P-199 - Preliminary assessment of a sampling method for Emaravirus rosae in asymptomatic plants.

Emaravirus rosae, the causative agent of Rose Rosette Disease (RRD), is a significant threat to global rose cultivation, impacting both the economic value and diversity of rose varieties. The virus causes substantial financial losses and is detrimental to rose plants, which are highly valued in public gardens, landscaping, and the pharmaceutical industry. Classic symptoms of RRD are abnormal growth (e.g., excessive thorniness, witches' broom), leaf reddening, and deformed buds and flowers, severely diminishing the aesthetic and commercial value of roses, reducing production and marketability. The symptoms of RRV are highly variable, depending on the rose cultivar, disease stage, and environmental factors. Noteworthy, roses can remain asymptomatic for 30–146 days post-infection, allowing the disease to be spread unnoticed to nearby plants by mites. This delayed symptom expression underscores the importance of developing rapid and accurate diagnostic tools for early detection. Twenty 'knock out' rose plants were graft inoculated with RRV-infected tissue and tested by RT-qPCR while still non-symptomatic. Roses were visually divided into four quadrants, and two samples of leaves and young branches were sampled in each quadrant to total eight samples per plant. RRD detection. Results from direct virus trapping in plastic and RRV RT-qPCR are presented from each of the empirically divided four plant sections.