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Apr 29, 2008 - D. L. Corsini & J. J. Pavek & M. I. Vales & S. R. James &. D. C. Hane & C. C. Shock & B. A. ...... We also thank Jim Whitmore and Lori. Ewing ...
Am. J. Pot Res (2008) 85:198–209 DOI 10.1007/s12230-008-9013-7

Premier Russet: A Dual-Purpose, Potato Cultivar with Significant Resistance to Low Temperature Sweetening During Long-Term Storage R. G. Novy & J. L. Whitworth & J. C. Stark & S. L. Love & D. L. Corsini & J. J. Pavek & M. I. Vales & S. R. James & D. C. Hane & C. C. Shock & B. A. Charlton & C. R. Brown & N. R. Knowles & M. J. Pavek & T. L. Brandt & N. Olsen

Published online: 29 April 2008 # Potato Association of America 2008

Abstract Premier Russet is a russet-skinned, high yielding potato cultivar suitable for processing or fresh-pack. Premier Russet is notable for its resistance to the accumulation of reducing sugars in its tubers. This characteristic allows tubers of Premier Russet to be stored at temperatures as low as 5.6°C for 250 days without the need for reconditioning prior to processing. The low temperature sweetening resistance of Premier Russet allows for its storage at colder temperatures which contributes to prolonged tuber dormancy and quality, and to a reduction in the incidence and

R. G. Novy (*) : J. L. Whitworth US Dept. of Agriculture (USDA)Agricultural Research Service (ARS), Aberdeen Research & Extension (R & E) Center, Aberdeen, ID 83210, USA e-mail: [email protected] J. C. Stark : S. L. Love Aberdeen R & E Center, University of Idaho, Aberdeen, ID 83210, USA D. L. Corsini : J. J. Pavek Retired from the USDA-ARS, Aberdeen, ID 83210, USA

severity of storage diseases associated with the higher storage temperatures typically used for industry-standard cultivars such as Russet Burbank and Ranger Russet. Premier Russet was released in 2006 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Northwest Potato Variety (Tri-State) Development Program. In full-season trials conducted over a 3-year period in the states of Idaho, Oregon, Washington, Colorado, California, New Mexico, and Texas, Premier Russet averaged 5% and 4% higher

D. C. Hane Hermiston Agricultural R & E Center, Oregon State University, Hermiston, OR 97838, USA C. C. Shock Malheur Experiment Station, Oregon State University, Ontario, OR 97914, USA B. A. Charlton Klamath Basin R & E Center, Oregon State University, Klamath Falls, OR 97603, USA C. R. Brown USDA-ARS, Prosser, WA 99350, USA

M. I. Vales Oregon State University, Corvallis, OR 97331, USA

N. R. Knowles : M. J. Pavek Washington State University, Pullman, WA 99164, USA

S. R. James Central Oregon Ag Research Center, Oregon State University, Madras, OR 97741, USA

T. L. Brandt : N. Olsen Twin Falls R & E Center, University of Idaho, Twin Falls, ID 83303, USA

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yields than Ranger Russet and Russet Burbank, respectively, and had a higher percentage of US No. 1 yield than either cultivar. Specific gravity of Premier Russet is consistently greater than that of Ranger Russet or Russet Burbank. Premier Russet is resistant to common and powdery scab, very resistant to the common strain of potato virus Y (PVYO), and moderately resistant to Verticillium wilt, early blight of the foliage and tuber, Pectobacterium (Erwinia) soft rot, and to galling of roots by powdery scab. Blackspot bruise reaction for Premier Russet is similar to that of Ranger Russet. The incidence of hollow heart in Premier Russet is higher than that of Ranger Russet or Russet Burbank. Cultural recommendations to manage hollow heart in Premier Russet are provided. Resumen Premier Russet es un cultivar de papa de cáscara rugosa y alto rendimiento, conveniente para procesamiento o consumo fresco. El “LS” en su designación clonal es una observación “bajo en azúcar” y es descriptivo de la resistencia que tiene este cultivar para la acumulación de azúcares reductores en el tubérculo. Esta característica permite que los tubérculos de Premier Russet se almacenen a temperatura tan baja como 5.6 C por 250 días sin necesidad de condicionamiento antes de procesar. La resistencia a endulzar por baja temperatura de Premier Russet permite su almacenamiento a menores temperaturas lo cual contribuye al prolongado estado de latencia y la calidad del tubérculo, y a la reducción en incidencia y severidad de enfermedades de almacén asociadas con alta temperatura típicamente usadas para cultivares estándar de la industria como Russet Burbank y Ranger Russet. Premier Russet fue liberada el 2006 por USDA-ARS y las Estaciones Experimentales Agrícolas de Idaho, Oregon y Washington y es producto del Programa de Desarrollo (Tri - State) de variedades de Papa Noroccidental. En

Fig. 1 Pedigree of Premier Russet

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pruebas del periodo de cultivo completo realizadas durante tres años en los estados de Idaho, Oregon y Washington, Colorado, California, Nuevo México y Texas, Premier Russet dio 5% y 4% rendimientos mas altos que Ranger Russet y Russet Burbank, respectivamente y tuvo los más altos porcentajes de producción de US N° 1 que ambos cultivares. La gravedad específica de Premier Russet es consistentemente mayor que Ranger Russet y Russet Burbank. Premier Russet es resistente a la sarna común y a la roña, muy resistente a la variante común del virus Y de la papa (PVY°) y moderadamente resistente a la marchitez, por Verticillium, tizón temprano del follaje y el tubérculo, pudrición blanda por Pectobacterium (Erwinia) y agallamiento de las raíces por roña. La reacción de mancha negra por magulladura de Premier Russet es similar a la de Ranger Russet. La incidencia de corazón vacío es más alta que en Ranger Russet o Russet Burbank. Se dan recomendaciones culturales para el manejo de corazón vacío en Premier Russet. Keywords Solanum tuberosum . Variety . Breeding . Cold-sweetening resistance . Processing

Introduction Premier Russet was first grown and selected in the field at Aberdeen, ID in 1995 and was given the clonal designation A93157-6. It originated from a hybridization by J. J. Pavek in 1993 between breeding clones A87149-4 and A88108-7 (Fig. 1). Following evaluations of processing characteristics, the “LS” designation was appended to the clonal designation A93157-6 in 1998 to indicate its “Low Sugar” characteristic. This trait is characterized by reduced conversion of sucrose to reducing sugars (glucose and fructose) following long-term storage of tubers at temper-

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atures as low as 5.6 C. The resistance to “cold-sweetening” exhibited by Premier Russet reduces the incidence of darkcolored French fries and frozen potato products associated with high reducing sugar concentrations. Potato cultivars in the pedigree of Premier Russet (Fig. 1) include Bannock Russet (Novy et al. 2002), Western Russet (Love et al. 2006), BelRus (Webb et al. 1981), Targhee (Pavek et al. 1973), Butte (Pavek et al. 1978), and Penobscot (Simpson and Akeley 1964). Parent A88108-7, which exhibited cold-sweetening resistance, is believed to be the primary ancestral contributor to the low concentration of reducing sugars in tubers of Premier Russet. Of interest was the finding that the parents of A88108-7, A79179-2 and Western Russet, did not express cold-sweetening resistance based on processing evaluations of tubers stored at 4.4°C and 7.2°C for 3 to 4 months. The expression of cold-sweetening resistance in A88108-7 from two parents lacking cold-sweetening resistance may be an example of the expression of recessive alleles contributed by both parents. Another possible explanation is that cold-sweetening resistance is an example of hypostasis, whereby a dominant, nonallelic, modifier gene suppressed its expression in a parent of A88108-7. Subsequent non-transmission of the suppressor gene to A88108-7 allowed for the expression of coldsweetening resistance in this breeding clone. Further analysis of the segregation of cold-sweetening resistance in the progeny of Premier Russet is warranted to aid in elucidating the inheritance of this novel trait. Premier Russet was evaluated as a 12-hill selection in 1996, and from 1997 through 2000 in replicated yield trials in Idaho. Premier Russet was entered in Tri-State trials in Idaho, Oregon, and Washington in 2001 and 2002, and subsequently advanced to the Western Regional Potato Variety Trials where it was evaluated at sites in California, Colorado, Idaho, New Mexico, Oregon, Texas, and Washington in 2003 through 2005. Subsequent seed increases and commercial trials of Premier Russet were conducted in Idaho, Oregon, and Washington. On the basis of its agronomic performance in research and commercial trials, and its maintenance of low concentrations of reducing sugars in stored tubers, the decision was made by the Northwest (Tri-State) Potato Variety Development Program Committee to release Premier Russet. Release documents for Premier Russet were completed in 2006.

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Plants Growth habit: Medium-sized, erect to semi-erect vine with a late maturity similar to that of Russet Burbank (natural vine senescence occurs 121 to 130 days after planting; Fig. 2a and b). Stems: Green, with no or weakly expressed anthocyanin pigmentation and straight-edged stem wings. Leaves (Fig. 2b): Medium to dark-green, moderately pubescent with a medium-open silhouette; petiole pigmentation is weakly expressed; both terminal and primary leaflets are small relative to most other potato cultivars. Terminal leaflets: Narrowly ovate, with acuminate tip, obtuse base, and wavy margins; average length of 78 mm, width of 46 mm (160 leaves). Primary leaflets: Range of two to four pairs, with an average of 3.2; narrowly ovate with an acuminate tip and cordate base. Secondary and tertiary leaflets: Range of two to fourteen pairs, average of 7.0. Stipules: Medium, semi-clasping. Flowers Range of two to ten inflorescences per plant, average of 4.7, with a range of three to 28 buds per inflorescence; weakly pigmented calyx (Fig. 2c). Corolla: White, semi-stellate. Anthers: Yellow, broad cone-shaped, with good pollen shed and fertility; successfully used as both a male and female parent in sexual hybridizations. Stigma: Capitate. Berries: Medium to heavy berry set in the field. Tubers Long; width and thickness comparable to Russet Burbank, but an average of 12 mm shorter than Russet Burbank (160 tubers, 200 to 250 g); mean length: 111 mm (range 67 to 142), mean width: 65 mm (range of 53 to 77), mean thickness: 59 (range 46 to 74; Fig. 2d and e). Set: Low to medium (five to eight per hill). Skin: Medium russet. Eyes: Intermediate depth, with a mean number of 20.7 eyes per tuber which are evenly distributed; eyebrows are slightly prominent. Flesh: White. Dormancy: Storage trials were conducted over 3 years with no sprout inhibitors applied to tubers. Average tuber dormancies for Premier Russet were 120, 100, and 85 days after harvest (DAH) at storage at temperatures of 5.6°C, 7.2°C, and 8.9°C, respectively. Russet Burbank tuber dormancies at the same storage temperatures were 175, 155, and 130 DAH, respectively. Duration of dormancy was defined as the number of days from harvest until 80% of potatoes had at least one sprout ≥5 mm in length.

Varietal Description Light Sprouts Plant and tuber descriptions of Premier Russet were obtained from field evaluations conducted at Aberdeen, ID unless noted otherwise.

Ovoid shape; tip is green with an open growth habit and medium pubescence; base of sprout has blue-violet pig-

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Fig. 2 Premier Russet: a plant, b leaf, c inflorescence d external and internal tuber appearance, e grouping of field-grown tubers, and f light sprout on tuber

mentation that is strongly expressed. Root initial frequency is similar to that of Russet Burbank (Fig. 2f). Agronomic Performance Premier Russet is a high-yielding cultivar with total and US No. 1 yields similar to Ranger Russet, and surpassing Russet Burbank by 5.1 and 17.1 t/ha, respectively, in fullseason trials conducted in southeastern Idaho (Table 1). The percent of tubers with US No. 1 grade (US Standards for Grades of Potatoes 1997) was 85%, and was greater than Ranger Russet (82%) and Russet Burbank (55%). The tuber size distribution of Premier Russet closely approximated that of Ranger Russet, while tuber size was larger with less cullage in comparison to Russet Burbank. Premier Russet also was evaluated over a 5 year period in trials conducted in Idaho, Oregon, and Washington (Table 2). Total and US No. 1 yields of Premier Russet exceeded Russet Burbank at all locations. In comparisons with Ranger Russet, Premier Russet had lower total yields in Idaho and Washington, but comparable US No. 1 yields

in both states. In Oregon, Premier Russet had substantially higher total and US No. 1 yields than did Ranger Russet. In 3 years of evaluations in the Western Regional Potato Variety Trials (Table 3), Premier Russet displayed higher total yield and percentage of US No. 1 yield, relative to Ranger Russet and Russet Burbank, when averaged across all locations. However, yield and percent US No. 1 rankings among the three entries varied at each location, with the exception that the percentage of US No. 1 yield of Premier Russet was almost always higher (seven of eight locations) than that of Russet Burbank. At the Colorado location, Premier Russet and Russet Burbank were identical, with 83% US No.1 yield. Tuber Quality Characteristics and Usage Processing Characteristics Premier Russet is notable for the production of tubers with low concentrations of reducing sugars following long-term storage at 5.6°C (Fig. 3). Russet Burbank glucose concen-

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Table 1 Average total yield, US No. 1 yield, percent US No. 1, specific gravity, tuber size distribution, and French fry color of Premier Russet, Ranger Russet, and Russet Burbank from ten full-season yield trials (125–135 days) conducted at Aberdeen, ID from 1997–2006 Cultivar

Premier Russet Ranger Russet Russet Burbank

Yield (t/ha) Total

US No. 1

48.6 48.9 43.5

41.1 40.0 24.0

% No. 1

85 82 55

Specific gravitya

1.091 1.089 1.077

Fry colorb

Tuber Size Distribution as Percent of Total Yield >341 g

170–341 g

114–169 g

341 g with hollow heart and brown center e Average of 18 trials; ratings obtained following controlled bruising evaluations conducted in the lab. f Value is percent weight loss during 9 months of storage in 2005 to 2006. Value reflects an average across three storage temperatures of 5.6°C, 7.2°C, and 8.9°C. b

rot (Fusarium spp.) and the Columbia root-knot nematode (Meloidogyne chitwoodi). Premier Russet also is considered susceptible to foliar late blight, however, it may be less susceptible to infection than other potato varieties on the basis of evaluations at five sites in the 2006 National Late Blight Trials coordinated by Dr. Kathy Haynes, USDA-ARS, Beltsville, MD. Infection by PLRV and potato virus X (PVX) is similar to observations for Russet Burbank; it is considered very susceptible to these two viruses Premier Russet is susceptible to bacterial ring rot (Clavibacter michiganensis subsp. sepedonicus). In inoculated, non-replicated, field evaluations conducted in Oregon, symptoms of infection in leaves were expressed as mild, inter-veinal mottling and lighter-colored leaves relative to non-infected check plants. Typical symptoms of tuber infection were also expressed (Jeff McMorran, Oregon State University Certification and Extension Specialist, unpublished data). Assignments of disease resistance/susceptibility ratings were based on a minimum of 2 years of replicated field evaluations. Verticillium wilt (Verticillium dahliae) evaluations were conducted at Aberdeen, ID and Hermiston, OR using naturally occurring inocula and the protocols of Corsini et al. (1988). Common scab and early blight evaluations were conducted at Aberdeen, ID using naturally occurring inocula

Disease and Pest Responses Premier Russet is notable for having resistance to common (Streptomyces scabies) and powdery (Spongospora subterranean) scab of the tuber, as well as being very resistant to the common strain of potato virus Y (PVYO) in field evaluations where the virus was both mechanically inoculated and aphid transmitted (Table 8). Mechanical inoculations of Premier Russet in the greenhouse with necrotic strains of PVY have shown that it does not have the same high level of resistance observed with PVYO. Relative to other cultivars considered susceptible to all strains of PVY, Premier Russet when challenged with PVYN, PVYN:O, and PVYNTN displays a reduced infection rate with an associated delayed detection both visually and with ELISA relative to susceptible potato cultivars. These findings suggest that the mechanism conferring resistance to PVYO may also confer a moderate level of resistance to other PVY strains. Premier Russet is moderately resistant to Verticillium wilt (Verticillium dahliae), early blight of the foliage and tuber (Alternaria solani), Pectobacterium (Erwinia) soft rot, and to galling of roots by powdery scab. It is considered moderately susceptible to pink rot (Phytophthora erythroseptica), tuber late blight (Phytophthora infestans), net necrosis from potato leafroll virus (PLRV), and corky ringspot from tobacco rattle virus. It is susceptible to dry

Table 7 Sensory evaluations of Premier Russet and Russet Burbank baked potatoes Cultivar

Premier Russet Russet Burbank

Early-storagea

Late-storageb

Color

Texture

Flavor

Overall appeal

Color

Texture

Flavor

Overall appeal

6.2 6.4

5.9 5.9

5.7 5.7

5.7 5.7

6.2 6.4

5.7 5.9

5.6 5.6

5.6 5.8

Blind sensory evaluations were conducted in Blackfoot, ID using 10 to 12 trained panelists. Values are the means of three sessions conducted over a 3 year period from 2004–2006 (one session/year). Tubers were rated for color, texture, flavor, and overall appeal using a scale with 1 = very poor quality and 9 = exceptional quality. a Early-storage evaluations were conducted approximately 1 month after harvest, prior to the time that the final holding temperature of 4.4°C was reached. b Late-storage evaluations were conducted following 5 to 6 months storage at 4.4°C.

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Table 8 Disease response of Premier Russet relative to Ranger Russet, and Russet Burbank Cultivar

Premier Russet Ranger Russet Russet Burbank

Vert. wilt

Pink rot

Common Powdery scab scab

Early blight

Late blight

Virusesa

Symptoms of Virus Infection

Storage Diseases

Root galling

Tuber Foliar Tuber Foliar Tuber PLRV PVYO PVX Net Corky necrosis ringspot

Soft rot

Dry rot

MR

MS

R

MR

R

MR

MR

S

MS

VS

VR

VS

MS

MS

MR

S

MR

MS

S

MS

MR

S

MS

S

VS

S

MR

R

MS

S

MS

MS

S

S

MR

MS

MR

S

MS

S

S

VS

S

VS

S

S

S

S

Responses of Premier Russet to diseases were based on a minimum of 2 years of controlled field evaluations. Responses were defined as very resistant (VR), resistant (R), moderately resistant (MR), moderately susceptible (MS), susceptible (S), and very susceptible (VS). Disease evaluations were conducted at the following locations: Verticillium wilt: Aberdeen, ID and Hermiston, OR; Pink rot: Parker, ID; Common scab: Aberdeen, ID and Antigo, WI; Early blight, Pectobacterium (Erwinia) soft rot, Fusarium dry rot: Aberdeen, ID; Powdery scab of tuber: Potter County, PA, Parker, ID, and Suring, WI; Powdery scab of roots: Parker, ID; Viruses and PLRV net necrosis: Kimberly, ID; Late blight: Corvallis, OR; Corky ringspot: Prosser, WA. a Virus responses are based on seed borne infections as determined by ELISA, following field infection with PLRV from aphid vectored sources of inter-planted virus infected potato, mechanical inoculation and aphid vectored PVY, and mechanical inoculation with PVX.

and consisted of three replicates in a randomized complete block (RCB) design with analyzed data used for assigning disease reactions. Common scab evaluations also were conducted by Dr. Walt Stevenson and Vaughan James, University of Wisconsin-Madison. The trial was conducted in 2006 at the Langlade County Research Area Antigo, WI in a field with a history of common scab. Hydrated lime was applied to promote the potential for development of common scab. The trial was a randomized complete block design with four replications. At harvest, undersize tubers were graded out and tubers were washed. Forty tubers from each plot were then chosen at random (cull potatoes were included in this sampling) and assessed for scab severity (area covered by lesions and lesion type). Powdery scab evaluations were conducted at Parker, ID, Potter County, PA, and Suring, WI. Powdery scab trials conducted by Dr. Jeff Miller at Parker, ID in 2003 and 2005 consisted of three replications in a RCB design with root galling and tuber lesion severity used in assignment of cultivar response. Potter County, PA evaluations were conducted in 2006 in a naturally infested field by Dr. Barbara Christ, Xinshun Qu, and Sara May, The Pennsylvania State University. Experimental design was a randomized complete block with four replications of 15 hill plots. Harvested tubers were visually assessed and the number of tubers with powdery scab was determined from the total number of tubers per plot. Disease incidence was calculated as the percentage of tubers with powdery scab. Suring, WI evaluations were conducted by Dr. Walt Stevenson and Vaughan James in 2006. The trial was located in a muck field, pH 5.4, to which the powdery scab pathogen had been introduced in 2004 on seed purchased from out-ofstate. A randomized complete block design with four

replications was used. A sample of 40 tubers from the US No. 1 size category was chosen randomly from each plot at harvest, washed, and then assessed for severity of powdery scab. Late blight field evaluations were conducted at Corvallis, OR as described by Mosley et al. (2003). Evaluations of PLRV, PVY, and PVX resistances were conducted at Kimberly, ID using virus-infected spreader rows as described by Corsini et al. (1994). Corky ringspot evaluations in a RCB design were conducted in the Egin Bench region of Idaho, and the Columbia Basin of Washington and Oregon using protocols described by Brown et al. (2000). Storage disease assessments were as described by Corsini and Pavek (1986). Columbia root-knot nematode ratings were provided by Dr. Chuck Brown, USDA-ARS, with field evaluation methods outlined in Brown et al. (2006).

Biochemical and Nutritional Characteristics Tubers of Premier Russet, Ranger Russet, and Russet Burbank, grown at Aberdeen, ID, were analyzed over a 3year period to assess biochemical and nutritional components 6 weeks after harvest (Table 9). Premier Russet was higher in dry matter content and percentage of protein than either Ranger Russet or Russet Burbank. Sucrose levels were higher in Premier Russet than in the check cultivars, while glucose percentages were 66% and 57% lower than levels observed in Ranger Russet and Russet Burbank, respectively. Vitamin C content of Premier Russet was similar to that of Russet Burbank, both of which were lower than Ranger Russet, a cultivar noted for its high levels of ascorbic acid (Love et al. 2004). Total glycoalkaloids for

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Table 9 Biochemical analyses of Premier Russet, Ranger Russet, and Russet Burbank tubers from the 2003 to 2005 Western Regional Potato Variety Trials at Aberdeen, ID Cultivar

Premier Russet Ranger Russet Russet Burbank

Dry matter (%)

Sucrose (% FWBa)

Glucose (% FWBa)

Protein (% DWBa)

Vitamin C (mg/100 g FWBa)

Total glycoalkaloids (mg/100 g FWBa)

22.5 21.9 19.8

0.25 0.21 0.16

0.03 0.09 0.07

6.3 5.6 5.3

25.4 34.6 23.6

4.3 4.4 3.6

Analyses were conducted on freeze-dried tuber tissue at Aberdeen, ID; tissue was taken from tubers stored at 7.2°C for 6 weeks following their harvest. FWB fresh weight basis; DWB dry weight basis a Sucrose and glucose values of 0.15% and 0.10% respectively are maximum values for acceptable fry color in this evaluation, with glucose being the greater contributor to fry color.

Premier Russet were 4.3 mg/100 g tuber fresh weight, which were comparable to levels observed in the check cultivars and far below the critical threshold of 20 mg/100 g tuber fresh weight.

Management Production Studies on management practices optimal for production of Premier Russet were conducted in southern Idaho and in the Columbia Basin of Oregon and Washington. Results of these studies may provide growers in other production regions with a foundation for the development of management guidelines specific for their locale. Southern Idaho Seed spacing trials indicate that the optimal commercial spacing for seed pieces of Premier Russet on rows spaced 91 cm apart is 23 to 28 cm. Optimal seed size ranges from 55 to 85 g with a 13 to 15 cm planting depth. Seed should be checked for dry rot and treated with an effective fungicide if needed, due to the susceptibility of Premier Russet to dry rot. Fertility management recommendations were developed based on replicated field trials conducted over 3 years at Aberdeen, ID. Total nitrogen application recommendations for Premier Russet are approximately 90% of recommendations for Russet Burbank (Stark et al. 2004), with most nitrogen applied during tuber bulking. For southern Idaho, total nitrogen (soil residual plus applied) recommendations range from about 235 kg ha−1 in areas with a 45 t ha−1 yield potential to 325 kg ha−1 in areas with a 67 t ha−1 yield potential. Nitrogen uptake decreases substantially after August 10 so applications should not be made after that time. Petiole nitrate sufficiency levels run about 3,000 to 5,000 ppm higher than for Russet Burbank early in the season, about the same as Russet Burbank during mid-

season and about 2,000–4,000 ppm lower late in the season. Phosphorus requirements for Premier Russet are approximately 10 to 20% higher than those of Russet Burbank. Premier Russet has good tolerance to water stress, but soil moisture should still be maintained between 65% to 80% available soil moisture (ASM) in the root zone (0 to 46 cm soil depth) during tuber development and bulking for optimal yield and quality. Recommended ASM is equivalent to −50 and −20 kPA on a silt loam soil. Recommendations for minimizing hollow heart in southeast Idaho include 20 to 23 cm seed piece spacing, lower nitrogen applications early in the season, avoidance of excessive, early season soil moisture, and a later planting date if possible; cooler soil temperatures during early tuber development also appear to exacerbate hollow heart in Premier Russet. Premier Russet has not been observed as being sensitive to metribuzin when applied at labeled rates. Premier Russet is similar to Ranger Russet with respect to blackspot bruise. Available soil moisture should be maintained above 60% during tuber maturation prior to harvest. Bruising can be minimized by optimization of harvest, transport, and cellar piling operations to reduce impacts that contribute to bruising. Columbia Basin of Washington and Oregon Washington Optimal seed size is 42.5 to 80.0 grams spaced at 23 to 28 cm for late harvest and 28 to 33 cm for early harvest (110–130 days after planting). Recommended final planting depth prior to hilling is 20 cm below soil level in rows spaced 86 cm apart. Water management is very similar to guidelines for Russet Burbank. Available soil moisture should be maintained at 75% to 85% from full emergence until late bulking; as vines senesce, ASM should be reduced to 60% to 65%. Nutrient management guidelines for Premier Russet, with the exception of nitrogen, are similar to those for Russet Burbank (Lang et al. 1999). Nitrogen recommendations for Premier Russet include 140 to 168 kg ha−1 of available

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nitrogen (soil residual + applied) in the root zone at emergence. Petiole samples should be collected approximately 1 week prior to row closure and continue through the season until late bulking; petiole NO3% of 17,000 to 22,000 ppm and total soil nitrogen above 56.0 kg ha−1 should be maintained until the start of early bulking (approximately 90 days after planting [DAP]). Thereafter, allow depletion of soil nitrogen with a corresponding decline in petiole reading between 12,000 and 15,000 ppm at mid-bulking (approximately 115 DAP), and then between 6,000 and 10,000 ppm at late bulking (approximately 125 DAP). Avoidance of excessive nitrogen is recommended as it may contribute to hollow heart and lowered tuber solids. Total season nitrogen (including soil residual) for Premier Russet should be between 295 and 340 kg ha−1 in a typical growing season. Oregon Seed size, in-row spacing, and planting depth recommendations are similar to those outlined above for Washington. Fertility management guidelines presented are standardized for the needs of Russet Burbank; however, Premier Russet also has performed well with the following nutrient inputs (in kg ha−1): (1) 224 K2O and 2.3 of boron broadcast at pre-plant, (2) 67 nitrogen, 90 of P2O5, and 45 of sulfur banded with planter, and (3) an additional 269 of nitrogen provided from early June through late July by weekly applications via pivot irrigation. Seasonal irrigation amounts were approximately 78.7 cm.

Storage Detailed storage recommendations for Premier Russet have been published (Brandt et al. 2007) and may be accessed via the internet at http://info.ag.uidaho.edu/pdf/CIS/CIS1142.pdf.

Seed Availability In 2007, seed was available from potato seed growers in Idaho, Oregon, Washington, Montana, Colorado, Wisconsin, South Dakota, North Dakota, and in Canada. Contact information for these growers is listed at http://www.pvmi. org/seed_growers/seed_growers.htm. Smaller amounts of seed, for research purposes, can be obtained by contacting the corresponding author. The University of Idaho, acting on behalf of the Northwest (Tri-State) Potato Variety Development Program, has filed an application for Plant Variety Protection for Premier Russet, with licensing of this cultivar by the Potato Variety Management Institute (PVMI). Acknowledgements The authors thank Margaret Bain, Eric Eldredge, Mary Jo Frazier, Nora Fuller, Darren Hall, Mark Fristad, Charlene Miller, Tom Salaiz, Brian Schneider, Lura Schroeder, Penny Tubbs, Steve

Am. J. Pot Res (2008) 85:198–209 Wheeler, and Solomon Yilma for their contributions to the development and release of Premier Russet. We also thank Jim Whitmore and Lori Ewing, University of Idaho, for their efforts in developing foundation and certified seed of Premier Russet, as well as our industry cooperators, our collaborators in the Western Regional Potato Variety Trials, and the Idaho, Washington, and Oregon potato commissions. Special thanks as well to Kathy Haynes and Creighton Miller for their reviews of this manuscript and their helpful comments. Development of Premier Russet was partially funded by the USDA/CSREES Special Potato Program Grant.

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Am. J. Pot Res (2008) 85:198–209 Ross, F.A. 1959. Dinitrophenol method for reducing sugars. In: W.F. Talburt and O. Smith, (eds.), Potato Processing, AVI Publ., Westport, Connecticut pp. 469–470. Simpson, G.W., and R.V. Akeley. 1964. Penobscot: A new variety of potato with leafroll resistance and high solids. Am Potato J 62: 517. Stark, J., D. Westermann, and B. Hopkins. 2004. Nutrient management guidelines for Russet Burbank potatoes. University of Idaho Extension Bulletin No. 840, 12 p.

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