Abstract
Potato virus Y (PVY) is a major pathogen in global potato production, particularly within seed potato systems, where it causes significant yield and quality losses. PVY is notoriously challenging to manage due to the large number of aphid vector species, its non-persistent transmission mode, and the limited efficacy of insecticides in controlling non-persistent virus spread. The use of broad-spectrum insecticides for PVY management is not only costly and often ineffective but also harmful to beneficial insect communities that contribute to pest control.This dissertation investigates integrated pest management strategies for reducing PVY transmission, with a focus on the efficacy of mineral crop oils under overhead irrigation, their impact on beneficial arthropods, and the development of tools to optimize oil application timing. The research was conducted in Idaho, a leading seed potato production region that relies on overhead irrigation, where sustainable solutions for PVY management are urgently needed.
Four core studies form the basis of this research. First, a five-year field study evaluated the efficacy of mineral oils, with and without insecticides, in reducing PVY infection, while also assessing their impact on beneficial arthropod populations under overhead irrigation. Second, a greenhouse study simulated in-field overhead irrigation to examine its effects on the performance of mineral crop oils in reducing PVY transmission. Third, field trials assessed age-related resistance in two potato cultivars, determining PVY susceptibility based on plant age and its effects on yield and virus translocation into tubers. Finally, aphid monitoring and environmental data were collected from seed potato fields, with generalized additive mixed models (GAMMs) used to predict aphid abundance and optimize PVY management timing.
Key findings demonstrated that season-long applications of mineral oil, particularly when combined with insecticides, effectively reduced PVY transmission without negatively affecting beneficial arthropod communities, underscoring the value of mineral oils in sustainable agriculture. Greenhouse studies further revealed that overhead irrigation did not significantly diminish the efficacy of mineral oils in controlling aphid-transmitted PVY. In field trials, potato plants exhibited higher yields and fewer PVY-infected progeny tubers when the virus was introduced later in the season, though this response was cultivar-dependent. ‘Russet Burbank’ displayed greater resistance compared to ‘Yukon Gold,’ but this resistance alone was insufficient for comprehensive PVY control. Lastly, aphid monitoring identified key taxa potentially responsible for PVY transmission in Idaho seed potato regions, with GAMM models based on growing degree days providing valuable insights for optimizing management timing.
The integrated pest management strategies outlined in this dissertation—combining mineral oils, selective insecticide use, and targeted application timing—offer an effective framework for PVY management. These findings provide practical recommendations for seed potato growers, emphasizing the importance of season-long mineral oil applications adjusted for aphid pressure and plant age. Additionally, this approach supports the conservation of beneficial arthropods, which may aid in the biological control of aphids and other potato pests.