiple years, thereby reducing application frequency and costs. Fungicides were applied either once in autumn 2023 or both in autumn 2023 and 2024. Plots were assessed in spring 2025 for % SDS. Out of all fungicides tested, only isofetamid effectively reduced SDS over multiple years. These findings give turfgrass managers alternative and more cost-effective options for improving SDS fungicidal efficiency.