Russet Nugget: A fresh market and processing potato cultivar with resistance to common scab

Russet Nugget is an oblong, smooth, high yielding potato with fresh market and processing qualities. It emerges quickly, produces an erect, large, vigorous vine with a profusion of white flowers, and is late maturing. Russet Nugget is very resistant to common scab, and moderately resistant to leafroll net necrosis,Vertcillium wilt, and early blight (tuber and foliage). In the San Luis Valley of Colorado, yield of Russet Nugget is comparable to Russet Burbank, with a significantly greater percentage of U.S. No. 1 tubers. In Texas, total yield is comparable to Norgold 40, with a slightly lower percentage of U.S. No. 1 tubers. Tubers of Russet Nugget have high specific gravity and vitamin C content.     

Freeing Russet Burbank potato plants from ring rot by stem cutting and tuber propagation

Apical stem cuttings removed from potato plants (cv. Russet Burbank) infected withCorynebacterium sepedonicum and expressing mild symptoms of bacterial ring rot were demonstrated to be free from the pathogen. This material remained free of ring rot through two additional stem cutting generations and when grown in the field for four successive tuber generations.     

Elimination of bacterial ring rot (Corynebacterium sepedonicum [Spieck. and Kotth.] Skapt. and Burkh.) by in vitro culture of sprout tissue

Summary Apical explants from sprout tissue, cultured in vitro, of potato tubers (cv. Russet Burbank) infected withCorynebacterium sepedonicum were demonstrated to be free of the pathogen. The material remained free of the pathogen through three in vitro generations and through two tuber generations produced from the in vitro plantlets. Contribution 3878878.     

Effects of Soil Water Level,Black Dot (Colletotrichum coccodes) Infested Soil and Nutrient Depletion on Potato in a Controlled Environment

The effects of soil water level and soil infested or not infested with Colletotrichum coccodes were quantified and compared on Umatilla Russet potato in repeated greenhouse trials. Nitrogen levels in leaflets and tuber yield differed significantly for effect of water level but there was no effect for soil infestation in both trials. More leaflet N as measured by chlorophyll and less tuber yield occurred in the low than the medium and high soil water treatments. Number of progeny tubers was not affected by C. coccodes but numbers were significantly less for the low water level than the high water level in one trial. Root weight was significantly reduced by C. coccodes in both trials and was significantly less in the high than the low and medium soil water levels in one trial. Incidence of infected progeny tubers was significantly reduced in infested soils for the low soil water compared to the medium or high soil water levels in one trial. The effect of increasing levels of water in infested soils had large and significant increases for percentage of stem area with sclerotia in both trials. Managing soil water by not overwatering in irrigated potato fields in the presence of C. coccodes may reduce black dot severity and quantity of sclerotia that potentially can overwinter and serve as sources of infection for subsequent crops. Analyses demonstrated a potential for significant associations between plant and disease variables not evidence for cause and effect.     

Investigations into the mode of resistance of potato tubers toFusarium roseum ‘Sambucinum’

In a histological study comparing tuber resistance of potato clone B7200-33 and susceptible variety “Russet Burbank” toFusarium roseum ‘Sambucinum’, the formation of suberin and wound periderm was found to be an important resistance mechanism. In B7200-33 tubers a continuous suberin layer was formed whereas in ‘Russet Burbank’ tubers the suberin was formed in clumps so that the pathogen easily could invade the tissue between the clumps but not through a continuous layer. Wound periderm also was formed at a more rapid rate in B7200-33 than in ‘Russet Burbank’ tubers thereby “walling off” the pathogen and reducing decay.     

Electrophoretic characterization of North American potato cultivars

A total of 112 named cultivars and advanced breeding lines were assayed through horizontal starch electrophoresis to test the utility of isozyme loci as a means to objectively identify potato cultivars. Both leaf and tuber tissue were sampled in thirteen enzyme systems. Two buffer systems (Histidine-citrate, pH 5.7 and Lithium-borate, pH 8.3) were used to resolve 16 isozyme loci, of which 14 were scorable without progeny testing. A total of 43 scorable allozymes were detected. All cultivars or advanced breeding lines that were the result of hybridization were discriminated by their sum electrophoretic pattern, whereas, sports (i.e., Russet Burbank vs. Burbank) or line selections (i.e., Norgold Russet “M1” vs. “M2”) have patterns that are identical to the original mother clone. The allelic diversity within and among cultivars indicate that horizontal starch electrophoresis offers an objective means to discriminate sexually-derived potato cultivars.     

Fertility and management practices to control verticillium wilt of the russet burbank potato

Management practices for the suppression of Verticillium wilt of Russet Burbank potato include sanitation, use of optimum sprinkler-irrigation practices, soil solarization, and an adequate soil fertility program. Among all cultural factors considered, nitrogen (N) deficiency in potato tissue was most commonly associated with the severity of Verticiilium wilt in Russet Burbank potato. Field studies have shown that increased N availability suppresses Verticiilium incidence on cv Russet Burbank while having no effect on cv Norgold Russet. Studies from both greenhouse and field show that the colonization ofV dahliae in potato stem tissue is suppressed in cv Russet Burbank when the availability of Phosphorous (P) is increased to the optimum. Following one season of cropping with Russet Burbank potato, the treatment providing the optimal N availability also suppressed the increases ofV dahliae populations in the soil during the following year of consecutive cropping. Similarly, after two seasons of continuous potato cropping, treatments with optimal P had lower soil populations ofV. dahliae in soil. Results show the suppression of Verticiilium wilt with optimal fertility. Verticiilium wilt [caused by eitherVerticiilium dahliae Kleb, (microsclerotial form) orVerticiilium albo- atrum Reinke and Berthold (dark mycelial form)] is one of the most severe diseases of potato in the United States. Potato yields, tuber size, and specific gravity may be substantially reduced by this disease, depending on severity, time of occurrence, and growing season. In Idaho and other arid growing regions of the United States, Verticiilium wilt is caused byVerticillium dahliae Kleb. Idaho field studies involving cropping practices, soil fumigation treatments, solarization, and Verticillium-resistant potato clones all support the importance ofV dahliae upon potato yield. Data from these studies show that yield losses due toV. dahliae commonly approximate 5 to 12 metric T/ha (5, 6). Table 1 illustrates the effect of several cropping practices upon relativeV dahliae populations in soil with the effects upon both disease severity and potato yield. With continuous cropping of Russet Burbank,V dahliae populations in soil increased, and yields were reduced by 18 to 19 metric Tlha when compared to locations that had been allowed to remain either weed-free and fallow or where corn had been previously cropped. It was estimated thatV dahliae was influencing yield by about 10 to 12 metric Tlha based on a regression analysis of yield as a function ofV dahliae populations in soil. Similarly, whenV dahliae was suppressed by fumigation treatments involving mixtures of dichloropropene and picfume, yields more significantly increased by 6.5 to 12 metric T/ha (5). Although many factors may influence yields, clones with higher Verticillium resistance than Russet Burbank generally out-yield Russet Burbank. Figure 1 demonstrates the effect of solarization (a technique involving the laying of clear plastic on soil for the purpose of elevating soil temperatures to killV dahliae). When Verticillium was controlled in this manner (lo), there was no significant yield difference between the Russet Burbank potato and the highly resistant A68113-4 clone. The A68113-4 clone grown in non-solarized soil out-yielded the Russet Burbank in non-solarized soil by 31 percent while the solarization treatment significantly increased yield for the Russet Burbank and A68113-4 clones by 46 and 18 percent, respectively. These yield responses were observed in a field where inoculum levels ofV dahliae were relatively low (2.10 cfulgrn of soil). With these losses, the need to develop control procedures is great and to achieve this control the need also exists to accurately evaluate the effect of treatments uponV dahliae. Our Idaho studies have routinely utilized such a procedure (9) in combination with comparisons of both disease severity and yield.     

Alturas: A multi-purpose, Russet potato cultivar with high yield and tuber specific gravity

‘Alturas’, a late-maturing, high-yielding, russet potato cultivar with high tuber specific gravity, was released in 2002 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington. Originally selected for dehydration processing, its cold-sweetening resistance also makes it suitable for processing out of storage into french fries and other frozen potato products. Culinary quality is high, with larger tubers suitable for fresh market if heavily russeted skin is not essential. Alturas consistently produced greater total and U.S. No. 1 yields than ‘Russet Burbank’ and ‘Ranger Russet’ in southern Idaho trials. Across other western trial sites, total yields of Alturas have on average been 29% and 14% greater than Russet Burbank and Ranger Russet, respectively. Alturas is resistant to Verticillium wilt (Verticillium dahliae) and early blight (Alternaria solani). Compared with Russet Burbank and Ranger Russet, Alturas is less susceptible to corky ringspot and foliar and tuber infection by late blight (Phytophthora infestans). It also is less susceptible to tuber net necrosis and Fusarium dry rot than Russet Burbank, and is more resistant to common scab (Streptomyces scabies) than Ranger Russet. However, Alturas is more susceptible to infection by PVY and PVX than Ranger Russet. Total nitrogen application recommendations for Alturas are approximately 40% less than those for Russet Burbank. Alturas requires 15% to 20% more water during the growing season than does Russet Bur-bank.     

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.     

Wallowa Russet: A full season long Russet for processing and fresh market

The Agricultural Experiment Stations of Oregon, Idaho, and Washington and the U.S. Department of Agriculture jointly released Wallowa Russet in 2002. This late maturing variety is most suitable for frozen french fry use, but may find limited fresh market potential because of outstanding flavor and texture when baked. Wallowa Russet was evaluated as AO87277-6 in Oregon irrigated trials from 1993 through 1999, and in western regional trials from 1997 through 1999. Averaged over 13 locations in seven states, Wallowa Russet produced total yields of 55.6 mt/ha compared to 53.5 and 45.7 mt/ha for Russet Burbank and Russet Norkotah, respectively, and U.S. No.1 yields of 44.4 mt/ha compared to 30.7 and 36.0 mt/ha for Russet Burbank and Russet Norkotah. Specific gravity is consistently higher for Walowa Russet than for Russet Burbank and fry color is as light or lighter; sugar end development is less than that observed in Russet Burbank. Wallowa Russet is similar to Russet Burbank in susceptibility toVerticillium wilt, foliar early blight (Alternaria solani), and potato leafroll virus (PLRV). However, Wallowa Russet develops less net necrosis than Russet Burbank from PLRV infection. Wallowa Russet is more susceptible to common scab (Streptomyces scabies) than Russet Burbank. It has moderate resistance to potato virus Y (PVY). Tubers of Wallowa Russet are less susceptible to tuber infection and decay caused by potato late blight (Phytophthora infestans) than Russet Norkotah and Ranger Russet. Wallowa Russet has less hollow heart, brown center, blackspot bruise, and fewer growth cracks than Russet Burbank but is more susceptible to shatter bruise. Vitamin C is higher for Wallowa Russet (30.4 mg/100 g fresh weight) than for Russet Burbank (21.9) or Russet Norkotah (22.0), and protein content averaged 5.6% compared to 4.7% and 4.9% for Russet Burbank and Russet Norkotah, respectively.     

Evaluating Incidence of Helminthosporium solani and Colletotrichum coccodes on Asymptomatic Organic Potatoes and Screening Potato Lines for Resistance to Silver Scurf

Silver scurf, caused by Helminthosporium solani, and black dot, caused by Colletotrichum coccodes, cause tuber blemishes on potato (Solanum tuberosum L.) which affect processing and fresh market trade. Tubers from ten cultivars were collected at harvest from three organic farms in Wisconsin and categorized as symptomatic or asymptomatic based on visual symptoms of silver scurf and black dot and/or signs of H. solani and C. coccodes. Tuber incubation and PCR assays were performed on asymptomatic tubers to detect H. solani and C. coccodes. Tuber incubation and PCR assays were in slight to fair agreement (kappa coefficient <0.4) for detecting both pathogens. Most asymptomatic tubers tested were positive by one or both assays for H. solani (75 %) or C. coccodes (94 %). Minituber inoculation assays were also performed to screen potato lines for resistance to silver scurf. Of the 14 lines tested, a diploid interspecific hybrid, C287, had consistently low sporulation, suggesting it has partial resistance to silver scurf. Since the majority of tubers harvested are already infected with one or both pathogens further research should focus on organically acceptable management practices that may inhibit disease development in field and in storage.     

Interaction ofErwinia spp. andFusarium roseum ‘Sambucinum’ on the Russet Burbank potato

Laboratory and field studies with the Russet Burbank (RB) potato provide evidence for synergism betweenErwinia carotovora var. atroseptica (Ea) andFusarium roseunt ‘Sambucinum’ (Fs). When these pathogens were inoculated together, the severity of tuber rot was significantly greater than when either pathogen was inoculated separately. Similarly, these pathogens interacted to reduce yield. When both organisms were uniformly applied to puncture wounds on potato seed (inoculum suspension consisted of 10⁸ cells/ml Ea and 10⁵ cells/ml Fs), the total yield was reduced by 46% and U.S. #1 yield by 53%. These reductions occurred even though blackleg symptoms (caused by Ea) were negligible (< 1%). In contrast, inoculations withErwinia carotovora var.carotovora (Ec) and Fs did not interact to reduce potato yield. Potato yields were also not influenced when these pathogens (Ea, Ec, Fs) were separately inoculated.Verticillium wilt (Verticillium dahliae) was significantly less when tubers were inoculated with either Ea, Ec, Fs, Ea + Fs, or Ec + Fs than with uninoculated tubers.     

Cultivar and seedpiece spacing effects on potato competitiveness with weeds

Field studies were conducted in 1991 and 1992 to evaluate the effects of cultivar, row spacing, and within-row spacing on potato yield and quality under weedy and weed-free conditions. Cultivars tested were Russet Burbank, an indeterminate, large-vined cultivar, and Frontier Russet, a determinate, small-vined cultivar. The two cultivars were grown under weedy and weedfree conditions with either 76 or 91 cm row spacings in factorial combination with either 15, 25, or 35 cm within-row spacings. The major competitive weeds were redroot pigweed, common lambsquarter and hairy nightshade. The weedy plots consistently produced less vine and tuber biomass and less total and U.S. No. 1 tuber yield than the weed-free plots. The time of weed emergence strongly affected potato competitiveness with weeds. In 1991, weeds emerged after potatoes, giving the crop some competitive advantage. In 1992, weeds emerged before the potatoes, resulting in heavy competition and large decreases in vine and tuber production for both cultivars. Reductions in U.S. No. 1 tuber yield were proportionally greater than the reductions in total yield. Weedy plots in 1991 and 1992 produced 25% and 68% less total yield and 43% and 92% less U.S. No. 1 yield, respectively, than weed-free plots. Russet Burbank was more competitive with weeds than Frontier Russet. Frontier Russet suffered substantial losses in productivity due to the presence of weeds, even under moderate weed pressure in 1991. Decreasing the row width from 91 to 76 cm did not provide a competitive advantage for potatoes as measured by vine or tuber biomass, or tuber yield. Decreasing within-row spacing under weedy conditions provided some competitive advantage and resulted in higher vine and tuber biomass and greater total tuber yield. The closer within-row spacing resulted in a substantial decrease in U.S. No. 1 yield with Russet Burbank but a slight increase with Frontier Russet. There were several significant interactions involving cultivar, weed level, and within-row spacing. These were due, in part, to each cultivar’s unique response to inter-and intraspecies competition. Cultivar had a greater influence on competitiveness than any plant spatial arrangement.     

Century Russet: A high-yielding fresh market cultivar with verticillium resistance

Century Russet, a high-yielding, late-maturing variety suitable for fresh tablestock use, was jointly released in 1995 by Agricultural Experiment Stations in Oregon, Idaho, Washington, Colorado, California, and Texas and the USDA Agricultural Research Service. Extremely high yields have been observed for Century Russet in variety trials conducted in Oregon and throughout the western United States under a wide range of soil and climatic conditions. Century Russet produced 40 percent higher marketable yields than Russet Burbank and 67 percent higher marketable yields than Russet Norkotah in 11 regional trials conducted over a three-year period in sevenwestern states. Uniform tuber shape, high yields of count carton sizes, and attractive tuber appearance make Century Russet well suited for the fresh market industry. It is not recommended for chipping or processing into frozen products because of low solids and dark fry color. Century Russet is highly resistant toVerticillium wilt and consistently develops less hollow heart, brown center, and other internal defects than Russet Burbank. It requires more time between vine kill and harvest than Russet Burbank for adequate tuber maturity and skin set. Bruised Century Russet tubers are susceptible to early blight andFusarium infection.     

Fresh Market Evaluation of Six Russet-Type Potato Varieties and Four Russet Norkotah Strains

In 2016, Russet Norkotah was the second most widely grown potato variety in the US; however, recent research has identified alternatives with excellent production economics. During 2011–2013, fresh market variety research was conducted in the Columbia Basin of central Washington, a long-season production region. Russet Norkotah was compared to five varieties–Classic Russet, Mountain Gem Russet, Russet Burbank, Targhee Russet, and Teton Russet–and four sub-clonal strains–CO-3, CO-8, TX-278, and TX-296–derived from Russet Norkotah. Each variety was evaluated for early- (104 days between planting and vine kill) and late- (150 days between planting and vine kill) harvest tuber size profile, grade, and yield, grower economic value, susceptibility to blackspot bruise and shatter bruise, emergence, stem and at-harvest tuber numbers, tuber length-to-width ratios, and quality. When harvested early, Classic Russet and Mountain Gem Russet produced 30% and 15% more gross revenue than Russet Norkotah, respectively. All other varieties and Russet Norkotah strains except CO-3 produced as much early-harvest gross revenue as Russet Norkotah. CO-3 early-harvest revenue was close to 50% lower than that of Russet Norkotah. All varieties and Russet Norkotah strains produced significantly greater late-harvest yields and gross returns than Russet Norkotah. Late-harvest gross revenue for Targhee Russet and Mountain Gem Russet was 38% and 34% higher than Russet Norkotah, respectively. Classic Russet, Mountain Gem Russet, Targhee Russet, and Teton Russet had significantly more shatter bruise following the late harvest than Russet Norkotah and all Russet Norkotah strains. Russet Burbank was among the most susceptible to blackspot and Targhee Russet the least, with 32% and 2.1%, respectively. If bruising is mitigated, Mountain Gem Russet, Classic Russet, and Teton Russet may be suitable alternatives to Russet Norkotah and Russet Norkotah strains for both early and late harvests.     

Payette Russet: a Dual-Purpose Potato Cultivar with Cold-Sweetening Resistance,Low Acrylamide Formation,and Resistance to Late Blight and Potato Virus Y

Payette Russet is a full season, russet-skinned potato cultivar notable for its cold-sweetening resistance and associated low acrylamide formation, making it ideally suited for processing into French fries and other potato products. Low asparagine and reducing sugar concentrations in Payette Russet tubers contribute to an 81 % reduction in acrylamide content in French fries relative to cultivars Ranger Russet and Russet Burbank following eight months storage at 9 °C. In three years of evaluations in the Western Regional Potato Variety Trials, average yield of Payette Russet was intermediate between Ranger Russet and Russet Burbank, but Payette Russet had the highest U.S. No. 1 yield when averaged across all eight trial locations. Acceptably low tuber glucose concentrations (<0.10 % glucose FWB) were maintained in Payette Russet following up to nine months storage at temperatures as low as 5.6 °C with consistently acceptable French fry color scores obtained (USDA value ≤2.0). Reducing sugars are also maintained uniformly throughout Payette Russet tubers, resulting in a low incidence of sugar ends and reduced mottling in French fries relative to standard processing cultivars. Long tuber dormancy also benefits long-term storage for processing. With its russet skin, Payette Russet could also be used for fresh-pack, and its assemblage of disease resistances makes it especially suitable for organic production, or for use by growers and companies seeking greater sustainability in their production. Payette Russet is resistant to foliar and tuber late blight, common scab, and has extreme resistance to PVY conferred by the presence of the Rysto resistance gene. Payette Russet also has a moderate level of resistance to Verticillium wilt, early blight, and corky ringspot. It is susceptible to Fusarium dry rot (F. sambucinum), therefore production and storage management guidelines are provided to minimize tuber infection. Payette Russet displays a low incidence of second growth and growth cracks, especially relative to Russet Burbank, and is intermediate between Ranger Russet and Russet Burbank for incidence of hollow heart/brown center. Blackspot bruise expression for Payette Russet is similar to Russet Burbank and reduced relative to Ranger Russet. Payette Russet was more susceptible to shatter bruise, internal brown spot, and tuber weight loss in storage relative to the industry standard cultivars. Payette Russet was released in 2015 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Northwest (Tri-State) Potato Variety Development Program.     

Pathogenicity of Washington and Oregon isolates of tobacco rattle virus on potato

Soil samples from corky ringspot (CRS) problem fields of potato in the states of Washington and Oregon were collected and planted withNicotiana tabacum ‘Samsun NN’ tobacco to bait tobacco rattle virus (TRV) and to increaseParatrichodorus allius populations, the vector of TRV. Pathogenicity of three isolates of TRV was assessed on Russet Burbank and Russet Norkotah plants usingP. allius as the vector. The most severe CRS tuber symptoms were with TRV from Pasco, WA, followed by Umatilla, OR, and Mattawa, WA, indicating a distinct variation in virulence among virus isolates. The lowest number ofP. allius that transmitted TRV resulting in CRS symptoms on Russet Norkotah was three nematodes per 250 cm³ soil. When potato plants were exposed toP. allius at different times in their growth, tubers on older plants were more resistant than younger tubers to CRS. Severity of CRS tuber symptoms was correlated with age of potato plants in pot culture. Reproduction ofP. allius on potato roots did not influence the incidence and severity of tubers symptoms. Under similar conditions, Bintje, a variety known to be resistant to CRS, served as a host forP. allius, yet remained asymptomatic. The protocol employed in these studies is appropriate for testing potato germplasm for resistance to CRS.     

Selection, evaluation, and identification of improved Russet Norkotah strains

Strain (sub-clonal, line, or intraclonal) selection for certain characteristics within some potato varieties has been very successful e.g. improved skin type (Russet Burbank from Burbank), improved skin color (Red LaSoda from LaSoda; Red Norland and Dark Red Norland from Norland), and improved vine vigor and yield (Norgold Russet M from Norgold Russet). In 1989, strain selection with Russet Norkotah was initiated by the Texas Potato Variety Development Program. Some 192 giant hill and/or tall type plants were selected from seedsmen and/or commercial Russet Norkotah fields in Colorado, while 183 were selected from commercial fields in Texas. Replicated yield trials with the final 13 of the original strain selections and Russet Norkotah were conducted in 1992, 1993, and 1994 in both Colorado and Texas. A mixed model analysis of variance was performed followed by disjoint cluster analysis in order to group strains into high, medium, and low yielding classes or clusters. Canonical discriminant analysis was performed to confirm the three clusters and to determine the extent to which various yield attributes are related and can be used to separate the three clusters. Several strains including TXNS (Texas Norkotah Strain) 112, TXNS 134, and TXNS 278 were identified as superior in Colorado, while TXNS 223, TXNS 249, and TXNS 296 were similarly identified for Texas growing conditions. These strains usually outyielded Russet Norkotah by 20–30%.     

Factors influencing time to breakdown (TTB) of cooked potato tissue

Cooking ability or time-to-breakdown (TTB) of different portions of potato tubers was determined by taking cores 1.27 cm (1/2inch) in diameter and 0.95 cm (3/8 inch) long from 12 locations in the tubers and cooking until penetration of a weighted rod pressing on the cores. Cores from the stem portion, on the average, required over twice as long for penetration of the rod during cooking as compared to cores from the bud section. The cores from the middle longitudinal portion of the tuber took longer to cook than cores from either side. Low specific gravity (1.070) tubers took significantly longer to cook than cores from high specific gravity (1.090) potatoes. However, when specific gravity of individual cores was determined with a pycnometer and TTB determined for the same samples, no relationships could be established. Cores from the stem portion took longer for TTB regardless of specific gravity or starch content. The data suggested much greater influence of cell wall structure as would be obtained from different portions of the tuber on TTB than starch content of the cells. No differences in TTB were obtained from tubers of high or low fertility or between Norgold Russet and Russet Burbank varieties, except Norgold was more uniform in cooking time between the stem and bud portion than Russet Burbank.