RUSSET
NORKOTAH
RUSSET
NORKOTAH – SELECTION 3
RUSSET
NORKOTAH – SELECTION 8
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.
Russet
Norkotah is an early maturing cultivar released in 1987 by North Dakota State
University (APJ 65:597-604, 1988).
Primary use is for the fresh market, and it is particularly suited for
baking. It is widely adapted in North
America and performs very well in the San Luis Valley. In order to address the weaknesses of
standard Russet Norkotah including a high requirement for nitrogen fertility
and weak vines, Dr. David Holm began a concerted effort in 1991 to identify
superior genotypes able to withstand stress situations more favorably. After several years of evaluation, two lines
stood out in offering advantages in reduced nitrogen requirements and in stress
situations.
Vine
maturity of Selection 3 is later by about seven days when compared to the
standard. Vine maturity for Selection 8
is early, although intermediate between the standard and Selection 3. Application for U.S. Plant Variety
Protection has been made for the two selections (Colorado Russet Norkotah
Selection 3 - PV#9800256; Colorado Russet Norkotah Selection 8 - PV#9800255).
Plant/roots: Plants emerge quickly with a medium, slightly upright vine and
white flowers. Selection 3 vines are
medium to large, and more upright than those of the standard or Selection
8. Selection 3 blooms more heavily than
the standard and the flowering period is longer. All have a determinate growth habit. Root systems for standard Russet Norkotah and Selection 8 tend to
be shallow and concentrated. Selection
3 has a medium sized root system. The
selections are not as susceptible to hail damage as standard Russet Norkotah,
and will demonstrate some recovery following such an event.
Tubers: Tubers have white flesh, are long and blocky with
medium to heavy russet skin. Eyes are
shallow, numerous and well distributed.
Specific gravity levels are medium (1.080). Although not considered a processing cultivar, Russet Norkotah
will fry directly from the field.
Yield potential: Yield potential
varies from 450 cwt per acre to 500 cwt plus, with proper management. All produce a high percentage of US No. 1
tubers.
Pre-planting
considerations: Tubers have medium
dormancy. Some producers have indicated
that Selection 3 has slightly longer dormancy than the standard. Whole or cut seed is acceptable, however,
cut seed may be preferred as the increased stem number aids in limiting
oversized tubers late in the season.
Tuber size is also controlled through closer within-row seed
spacing. Avoid prolonged warming of
seed to minimize excessive sprouting and physiological aging (no more than two
weeks at 60 F). Precutting may age seed
physiologically, as well, but research in Colorado indicates this may not be a
significant problem if proper storage conditions after cutting are utilized. Avoid planting seed in cool soils, since
delayed emergence may aggravate Rhizoctonia
stem canker and result in reduced fertilizer uptake. Plant 4 to 6 inches deep in a broad, well-shaped hill to minimize
late season greening. Selection 3 will
perform better at the deeper planting depth.
Fertility: Apply total fertilizer in the range: N(210-230#), P(120-200#),
K(0-40#) for standard Russet Norkotah.
Performance of Selection 8 has been maximized with applications in the
range: N(160-180#), P(120-170#),
K(0-40#). For Selection 3, applications
in the range of: N(130-150#),
P(100-150#), K(0-40#) are suitable. Pre-plant N applications are critical for
the early vine growth necessary to support maximum yields, particularly for
standard Russet Norkotah (110-140#).
This should be reduced to a range of 80-100# for the selections.
Sprinkler applied N should be in the range of 90 to 100# for the standard, 80#
for Selection 8, and 40-70# for Selection 3.
All may benefit from applications at a rate of 7-10# per application, but
not exceeding 20# per application. High
N rates will delay tuberization of Selection 3 resulting in misshapen tubers,
skin-set problems, etc. under short growing seasons. Performance in alkali soils is reduced for the standard.
Irrigation: The interval at the maximum ET is approximately 2.5
days. Drought tolerance of Selection 8
is similar to the standard. However,
due to a larger vine, but similar rooting characteristics, producers may prefer
to shorten the interval to 2 days and decrease application rates slightly to
match ET, in order to avoid moisture stress.
The selections may require prolonged irrigation later in the season,
when compared to the standard due to slightly later vine maturity, however,
once vine senescence has begun, water needs must be monitored closely. Producers should strive to avoid late season
over-watering, since it creates ideal conditions for expression of many
diseases such as blackleg, pink rot and leak.
The selections may display tuber malformations, skin set problems, and
deep eyes if irrigation is erratic, temperatures are extremely high, or
nitrogen fertility excessive.
Weeds: The selections compete better with weeds than standard Russet
Norkotah. No sensitivities to major
potato herbicides have been demonstrated by the standard, or the selections.
Insects: Standard insect control measures are suitable,
however timing and rotation of pesticides are important due to preference by
aphids and virus spread. It is
especially important to continue applications into late season for the selections
since vines remain succulent and green longer than the standard.
Fungicides: Three to five fungicide applications may be necessary to control
foliar early blight for standard Russet Norkotah. Due to the later maturity, susceptibility to foliar early blight
and Verticillium wilt are slightly less for the selections when compared to the
standard.
Tuberization/bulking: Tuber set is light to medium and high in the hill. Greening may be a problem without proper
hill conformation. Tuber bulking occurs
in a short interval during early to mid-season at an extremely rapid rate. Russet Norkotah is moderately resistant to
blackspot bruise. The selections are
somewhat susceptible to growth cracks, deep eyes, misshapen tubers and hollow
heart if not appropriately managed.
Physiological pigmentation (internal purpling) may appear in tubers of
all if proper planting depths, hill conformation and sound nitrogen fertility
management are not adhered to.
Vine Kill: Average days from planting to vine kill are 95 to 110. Unlike standard Russet Norkotah, vine kill
may be required for the selections.
Adequate skin set occurs in 14 to 21 days. Tubers may become excessively large late in the season, so close
monitoring is warranted by early August.
Russet
Norkotah and the selections generally have few storage problems. However, leak, pink rot, blackleg and silver
scurf may become serious when proper field and storage management are not
practiced. Russet Norkotah is not
considered a long-term storage cultivar.
Due to a propensity for pressure bruise and blackspot bruise
development, consider marketing prior to March 1. A note; some producers feel that they may be able to store
Selection 3 slightly longer due to stronger dormancy.
Potato
early dying, caused by Verticillium dahliae is a problem in some years, but
can be easily confused with natural vine senescence. It is not as prevalent for the selections when compared to the
standard. Soil-borne diseases such as
leak, pink rot and silver scurf can be quite common and serious.
Bacterial
ring rot symptom expression is erratic and may be difficult to see under some
circumstances for Russet Norkotah.
Symptoms can be mild and tend to appear only after vines begin senescing
(90+ days after planting). Expression
for the selections is adequate and similar to the standard. Reaction to PVY infection is mild to
latent. Infected plants are difficult
to detect early in the growing season, but usually become somewhat more
detectable as the plants age. Yield
losses due to PVY will be in the 30-40% range for individual plants based on
research conducted in the Pacific Northwest and in Colorado. Expression of symptoms may be delayed for
the selections when excessive N is applied.
Toxic
seedpiece decay syndrome is characterized by severe plant wilting just prior to
tuberization, when the plants are switching from seedpiece nutrition to the
root system. Plants appear windburned
with dehydrated leaf margins in the upper canopy. 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 linked with warm weather. Toxic seedpiece decay syndrome is rarely
seen in the selections.
Foliar
early blight Susceptible
- Moderately susceptible for the selections
Verticillium wilt Susceptible - Moderately susceptible for the
selections
Blackleg Susceptible
Seedpiece
decay Susceptible
Leafroll
virus Susceptible
Leafroll
net necrosis Resistant
PVY Susceptible,
latent reaction possible
PVX Susceptible
Common
scab Moderately
resistant
Powdery
scab Resistant
Bacterial
ring rot Susceptible
Late
blight Susceptible
Tuber
early blight Moderately
resistant
Bacterial
soft rot Susceptible
Fusarium dry rot Susceptible
Pythium leak Susceptible
Pink
rot (P. erythroseptica) Susceptible
Silver
scurf Susceptible
Rhizoctonia scurf Moderate
Disease reaction ratings = susceptible, moderately susceptible, moderate, moderately resistant and resistant.
Spring 1999