Optimizing Irrigation and Disease Management Guidelines for Russet Potatoes with Deficit Irrigation

Commodities

Practices

This project evaluates the impacts of deficit irrigation on Russet potato yield, quality, and incidence/severity of potato diseases. In 2024, 96% of Minnesota's dedicated potato acreage relied on irrigation. Water levels below crop needs may negatively impact yields and induce tuber disorders, while overwatering can perpetuate soft rots and the leaching of water and nutrients, particularly in sandy soils.

Plant pathogens are significant threats in potato production. Previous and current work has focused on soilborne fungal pathogens with an emphasis on potato early dying (PED) caused by Verticillium wilt and black dot. Bacterial diseases such as soft rot, black leg and aerial stem rot reduce plant emergence and stand counts. Soft rot is especially problematic post-harvest as it spreads rapidly in moist storage conditions. A current lack of resistant varieties and effective chemical control options call for improved integrated disease management strategies.

This work will complement previous studies with new objectives to assess the incidence and severity of bacterial pathogens under varied irrigation rates and by introducing a wider-grown variety for comparison to a variety with known tolerance to abiotic stress. Our previous work indicated that tuber quality, yield, and disease incidence were not impacted by reduced irrigation with stress-tolerant variety Dakota Russet. A 2024 field study tested three irrigation rates (60, 80, and 100% of full irrigation) to assess impacts on tuber diseases. In 2025, fields were infested with a causal agent of PED, Colletotrichum coccodes, to evaluate deficit irrigation impacts on PED. Sixty percent of full irrigation had significantly higher irrigation water productivity rate compared to the other treatments (2024, p = 0.003 and 2025, p = 0.001). Findings indicated no detrimental impacts on yield and quality under reduced irrigation. In the proposed study, abiotic stress tolerant variety (Dakota Russet) will be compared to the widest grown variety in the United States (Russet Burbank). This will be achieved through the following project objectives:

• Evaluate the impact of deficit irrigation on Russet potato irrigation use efficiency, quality, and yield.
• Evaluate the impacts of deficit irrigation treatments on the incidence and severity of Verticillium wilt, black dot, and other soil-borne fungal diseases.
• Assess the potential of reduced irrigation for control of bacterial diseases and characterize causal agents of potato soft rots, black leg, and aerial stem rot.

Findings from this project will provide field-tested guidelines for maximizing irrigation efficiency and disease management.

Russet potatoes represent the majority of US potato production, accounting for ~70% of planted acres in the US (USDA NASS 2024). This project will develop integrated management strategies that optimize Russet variety selection, irrigation management, and disease control. Grower interests have guided project objectives, ensuring that findings will be applicable and beneficial. This work is supported by the Irrigators Association of Minnesota, the Area II Potato Growers Association (representing ~40 growing families), and the Northland Potato Growers Association (covering 72,000 acres in North Dakota, 8,800 acres in Minnesota).

Findings will benefit crop advisors, extension agencies, irrigation specialists, water conservation advocates, and potato growers throughout the Midwest. Data from the project will be implemented in disease forecasting and early disease detection models, setting the basis for weather-based management strategies. Genetic identification of soft rot causal agents will increase understanding of pathogen populations within Minnesota. We will generate a scientific publication on the relationship between irrigation rates, variety selection, and disease. Guidelines will be shared at multiple outreach and extension events (SPRF field day, Area II Potato Growers and Northland Potato Growers Workshop, and extension handouts). Findings will be presented at upcoming academic conferences (Plant Health 2026 and Potato Association of America 2027). Project findings may show that deficit irrigation is more than just water conservation strategy, it may be used to reduce losses to diseases and maintain the economic viability of potato production. This research supports farmers who are interested in adapting sustainable agriculture methods without sacrificing yields, quality, and profits.