Update on PVY Management in New Brunswick, Canada, and Recent Field Trials of Mineral Oil, Insecticidal and Biological Agents to Reduce PVY Spread

Tuesday, July 27, 2021
3:15 PM - 3:35 PM

New Brunswick is an important seed potato producer in eastern Canada. Potato virus Y (PVY) is a major disease agent in this industry, that has been a major focus of management over the past decade. Since 2009, average post-harvest PVY in NB seed lots dropped from 11.8% to less than 1%, with a record low of 0.43% in 2016. A resurgence in 2017-18 doubled mean PVY level across NB, which has only slowly dropped to 0.55% by 2020. The ~20-fold reduction in average PVY in the industry occurred through an increasingly strict provincial post-harvest testing program, and evolving evidenced-based in-field management to reduce its spread on the farm. Since 2014, statistical modeling shows that PVY inoculum in seed, early-season aphid abundance and spring temperatures are strongly predictive of post-harvest PVY, and may explain the 2017-18 resurgence. Since 2009, PVY strain dominance shifted from the traditionally common PVYO strain, to the more cryptic PVYN:O, PVYN-Wi and PVYNTN strains. Studying the impact of these novel strains on the statistical modeling of post-harvest PVY level is ongoing. Since 2018, our research group have studied a range of alternative foliar sprays to slow aphid-vectored transmission of PVY in replicated experimental field trials. These sprays include a range of individual and combined mineral oil, chemical insecticide and biological treatments, and were compared to maximize PVY protection, while minimizing costs and environmental impact. This study confirmed the synergistic effect of combined oil and insecticide spray, determined low-cost alternatives to conventionally used insecticide sprays (e.g. deltamethrin versus lambda-cyhalothrin) and relative cost effectiveness of biologically-based treatments (i.e. LifeGard WG). Though effective at PVY control, the biological-treated plots showed slightly lowered tuber yield. More general recommendations on spray program management, rogueing and volunteer and weed management will be discussed in concluding the presentation.
Plant Protection