A P R I L 2 0 1 6 POTATO GROWER 19 Trailblazer Bannock Russet and Shepody are some entries with a high propensity for over-sized tubers. Some of these entries do not set many tubers per plant data not presented here so within-row spac- ing may need to be tightened up perhaps to 10 inches to allow for development of a smaller tuber size profile. ND113100-1Russ ND1131 74B-2Russ and Shepody produced more than 10 US No. 2 tubers. Tubers were generally culled due to misshapen tubers or growth cracks ND113174B-2Russ and Shepody had a high propensity for culls. Several advancing selections and industry standards had outstanding French fry color when fried at har- vest and after storage at 45F for 8 weeks Table 3. Many demonstrate sugar end resistance and while most clones considered resistant to sugar ends had some they were light enough to be manageable during processing. ND8068-5Russ ND09 1938BR-2Russ ND102647-3Russ ND102719B-1Russ Dakota Russet and Dakota Trailblazer would be con- sidered resistant. ND113174B-2 Russ and Russet Burbank had the most severe and the most sugar ends as defined by the industry. Our pro- gram assesses a sugar end as any color deviation from the main fry. This is more stringent than the pro- cessing industry that requires a score of a 3 or 4 on the color chart to be called a sugar end. Clones with stem end colors 2 or less can usually be managed during processing. Our research efforts are designed to iden- tify processing both chip and frozen germplasm that will reliably and consistently process from long- term cold 38F and 42F 3.3C andor 5.5C storage. As we grade a field zero time sample is collected for immediate French fry processing. French fryfrozen processing selec- tions are also evaluated from 45F 7.2C storage after eight weeks and again the following May or June for fry color stem end fry color sugar ends and other defects. All clones with processing potential chip and frozen are chipped from 38F after 8 weeks of storage as we seek geno- types that will reliably process from that temperature. Trial entries were evaluated for inter- nal defects. ND102647-3Russ Bannock Russet Dakota Trailblazer and Russet Burbank had high per- centages of hollow heart Table 1. The latter three had a high percent- age of oversized tubers while the ND102647-3Russ tended to have a smaller profile. This selection will need to be monitored to see if it is susceptible to hollow heart due to cool temperatures during early tuber bulking as Russet Burbank is or if it is more similar to Norgold Russet and thus is more susceptible to late season manifestations. Trial entries are also evaluated for blackspot and shatter bruise potential. Blackspot bruise Table 1 results when polyphenol oxidase and tyrosine combine within damaged cells due to tubers bumping around during harvest and handling. Usually the skin is not broken and bruises are dif- ficult to detect without peeling. Based on our ratings producers should use management practices to maximize the marketing of bruise- free tubers including a pre-harvest irrigation if appropriate maintain belts and conveyors full of tubers and soil as the potatoes move through the harvester limit drops and utilize padding on harvesters in trucks and on conveyors going into storage. Shatter bruise potential was evaluated following storage at 45F. No clone stood out as having signifi- cant potential for shatter however keeping tubers properly hydrated using bruise-free management tech- niques and minimizing damage limit shatters. Shatter bruises may be a possible entrance point for pathogens such as Fusarium gramin- earum Fusarium sambucinum and Fusarium coeruleum. The most promising advancing dual- purpose frozen processing and tablestock russet selections included AND97279-5Russ ND8068-5Russ ND039194AB-1Russ ND060761B- 3Russ and ND102719B-1Russ. The most advanced is ND8068-5Russ. ND8068-5Russ has very early maturi- ty about seven to ten days earlier than standard Russet Norkotah thus will not compete with late season cultivars for yield however it sizes early and has potential as an early russet for packing or may be used in place of Shepody or Ranger Russet as a clone for opening processing plants in mid-July. The NDSU potato improvement team wishes to express our gratitude to Hoverson Farms for hosting this research trial. We are appreciative of the opportunity to conduct coopera- tive and interdisciplinary research and are grateful to our many grower industry and research cooperators in North Dakota Minnesota and beyond for funding and certified seed potatoes in support of our efforts.