Summit Farms - Norkotah 223

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Norkotah 223

Texas line selections will have slightly larger vines, anore extensive root system, slightly longer maturiy and more resistence to environmental stresses than the standard Norkotah. Advantages are high yeilds, nice tuber shape and will perform better in a larger variety of soils than other lines . Texas selections were double selected for both resistence to early dying and heat resistance.

Russet Norkotah is a early-maturing potato released in 1987 by North Dakota State University (APJ 65:597-604, 1988). It is primarily a fresh market potato with good boiling and baking qualities. It is widely adapted to the western U.S. and performs especially well in the San Luis Valley. Selection were made at Texas A&M in the early 1990's. Five selections survived grower trials. Plant/roots are fast emerging with a medium, slightly upright vine and white flowers; it has a determinate growth habit. All the Texas selections

have a slightly bigger vine than the standard. The line 278 is the biggest and the others have similar vine size. the selections root system is more developed and extensive than the standard Norkotah. They are susceptible to hail damage, but better than the standard. Tubers are white flesh, long to slightly oblong with medium to heavy russeted skin. Eyes are shallow, numerous and well distributed; medium specific gravity (1.085) Although not considered suitable as a processing potato, it will fry directly from the field. It has a oblong shape, russet skin, white flesh, and early to medium maturing. 450 to 500 cwt range with a high percentage of U.S. #1's. Apply total fertilizer in the following range: N(180-200#), P(I20-200#), K(O-40#). Performance in alkali soils is moderate. Pre-plant N applications (110-140#) are critical for early vine growth necessary to support maximum yields; high N rates do not delay tuberization. Sprinkler applied N should be in the 40 to 90# range at a rate of 15# per application. Irrigation interval at the maximum ET is 2.5 days. Drought tolerance is poor; significant yield reduction occurs if plants are moisture stressed. Adequate irrigation applied at short intervals coupled with high early season fertility will help this cultivar develop necessary vine growth prior to tuberization. After tuberization, vine growth often slows dramatically. Subsequent rapid tuber bulking and early vine senescence results in minimum late season water requirements. Growers should strive to avoid late season over watering since it creates ideal conditions for expression of many diseases such as blackleg or leak. All selection compete fair against weeds, but is not sensitive to any major herbicides. Standard insect control measures generally are effective but time and rotate insecticides properly because of high aphid preference and virus spread. Three to five fungicide applications may be necessary to control foliar early blight. Tuber set is light to medium, high in the hill. Greening may be a problem without good hill management. Tuber bulking occurs in a short interval during early to mid season at an extremely rapid rate. Russet Norkotah is moderately resistant to blackspot and resistant to growth cracks, second growth and hollow heart. Average days from planting to vine kill are 95 to 110. Vine killing usually in not required, however, if senescence is not complete, vines are killed easily; adequate skin set occurs in 12 to 21 days. Tubers can become large late in the season, so close monitoring is necessary after early August. Pre-planting considerations: Tubers have a medium dormancy. Whole or cut seed is acceptable. However, cut seed often is preferred since the increased stem number helps prevent over sizing of tubers late in the season. Closer seed spacing also will help control tuber size. Avoid prolonged warming (usually no more than 60 F for two weeks) to minimize excessive sprouting and physiological aging. Precutting seed a month or more before planting also can add physiological aging. Avoid planting seed in cool soils; delayed emergence can aggravate rhizoctonia stem cankering and result in poor fertilizer uptake. Plant this cultivar 4 - 6 inches deep in a broad, well shaped hill to control late season greening. Russet Norkotah generally has few storage problems, but leak, blackleg and silver scurf can become serious. This cultivar is not considered a long-term storage potato. It should be marketed by mid-March because tuber dehydration can result in pressure bruises and blackspot development. Potato early dying caused by Verticillium dahliae is a problem in some years, but can be easily confused with natural vine senescence. Soil-borne disease problems such as leak and silver scurf also can be serious. Bacterial Ring Rot symptom expression is erratic and difficult to see under most circumstances. Symptoms are mild and tend to appear only after vines begin senescing ( 90+ days after planting). Reaction to PVY infection in mild to latent. The selection 3 is more latent in expressing PVY than the standard. Infected plants are difficult to detect early in the growing season, but usually express mild symptoms that become somewhat more detectable as the plants age. Infected plants tend to die by mid-season with potentially significant yield losses when PVY incidence is high. Toxic-seedpiece-decay syndrome is characterized by sever plant wilting just prior to tuberization, when the plants are switching from seed piece nutrition to their root system. Plants appear win burned with dehydrated leaf margins in the upper conopy. A light brown, jelly-type rotted mass is all that is left of the seedpiece and brown streaks may be visible in the lower stem. Normally the plant recovers within a couple of weeks. This problem may be present when early season wet conditions are liked with warm weather. Susceptible to Foliar Early Blight, Verticillium Wilt, Blackleg, Seedpiece decay, Leafroll Virus, Leafroll Net Necrosis, PVY, PVX, Bacterial Ring Rot, Bacterial Soft Rot, Fusarium Dry Rot, Leak, Pink Rot, and Silver Scurf. Moderately resistant to Common Scab and Rhizoctonia Scurf.