M A Y / J U N E 2 0 1 7 POTATO GROWER 11 (>10 oz.); however, the check culti- vars of Ivory Crisp, Atlantic, Lamoka, Dakota Crisp and Dakota Diamond all had more than 14%. There were very few US No. 2s or culls; tubers were culled or dropped in grade primarily due to growth cracks or misshapen tubers. At grad- ing, little scab (common) was noted, although Snowden and Ivory Crisp had a trace (pit scab). Tuber shaped ranged from round to oblong (data not shown), and all would be acceptable to the chip processors from a shape standpoint. Skin color (data not presented) ranged from white to flaky (slight netting for Atlantic, Snowden and Waneta); ND7818-1Y is yellow. Flesh colors when cut for internal disorders were white, creamy and ND7818-1Y has medium yellow flesh. Mean hollow heart/brown center was 0%, thus not reported. Mean specific gravity, an important attribute and indirect measure of tuber dry matter, was 1.0913, with a range of 1.0760 for ND7818-1Y to 1.1052 for ND8305-1 (Table 3). Specific gravity in the Northern Plains tends to be quite high across market types, although in 2016 due to the heavy rains and hail, clones with later maturity particularly tended to have lower levels, consis- tent with not having had time to attain chemical maturity prior to vine kill after suffering hail damage. Our focus continues to be identifi- cation of chip processing germplasm that will reliably and consistently process from long-term cold storage. As we grade, chip pro- cessing selections are sampled, and stored at 42oF and 38oF (5.5C and 3.3C) for eight weeks (Table 3); a second set is evaluated the follow- ing June (materials from this trial will be chipped around June 7). In response to industry needs and con- sumer demands, potato producers and industry personnel are seeking potato cultivars which process (chip, French fry and other frozen products) reliably from long-term storage. Current commercially acceptable cultivars tend to perform well through March (for most northern production areas), but quality (chip fry color and defects) generally declines thereafter. The chip industry would like to have the option of storing potatoes for nearly 12 months and processing with light chip colors and few defects. Several factors affect storability, including sugar accumulation in storage, dry matter, bruise suscepti- bility, pathogen susceptibility, and respiration. Chip scores from the field varied from 3 to 7 using the USDA chip color chart (HunterLab instrument values of 49.17 to 61.18). All clones rated as unaccept- able from 38F storage, although ND8305-1 did rate a 7 on the color chart. ND8305-1, like ND8331Cb-1, has had mixed reviews in the past eight years of evaluation; while chip color is always excellent, yield, grade and tuber shape have been inconsistent, thus it was determined to maintain it for parental germplasm, but it will no longer be considered for cultivar release. Following eight weeks storage at 42F (5.5C), chip color chart ratings ranged from 3 for ND7519-1, to 9 for Snowden. These scores are indicative of the tremendous abiotic stress level the trial was under, and the inability of many of them to attain chemical maturity prior to vinekill; some with early maturity may have been overmature by the time we were able to harvest after vinekill because of wet soils. HunterLab instrument scores aver- aged 51.23; ND7519-1 had the brightest chip color score of 58.10. All trial entries are evaluated for blackspot and shatter bruise poten- tial (Table 1). Blackspot bruise is evaluated using the method of Pavek and Corsini. Tubers from 45F storage are peeled using an abrasive peeler and held overnight at room temperature; dis- coloration resulting from a mixing of cell components (polyphenol oxidase and tyrosine) due to cell damage elicited by the peeling is rated on the stem end, providing an assessment of bruise potential. For the 24 genotypes reported here, the range was 1.1 for ND7799c-1 and Dakota Pearl, to 3.5 for Snowden, with a mean of 2.2. Shatter bruise potential is evaluated for tubers from 45F storage using a bruising chamber made with digger chain baffles. The range was 1.8 for Waneta to 3.5 for NorValley. Finally, a general rating score of 1 (poor) to 5 (perfect) is given based on yield, shape, tuber size profile, appearance, and external defects. The mean general rating was 3.4, with a range of 2.3 to 4.1. Many commercially acceptable cultivars rated very high (3.8-4.1); similarly, ND7799c-1 and ND7519-1 our two most promising chip processing selections rated 4.0 and 3.9, respec- tively. Figures 1 and 2 summarizing