| RUSSET
NORKOTAH STRAINS
Profile
Since
its release in 1987 by Dr. Robert Johansen of No. Dakota State Univ.,
Russet Norkotah replaced Norgold Russet and became the major fresh-market,
early-season russet cultivar in the USA. It is noted for its long
and smooth russet appearance, its “football” shaped tubers. Because
of its broad adaptability, it is widely used geographically. It
does have a few weakness. Its vine is small and does not usually
cause row closure thereby weed control can be a concern. It has
poor tolerance to hail or heat. The roots are shallow and concentrated.
And, the cultivar is sensitive to many pests including early dying
and early blight.
For
these reasons, in the early 1990s, Drs. Dave Holm of Colorado
St. Univ. and J. Creighton Miller, Jr., of Texas A & M Univ.
embarked on looking for giant hill strains of Russet Norkotah. This
was much like the earlier search on giant hill strains of Norgold
Russet in the 1980s in Nebraska (Leever, Trank, Shaver, Miller,
Pavlista. 1994. Am Potato J 71:133-144). From the efforts on Russet
Norkotah, Dave picked two strains -- CO # 3 and # 8, and Creighton
identified several others -- TX # 102, 112, 223, and 278, and more
recently # 296. A common characteristic of all these strains are
a later maturity and a larger vine.
CO
#3 is the largest and matures the latest of these strains. It is
upright and three to six inches taller than the standard Russet
Norkotah. Maturity may be as much as two weeks later than
Russet Norkotah. It has shown some tolerance of heat in Texas. It
yields well at less nitrogen but has a tendency to form mis-shaped
tubers. If nitrogen is over-used, tuber initiation is delayed and
tuber bulking slowed.
CO
#8 is more prostate than #3 and not quite as tall, 1-3 inches over
the standard. It matures about a week later than the standard Russet
Norkotah. It yields well is resistant to producing off-type or mis-shaped
tubers.
TX
strains #102, #112, #223, #278, and #296 were selected for better
tolerance to late season diseases especially the early dying complex.
They seem to be more forgiving of weather stress. They also tend
to produce more US grade 1 and less mis-shaped tubers.
Fertilization
Fertility
needs on the two Colorado strains have been studied and reported
by Dr. Susie Thompson of CSU, currently with NDSU. These recommendations
are given in Table
1,
and may also be used as guide for the Texas strains. A study on
CO #3 and #8 with respect to nitrogen levels was conducted in Greeley,
CO, in 1998, and the yield data are presented in
Figure 1.
From these data, only CO #8 with 150 lb N/a gave significantly higher
yield than the standard with 230 lb N/a. In general, CO #3 requires
40% less nitrogen than standard Russet Norkotah, CO #8 needs 25%
less N, and for the Texas strian, #112 needs about 40% less, #223
about 20% less, and #278 about 30% less. The strains seem to need
about 50 lb nitrogen/acre less to achieve the same yield in the
same number of days as the standard Russet Norkotah. Pre-plant nitrogen
is critical and should be half to two-thirds of the total applied.
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