A groundbreaking study published in the Potato Virus Initiative Newsletter 2024 by researchers Kelie Yoho and Erik Wenninger from the University of Idaho has highlighted the potential of mineral crop oils as an effective strategy for managing Potato Virus Y (PVY) transmission in potato crops, particularly in regions that rely on overhead irrigation.
Background on PVY Management
Managing Potato Virus Y is a significant challenge for growers, as the virus is transmitted non-persistently by various aphid vectors that can quickly infect plants. Traditional insecticides often do not work quickly enough to prevent PVY transmission before healthy plants become infected. The integration of mineral crop oils into existing integrated pest management (IPM) programs has been proposed as a viable solution. These oils have low environmental persistence, limited effects on non-target organisms, and have been shown to reduce the transmission of non-persistent viruses when applied consistently.
However, a notable gap in knowledge has hindered the adoption of mineral crop oils within PVY-focused IPM programs, particularly concerning their effectiveness under overhead irrigation conditions, which is standard in Idaho potato farming.
Objectives of the Study
To address this knowledge gap, the research team conducted field trials aimed at:
- Evaluating the efficacy of mineral crop oils in reducing the in-season spread of PVY under overhead irrigation.
- Assessing how different PVY-focused IPM spray regimes impact beneficial arthropod communities in potato crops.
Methodology
In their experiments, ‘Russet Burbank’ potatoes were grown under typical field conditions and subjected to one of four IPM regimens from emergence until vine kill. The treatments included:
- An untreated control (UTC).
- A weekly application of a 0.75% mineral crop oil solution.
- An insecticide-only treatment using imidacloprid followed by rotating insecticides.
- A combination treatment of both crop oil and insecticides.
The effectiveness of these treatments was assessed based on the incidence of PVY in tubers, as well as the impact on beneficial insect populations through vacuum sampling conducted throughout the growing season.
Key Findings
The results from the trials demonstrated that the application of mineral crop oils significantly reduced the in-season spread of PVY. When used alone, the mineral oil treatments effectively lowered infection rates compared to the untreated controls. However, the combination of mineral crop oils with insecticides provided even greater reductions in PVY incidence, particularly in years with high disease pressure.
Specifically, in years with lower PVY infection rates, the mineral oil-only and combination treatments showed comparable success, reducing infection rates by 3-6% compared to the UTC. In contrast, during high disease pressure years, the combination treatment achieved infection rate reductions of 21% and 23%, whereas the oil-only treatment yielded reductions of only 14% and 8%.
Implications for Beneficial Arthropods
Importantly, the study indicated that the use of mineral crop oils did not adversely affect the species richness and abundance of beneficial arthropod communities. This outcome is critical for sustainable pest management, as preserving natural enemies can contribute to overall pest control strategies within IPM programs.
Next Steps for Research
Moving forward, researchers aim to refine their understanding of the timing and application of mineral crop oils, particularly in relation to the onset of a potato plant’s innate resistance to PVY. This ongoing research will focus on identifying optimal timing for oil applications and developing predictive models for aphid migrations.
As the challenges posed by Potato Virus Y persist, the findings from this study provide valuable insights and recommendations for potato growers in Idaho and beyond, helping to improve management practices and crop health.
Source: Potato Virus Initiative Newsletter 2024
Image: Vacuum sampling was used to sample beneficial arthropods from the foliage of potato plots.
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