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.
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.
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.
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.
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.
Bacterial ring rot foliar expression is adequate and occurs within 90 days after planting.
Foliar early blight Susceptible
Verticillium wilt Unknown
Seedpiece decay Susceptible
Leafroll virus Susceptible
Leafroll net necrosis Unknown
PVY Very Susceptible – Can be latent early season
Common scab Unknown
Bacterial ring rot Susceptible
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.