Epidemiological drivers of turnip yellows virus and its vector Myzus persicae in Australian canola (Brassica napus) systems: a 3-year study of commercial crops and noncrop vegetation.

BACKGROUND: Turnip yellows virus (TuYV) is one of the most economically important viral pathogens of Brassica napus (canola) in Australia. However, the relative contributions of noncrop reservoirs, aphid vectors and virus genetic variation to TuYV epidemiology remain only partly resolved. Myzus persicae is the principal vector of TuYV and a major pest of B. napus production globally. In Australia, both M. persicae and TuYV persist between growing seasons in weeds and volunteer B. napus plants that can facilitate early-season crop infection. RESULTS: We conducted a 3-year study across southeastern and southwestern Australia to identify key noncrop reservoirs of M. persicae and TuYV, quantify seasonal and regional patterns of infection, characterize TuYV P5 variants, and assess predictors of TuYV occurrence in B. napus fields. Arctotheca calendula and Raphanus raphanistrum were identified as major reservoirs of both M. persicae and TuYV. P5-II was the predominant virus genotype, accounting for >97% of TuYV-positive samples. Disease symptoms were a reliable indicator of infection in B. napus during spring and earlier crop sowing dates were associated with increased TuYV incidence. CONCLUSION: The identification of key reservoir hosts and the strong association between earlier sowing and increased disease incidence highlight opportunities for targeted weed management, strategic sowing decisions and improved surveillance. These results provide new insights into the ecology of the M. persicae-TuYV-B. napus pathosystem, and support the development of integrated management strategies to reduce TuYV spread and minimize yield losses in Australian B. napus crops. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.