A plot design to sequentially harvest early generation selections and its use in evaluating fresh market characteristics of three new cultivars

A plot design was developed to compare changing yield and quality characteristics of early generation selections in our potato breeding program over a 6-wk harvest season. In this design all replicates for one harvest date are located within one row to facilitate harvesting and the variety plot arrangements in adjacent rows are identical to eliminate inter-variety plant competition effects. To illustrate the usefulness of this design, three new fresh market cultivars, Norkotah Russet, HiLite Russet, and Frontier Russet, and a standard commercial cultivar, Norgold Russet, were harvested every 10 to 14 days from late July through early September to measure earliness and optimum time of harvest for each cultivar. Each cultivar was found to have a characteristic maturation pattern. Total and marketable yields and tuber size distribution generally improved in all four cultivars as the harvest season progressed. However, the yield of marketable tubers of Norkotah and Frontier peaked and then decreased later in the season as many tubers became oversized (over 340 gms). Tuber number per plot was a stable attribute and was judged to be the most important factor determining performance of each line. Norkotah and Frontier produced fewer tubers and showed rapid tuber bulking and early production of marketable tubers of preferred sizes. HiLite produced more tubers than the other cultivars so had higher percentages of undersized tubers in late July and early August, but it produced high yields and desirable size distributions in late August and early September. Specific gravities for all three new cultivars decreased during early August, increased in mid-August as plants died, and then declined. HiLite and Frontier had higher solids than Norgold and Norkotah throughout the season.     

Potato Cultivar Response to Seasonal Drought Patterns

The ability to minimize potato yield and quality losses due to drought can be greatly improved by understanding the relative responses of different cultivars to seasonal variations in water supply. To address this need, we initiated a 2 year field experiment to determine the responses of the six potato cultivars to different seasonal drought patterns, including 1) full season irrigation at 100 % ET, 2) irrigation at 100 % ET terminated during late bulking , 3) full season irrigation at 70 % ET , 4) irrigation at 70 % ET terminated during late bulking , and 5) a gradual reduction in irrigation from 100 % ET during tuber initiation through early bulking, to 70 % ET during mid-bulking, and 50 % ET through late bulking. GemStar Russet and Ranger Russet, two medium-late maturing cultivars, generally produced the highest yields across the range of drought treatments, but both were fairly sensitive to changes in drought severity. Alturas, a late maturing cultivar, produced relatively high yields with full irrigation, but exhibited the greatest sensitivity to increasing drought severity, particularly when severe late-season water deficits were imposed. Yields for the early maturing cultivar Russet Norkotah were relatively low overall, but it was the least sensitive to changes in drought severity, particularly when late season drought was imposed. Russet Burbank produced comparatively high total yields across the range of drought treatments, but U.S. No. 1 yields were substantially reduced by each seasonal drought pattern. However, it was less sensitive to changes in drought severity than GemStar Russet, Ranger Russet and Alturas. Total and U.S. No. 1 yields for Summit Russet were low for each drought treatment and it exhibited intermediate sensitivity to changes in drought severity. GemStar Russet had the highest water use efficiency based on U.S. No. 1 yield.     

Nitrogen fertilization of irrigated Russet potatoes in southcentral Alaska

Allagash Russet, BelRus, Frontier Russet, HiLite Russet, Russet Norkotah and Russet Burbank were evaluated with preplant N fertilizer levels of 0, 67, 134, 201, and 201 kg N/ha in a split application on a Knik silt loam in 1990 and 1991 near Palmer, Alaska. BelRus and Russet Norkotah yielded less marketable tubers than the other cultivars and Russet Burbank performed well under warm, dry 1990 conditions and poorly when conditions were cool and wet (1991). Allagash, HiLite and Frontier Russets were consistent producers with marketable tuber yields averaging 35.4, 32.3, and 32.2 t/ha, respectively. Marketable tuber yield was maximized with approximately 175 kg total N/ha (residual soil plus applied) and approached 43 t/ha in 1990. Splitting the N application had no significant effect on tuber yield. Newly released russets appear promising for commercial Alaska producers.     

The effect of irrigation regime and subsoiling on yield and quality of three potato cultivars

A study was conducted on sand and loam soils to evaluate the response of three potato cultivars to subsoiling and irrigation frequency. Subsoiling was of little benefit on the loam soil. On the sand, subsoiling promoted deep rooting and allowed potatoes to avoid water stress usually associated with four days between irrigations. Russet Burbank was much more sensitive to water stress than was Nooksack or Lemhi, especially in the percentage of tubers not graded U.S. No. 1. Benefits from subsoiling may be inadequate to justify the cost if a reliable high-frequency irrigation system is available.     

Effect of seed piece size on performance of three potato varieties in the Klamath Basin of Oregon

A survey of cut seed lots from Klamath Basin commercial potato operations showed poor uniformity of seed piece size and numerous undersize seed pieces in most of the 18 seed lots examined over two years. Experiments were conducted in 1995, 1996, and 1997 to evaluate effects of seed piece size on the performance of Russet Burbank, Russet Norkotah, and Century Russet cultivars. Weighed seed tubers were cut into four pieces to obtain seed piece sizes of 21, 35, 50, 64, and 78 g (+/-2 g). Seed pieces less than 50 g resulted in delayed emergence and reduced stem numbers in all varieties. Effects of seed piece size on yield and tuber size distribution were greatest for Century Russet and least for Russet Norkotah, but were significant for all varieties over the three-year study. Increasing seed piece size increased yield of U.S. No.1 and total yield, while reducing tuber size. An economic analysis, based on crop values for fresh market use and seed costs, found optimum seed piece sizes of 64 g for Russet Burbank and Century Russet and 50 g for Russet Norkotah.     

Effect of declining or interrupted irrigation on yield and quality of three potato cultivars grown on sandy soil

Many potatoes in the Northwest are grown on sandy soils with sprinkler irrigation. The low water holding capacity and restricted rooting often associated with coarse-textured soils create conditions where water stress injury is likely. Temporary water shortage due to irrigation system failure is a hazard on these soils. The Russet Burbank cultivar is often severely injured by such water stress. It is not known how the cultivars Nooksack and Lemhi respond to these conditions. A study was conducted to compare the responses of Russet Burbank, Nooksack, and Lemhi cultivars to interruptions in irrigation during tuber initiation or during bulking, and to gradually increasing water stress from declining water application rates during the last 8 to 10 weeks of the growing season. In most categories evaluated, Russet Burbank was most injured by water stress, especially in percent U.S. No. 1 tubers. Much of the decrease in U.S. No. 1 tubers was due to small size. Nooksack generally was the least affected by water stress while Lemhi was affected slightly more than Nooksack. Both Nooksack and Lemhi withstood periods of water stress and produced satisfactory yields and grades of tubers while Russet Burbank did not produce profitable levels of marketable tubers.     

Russet Norkotah: A new russet-skinned potato cultivar with wide adaptation

Russet Norkotah is a long, smooth, shallow-eyed, russet-skinned potato cultivar with wide adaptation. It has a smooth golden russet-skin and produces a high percent of medium sized U.S. No. 1 tubers that are good count-carton size.     

Teton Russet: An Early-Maturing,Dual-Purpose Potato Cultivar Having Higher Protein and Vitamin C Content,Low Asparagine,and Resistances to Common Scab and Fusarium Dry Rot

Teton Russet is an early-maturing, medium-russeted, potato cultivar with high merit for both fresh-pack and processing. In early harvest trials in the Pacific Northwest, Teton Russet had total yields similar to Russet Norkotah, and higher than Ranger Russet and Russet Burbank. Marketable yield of Teton Russet in the early harvest trials was also comparable to or higher than Russet Norkotah in Washington and Oregon, and higher than Ranger Russet and Russet Burbank at these sites, as well as in Idaho. In full-season trials, while total yield of the earlier-maturing Teton Russet tended to be lower than Ranger Russet and Russet Burbank, marketable yield was generally higher than Russet Burbank across the majority of sites due to its higher percentage of U.S. No. 1 tubers. Teton Russet is suitable for processing, with acceptable fry color following up to 8 months of storage at 8.9 °C. Uniformity of fry color was also very consistent. Teton Russet has shown lower levels of the amino acid asparagine relative to Ranger Russet and Russet Burbank which may contribute to lower acrylamide levels in French fries and other processed potato products. Teton Russet is notable for having resistance to common scab (Streptomyces spp.) and Fusarium dry rot, and is moderately resistant to tuber net necrosis. Analyses have also shown Teton Russet to have significantly higher protein levels than Russet Norkotah, Ranger Russet, and Russet Burbank, as well as higher vitamin C content than Russet Norkotah and Russet Burbank. Teton Russet was released in 2011 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.     

Impact of early-season water deficits on Russet Burbank plant development,tuber yield and quality

Russet Burbank potatoes grown on Owyhee silt loam were subjected to early-season moisture stress by delaying initiation of furrow irrigation up to seven weeks after planting. A range of water stress treatments from 4 to 7 weeks after planting resulted in reduced plant size, tuber number and total tuber weight per plant 8 1/2 weeks after planting. Early-season water stress resulting from delayed irrigation onset was associated with improved tuber quality at harvest. Plants water stressed before tuber initiation had fewer tubers with dark stem-end fry colors, reduced percentage of US No. 2 potatoes, and increased percentage and size of US No. 1 potatoes. Increasing duration of soil water potential below -60 kPa early in the season was associated with declining total yield in 1985 but not in 1986. To obtain optimum yield and processing quality, the first irrigation should be no sooner than full plant emergence.     

Pomerelle Russet: an Early Maturing Potato Variety with High Yields of U.S. No. 1 Tubers Suitable for Fresh Market and mid-Storage Processing and Tolerance to Potato Mop-top Virus

Pomerelle Russet is an early maturing fresh potato variety, which produces moderately high early-season (95–110 days after planting) yields of long tubers with brown-russet skin. It is notable for its very attractive, smooth tubers and resistances to internal and external defects with a high percentage of U.S. No. 1 tubers. Fresh merit ratings for Pomerelle Russet in trials conducted in Idaho, Oregon and Washington were consistently higher than Russet Burbank and Russet Norkotah. Early harvest yields for Pomerelle Russet are generally comparable to Russet Norkotah with a higher percentage of U.S. No. 1 tubers. Compared to Russet Burbank and Russet Norkotah, Pomerelle Russet has greater resistance to Potato mop-top virus, soft rot, corky ringspot and tuber infections from late blight. It also has higher protein and vitamin C concentrations than Ranger Russet, Russet Burbank and Russet Norkotah, indicating that it can provide an enhanced level of dietary protein and vitamin C relative to these standard potato varieties. Pomerelle Russet has moderate specific gravity and good resistance to sugar ends. It also has moderately long dormancy, about 30 days shorter than Russet Burbank. Average post-harvest processing ratings for Pomerelle Russet were similar to Ranger Russet and greater than Russet Burbank. Pomerelle Russet also has maintained acceptable fry color for about 180–200 days in storage at 8.9 °C, indicating potential for processing out of mid-term storage, with improved fry color uniformity relative to industry standards. However, its primary use appears to be as a high quality, early fresh variety.     

GemStar russet: A potato variety with high yield, good culinary quality, excellent fresh market appearance, and resistance to common scab

GemStar Russet, derived from the cross Gem Russet x A8341-5, was released in 2004 by the USDA/ARS and the agricultural experiment stations of Idaho, Oregon, and Washington. The foliage of GemStar Russet is dark yellowish-green, spreading, with large leaves and abundant white flowers. The tubers are brown, medium to heavily russeted, oblong, with a slightly prominent eyebrow, white flesh, and indistinct pith. GemStar Russet was compared with Russet Burbank and Russet Norkotah in trials across the Pacific Northwest for yield, quality, and disease response. Except for locations in southern Idaho, in general, GemStar Russet produced slightly lower total yield than Russet Burbank, but much higher U.S. No. 1 yield. When compared with Russet Norkotah, GemStar Russet produced similar total and U.S. No. 1 yields in early harvest trials but higher total and U.S. No. 1 yields in late-harvest trials. When observed for defect problems, GemStar Russet exhibited resistance to second growth, growth cracks, and stemend discoloration, moderate resistance to blackspot and shatter bruising, but a high level of susceptibility to hollow heart. In product quality tests, GemStar Russet was rated superior to Russet Burbank for french fry quality and comparable for baked potato quality. GemStar Russet was found to be immune to PVX, resistant to common scab and powdery scab, moderately resistant to Verticillium wilt, tuber net necrosis caused by PLRV, and corky ringspot. It demonstrated susceptibility to late blight, PLRV, dry rot, soft rot, and ringrot and extreme susceptibility to PVY^o. Biochemical analysis of GemStar Russet tubers showed them to be higher in protein and much higher in vitamin C than those of Russet Burbank or Russet Norkotah. Three-year average for tuber glycoalkaloid concentration was 1.5 mg 100 g^?1.     

Auxin Modulates Gibberellin-Induced Effects on Growth,Yield, and Raw Product Recovery for Frozen Processing in Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.)

Tuber shape phenotype is an important determinant of raw product (≥7.6-cm-long French fries) recovery for frozen processing. Tuber length-to-width (L/W) ratios ≥1.8 translate to maximum yield of raw product; however, some cultivars produce tubers with much lower L/W ratios. While gibberellin (GA) can be used to elongate tubers, it also decreases tuber size and can thereby attenuate raw product recovery. We investigated the utility of GA and naphthaleneacetic acid (NAA) combination treatments for modifying tuber set, size, and shape to increase yield of raw product from ‘Payette Russet’ and ‘Alturas’; two late-season frozen-processing cultivars that often produce tubers with undesirably low L/W ratios. Models describing L/W ratio and fry yield by tuber size class were developed to translate total U.S. No. 1 tuber yields (>113 g) into yield of raw product. Increases in the L/W ratios of 113–284-g tubers had a greater effect on recovery of French fries (% fresh wt) than for tubers >284 g. Undersize (<113 g) and oversize (>340 g) tubers yielded 0 and 96% fries, respectively, regardless of L/W ratio. GA applied as a seed treatment effectively hastened emergence and altered tuber shape by increasing the L/W ratios of ‘Alturas’ and ‘Payette Russet’ tubers, enhancing total fry yield for the 113–340-g tubers by 24–46%, depending on concentration and application technique (dip, spray, in-furrow). However, GA also decreased apical dominance and shifted tuber size distribution away from >284-g tubers toward higher yields of <170-g tubers, erasing the gains in fry yield when all size classes (>113 g) were considered. When combined with GA, NAA maintained apical dominance, attenuated the shift in tuber size distribution, had no effect on the GA-induced increase in tuber L/W ratio, and only partly moderated the GA-induced stimulation of plant emergence. Raw product yield from ‘Payette Russet’ increased 12–39% in spray application trials by using NAA to confine the effect of GA to tuber shape and limit the loss of U.S. No. 1 tubers to undersize. Increases in tuber L/W ratio with GA/NAA seed treatments translated to increased yield of fries only when the relative concentrations were adjusted to minimize loss of >284-g tubers and gain in undersize tubers, as dictated by cultivar sensitivity to GA. ‘Alturas’ was less sensitive to GA than ‘Payette Russet’ for shifts in tuber size distribution but not shape, resulting in 17% increase in raw product with GA alone in pre-plant seed spray application studies. GA/NAA combination treatments provide an effective approach to manipulate tuber size distribution and enhance the yield of raw product for frozen processing in cultivars with a rounder tuber shape phenotype.     

Response of russet norkotah clonal selections to nitrogen fertilization

The low vine vigor and high N requirement of Russet Norkotah may lead to N loss and groundwater contamination on coarse-textured soils. Recent clonal selections from Texas have produced strains that have larger and stronger vines, which may alter N requirements. This twoyear study examined the N use efficiency (NUE), yield, and quality of Russet Norkotah strain selections fertilized with different N levels on a Hubbard loamy sand in central Minnesota. The selections, Texas Norkotah Strain (TXNS) 112, TXNS 223, and TXNS 278 were grown with standard Russet Norkotah under irrigated conditions and received total N levels of 28, 112, 224, or 336 kg ha^-1. Total, marketable, and large (>340 g) tuber yields increased linearly (P>0.05) with rate of N application in 1998 but not in 1997. The genotype main effect was not significant for any of the tuber yield parameters measured based on fresh weight. Vine, tuber, and total dry biomass yields were 116%, 5.8%, and 13.2%, respectively, higher with the selections than Russet Norkotah. Harvest index (HI), or the proportion of total dry matter partitioned to tubers, was 7% greater for Russet Norkotah than the TXNS selections, reflecting the larger vine growth of the selections. The selections accumulated significantly higher N in the vines (0.113 kg kg^-1 N) than the standard clone (0.053 kg kg^-1 N) as N rate increased from 28 to 336 kg ha^-1, and the difference between the selections and the standard clone was larger at higher N rates than at lower N rates. Russet Norkotah partitioned 10% more N to tubers than did the TXNS selections, reflecting the difference in HI between the standard cultivar and its clones. Nitrogen recovered from fertilizer N applied in addition to the 28 kg ha^-1 starter N (NUE₂₈) averaged 36% and varied little with genotype, N rate, or cropping year. Biomass accumulation from similar N additions (AUE), however, was significantly higher for the selections than Russet Norkotah at 112 kg N ha^-1 in 1997 only. At low N rate (112 kg ha^-1), the selections had higher physiological use efficiency (PUE₂₈) (mean 45.9 g g¹) than Russet Norkotah (25.9 g g¹). Results from this study demonstrate that, although N recovery was similar for the four genotypes, the Texas Norkotah strains produced greater biomass than Russet Norkotah per kg N applied at low rate in 1997 and per kg of fertilizer N absorbed by the plant in both years. However, under the conditions of this study, higher biomass of the selections did not translate into a marketable yield advantage over the standard cultivar.     

Potato response to split nitrogen timing with varying amounts of excessive irrigation

Irrigation and nitrogen management are two of the most important factors affecting production efficiency and environmental quality in potato cropping systems. Field studies were conducted in 1990 and 1991 to determine the interactive effects of irrigation amount and N timing on potato yield, quality and nitrate leaching potential. Sprinkler irrigation was applied at approximately 1.0, 1.2 or 1.4 times estimated evapotranspiration (ET) to Russet Burbank potatoes grown on a silt loam soil. Following tuber initiation, a total of 132 kg N/ha was applied through the irrigation system to N treatment subplots using either six weekly 22 kg N/ha applications or 3 biweekly 44 kg N/ha applications. Excessive irrigation reduced root zone and petiole NO₃-N concentrations during substantial portions of the tuber bulking period. Biweekly 44 kg N/ha applications in 1991 produced higher and more consistent earlyseason root zone NO₃-N concentrations in the 1.2 and 1.4 ET plots than did the weekly 22 kg N/ha applications. Late-season tuber dry weight, total plant dry weight and plant N uptake were not affected by irrigation rate or N timing. However, excessive irrigation reduced U.S. No. 1 yield and yield of tubers >284 g in both 1990 and 1991 and reduced total yield in 1990. Biweekly N applications produced higher U.S. No. 1 yields than weekly N applications at all irrigation levels. Excessive irrigation also reduced NO₃-N remaining in the top 60 cm of soil at the end of the growing season. These results show that irrigating at optimal rates and applying split N at two week intervals on a silt loam soil can maximize Russet Burbank yield and quality while minimizing NO₃-N losses.     

Reveille Russet: An Early,Widely Adapted,High-Count-Carton Russet for the Fresh Market

Reveille Russet (ATX91137-1Ru) is a uniform, medium-early, high yielding, high pack-out, fresh market russet cultivar, with wide adaptability, released by Texas A&M AgriLife Research in 2015. It resulted from a cross of Bannock Russet(♀) and breeding clone A8343–12(♂). Reveille Russet produces attractive, oblong tubers, with medium russeting, white flesh and excellent culinary qualities. It has a lower incidence of internal defects and a higher percentage of marketable tubers in the 170 to 284 g and 284 to 510 g (6 to 10 oz. and 10 to 18 oz.) size classes than Russet Norkotah. Reveille Russet is resistant to hollow heart, second growth and blackspot bruise. It also stores longer and tends to wound-heal to a lighter brown color upon skinning during harvest and/or handling than Russet Norkotah.     

Discriminating Russet Norkotah intraclonal selections using canonical and cluster analysis

Intraclonal selection has been used to develop improved versions of existing popular potato cultivars. The approach is usually undertaken to overcome trait deficiencies that limit production/acceptance of the cultivar. Because of close genetic relationships, discriminating between strains and the original cultivar is more difficult than discriminating between conventionally derived hybrid cultivars. The objective of this investigation was to determine the genetic relationship between several Russet Norkotah intraclonal selections (strains) using statistical analysis. Russet Norkotah and seven Russet Norkotah strains (TXNS102, TXNS112, TXNS223, TXNS278, TXNS296, CORN3 and CORN8) were grown in 2000 and 2001 in New Brunswick, Canada, and several plant and tuber traits were measured. Hierarchical cluster analysis and canonical discriminant analysis demonstrated that the Russet Norkotah strains differ in a significant manner from the original cultivar and are therefore distinct and unique cultivars.     

深松对春玉米田土壤贮水性能及玉米子粒水分利用效率的影响

针对内蒙古春玉米产区耕层土壤质量下降、土壤容重增加、土壤保水蓄水能力下降等问题,试验以先玉335为供试材料,采用裂区试验设计,主区为深松季节,副区为深松深度。研究结果表明,土默川平原灌区深松处理下,土壤含水量较春季浅旋(CK)提升5.23%～9.89%;河套平原灌区深松处理下,土壤含水量较CK提升3.23%～7.34%。土默川平原灌区深松处理土壤容重较CK降低1.21%～11.52%;河套平原灌区深松(SS)土壤容重较CK降低0.61%～8.33%。土默川平原灌区春玉米产量提升7.84%～22.68%,玉米水分利用效率提升4.31%～25.32%,河套平原灌区产量提升7.73%～23.92%,玉米水分利用效率提升6.06%～29.63%。供试深松模式中,推荐秋季深松50 cm为最合理深松模式。     

测墒补灌条件下深松和耙压对冬小麦耗水特性和产量的影响

为探索适于冬小麦高产节水的耕作模式,通过裂区试验,在小麦全生育期不灌溉、拔节期和开花期测墒补灌两种水分管理方式下,设置旋耕、深松+旋耕、深松+旋耕+耙压2遍共3种耕作方式,研究了测墒补灌条件下深松和耙压对冬小麦耗水特性和籽粒产量的影响。结果表明,深松能明显促进小麦拔节后对0~200cm土层土壤贮水的吸收,显著提高产量和水分利用效率。与深松+旋耕处理相比,深松+旋耕+耙压2遍处理显著减少小麦播种至越冬前对土壤水分的消耗,在全生育期无灌水的条件下总耗水量减少,籽粒产量和水分利用效率明显提高;在小麦拔节期和开花期测墒补灌条件下,深松+旋耕+耙压2遍处理小麦在拔节至开花期和开花至成熟期的阶段耗水量和日耗水量明显提高,籽粒产量显著增加,水分利用效率无显著变化。     

Potato Cultivar and Seed Type Affect the Development of Systemic <Emphasis Type="Italic">Potato virus Y</Emphasis> (PVY<Superscript>N-Wi</Superscript>) Infection

Potato virus Y (PVY) infection is one of the greatest challenges to seed potato production in the United States. To determine how cultivar and seed type affect the development of systemic PVY infection, Russet Burbank and Russet Norkotah Colorado 3 cultivars were grown from two types of pre-nuclear seed (i.e., plantlets and minitubers) and Generation 3 (G3) tubers and challenged with PVY strain Wilga (PVY^N-Wi). Systemic PVY infection was measured by assaying spread of virus from the inoculation site to upper non-inoculated leaves. The Burbank cultivar had a lower incidence of systemic PVY infection compared to the incidence of systemic PVY that developed in the Colorado 3 cultivar. Furthermore, Burbank plants grown from G3 tubers had a lower incidence of systemic PVY infection, as compared to Burbank plants grown from plantlets. Together our results indicate that both cultivar and seed type affect the development of systemic PVY^N-Wi infections post-inoculation.     

Klamath Russet: A Full Season, Fresh Market, Long Russet

Klamath Russet, a late-maturing cultivar for fresh market use, was jointly released by the Agricultural Experiment Stations of Oregon, Idaho, and Washington and the U.S. Department of Agriculture in 2000. Klamath Russet was tested in irrigated trials in Oregon from 1990 to 1999 and in Western Regional Trials from 1994 to 1996. Klamath Russet yields of U.S. #ls have exceeded those for Russet Burbank and Russet Norkotah by more than 30%, averaged across all trials. Klamath Russet is moderately resistant to Verticillium wilt and highly resistant to common scab. Specific gravity for Klamath Russet has averaged 1.076 across all trials compared with 1.070 and 1.081 for Russet Norkotah and Russet Burbank, respectively. Klamath Russet is not considered suitable for french fry production because of high sugar and low starch contents.