SILVERTON RUSSET

 

Prepared by Susie Thompson, Ph.D. and Robert D. Davidson, Ph.D., Department of Horticulture & Landscape Architecture, San Luis Valley Research Center, Colorado State University

 

This profile was developed for production in the San Luis Valley.  While some guidelines may be appropriate regardless of growing area, fine-tuning for specific production locales is recommended.

 

Silverton Russet is a high yielding, medium maturing, medium russet-skinned, dual-purpose cultivar.  The Colorado and Idaho Agricultural Experiment Stations and the USDA schedule release for 1999.  Silverton was tested as AC83064-6.  Parentage of Silverton is CalWhite (A76147-2) x A7875-5.  It has medium specific gravity and attractive tuber type.  Plant Variety Protection will be applied for.

 

Plants/roots:  Emergence is rapid.  The vine is medium-sized and upright to spreading with white flowers.  It has a determinate growth habit and a moderate to shallow root system. 

 

Tubers:  Tubers have white flesh, are oblong to long, with medium russet skin.  Eyes are shallow and distributed more heavily near the apical end.  Specific gravity is medium (1.080). 

 

Yield potential:  Yield potential may exceed 400 cwt. per acre,  with a high percentage of US No. 1 tubers.

 

GROWING SEASON MANAGEMENT

Pre-planting considerations:  Tubers have a short to medium dormancy.  Whole or cut seed is acceptable.  Monitor size of seed, as sparse eye distribution on larger seed may result in “blind” seed pieces and stand problems.  A seed spacing of 10 to 12 inches may optimize yield and desired tuber size for the commercial market.  Plant this cultivar at about a 4-inch depth.

 

Fertility:  Apply total fertilizer in the following range N(180-200#), P(120-200#), K (0-100#).  Fertility needs are slightly less when compared to other major russet cultivars, such as Russet Norkotah.  Pre-plant N applications should be in the range of 90-100#.  Timing of tuberization is not affected by N applications.  Spoon-feed remaining N at the rate of 7-10# per application (do not exceed 20# per application).  Skin set may be difficult to achieve if nitrogen levels are high prior to vine desiccation.  This may perpetuate skinning and tuber early blight problems in storage.

 

Irrigation:  Interval at the maximum ET is 2.5-3 days.  Drought tolerance is moderate.

 

Pest control

Weeds:  Competes well with weeds.  Silverton Russet is sensitive to metribuzin (Sencor, Lexone) applications. 

Insects:  Standard insect control measures generally are effective, but timing and rotation of appropriate control is important due to high aphid preference and virus spread. 

Fungicides:  Frequency of fungicide applications is the same as for other popular russet cultivars.  Silverton may be slightly more susceptible to foliar early blight, so adequate protection is warranted.

 

Tuberization/bulking:  Silverton sets about 8 tubers per plant.  Tubers are set in the middle of the hill.  Tuber initiation and bulking rate are medium.  Heat runners may develop if soil temperatures are high during the late vegetative and tuber bulking phases.  Silverton is moderately resistant to blackspot bruise.

 

Vine kill:  Average days from planting to vine kill are 115-120.  Vine killing is required, particularly if nitrogen applications have exceeded requirements.  Adequate skin set occurs within 21 days.

 

STORAGE MANAGEMENT

Silverton Russet stores well.  It is imperative that producers minimize bruising to prevent tuber early blight from developing within the storage.  Movement from storage would fit the same window as Russet Norkotah, in terms of marketing.

 

DISEASE REACTION

Bacterial ring rot foliar expression is adequate and occurs within 90 days after planting. 

 

Field

Foliar early blight                      Susceptible

Verticillium wilt                       Unknown

Blackleg                                   Susceptible

Seedpiece decay                      Susceptible

Leafroll virus                             Susceptible

Leafroll net necrosis                  Unknown

PVY                                        Very Susceptible – Can be latent early season

PVX                                        Susceptible

Common scab                          Unknown

Bacterial ring rot                       Susceptible

 

Storage

Tuber early blight                      Susceptible

Bacterial soft rot                       Susceptible

Fusarium dry rot                     Susceptible

Pythium leak                           Unknown

Pink rot (Phytophthora)          Unknown

Silver scurf                               Unknown

Rhizoctonia scurf                     Susceptible

Disease reaction ratings = susceptible, moderately susceptible, moderate, moderately resistant and resistant.

12/99