Clearwater Russet is a medium-late maturing, russet-skinned, potato cultivar suitable for processing or fresh pack. It is notable for having a low incidence of external defects that contributes to its high U. S. No 1 yield relative to the dual-purpose industry standard, Russet Burbank. Clearwater Russet also maintains low glucose concentrations in its tubers during long-term storage making it an exceptional processing variety. With its low incidence of sugar ends and cold-induced sweetening resistance, Clearwater Russet can be stored at a temperature of 7.2°C for up to 250 days without the need for reconditioning; fry color from this storage regime is consistently ≤1.0 (USDA Fry Color Scale). This cultivar is also notable for its high tuber protein content, which was 33% greater than that of Russet Burbank. In full-season trials conducted over a 3-year period in California, Colorado, Idaho, Oregon, and Washington, Clearwater Russet had total yields slightly lower than Ranger Russet and Russet Burbank, but averaged 1% and 33% higher U. S. No. 1 yields, respectively, across all states. Average specific gravity of Clearwater Russet is comparable to Ranger Russet and significantly higher than Russet Burbank. Clearwater Russet is resistant to potato virus X (PVX) and tuber late blight and is moderately resistant to Verticillium wilt, common scab, and the common strain of potato virus Y (PVYO). Symptoms of infection with two necrotic strains of PVY were not observed in tubers of Clearwater Russet or Russet Burbank, but were observed in Ranger Russet. Blackspot bruise reaction for Clearwater Russet is less pronounced than for either Ranger Russet or Russet Burbank. The incidence of hollow heart in Clearwater Russet is intermediate between Ranger Russet and Russet Burbank. Internal brown spot has been noted as a problem for Clearwater Russet in the Columbia Basin of Oregon, but has not been observed as problematic in other growing regions. Clearwater Russet was released in 2008 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.
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Acknowledgements The authors thank Margaret Bain, Mel Chapel, Mary Jo Frazier, Nora Fuller, Darren Hall, Mark Fristad, Zach Holden, Charlene Miller, Tom Salaiz, Brian Schneider, Lura Schroeder, Penny Tubbs, Steve Wheeler, and Solomon Yilma for their contributions to the development and release of Clearwater Russet, as well as Kathy Haynes, USDA-ARS, Beltsville, MD for her review and suggestions for improvement of the manuscript prior to submission for publication. We also thank Jim Whitmore and Lori Ewing, University of Idaho, for their efforts in developing foundation and certified seed of Clearwater Russet, as well as our industry cooperators, our collaborators in the Western Regional Potato Variety Trials, and the Idaho, Washington, and Oregon potato commissions. We also thank Jeanne Debons with Potato Variety Management Institute for the use of her photo of Clearwater Russet tubers in Fig. 2. Development of Clearwater Russet was partially funded by the USDA/CSREES Special Potato Program Grant.
- Solanum tuberosum