Northwest Norkotah

NW 111 & 218 Growing Information

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Seed Storage and Size

Seed Spacing

NWN 111 & 218 varieties: 9 to 10 inches (about 27-30 cwt/acre)

Nitrogen Fertilizer Recommendations

Soil nitrogen (NO₃ + NH₄)^1,2 should be tested prior to planting

Economic return was maximized at total seasonal rates of 210-230 lbs. N/a, and 260-280 lbs. N/s for NWN and NWN 218, respectively. See figure 1.

Figure 1 summary

Gross economic return for NWN 11 and NWN 20181 compared to R. Norkotah. Maximum economic return was found between 210-230 lbs. N/a for NWN 111 and 260-280 lbs. N/a for NWN 218. Both selections had significantly higher returns than R. Norkotah.

Footnotes 1 and 2

¹ Soil test N = Nitrate-N + Ammonium N

² Following grain or corn, add 15 lbs N/acre for each ton of straw or stalks up to a total of 60 lbs N/acre

If the field has not been fumigated or has not been out of potatoes for at least 4 years, apply an additional 40-50lbs N/acre

Nitrogen Timing

Apply 50-60% of total seasonal N preplant with 75% applied by row closure. The remaining N applications made during tuber bulking should be guided by petiole nitrate-N and soil nitrogen tests. All seasonal nitrogen applications should be completed by the end of July or beginning of August. Late applications of nitrogen delay senescence which may impact tuber bulking and skin set.

Petiole Nitrate Concentrations (for NWN 111)

Tuber set: 18,000 to 20,000 ppm

Early tuber bulking: 16,000 to 18,000 ppm

Late tuber bulking: 14,000 to 16,000 ppm

Maturation: 10,000 to 14,000 ppm

Petiole Nitrate Concentrations (for NWN 218)

Tuber set: 20,000 to 22,000 ppm

Early tuber bulking: 17,000 to 19,000 ppm

Late tuber bulking: 16,000 to 18,000 ppm

Maturation: 13,000 to 15,000 ppm

Phosphorus, Potassium, and other Nutrients

Follow recommendations for Russet Burbank

Irrigation

The water use pattern for NWN 111 & 218 varieties is similar to Russet Burbank. Maintain available soil moisture above 65-70% throughout tuber bulking but adjust water application amounts later in the season as the plants start to senesce.

As plants begin to senesce and use less water, irrigation needs to be closely monitored to avoid overwatering that can produce enlarged lenticels and increased disease problems.

Diseases

As with other Norkotah line selections, NWN 111 & 218 varieties are susceptible to PVY, early blight and late blight, so follow standard management practices for these diseases.

Vine Kill

NWN 111 & 218 varieties mature later in the season so kill vines 16-21 days before harvest for adequate maturity.

Note: It is important to use the recommended 9-10 inch seed piece spacing and the nitrogen fertilizer application rates listed above as over-fertilizing and too wide spacing may affect the optimal tuber size profile and increase the possibility of hollow heart development.