Assessing UV-C radiation treatments for dollar spot suppression in seashore paspalum

Dollar spot, caused by Clarireedia spp., is one of the most detrimental diseases of turfgrass worldwide, and control strategies usually involve frequent fungicide applications. These treatments are expensive, require special equipment and can contribute to fungicide resistance issues, underscoring the need for alternative management strategies. UV-C radiation has proven effective as a disease management tool in various cropping systems but is still largely unexplored in turfgrass. This study aimed to test the effects of UV-C radiation against dollar spot in seashore paspalum and to evaluate its impact on plant health and performance. In assessing UV-C's efficacy directly against C. monteithiana, daily radiation treatments ranging from 27.5 J m-2 to 77.0 J m-2 were shown to effectively reduce mycelial growth. Additionally, in vitro UV-C treatment administered in darkness was observed to be more effective in reducing pathogen growth than treatment administered in lighted conditions. In a growth chamber setting, daily 66.0 J m-2 UV-C treatment significantly reduced dollar spot severity in seashore paspalum without causing phytotoxic damage to plant tissues. In field trials, a novel UV-C application system was implemented by modifying a robotic mower to autonomously deliver UV-C radiation to seashore paspalum plots. UV-C treatment in the field significantly reduced dollar spot severity. Moreover, UV-C treatment led to several physiological and performance enhancements, including increased chlorophyll content, shoot density, surface firmness, and green speed. Findings from this study indicate that UV-C radiation may be used as an effective physical control to complement existing dollar spot management practices.