Turnip yellows virus management in <i>Brassica napus</i> : neonicotinoid seed treatments, foliar insecticide timing, and host resistance

BACKGROUND: Turnip yellows virus (TuYV) is a phloem-limited virus transmitted by Myzus persicae (green peach aphid) that causes substantial yield loss in canola (Brassica napus). In Australia, TuYV control has relied upon neonicotinoid seed treatments (NSTs) and foliar insecticides, but their effectiveness is questionable. Most local cultivars are susceptible to TuYV, though the cultivar Stingray carries partial resistance that has not been rigorously tested in the field. This study evaluated NSTs, three foliar insecticide timings, and Stingray's partial resistance for TuYV management. RESULTS: Four field experiments were conducted in which primary infection was simulated by transplanting TuYV-infected, M. persicae-infested canola plants. Aphid populations and TuYV incidence were assessed every 14 days after aphid release up until 42-70 days. NSTs provided no significant reduction of aphid infestation or TuYV spread. Foliar insecticides applied 3 days before aphid release reduced M. persicae infestation, but only mildly limited TuYV spread. A foliar insecticide applied 2 weeks after aphid release provided stronger aphid control translating into significant suppression of TuYV spread, but if delayed to 4 weeks after aphid release achieved only minimal late suppression of TuYV spread. In contrast to insecticide application, resistance in Stingray consistently provided robust suppression of TuYV. CONCLUSION: TuYV control tactics targeting its vector need to be highly robust; NSTs are insufficient, and foliar insecticide effectiveness depends on precise timing. Incorporating resistance into commercial cultivars will provide a stronger foundation for TuYV management and reduce reliance on insecticides. © 2026 Society of Chemical Industry.