Spray‐induced gene silencing as a novel strategy for managing dollar spot in creeping bentgrass caused by Clarireedia jacksonii

Abstract BACKGROUND Clarireedia jacksonii , the causal agent of dollar spot, is a major turfgrass pathogen for which sustainable management options remain limited by intensive fungicide use and resistance. Creeping bentgrass ( Agrostis stolonifera L.), widely used on golf greens and other fine turf applications, is particularly vulnerable, highlighting the need for alternative, eco‐friendly solutions. Here, we evaluate spray‐induced gene silencing (SIGS) as a novel disease control strategy using an in planta dsRNA screening approach. RESULTS Thirty‐two double‐stranded RNAs (dsRNAs) targeting candidate genes were screened. Eight targets significantly reduced disease severity by approximately 34.7–45.5% relative to the control, with dsRNA targeting the microbial opsin homolog cop1 identified as the most effective target. Cy5‐labeled dsRNA imaging following nuclease treatment demonstrated exogenous dsRNA uptake by C. jacksonii . Detection of target‐specific siRNAs and significant reductions in transcript levels confirmed active RNA interference (RNAi) in C. jacksonii . Notably, the screen distinguished effective targets from genes silenced in vitro but not affecting disease in planta . Furthermore, fragments of dsRNA‐ cop1 (222–777 bp) provided statistically equivalent suppression, indicating design flexibility. CONCLUSION This study validates SIGS as a viable strategy for dollar spot management, provides mechanistic evidence of dsRNA uptake and processing in C. jacksonii , and offers practical insights and foundational molecular data to support the development of sustainable, RNAi‐based biopesticides. © 2026 Society of Chemical Industry.